Author name code: chaplin ADS astronomy entries on 2022-09-14 author:"Chaplin, William J." ------------------------------------------------------------------------ Title: Unexpected solar-cycle variation of acoustic mode power in Sun-as-a-star observations Authors: Howe, Rachel; Chaplin, W. J.; Elsworth, Y. P.; Hale, S. J.; Nielsen, M. B. Bibcode: 2022MNRAS.514.3821H Altcode: 2022arXiv220515655H; 2022MNRAS.tmp.1518H We examine the solar-cycle variation of the power in the low-degree helioseismic modes by looking at binned power spectra from 45 yr of observations with the Birmingham Solar Oscillations Network, which provides a more robust estimate of the mode power than that obtained by peak fitting. The solar-cycle variation of acoustic mode power in the 5-min band is clearly seen. Unusually, even though Cycle 24 was substantially weaker in terms of surface magnetic activity than Cycle 23, the reduction in mode power at solar maximum is very similar for the two cycles, suggesting that the relationship between mode power and magnetic activity is more complex than has previously been thought. This is in contrast to the mode frequencies, which show a strong correlation with activity with only subtle differences in the response across different solar cycles. Title: Solar-like oscillations and ellipsoidal variations in TESS observations of the binary 12 Boötis Authors: Ball, Warrick H.; Miglio, Andrea; Chaplin, William J.; Stassun, Keivan G.; García, Rafael; González-Cuesta, Lucia; Mathur, Savita; Appourchaux, Thierry; Benomar, Othman; Buzasi, Derek L.; Jiang, Chen; Kayhan, Cenk; Örtel, Sibel; Orhan, Zeynep Çelik; Yıldız, Mutlu; Ong, J. M. Joel; Basu, Sarbani Bibcode: 2022MNRAS.tmp.2121B Altcode: 2022arXiv220802302B Binary stars in which oscillations can be studied in either or both components can provide powerful constraints on our understanding of stellar physics. The bright binary 12 Boötis (12 Boo) is a particularly promising system because the primary is roughly 60 per cent brighter than the secondary despite being only a few per cent more massive. Both stars have substantial surface convection zones and are therefore, presumably, solar-like oscillators. We report here the first detection of solar-like oscillations and ellipsoidal variations in the TESS light curve of 12 Boo. Though the solar-like oscillations are not clear enough to unambiguously measure individual mode frequencies, we combine global asteroseismic parameters and a precise fit to the spectral energy distribution (SED) to provide new constraints on the properties of the system that are several times more precise than values in the literature. The SED fit alone provides new effective temperatures, luminosities and radii of 6115 ± 45 K, 7.531 ± 0.110 L⊙ and 2.450 ± 0.045 R⊙ for 12 Boo A and 6200 ± 60 K, 4.692 ± 0.095 L⊙ and 1.901 ± 0.045 R⊙ for 12 Boo B. When combined with our asteroseismic constraints on 12 Boo A, we obtain an age of $2.67^{+0.12}_{-0.16}\, \mathrm{Gyr}$, which is consistent with that of 12 Boo B. Title: A probabilistic method for detecting solar-like oscillations using meaningful prior information. Application to TESS 2-minute photometry Authors: Nielsen, M. B.; Hatt, E.; Chaplin, W. J.; Ball, W. H.; Davies, G. R. Bibcode: 2022A&A...663A..51N Altcode: 2022arXiv220309404N Context. Current and future space-based observatories such as the Transiting Exoplanet Survey Satellite (TESS) and PLATO are set to provide an enormous amount of new data on oscillating stars, and in particular stars that oscillate similar to the Sun. Solar-like oscillators constitute the majority of known oscillating stars and so automated analysis methods are becoming an ever increasing necessity to make as much use of these data as possible.
Aims: Here we aim to construct an algorithm that can automatically determine if a given time series of photometric measurements shows evidence of solar-like oscillations. The algorithm is aimed at analyzing data from the TESS mission and the future PLATO mission, and in particular stars in the main-sequence and subgiant evolutionary stages.
Methods: The algorithm first tests the range of observable frequencies in the power spectrum of a TESS light curve for an excess that is consistent with that expected from solar-like oscillations. In addition, the algorithm tests if a repeating pattern of oscillation frequencies is present in the time series, and whether it is consistent with the large separation seen in solar-like oscillators. Both methods use scaling relations and observations which were established and obtained during the CoRoT, Kepler, and K2 missions.
Results: Using a set of test data consisting of visually confirmed solar-like oscillators and nonoscillators observed by TESS, we find that the proposed algorithm can attain a 94.7% true positive (TP) rate and a 8.2% false positive (FP) rate at peak accuracy. However, by applying stricter selection criteria, the FP rate can be reduced to ≈ 2%, while retaining an 80% TP rate. Title: ET White Paper: To Find the First Earth 2.0 Authors: Ge, Jian; Zhang, Hui; Zang, Weicheng; Deng, Hongping; Mao, Shude; Xie, Ji-Wei; Liu, Hui-Gen; Zhou, Ji-Lin; Willis, Kevin; Huang, Chelsea; Howell, Steve B.; Feng, Fabo; Zhu, Jiapeng; Yao, Xinyu; Liu, Beibei; Aizawa, Masataka; Zhu, Wei; Li, Ya-Ping; Ma, Bo; Ye, Quanzhi; Yu, Jie; Xiang, Maosheng; Yu, Cong; Liu, Shangfei; Yang, Ming; Wang, Mu-Tian; Shi, Xian; Fang, Tong; Zong, Weikai; Liu, Jinzhong; Zhang, Yu; Zhang, Liyun; El-Badry, Kareem; Shen, Rongfeng; Tam, Pak-Hin Thomas; Hu, Zhecheng; Yang, Yanlv; Zou, Yuan-Chuan; Wu, Jia-Li; Lei, Wei-Hua; Wei, Jun-Jie; Wu, Xue-Feng; Sun, Tian-Rui; Wang, Fa-Yin; Zhang, Bin-Bin; Xu, Dong; Yang, Yuan-Pei; Li, Wen-Xiong; Xiang, Dan-Feng; Wang, Xiaofeng; Wang, Tinggui; Zhang, Bing; Jia, Peng; Yuan, Haibo; Zhang, Jinghua; Xuesong Wang, Sharon; Gan, Tianjun; Wang, Wei; Zhao, Yinan; Liu, Yujuan; Wei, Chuanxin; Kang, Yanwu; Yang, Baoyu; Qi, Chao; Liu, Xiaohua; Zhang, Quan; Zhu, Yuji; Zhou, Dan; Zhang, Congcong; Yu, Yong; Zhang, Yongshuai; Li, Yan; Tang, Zhenghong; Wang, Chaoyan; Wang, Fengtao; Li, Wei; Cheng, Pengfei; Shen, Chao; Li, Baopeng; Pan, Yue; Yang, Sen; Gao, Wei; Song, Zongxi; Wang, Jian; Zhang, Hongfei; Chen, Cheng; Wang, Hui; Zhang, Jun; Wang, Zhiyue; Zeng, Feng; Zheng, Zhenhao; Zhu, Jie; Guo, Yingfan; Zhang, Yihao; Li, Yudong; Wen, Lin; Feng, Jie; Chen, Wen; Chen, Kun; Han, Xingbo; Yang, Yingquan; Wang, Haoyu; Duan, Xuliang; Huang, Jiangjiang; Liang, Hong; Bi, Shaolan; Gai, Ning; Ge, Zhishuai; Guo, Zhao; Huang, Yang; Li, Gang; Li, Haining; Li, Tanda; Yuxi; Lu; Rix, Hans-Walter; Shi, Jianrong; Song, Fen; Tang, Yanke; Ting, Yuan-Sen; Wu, Tao; Wu, Yaqian; Yang, Taozhi; Yin, Qing-Zhu; Gould, Andrew; Lee, Chung-Uk; Dong, Subo; Yee, Jennifer C.; Shvartzvald, Yossi; Yang, Hongjing; Kuang, Renkun; Zhang, Jiyuan; Liao, Shilong; Qi, Zhaoxiang; Yang, Jun; Zhang, Ruisheng; Jiang, Chen; Ou, Jian-Wen; Li, Yaguang; Beck, Paul; Bedding, Timothy R.; Campante, Tiago L.; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; García, Rafael A.; Gaulme, Patrick; Gizon, Laurent; Hekker, Saskia; Huber, Daniel; Khanna, Shourya; Li, Yan; Mathur, Savita; Miglio, Andrea; Mosser, Benoît; Ong, J. M. Joel; Santos, Ângela R. G.; Stello, Dennis; Bowman, Dominic M.; Lares-Martiz, Mariel; Murphy, Simon; Niu, Jia-Shu; Ma, Xiao-Yu; Molnár, László; Fu, Jian-Ning; De Cat, Peter; Su, Jie; consortium, the ET Bibcode: 2022arXiv220606693G Altcode: We propose to develop a wide-field and ultra-high-precision photometric survey mission, temporarily named "Earth 2.0 (ET)". This mission is designed to measure, for the first time, the occurrence rate and the orbital distributions of Earth-sized planets. ET consists of seven 30cm telescopes, to be launched to the Earth-Sun's L2 point. Six of these are transit telescopes with a field of view of 500 square degrees. Staring in the direction that encompasses the original Kepler field for four continuous years, this monitoring will return tens of thousands of transiting planets, including the elusive Earth twins orbiting solar-type stars. The seventh telescope is a 30cm microlensing telescope that will monitor an area of 4 square degrees toward the galactic bulge. This, combined with simultaneous ground-based KMTNet observations, will measure masses for hundreds of long-period and free-floating planets. Together, the transit and the microlensing telescopes will revolutionize our understandings of terrestrial planets across a large swath of orbital distances and free space. In addition, the survey data will also facilitate studies in the fields of asteroseismology, Galactic archeology, time-domain sciences, and black holes in binaries. Title: Stellar dating using chemical clocks and Bayesian inference Authors: Moya, A.; Sarro, L. M.; Delgado-Mena, E.; Chaplin, W. J.; Adibekyan, V.; Blanco-Cuaresma, S. Bibcode: 2022A&A...660A..15M Altcode: 2022arXiv220105228M Context. Dating stars is a major challenge with a deep impact on many astrophysical fields. One of the most promising techniques for this is using chemical abundances. Recent space- and ground-based facilities have improved the quantity of stars with accurate observations. This has opened the door for using Bayesian inference tools to maximise the information we can extract from them.
Aims: Our aim is to present accurate and reliable stellar age estimates of FGK stars using chemical abundances and stellar parameters.
Methods: We used one of the most flexible Bayesian inference techniques (hierarchical Bayesian models) to exceed current possibilities in the use of chemical abundances for stellar dating. Our model is a data-driven model. We used a training set that has been presented in the literature with ages estimated with isochrones and accurate stellar abundances and general characteristics. The core of the model is a prescription of certain abundance ratios as linear combinations of stellar properties including age. We gathered four different testing sets to assess the accuracy, precision, and limits of our model. We also trained a model using chemical abundances alone.
Results: We found that our age estimates and those coming from asteroseismology, other accurate sources, and also with ten Gaia benchmark stars agree well. The mean absolute difference of our estimates compared with those used as reference is 0.9 Ga, with a mean difference of 0.01 Ga. When using open clusters, we reached a very good agreement for Hyades, NGC 2632, Ruprecht 147, and IC 4651. We also found outliers that are a reflection of chemical peculiarities and/or stars at the limit of the validity ranges of the training set. The model that only uses chemical abundances shows slightly worse mean absolute difference (1.18 Ga) and mean difference (−0.12 Ga). Title: The K2 Galactic Archaeology Program Data Release 3: Age-abundance Patterns in C1-C8 and C10-C18 Authors: Zinn, Joel C.; Stello, Dennis; Elsworth, Yvonne; García, Rafael A.; Kallinger, Thomas; Mathur, Savita; Mosser, Benoît; Hon, Marc; Bugnet, Lisa; Jones, Caitlin; Reyes, Claudia; Sharma, Sanjib; Schönrich, Ralph; Warfield, Jack T.; Luger, Rodrigo; Vanderburg, Andrew; Kobayashi, Chiaki; Pinsonneault, Marc H.; Johnson, Jennifer A.; Huber, Daniel; Buder, Sven; Joyce, Meridith; Bland-Hawthorn, Joss; Casagrande, Luca; Lewis, Geraint F.; Miglio, Andrea; Nordlander, Thomas; Davies, Guy R.; Silva, Gayandhi De; Chaplin, William J.; Silva Aguirre, Victor Bibcode: 2022ApJ...926..191Z Altcode: 2021arXiv210805455Z We present the third and final data release of the K2 Galactic Archaeology Program (K2 GAP) for Campaigns C1-C8 and C10-C18. We provide asteroseismic radius and mass coefficients, κ R and κ M , for ~19,000 red giant stars, which translate directly to radius and mass given a temperature. As such, K2 GAP DR3 represents the largest asteroseismic sample in the literature to date. K2 GAP DR3 stellar parameters are calibrated to be on an absolute parallactic scale based on Gaia DR2, with red giant branch and red clump evolutionary state classifications provided via a machine-learning approach. Combining these stellar parameters with GALAH DR3 spectroscopy, we determine asteroseismic ages with precisions of ~20%-30% and compare age-abundance relations to Galactic chemical evolution models among both low- and high-α populations for α, light, iron-peak, and neutron-capture elements. We confirm recent indications in the literature of both increased Ba production at late Galactic times as well as significant contributions to r-process enrichment from prompt sources associated with, e.g., core-collapse supernovae. With an eye toward other Galactic archeology applications, we characterize K2 GAP DR3 uncertainties and completeness using injection tests, suggesting that K2 GAP DR3 is largely unbiased in mass/age, with uncertainties of 2.9% (stat.) ± 0.1% (syst.) and 6.7% (stat.) ± 0.3% (syst.) in κ R and κ M for red giant branch stars and 4.7% (stat.) ± 0.3% (syst.) and 11% (stat.) ± 0.9% (syst.) for red clump stars. We also identify percent-level asteroseismic systematics, which are likely related to the time baseline of the underlying data, and which therefore should be considered in TESS asteroseismic analysis. Title: A 20 Second Cadence View of Solar-type Stars and Their Planets with TESS: Asteroseismology of Solar Analogs and a Recharacterization of π Men c Authors: Huber, Daniel; White, Timothy R.; Metcalfe, Travis S.; Chontos, Ashley; Fausnaugh, Michael M.; Ho, Cynthia S. K.; Van Eylen, Vincent; Ball, Warrick H.; Basu, Sarbani; Bedding, Timothy R.; Benomar, Othman; Bossini, Diego; Breton, Sylvain; Buzasi, Derek L.; Campante, Tiago L.; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Cunha, Margarida S.; Deal, Morgan; García, Rafael A.; García Muñoz, Antonio; Gehan, Charlotte; González-Cuesta, Lucía; Jiang, Chen; Kayhan, Cenk; Kjeldsen, Hans; Lundkvist, Mia S.; Mathis, Stéphane; Mathur, Savita; Monteiro, Mário J. P. F. G.; Nsamba, Benard; Ong, Jia Mian Joel; Pakštienė, Erika; Serenelli, Aldo M.; Silva Aguirre, Victor; Stassun, Keivan G.; Stello, Dennis; Norgaard Stilling, Sissel; Lykke Winther, Mark; Wu, Tao; Barclay, Thomas; Daylan, Tansu; Günther, Maximilian N.; Hermes, J. J.; Jenkins, Jon M.; Latham, David W.; Levine, Alan M.; Ricker, George R.; Seager, Sara; Shporer, Avi; Twicken, Joseph D.; Vanderspek, Roland K.; Winn, Joshua N. Bibcode: 2022AJ....163...79H Altcode: 2021arXiv210809109H We present an analysis of the first 20 second cadence light curves obtained by the TESS space telescope during its extended mission. We find improved precision of 20 second data compared to 2 minute data for bright stars when binned to the same cadence (≍10%-25% better for T ≲ 8 mag, reaching equal precision at T ≍ 13 mag), consistent with pre-flight expectations based on differences in cosmic-ray mitigation algorithms. We present two results enabled by this improvement. First, we use 20 second data to detect oscillations in three solar analogs (γ Pav, ζ Tuc, and π Men) and use asteroseismology to measure their radii, masses, densities, and ages to ≍1%, ≍3%, ≍1%, and ≍20% respectively, including systematic errors. Combining our asteroseismic ages with chromospheric activity measurements, we find evidence that the spread in the activity-age relation is linked to stellar mass and thus the depth of the convection zone. Second, we combine 20 second data and published radial velocities to recharacterize π Men c, which is now the closest transiting exoplanet for which detailed asteroseismology of the host star is possible. We show that π Men c is located at the upper edge of the planet radius valley for its orbital period, confirming that it has likely retained a volatile atmosphere and that the "asteroseismic radius valley" remains devoid of planets. Our analysis favors a low eccentricity for π Men c (<0.1 at 68% confidence), suggesting efficient tidal dissipation (Q/k 2,1 ≲ 2400) if it formed via high-eccentricity migration. Combined, these early results demonstrate the strong potential of TESS 20 second cadence data for stellar astrophysics and exoplanet science. Title: VizieR Online Data Catalog: APF radial velocity follow up of {iota} Draconis (Hill+, 2021) Authors: Hill, M. L.; Kane, S. R.; Campante, T. L.; Li, Z.; Dalba, P. A.; Brandt, T. D.; White, T. R.; Pope, B. J. S.; Stassun, K. G.; Fulton, B. J.; Corsaro, E.; Li, T.; Ong, J. M. J.; Bedding, T. R.; Bossini, D.; Buzasi, D. L.; Chaplin, W. J.; Cunha, M. S.; Garcia, R. A.; Breton, S. N.; Hon, M.; Huber, D.; Jiang, C.; Kayhan, C.; Kuszlewicz, J. S.; Mathur, S.; Serenelli, A.; Stello, D. Bibcode: 2022yCat..51620211H Altcode: 456 radial velocity observations were obtained by the Levy spectrometer on the Automated Planet Finder (APF) at Lick Observatory from 2018 February to 2021 February.

(1 data file). Title: TESS Asteroseismology of α Mensae: Benchmark Ages for a G7 Dwarf and Its M Dwarf Companion Authors: Chontos, Ashley; Huber, Daniel; Berger, Travis A.; Kjeldsen, Hans; Serenelli, Aldo M.; Silva Aguirre, Victor; Ball, Warrick H.; Basu, Sarbani; Bedding, Timothy R.; Chaplin, William J.; Claytor, Zachary R.; Corsaro, Enrico; Garcia, Rafael A.; Howell, Steve B.; Lundkvist, Mia S.; Mathur, Savita; Metcalfe, Travis S.; Nielsen, Martin B.; Mian Joel Ong, Jia; Çelik Orhan, Zeynep; Örtel, Sibel; Salama, Maissa; Stassun, Keivan G.; Townsend, R. H. D.; van Saders, Jennifer L.; Winther, Mark; Yildiz, Mutlu; Butler, R. Paul; Tinney, C. G.; Wittenmyer, Robert A. Bibcode: 2021ApJ...922..229C Altcode: 2020arXiv201210797C Asteroseismology of bright stars has become increasingly important as a method to determine the fundamental properties (in particular ages) of stars. The Kepler Space Telescope initiated a revolution by detecting oscillations in more than 500 main-sequence and subgiant stars. However, most Kepler stars are faint and therefore have limited constraints from independent methods such as long-baseline interferometry. Here we present the discovery of solar-like oscillations in α Men A, a naked-eye (V = 5.1) G7 dwarf in TESS's southern continuous viewing zone. Using a combination of astrometry, spectroscopy, and asteroseismology, we precisely characterize the solar analog α Men A (T eff = 5569 ± 62 K, R ⋆ = 0.960 ± 0.016 R ⊙, M ⋆ = 0.964 ± 0.045 M ⊙). To characterize the fully convective M dwarf companion, we derive empirical relations to estimate mass, radius, and temperature given the absolute Gaia magnitude and metallicity, yielding M ⋆ = 0.169 ± 0.006 M ⊙, R ⋆ = 0.19 ± 0.01 R ⊙, and T eff = 3054 ± 44 K. Our asteroseismic age of 6.2 ± 1.4 (stat) ± 0.6 (sys) Gyr for the primary places α Men B within a small population of M dwarfs with precisely measured ages. We combined multiple ground-based spectroscopy surveys to reveal an activity cycle of P = 13.1 ± 1.1 yr for α Men A, a period similar to that observed in the Sun. We used different gyrochronology models with the asteroseismic age to estimate a rotation period of ~30 days for the primary. Alpha Men A is now the closest (d = 10 pc) solar analog with a precise asteroseismic age from space-based photometry, making it a prime target for next-generation direct-imaging missions searching for true Earth analogs. Title: PLATO hare-and-hounds exercise: asteroseismic model fitting of main-sequence solar-like pulsators Authors: Cunha, M. S.; Roxburgh, I. W.; Aguirre Børsen-Koch, V.; Ball, W. H.; Basu, S.; Chaplin, W. J.; Goupil, M. -J.; Nsamba, B.; Ong, J.; Reese, D. R.; Verma, K.; Belkacem, K.; Campante, T.; Christensen-Dalsgaard, J.; Clara, M. T.; Deheuvels, S.; Monteiro, M. J. P. F. G.; Noll, A.; Ouazzani, R. M.; Rørsted, J. L.; Stokholm, A.; Winther, M. L. Bibcode: 2021MNRAS.508.5864C Altcode: 2021MNRAS.tmp.2643C; 2021arXiv211003332C Asteroseismology is a powerful tool to infer fundamental stellar properties. The use of these asteroseismic-inferred properties in a growing number of astrophysical contexts makes it vital to understand their accuracy. Consequently, we performed a hare-and-hounds exercise where the hares simulated data for six artificial main-sequence stars and the hounds inferred their properties based on different inference procedures. To mimic a pipeline such as that planned for the PLATO mission, all hounds used the same model grid. Some stars were simulated using the physics adopted in the grid, others a different one. The maximum relative differences found (in absolute value) between the inferred and true values of the mass, radius, and age were 4.32, 1.33, and 11.25 per cent, respectively. The largest systematic differences in radius and age were found for a star simulated assuming gravitational settling, not accounted for in the model grid, with biases of -0.88 per cent (radius) and 8.66 per cent (age). For the mass, the most significant bias (-3.16 per cent) was found for a star with a helium enrichment ratio outside the grid range. Moreover, an ~7 per cent dispersion in age was found when adopting different prescriptions for the surface corrections or shifting the classical observations by ±1σ. The choice of the relative weight given to the classical and seismic constraints also impacted significantly the accuracy and precision of the results. Interestingly, only a few frequencies were required to achieve accurate results on the mass and radius. For the age the same was true when at least one l = 2 mode was considered. Title: Asteroseismology of iota Draconis and Discovery of an Additional Long-period Companion Authors: Hill, Michelle L.; Kane, Stephen R.; Campante, Tiago L.; Li, Zhexing; Dalba, Paul A.; Brandt, Timothy D.; White, Timothy R.; Pope, Benjamin J. S.; Stassun, Keivan G.; Fulton, Benjamin J.; Corsaro, Enrico; Li, Tanda; Ong, J. M. Joel; Bedding, Timothy R.; Bossini, Diego; Buzasi, Derek L.; Chaplin, William J.; Cunha, Margarida S.; García, Rafael A.; Breton, Sylvain N.; Hon, Marc; Huber, Daniel; Jiang, Chen; Kayhan, Cenk; Kuszlewicz, James S.; Mathur, Savita; Serenelli, Aldo; Stello, Dennis Bibcode: 2021AJ....162..211H Altcode: 2021arXiv210713583H Giant stars as known exoplanet hosts are relatively rare due to the potential challenges in acquiring precision radial velocities and the small predicted transit depths. However, these giant host stars are also some of the brightest in the sky and so enable high signal-to-noise ratio follow-up measurements. Here, we report on new observations of the bright (V ~ 3.3) giant star ι Draconis (ι Dra), known to host a planet in a highly eccentric ~511 day period orbit. TESS observations of the star over 137 days reveal asteroseismic signatures, allowing us to constrain the stellar radius, mass, and age to ~2%, ~6%, and ~28%, respectively. We present the results of continued radial-velocity monitoring of the star using the Automated Planet Finder over several orbits of the planet. We provide more precise planet parameters of the known planet and, through the combination of our radial-velocity measurements with Hipparcos and Gaia astrometry, we discover an additional long-period companion with an orbital period of $\sim {68}_{-36}^{+60}$ yr. Mass predictions from our analysis place this substellar companion on the border of the planet and brown dwarf regimes. The bright nature of the star combined with the revised orbital architecture of the system provides an opportunity to study planetary orbital dynamics that evolve as the star moves into the giant phase of its evolution. Title: Hierarchically modelling Kepler dwarfs and subgiants to improve inference of stellar properties with asteroseismology Authors: Lyttle, Alexander J.; Davies, Guy R.; Li, Tanda; Carboneau, Lindsey M.; Leung, Ho-Hin; Westwood, Harry; Chaplin, William J.; Hall, Oliver J.; Huber, Daniel; Nielsen, Martin B.; Basu, Sarbani; García, Rafael A. Bibcode: 2021MNRAS.505.2427L Altcode: 2021arXiv210504482L; 2021MNRAS.tmp.1343L With recent advances in modelling stars using high-precision asteroseismology, the systematic effects associated with our assumptions of stellar helium abundance (Y) and the mixing-length theory parameter (αMLT) are becoming more important. We apply a new method to improve the inference of stellar parameters for a sample of Kepler dwarfs and subgiants across a narrow mass range ($0.8 \lt M \lt 1.2\, \rm M_\odot$). In this method, we include a statistical treatment of Y and the αMLT. We develop a hierarchical Bayesian model to encode information about the distribution of Y and αMLT in the population, fitting a linear helium enrichment law including an intrinsic spread around this relation and normal distribution in αMLT. We test various levels of pooling parameters, with and without solar data as a calibrator. When including the Sun as a star, we find the gradient for the enrichment law, $\Delta Y / \Delta Z = 1.05\substack{+0.28\-0.25}$ and the mean αMLT in the population, $\mu _\alpha = 1.90\substack{+0.10\-0.09}$. While accounting for the uncertainty in Y and αMLT, we are still able to report statistical uncertainties of 2.5 per cent in mass, 1.2 per cent in radius, and 12 per cent in age. Our method can also be applied to larger samples that will lead to improved constraints on both the population level inference and the star-by-star fundamental parameters. Title: VizieR Online Data Catalog: Oscillations in red giants from TESS data (Silva+, 2020) Authors: Silva Aguirre, V.; Stello, D.; Stokholm, A.; Mosumgaard, J. R.; Ball, W. H.; Basu, S.; Bossini, D.; Bugnet, L.; Buzasi, D.; Campante, T. L.; Carboneau, L.; Chaplin, W. J.; Corsaro, E.; Davies, G. R.; Elsworth, Y.; Garcia, R. A.; Gaulme, P.; Hall, O. J.; Handberg, R.; Hon, M.; Kallinger, T.; Kang, L.; Lund, M. N.; Mathur, S.; Mints, A.; Mosser, B.; Celik Orhan, Z.; Rodrigues, T. S.; Vrard, M.; Yildiz, M.; Zinn, J. C.; Ortel, S.; Beck, P. G.; Bell, K. J.; Guo, Z.; Jiang, C.; Kuszlewicz, J. S.; Kuehn, C. A.; Li, T.; Lundkvist, M. S.; Pinsonneault, M.; Tayar, J.; Cunha, M. S.; Hekker, S.; Huber, D.; Miglio, A.; Monteiro, M. J. P. F. G.; Slumstrup, D.; Winther, M. L.; Angelou, G.; Benomar, O.; Bodi, A.; de Moura, B. L.; Deheuvels, S.; Derekas, A.; di Mauro, M. P.; Dupret, M. -A.; Jimenez, A.; Lebreton, Y.; Matthews, J.; Nardetto, N.; Do Nascimento, J. D.; Pereira, F.; Rodriguez Diaz, L. F.; Serenelli, A. M.; Spitoni, E.; Stonkute, E.; Suarez, J. C.; Szabo, R.; van Eylen, V.; Ventura, R.; Verma, K.; Weiss, A.; Wu, T.; Barclay, T.; Christensen-Dalsgaard, J.; Jenkins, J. M.; Kjeldsen, H.; Ricker, G. R.; Seager, S.; Vanderspek, R. Bibcode: 2021yCat..18899034S Altcode: Since the onset of the "space revolution" of high-precision high-cadence photometry, asteroseismology has been demonstrated as a powerful tool for informing Galactic archeology investigations. The launch of the NASA Transiting Exoplanet Survey Satellite (TESS) mission has enabled seismic-based inferences to go full sky-providing a clear advantage for large ensemble studies of the different Milky Way components. Here we demonstrate its potential for investigating the Galaxy by carrying out the first asteroseismic ensemble study of red giant stars observed by TESS. We use a sample of 25 stars for which we measure their global asteroseimic observables and estimate their fundamental stellar properties, such as radius, mass, and age. Significant improvements are seen in the uncertainties of our estimates when combining seismic observables from TESS with astrometric measurements from the Gaia mission compared to when the seismology and astrometry are applied separately. Specifically, when combined we show that stellar radii can be determined to a precision of a few percent, masses to 5%-10%, and ages to the 20% level. This is comparable to the precision typically obtained using end-of-mission Kepler data.

(1 data file). Title: Asteroseismology of the Red-giant Hosts KOI-3886 and iota Draconis Authors: Campante, Tiago L.; Li, Tanda; Ong, J. M. Joel; Corsaro, Enrico; Hill, Michelle L.; Lillo-Box, Jorge; Bedding, Timothy R.; Bossini, Diego; Brandt, Timothy D.; Breton, Sylvain N.; Buzasi, Derek L.; Chaplin, William J.; Cunha, Margarida S.; García, Rafael A.; Hon, Marc; Huber, Daniel; Jiang, Chen; Kane, Stephen R.; Kayhan, Cenk; Kuszlewicz, James S.; Mathur, Savita; Pereira, Filipe; Santos, Nuno C.; Serenelli, Aldo; Stello, Dennis Bibcode: 2021tsc2.confE..84C Altcode: Kepler asteroseismology has played an important role in the characterization of host stars and their planetary systems. Target selection biases, however, meant that this synergy would remain mostly confined to main-sequence stars. The advent of TESS has since lifted this restriction, enabling the systematic search for transiting planets around seismic giants, as well as revisiting previously known evolved hosts using asteroseismology. Here, we present the detailed asteroseismic modeling of two high-luminosity red-giant branch hosts, KOI-3886 and iota Draconis. KOI-3886, observed by Kepler over 4 years and later by TESS over 1 sector, has been a longtime candidate host. iota Draconis, observed by TESS over 5 sectors, is known to host a planet in a highly eccentric orbit. The precise (~ 6%) seismic mass derived for iota Draconis was combined with new radial-velocity observations to detect an additional long-period companion. Regarding KOI-3886, asteroseismology was key in helping reveal the planet candidate as a false positive and reinterpreting the system as an eclipsing brown dwarf in a hierarchical triple with two evolved stars. This brings to light the importance of asteroseismology in the study of planetary orbital dynamics off the main sequence and its lesser known role in candidate vetting. Title: Haydn Authors: Miglio, Andrea; Girardi, Léo; Grundahl, Frank; Mosser, Benoit; Bastian, Nate; Bragaglia, Angela; Brogaard, Karsten; Buldgen, Gaël; Chantereau, William; Chaplin, William; Chiappini, Cristina; Dupret, Marc-Antoine; Eggenberger, Patrick; Gieles, Mark; Izzard, Robert; Kawata, Daisuke; Karoff, Christoffer; Lagarde, Nadège; Mackereth, Ted; Magrin, Demetrio; Meynet, Georges; Michel, Eric; Montalbán, Josefina; Nascimbeni, Valerio; Noels, Arlette; Piotto, Giampaolo; Ragazzoni, Roberto; Soszyński, Igor; Tolstoy, Eline; Toonen, Silvia; Triaud, Amaury; Vincenzo, Fiorenzo Bibcode: 2021ExA....51..963M Altcode: 2021ExA...tmp...21M; 2019arXiv190805129M In the last decade, the Kepler and CoRoT space-photometry missions have demonstrated the potential of asteroseismology as a novel, versatile and powerful tool to perform exquisite tests of stellar physics, and to enable precise and accurate characterisations of stellar properties, with impact on both exoplanetary and Galactic astrophysics. Based on our improved understanding of the strengths and limitations of such a tool, we argue for a new small/medium space mission dedicated to gathering high-precision, high-cadence, long photometric series in dense stellar fields. Such a mission will lead to breakthroughs in stellar astrophysics, especially in the metal poor regime, will elucidate the evolution and formation of open and globular clusters, and aid our understanding of the assembly history and chemodynamics of the Milky Way's bulge and a few nearby dwarf galaxies. Title: VizieR Online Data Catalog: Dwarf stars asteroseismic rotation rates (Hall+, 2021) Authors: Hall, O. J.; Davies, G. R.; van Saders, J.; Nielsen, M. B.; Lund, M. N.; Chaplin, W. J.; Garcia, R. A.; Amard, L.; Breimann, A. A.; Khan, S.; See, V.; Tayar, J. Bibcode: 2021yCatp061000501H Altcode: Parameters for the 94 stars for which seismic rotation rates were obtained in the paper. Temperatures (Teff), age, mass, metallicity ([Fe/H]) and surface gravity (log(g)) are adopted from the LEGACY (L, Lund et al., 2017ApJ...835..172L, Silva Aguirre et al., 2017ApJ...836..173S) and 'Kages' (K, Silva Aguirre et al., 2015MNRAS.452.2127S, Davies et al., 2016MNRAS.456.2183D) catalogues, as listed in the Source column. Projected splitting (νssin(i)), inclination angle (i) and asteroseismic rotation (P) are from the paper. Uncertainties were taken using the 15.9th and 84.1st percentiles of posterior distributions on the parameters, which are frequently asymmetrical in linear space. Reported values are the median of the posterior distributions. For parameters with no direct posterior samples (e.g. rotation) the full posterior samples were transformed before taking the summary statistics. The stellar type denotes whether a star is roughly classified as belonging to the main sequence (MS), Sub-Giants (SG) or 'hot' stars (H).

The flags indicate the following: 0; no issues, used in the gyrochronology analysis. 1; has either a number of effective samples neff<1000 for the asteroseismic splitting, or Gelman-Rubin convergence metric of R>1.1, indicating that rotation measurements for these stars are less robust than those with a flag of 0. 2; was found to strongly disagree with multiple literature values, excluded from the gyrochronology analysis. 3; fell outside the model range of the stellar models, and were therefore not used in the gyrochronology analysis.

(1 data file). Title: Impact of magnetic activity on inferred stellar properties of main-sequence Sun-like stars Authors: Thomas, Alexandra E. L.; Chaplin, William J.; Basu, Sarbani; Rendle, Ben; Davies, Guy; Miglio, Andrea Bibcode: 2021MNRAS.502.5808T Altcode: 2021MNRAS.tmp..387T; 2021arXiv210202566T The oscillation frequencies observed in Sun-like stars are susceptible to being shifted by magnetic activity effects. The measured shifts depend on a complex relationship involving the mode type, the field strength, and spatial distribution of activity, as well as the inclination angle of the star. Evidence of these shifts is also present in frequency separation ratios that are often used when inferring global properties of stars in order to avoid surface effects. However, one assumption when using frequency ratios for this purpose is that there are no near-surface perturbations that are non-spherically symmetric. In this work, we studied the impact on inferred stellar properties when using frequency ratios that are influenced by non-homogeneous activity distributions. We generate several sets of artificial oscillation frequencies with various amounts of shift and determine stellar properties using two separate pipelines. We find that for asteroseismic observations of Sun-like targets we can expect magnetic activity to affect mode frequencies that will bias the results from stellar modelling analysis. Although for most stellar properties this offset should be small, typically less than 0.5 per cent in mass, estimates of age and central hydrogen content can have an error of up to 5 per cent and 3 per cent, respectively. We expect a larger frequency shift and therefore larger bias for more active stars. We also warn that for stars with very high or low inclination angles, the response of modes to activity is more easily observable in the separation ratios and hence will incur a larger bias. Title: Orbital misalignment of the super-Earth π Men c with the spin of its star Authors: Kunovac Hodžić, Vedad; Triaud, Amaury H. M. J.; Cegla, Heather M.; Chaplin, William J.; Davies, Guy R. Bibcode: 2021MNRAS.502.2893K Altcode: 2021MNRAS.tmp..280H; 2020arXiv200711564K Planet-planet scattering events can leave an observable trace of a planet's migration history in the form of orbital misalignment with respect to the stellar spin axis, which is measurable from spectroscopic time-series taken during transit. We present high-resolution spectroscopic transits observed with ESPRESSO of the close-in super-Earth π Men c. The system also contains an outer giant planet on a wide, eccentric orbit, recently found to be inclined with respect to the inner planetary orbit. These characteristics are reminiscent of past dynamical interactions. We successfully retrieve the planet-occulted light during transit, and find evidence that the orbit of π Men c is moderately misaligned with the stellar spin axis with λ = - 24${_{.}^{\circ}}$0 ± 4${_{.}^{\circ}}$1 ($\psi = {26{_{.}^{\circ}} 9}^{+5{_{.}^{\circ}}8 }_{-4{_{.}^{\circ}}7 }$). This is consistent with the super-Earth π Men c having followed a high-eccentricity migration followed by tidal circularization, and hints that super-Earths can form at large distances from their star. We also detect clear signatures of solar-like oscillations within our ESPRESSO radial velocity time series, where we reach a radial velocity precision of ~20 cm s-1. We model the oscillations using Gaussian processes (GPs) and retrieve a frequency of maximum oscillation, $\nu _\mathrm{max}{} = 2771^{+65}_{-60}\, \mu \mathrm{Hz}$. These oscillations make it challenging to detect the Rossiter-McLaughlin effect using traditional methods. We are, however, successful using the reloaded Rossiter-McLaughlin approach. Finally, in the appendix, we also present physical parameters and ephemerides for π Men c from a GP transit analysis of the full Transiting Exoplanet Survey Satellite Cycle 1 data. Title: Prospects for Galactic and stellar astrophysics with asteroseismology of giant stars in the TESS continuous viewing zones and beyond Authors: Mackereth, J. Ted; Miglio, Andrea; Elsworth, Yvonne; Mosser, Benoit; Mathur, Savita; Garcia, Rafael A.; Nardiello, Domenico; Hall, Oliver J.; Vrard, Mathieu; Ball, Warrick H.; Basu, Sarbani; Beaton, Rachael L.; Beck, Paul G.; Bergemann, Maria; Bossini, Diego; Casagrande, Luca; Campante, Tiago L.; Chaplin, William J.; Chiappini, Cristina; Girardi, Léo; Jørgensen, Andreas Christ Sølvsten; Khan, Saniya; Montalbán, Josefina; Nielsen, Martin B.; Pinsonneault, Marc H.; Rodrigues, Thaíse S.; Serenelli, Aldo; Silva Aguirre, Victor; Stello, Dennis; Tayar, Jamie; Teske, Johanna; van Saders, Jennifer L.; Willett, Emma Bibcode: 2021MNRAS.502.1947M Altcode: 2020arXiv201200140M; 2021MNRAS.tmp..131M The NASA Transiting Exoplanet Survey Satellite (NASA-TESS) mission presents a treasure trove for understanding the stars it observes and the Milky Way, in which they reside. We present a first look at the prospects for Galactic and stellar astrophysics by performing initial asteroseismic analyses of bright (G < 11) red giant stars in the TESS southern continuous viewing zone (SCVZ). Using three independent pipelines, we detect νmax and Δν in 41 per cent of the 15 405 star parent sample (6388 stars), with consistency at a level of $\sim \! 2{{\ \rm per\ cent}}$ in νmax and $\sim \! 5{{\ \rm per\ cent}}$ in Δν. Based on this, we predict that seismology will be attainable for ~3 × 105 giants across the whole sky and at least 104 giants with ≥1 yr of observations in the TESS-CVZs, subject to improvements in analysis and data reduction techniques. The best quality TESS-CVZ data, for 5574 stars where pipelines returned consistent results, provide high-quality power spectra across a number of stellar evolutionary states. This makes possible studies of, for example, the asymptotic giant branch bump. Furthermore, we demonstrate that mixed ℓ = 1 modes and rotational splitting are cleanly observed in the 1-yr data set. By combining TESS-CVZ data with TESS-HERMES, SkyMapper, APOGEE, and Gaia, we demonstrate its strong potential for Galactic archaeology studies, providing good age precision and accuracy that reproduces well the age of high [α/Fe] stars and relationships between mass and kinematics from previous studies based on e.g. Kepler. Better quality astrometry and simpler target selection than the Kepler sample makes this data ideal for studies of the local star formation history and evolution of the Galactic disc. These results provide a strong case for detailed spectroscopic follow-up in the CVZs to complement that which has been (or will be) collected by current surveys. Title: Lifetimes and rotation within the solar mean magnetic field Authors: Ross, Eddie; Chaplin, William J.; Hale, Steven J.; Howe, Rachel; Elsworth, Yvonne P.; Davies, Guy R.; Nielsen, Martin Bo Bibcode: 2021MNRAS.502.5603R Altcode: 2021MNRAS.tmp..426C; 2021MNRAS.tmp..495R; 2021arXiv210204743R We have used very high-cadence (sub-minute) observations of the solar mean magnetic field (SMMF) from the Birmingham Solar Oscillations Network (BiSON) to investigate the morphology of the SMMF. The observations span a period from 1992 to 2012, and the high-cadence observations allowed the exploration of the power spectrum up to frequencies in the mHz range. The power spectrum contains several broad peaks from a rotationally modulated (RM) component, whose linewidths allowed us to measure, for the first time, the lifetime of the RM source. There is an additional broadband, background component in the power spectrum which we have shown is an artefact of power aliasing due to the low fill of the data. The sidereal rotation period of the RM component was measured as 25.23 ± 0.11 d and suggests that the signal is sensitive to a time-averaged latitude of ∼12°. We have also shown the RM lifetime to be 139.6 ± 18.5 d. This provides evidence to suggest that the RM component of the SMMF is connected to magnetic flux concentrations (MFCs) and active regions (ARs) of magnetic flux, based both on its lifetime and location on the solar disc. Title: TOI-257b (HD 19916b): a warm sub-saturn orbiting an evolved F-type star Authors: Addison, Brett C.; Wright, Duncan J.; Nicholson, Belinda A.; Cale, Bryson; Mocnik, Teo; Huber, Daniel; Plavchan, Peter; Wittenmyer, Robert A.; Vanderburg, Andrew; Chaplin, William J.; Chontos, Ashley; Clark, Jake T.; Eastman, Jason D.; Ziegler, Carl; Brahm, Rafael; Carter, Bradley D.; Clerte, Mathieu; Espinoza, Néstor; Horner, Jonathan; Bentley, John; Jordán, Andrés; Kane, Stephen R.; Kielkopf, John F.; Laychock, Emilie; Mengel, Matthew W.; Okumura, Jack; Stassun, Keivan G.; Bedding, Timothy R.; Bowler, Brendan P.; Burnelis, Andrius; Blanco-Cuaresma, Sergi; Collins, Michaela; Crossfield, Ian; Davis, Allen B.; Evensberget, Dag; Heitzmann, Alexis; Howell, Steve B.; Law, Nicholas; Mann, Andrew W.; Marsden, Stephen C.; Matson, Rachel A.; O'Connor, James H.; Shporer, Avi; Stevens, Catherine; Tinney, C. G.; Tylor, Christopher; Wang, Songhu; Zhang, Hui; Henning, Thomas; Kossakowski, Diana; Ricker, George; Sarkis, Paula; Schlecker, Martin; Torres, Pascal; Vanderspek, Roland; Latham, David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Mireles, Ismael; Rowden, Pam; Pepper, Joshua; Daylan, Tansu; Schlieder, Joshua E.; Collins, Karen A.; Collins, Kevin I.; Tan, Thiam-Guan; Ball, Warrick H.; Basu, Sarbani; Buzasi, Derek L.; Campante, Tiago L.; Corsaro, Enrico; González-Cuesta, L.; Davies, Guy R.; de Almeida, Leandro; do Nascimento, Jose-Dias, Jr.; García, Rafael A.; Guo, Zhao; Handberg, Rasmus; Hekker, Saskia; Hey, Daniel R.; Kallinger, Thomas; Kawaler, Steven D.; Kayhan, Cenk; Kuszlewicz, James S.; Lund, Mikkel N.; Lyttle, Alexander; Mathur, Savita; Miglio, Andrea; Mosser, Benoit; Nielsen, Martin B.; Serenelli, Aldo M.; Aguirre, Victor Silva; Themeßl, Nathalie Bibcode: 2021MNRAS.502.3704A Altcode: 2020arXiv200107345A; 2020MNRAS.tmp.3757A We report the discovery of a warm sub-Saturn, TOI-257b (HD 19916b), based on data from NASA's Transiting Exoplanet Survey Satellite (TESS). The transit signal was detected by TESS and confirmed to be of planetary origin based on radial velocity observations. An analysis of the TESS photometry, the MINERVA-Australis, FEROS, and HARPS radial velocities, and the asteroseismic data of the stellar oscillations reveals that TOI-257b has a mass of MP = 0.138 ± 0.023 $\rm {M_J}$ (43.9 ± 7.3 $\, M_{\rm \oplus}$ ), a radius of RP = 0.639 ± 0.013 $\rm {R_J}$ (7.16 ± 0.15 $\, \mathrm{ R}_{\rm \oplus}$ ), bulk density of $0.65^{+0.12}_{-0.11}$ (cgs), and period $18.38818^{+0.00085}_{-0.00084}$ $\rm {days}$ . TOI-257b orbits a bright (V = 7.612 mag) somewhat evolved late F-type star with M* = 1.390 ± 0.046 $\rm {M_{sun}}$ , R* = 1.888 ± 0.033 $\rm {R_{sun}}$ , Teff = 6075 ± 90 $\rm {K}$ , and vsin i = 11.3 ± 0.5 km s-1. Additionally, we find hints for a second non-transiting sub-Saturn mass planet on a ∼71 day orbit using the radial velocity data. This system joins the ranks of a small number of exoplanet host stars (∼100) that have been characterized with asteroseismology. Warm sub-Saturns are rare in the known sample of exoplanets, and thus the discovery of TOI-257b is important in the context of future work studying the formation and migration history of similar planetary systems. Title: Haiku CS20.5 - Weakened magnetic braking supported by asteroseismic rotation Authors: Hall, O. J.; Davies, G. R.; van Saders, J.; Nielsen, M. B.; Lund, M. N.; Chaplin, W. J.; Garcia, R. A.; Amard, L.; Breimann, A. A.; Khan, S.; See, V.; Tayar, J. Bibcode: 2021csss.confE..70H Altcode: Studies using asteroseismic ages and rotation rates from star-spot rotation have indicated that standard age-rotation relations may break down roughly half-way through the main sequence lifetime, a phenomenon referred to as weakened magnetic braking. While rotation rates from spots can be difficult to determine for older, less active stars, rotational splitting of asteroseismic oscillation frequencies can provide rotation rates for both active and quiescent stars, and so can confirm whether this effect really takes place on the main sequence. In this talk, I'll show how we obtained asteroseismic rotation rates of 91 main sequence stars showing high signal-to-noise modes of oscillation. Using these new rotation rates, along with effective temperatures, metallicities and seismic masses and ages, we built a hierarchical Bayesian mixture model that showed that our new ensemble more closely agreed with weakened magnetic braking, over a standard rotational evolution scenario. Title: VizieR Online Data Catalog: 117 exoplanets in habitable zone with Kepler DR25 (Bryson+, 2021) Authors: Bryson, S.; Kunimoto, M.; Kopparapu, R. K.; Coughlin, J. L.; Borucki, W. J.; Koch, D.; Aguirre, V. S.; Allen, C.; Barentsen, G.; Batalha, N. M.; Berger, T.; Boss, A.; Buchhave, L. A.; Burke, C. J.; Caldwell, D. A.; Campbell, J. R.; Catanzarite, J.; Chandrasekaran, H.; Chaplin, W. J.; Christiansen, J. L.; Christensen-Dalsgaard, J.; Ciardi, D. R.; Clarke, B. D.; Cochran, W. D.; Dotson, J. L.; Doyle, L. R.; Duarte, E. S.; Dunham, E. W.; Dupree, A. K.; Endl, M.; Fanson, J. L.; Ford, E. B.; Fujieh, M.; Gautier, T. N., III; Geary, J. C.; Gilliland, R. L.; Girouard, F. R.; Gould, A.; Haas, M. R.; Henze, C. E.; Holman, M. J.; Howard, A. W.; Howell, S. B.; Huber, D.; Hunter, R. C.; Jenkins, J. M.; Kjeldsen, H.; Kolodziejczak, J.; Larson, K.; Latham, D. W.; Li, J.; Mathur, S.; Meibom, S.; Middour, C.; Morris, R. L.; Morton, T. D.; Mullally, F.; Mullally, S. E.; Pletcher, D.; Prsa, A.; Quinn, S. N.; Quintana, E. V.; Ragozzine, D.; Ramirez, S. V.; Sanderfer, D. T.; Sasselov, D.; Seader, S. E.; Shabram, M.; Shporer, A.; Smith, J. C.; Steffen, J. H.; Still, M.; Torres, G.; Troeltzsch, J.; Twicken, J. D.; Uddin, A. K.; van Cleve, J. E.; Voss, J.; Weiss, L. M.; Welsh, W. F.; Wohler, B.; Zamudio, K. A. Bibcode: 2021yCat..51610036B Altcode: We present the occurrence rates for rocky planets in the habitable zones (HZs) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define {eta}{Earth} as the HZ occurrence of planets with radii between 0.5 and 1.5 R{Earth} orbiting stars with effective temperatures between 4800 and 6300K. We find that {eta}{Earth} for the conservative HZ is between 0.37-0.21+0.48 (errors reflect 68% credible intervals) and 0.60-0.36+0.90 planets per star, while the optimistic HZ occurrence is between 0.58-0.33+0.73 and 0.88-0.51+1.28 planets per star. These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available. The large uncertainties are due to the small number of detected small HZ planets. We find similar occurrence rates between using Poisson likelihood Bayesian analysis and using Approximate Bayesian Computation. Our results are corrected for catalog completeness and reliability. Both completeness and the planet occurrence rate are dependent on stellar effective temperature. We also present occurrence rates for various stellar populations and planet size ranges. We estimate with 95% confidence that, on average, the nearest HZ planet around G and K dwarfs is ~6pc away and there are ~4 HZ rocky planets around G and K dwarfs within 10pc of the Sun.

(1 data file). Title: Poster CS20.5 - Weakened magnetic braking supported by asteroseismic rotation Authors: Hall, Oliver James; Davies, G. R.; van Saders, J.; Nielsen, M. B.; Lund, M. N.; Chaplin, W. J.; Garcia, R. A.; Amard, L.; Breimann, A. A.; Khan, S.; See, V.; Tayar, J. Bibcode: 2021csss.confE..69H Altcode: Studies using asteroseismic ages and rotation rates from star-spot rotation have indicated that standard age-rotation relations may break down roughly half-way through the main sequence lifetime, a phenomenon referred to as weakened magnetic braking. While rotation rates from spots can be difficult to determine for older, less active stars, rotational splitting of asteroseismic oscillation frequencies can provide rotation rates for both active and quiescent stars, and so can confirm whether this effect really takes place on the main sequence. In this talk, I'll show how we obtained asteroseismic rotation rates of 91 main sequence stars showing high signal-to-noise modes of oscillation. Using these new rotation rates, along with effective temperatures, metallicities and seismic masses and ages, we built a hierarchical Bayesian mixture model that showed that our new ensemble more closely agreed with weakened magnetic braking, over a standard rotational evolution scenario. Title: VizieR Online Data Catalog: K2 GAP DR2: campaigns 4, 6 & 7 (Zinn+, 2020) Authors: Zinn, J. C.; Stello, D.; Elsworth, Y.; Garcia, R. A.; Kallinger, T.; Mathur, S.; Mosser, B.; Bugnet, L.; Jones, C.; Hon, M.; Sharma, S.; Schonrich, R.; Warfield, J. T.; Luger, R.; Pinsonneault, M. H.; Johnson, J. A.; Huber, D.; Silva Aguirre, V.; Chaplin, W. J.; Davies, G. R.; Miglio, A. Bibcode: 2021yCat..22510023Z Altcode: In the context of the Galactic Archaeology Program (GAP; Stello+ 2015ApJ...809L...3S), analyses of the Kepler K2 campaigns presented here were prioritized due to their coverage of the sky: the Galactic center (C7; 2015 Oct-Dec), the Galactic anticenter (C4; 2015 Feb-Apr), and out of the Galactic plane (C6; 2015 Jul-Sep).

(3 data files). Title: PBjam: A Python Package for Automating Asteroseismology of Solar-like Oscillators Authors: Nielsen, M. B.; Davies, G. R.; Ball, W. H.; Lyttle, A. J.; Li, T.; Hall, O. J.; Chaplin, W. J.; Gaulme, P.; Carboneau, L.; Ong, J. M. J.; García, R. A.; Mosser, B.; Roxburgh, I. W.; Corsaro, E.; Benomar, O.; Moya, A.; Lund, M. N. Bibcode: 2021AJ....161...62N Altcode: 2020arXiv201200580N Asteroseismology is an exceptional tool for studying stars using the properties of observed modes of oscillation. So far the process of performing an asteroseismic analysis of a star has remained somewhat esoteric and inaccessible to nonexperts. In this software paper we describe PBjam, an open-source Python package for analyzing the frequency spectra of solar-like oscillators in a simple but principled and automated way. The aim of PBjam is to provide a set of easy-to-use tools to extract information about the radial and quadropole oscillations in stars that oscillate like the Sun, which may then be used to infer bulk properties such as stellar mass, radius, age, or even structure. Asteroseismology and its data analysis methods are becoming increasingly important as space-based photometric observatories are producing a wealth of new data, allowing asteroseismology to be applied in a wide range of contexts such as exoplanet, stellar structure and evolution, and Galactic population studies. * Release 1.0.0 Zenodo, doi:10.5281/zenodo.4300079. Title: Science Extraction from TESS Observations of Known Exoplanet Hosts Authors: Kane, Stephen R.; Bean, Jacob L.; Campante, Tiago L.; Dalba, Paul A.; Fetherolf, Tara; Mocnik, Teo; Ostberg, Colby; Pepper, Joshua; Simpson, Emilie R.; Turnbull, Margaret C.; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Huber, Daniel; Chaplin, William J. Bibcode: 2021PASP..133a4402K Altcode: 2020arXiv201015164K The transit method of exoplanet discovery and characterization has enabled numerous breakthroughs in exoplanetary science. These include measurements of planetary radii, mass-radius relationships, stellar obliquities, bulk density constraints on interior models, and transmission spectroscopy as a means to study planetary atmospheres. The Transiting Exoplanet Survey Satellite (TESS) has added to the exoplanet inventory by observing a significant fraction of the celestial sphere, including many stars already known to host exoplanets. Here we describe the science extraction from TESS observations of known exoplanet hosts during the primary mission. These include transit detection of known exoplanets, discovery of additional exoplanets, detection of phase signatures and secondary eclipses, transit ephemeris refinement, and asteroseismology as a means to improve stellar and planetary parameters. We provide the statistics of TESS known host observations during Cycle 1 and 2, and present several examples of TESS photometry for known host stars observed with a long baseline. We outline the major discoveries from observations of known hosts during the primary mission. Finally, we describe the case for further observations of known exoplanet hosts during the TESS extended mission and the expected science yield. Title: The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Data Authors: Bryson, Steve; Kunimoto, Michelle; Kopparapu, Ravi K.; Coughlin, Jeffrey L.; Borucki, William J.; Koch, David; Aguirre, Victor Silva; Allen, Christopher; Barentsen, Geert; Batalha, Natalie M.; Berger, Travis; Boss, Alan; Buchhave, Lars A.; Burke, Christopher J.; Caldwell, Douglas A.; Campbell, Jennifer R.; Catanzarite, Joseph; Chandrasekaran, Hema; Chaplin, William J.; Christiansen, Jessie L.; Christensen-Dalsgaard, Jørgen; Ciardi, David R.; Clarke, Bruce D.; Cochran, William D.; Dotson, Jessie L.; Doyle, Laurance R.; Duarte, Eduardo Seperuelo; Dunham, Edward W.; Dupree, Andrea K.; Endl, Michael; Fanson, James L.; Ford, Eric B.; Fujieh, Maura; Gautier, Thomas N., III; Geary, John C.; Gilliland, Ronald L.; Girouard, Forrest R.; Gould, Alan; Haas, Michael R.; Henze, Christopher E.; Holman, Matthew J.; Howard, Andrew W.; Howell, Steve B.; Huber, Daniel; Hunter, Roger C.; Jenkins, Jon M.; Kjeldsen, Hans; Kolodziejczak, Jeffery; Larson, Kipp; Latham, David W.; Li, Jie; Mathur, Savita; Meibom, Søren; Middour, Chris; Morris, Robert L.; Morton, Timothy D.; Mullally, Fergal; Mullally, Susan E.; Pletcher, David; Prsa, Andrej; Quinn, Samuel N.; Quintana, Elisa V.; Ragozzine, Darin; Ramirez, Solange V.; Sanderfer, Dwight T.; Sasselov, Dimitar; Seader, Shawn E.; Shabram, Megan; Shporer, Avi; Smith, Jeffrey C.; Steffen, Jason H.; Still, Martin; Torres, Guillermo; Troeltzsch, John; Twicken, Joseph D.; Uddin, Akm Kamal; Van Cleve, Jeffrey E.; Voss, Janice; Weiss, Lauren M.; Welsh, William F.; Wohler, Bill; Zamudio, Khadeejah A. Bibcode: 2021AJ....161...36B Altcode: 2020arXiv201014812B We present the occurrence rates for rocky planets in the habitable zones (HZs) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define η⊕ as the HZ occurrence of planets with radii between 0.5 and 1.5 R⊕ orbiting stars with effective temperatures between 4800 and 6300 K. We find that η⊕ for the conservative HZ is between ${0.37}_{-0.21}^{+0.48}$ (errors reflect 68% credible intervals) and ${0.60}_{-0.36}^{+0.90}$ planets per star, while the optimistic HZ occurrence is between ${0.58}_{-0.33}^{+0.73}$ and ${0.88}_{-0.51}^{+1.28}$ planets per star. These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available. The large uncertainties are due to the small number of detected small HZ planets. We find similar occurrence rates between using Poisson likelihood Bayesian analysis and using Approximate Bayesian Computation. Our results are corrected for catalog completeness and reliability. Both completeness and the planet occurrence rate are dependent on stellar effective temperature. We also present occurrence rates for various stellar populations and planet size ranges. We estimate with 95% confidence that, on average, the nearest HZ planet around G and K dwarfs is ∼6 pc away and there are ∼4 HZ rocky planets around G and K dwarfs within 10 pc of the Sun. Title: Chronologically dating the early assembly of the Milky Way Authors: Montalbán, Josefina; Mackereth, J. Ted; Miglio, Andrea; Vincenzo, Fiorenzo; Chiappini, Cristina; Buldgen, Gael; Mosser, Benoît; Noels, Arlette; Scuflaire, Richard; Vrard, Mathieu; Willett, Emma; Davies, Guy R.; Hall, Oliver J.; Nielsen, Martin Bo; Khan, Saniya; Rendle, Ben M.; van Rossem, Walter E.; Ferguson, Jason W.; Chaplin, William J. Bibcode: 2021NatAs...5..640M Altcode: 2021NatAs.tmp...90M; 2020arXiv200601783M The standard cosmological model predicts that galaxies are built through hierarchical assembly on cosmological timescales1,2. The Milky Way, like other disk galaxies, underwent violent mergers and accretion of small satellite galaxies in its early history. Owing to Gaia Data Release 23 and spectroscopic surveys4, the stellar remnants of such mergers have been identified5-7. The chronological dating of such events is crucial to uncover the formation and evolution of the Galaxy at high redshift, but it has so far been challenging due to difficulties in obtaining precise ages for these oldest stars. Here we combine asteroseismology—the study of stellar oscillations—with kinematics and chemical abundances to estimate precise stellar ages (~11%) for a sample of stars observed by the Kepler space mission8. Crucially, this sample includes not only some of the oldest stars that were formed inside the Galaxy but also stars formed externally and subsequently accreted onto the Milky Way. Leveraging this resolution in age, we provide compelling evidence in favour of models in which the Galaxy had already formed a substantial population of its stars (which now reside mainly in its thick disk) before the infall of the satellite galaxy Gaia-Enceladus/Sausage5,6 around 10 billion years ago. Title: Age dissection of the Milky Way discs: Red giants in the Kepler field Authors: Miglio, A.; Chiappini, C.; Mackereth, J. T.; Davies, G. R.; Brogaard, K.; Casagrande, L.; Chaplin, W. J.; Girardi, L.; Kawata, D.; Khan, S.; Izzard, R.; Montalbán, J.; Mosser, B.; Vincenzo, F.; Bossini, D.; Noels, A.; Rodrigues, T.; Valentini, M.; Mandel, I. Bibcode: 2021A&A...645A..85M Altcode: 2020arXiv200414806M Ensemble studies of red-giant stars with exquisite asteroseismic (Kepler), spectroscopic (APOGEE), and astrometric (Gaia) constraints offer a novel opportunity to recast and address long-standing questions concerning the evolution of stars and of the Galaxy. Here, we infer masses and ages for nearly 5400 giants with available Kepler light curves and APOGEE spectra using the code PARAM, and discuss some of the systematics that may affect the accuracy of the inferred stellar properties. We then present patterns in mass, evolutionary state, age, chemical abundance, and orbital parameters that we deem robust against the systematic uncertainties explored. First, we look at age-chemical-abundances ([Fe/H] and [α/Fe]) relations. We find a dearth of young, metal-rich ([Fe/H] > 0.2) stars, and the existence of a significant population of old (8-9 Gyr), low-[α/Fe], super-solar metallicity stars, reminiscent of the age and metallicity of the well-studied open cluster NGC 6791. The age-chemo-kinematic properties of these stars indicate that efficient radial migration happens in the thin disc. We find that ages and masses of the nearly 400 α-element-rich red-giant-branch (RGB) stars in our sample are compatible with those of an old (∼11 Gyr), nearly coeval, chemical-thick disc population. Using a statistical model, we show that the width of the observed age distribution is dominated by the random uncertainties on age, and that the spread of the inferred intrinsic age distribution is such that 95% of the population was born within ∼1.5 Gyr. Moreover, we find a difference in the vertical velocity dispersion between low- and high-[α/Fe] populations. This discontinuity, together with the chemical one in the [α/Fe] versus [Fe/H] diagram, and with the inferred age distributions, not only confirms the different chemo-dynamical histories of the chemical-thick and thin discs, but it is also suggestive of a halt in the star formation (quenching) after the formation of the chemical-thick disc. We then exploit the almost coeval α-rich population to gain insight into processes that may have altered the mass of a star along its evolution, which are key to improving the mapping of the current, observed, stellar mass to the initial mass and thus to the age. Comparing the mass distribution of stars on the lower RGB (R < 11 R⊙) with those in the red clump (RC), we find evidence for a mean integrated RGB mass loss ⟨ΔM⟩ = 0.10 ± 0.02 M⊙. Finally, we find that the occurrence of massive (M ≳ 1.1 M⊙) α-rich stars is of the order of 5% on the RGB, and significantly higher in the RC, supporting the scenario in which most of these stars had undergone an interaction with a companion.

Table C.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/645/A85 Title: A next generation upgraded observing platform for the automated Birmingham Solar Oscillations Network (BiSON) Authors: Hale, S J; Chaplin, W J; Davies, G R; Elsworth, Y P Bibcode: 2021arXiv210110205H Altcode: The Birmingham Solar Oscillations Network (BiSON) is a collection of ground-based automated telescopes observing oscillations of the Sun. The network has been operating since the early 1990s. We present development work on a prototype next generation observation platform, BiSON:NG, based almost entirely on inexpensive off-the-shelf components, and where the footprint is reduced to a size that can be inexpensively installed on the roof of an existing building. Continuous development is essential in ensuring that automated networks such as BiSON are well placed to observe the next solar cycle and beyond. Title: Weakened magnetic braking supported by asteroseismic rotation rates of Kepler dwarfs Authors: Hall, Oliver J.; Davies, Guy R.; van Saders, Jennifer; Nielsen, Martin B.; Lund, Mikkel N.; Chaplin, William J.; García, Rafael A.; Amard, Louis; Breimann, Angela A.; Khan, Saniya; See, Victor; Tayar, Jamie Bibcode: 2021NatAs...5..707H Altcode: 2021NatAs.tmp...71H; 2021arXiv210410919H Studies using asteroseismic ages and rotation rates from star-spot rotation have indicated that standard age-rotation relations may break down roughly half way through the main sequence lifetime, a phenomenon referred to as weakened magnetic braking. Although rotation rates from spots can be difficult to determine for older, less active stars, rotational splitting of asteroseismic oscillation frequencies can provide rotation rates for both active and quiescent stars, and so can confirm whether this effect really takes place on the main sequence. We obtained asteroseismic rotation rates of 91 main sequence stars showing high signal-to-noise modes of oscillation. Using these new rotation rates, along with effective temperatures, metallicities and seismic masses and ages, we built a hierarchical Bayesian mixture model to determine whether the ensemble more closely agreed with a standard rotational evolution scenario, or one where weakened magnetic braking takes place. The weakened magnetic braking scenario was found to be 98.4% more likely for our stellar ensemble, adding to the growing body of evidence for this stage of stellar rotational evolution. This work presents a large catalogue of seismic rotation rates for stars on the main sequence, which opens up possibilities for more detailed ensemble analysis of rotational evolution with Kepler. Title: The K2 Galactic Archaeology Program Data Release 2: Asteroseismic Results from Campaigns 4, 6, and 7 Authors: Zinn, Joel C.; Stello, Dennis; Elsworth, Yvonne; García, Rafael A.; Kallinger, Thomas; Mathur, Savita; Mosser, Benoît; Bugnet, Lisa; Jones, Caitlin; Hon, Marc; Sharma, Sanjib; Schönrich, Ralph; Warfield, Jack T.; Luger, Rodrigo; Pinsonneault, Marc H.; Johnson, Jennifer A.; Huber, Daniel; Silva Aguirre, Victor; Chaplin, William J.; Davies, Guy R.; Miglio, Andrea Bibcode: 2020ApJS..251...23Z Altcode: 2020arXiv201204051Z Studies of Galactic structure and evolution have benefited enormously from Gaia kinematic information, though additional, intrinsic stellar parameters like age are required to best constrain Galactic models. Asteroseismology is the most precise method of providing such information for field star populations en masse, but existing samples for the most part have been limited to a few narrow fields of view by the CoRoT and Kepler missions. In an effort to provide well-characterized stellar parameters across a wide range in Galactic position, we present the second data release of red giant asteroseismic parameters for the K2 Galactic Archaeology Program (GAP). We provide ${\nu }_{\max }$ and ${\rm{\Delta }}\nu $ based on six independent pipeline analyses; first-ascent red giant branch (RGB) and red clump (RC) evolutionary state classifications from machine learning; and ready-to-use radius and mass coefficients, κR and κM, which, when appropriately multiplied by a solar-scaled effective temperature factor, yield physical stellar radii and masses. In total, we report 4395 radius and mass coefficients, with typical uncertainties of 3.3% (stat.) ± 1% (syst.) for κR and 7.7% (stat.) ± 2% (syst.) for κM among RGB stars, and 5.0% (stat.) ± 1% (syst.) for κR and 10.5% (stat.) ± 2% (syst.) for κM among RC stars. We verify that the sample is nearly complete—except for a dearth of stars with ${\nu }_{\max }\lesssim 10\mbox{--}20\,\mu \mathrm{Hz}$ —by comparing to Galactic models and visual inspection. Our asteroseismic radii agree with radii derived from Gaia Data Release 2 parallaxes to within 2.2% ± 0.3% for RGB stars and 2.0% ± 0.6% for RC stars. Title: A next generation upgraded observing platform for the automated Birmingham Solar Oscillations Network (BiSON) Authors: Hale, S. J.; Chaplin, W. J.; Davies, G. R.; Elsworth, Y. P. Bibcode: 2020SPIE11452E..22H Altcode: The Birmingham Solar Oscillations Network (BiSON) is a collection of ground-based automated telescopes observing oscillations of the Sun. The network has been operating since the early 1990s. We present development work on a prototype next generation observation platform, BiSON:NG, based almost entirely on inexpensive offthe-shelf components, and where the footprint is reduced to a size that can be inexpensively installed on the roof of an existing building. Continuous development is essential in ensuring that automated networks such as BiSON are well placed to observe the next solar cycle and beyond. Title: From solar-like to mira stars: a unifying description of stellar pulsators in the presence of stochastic noise Authors: Cunha, M. S.; Avelino, P. P.; Chaplin, W. J. Bibcode: 2020MNRAS.499.4687C Altcode: 2020arXiv200909873C; 2020MNRAS.tmp.2755C We discuss and characterize the power spectral density properties of a model aimed at describing pulsations in stars from the main-sequence to the asymptotic giant branch. We show that the predicted limit of the power spectral density for a pulsation mode in the presence of stochastic noise is always well approximated by a Lorentzian function. While in stars predominantly stochastically driven the width of the Lorentzian is defined by the mode lifetime, in stars where the driving is predominately coherent the width is defined by the amplitude of the stochastic perturbations. In stars where both drivings are comparable, the width is defined by both these parameters and is smaller than that expected from pure stochastic driving. We illustrate our model through numerical simulations and propose a well-defined classification of stars into predominantly stochastic (solar-like) and predominately coherent (classic) pulsators. We apply the model to the study of the Mira variable U Per, and the semiregular variable L2 Pup and, following our classification, conclude that they are both classical pulsators. Our model provides a natural explanation for the change in behaviour of the pulsation amplitude-period relation noted in several earlier works. Moreover, our study of L2 Pup enables us to test the scaling relation between the mode line width and effective temperature, confirming that an exponential scaling reproduces well the data all the way from the main sequence to the asymptotic giant branch, down to temperatures about 1000 K below what has been tested in previous studies. Title: Robust asteroseismic properties of the bright planet host HD 38529 Authors: Ball, Warrick H.; Chaplin, William J.; Nielsen, Martin B.; González-Cuesta, Lucia; Mathur, Savita; Santos, Ângela R. G.; García, Rafael; Buzasi, Derek; Mosser, Benoît; Deal, Morgan; Stokholm, Amalie; Mosumgaard, Jakob Rørsted; Silva Aguirre, Victor; Nsamba, Benard; Campante, Tiago; Cunha, Margarida S.; Ong, Joel; Basu, Sarbani; Örtel, Sibel; Çelik Orhan, Z.; Yıldız, Mutlu; Stassun, Keivan; Kane, Stephen R.; Huber, Daniel Bibcode: 2020MNRAS.499.6084B Altcode: 2020arXiv201007323B; 2020MNRAS.tmp.3009B The Transiting Exoplanet Survey Satellite (TESS) is recording short-cadence, high duty-cycle timeseries across most of the sky, which presents the opportunity to detect and study oscillations in interesting stars, in particular planet hosts. We have detected and analysed solar-like oscillations in the bright G4 subgiant HD 38529, which hosts an inner, roughly Jupiter-mass planet on a $14.3\, \mathrm{d}$ orbit and an outer, low-mass brown dwarf on a $2136\, \mathrm{d}$ orbit. We combine results from multiple stellar modelling teams to produce robust asteroseismic estimates of the star's properties, including its mass $M=1.48\pm 0.04\, \mathrm{M}_\odot {}$, radius $R=2.68\pm 0.03\, \mathrm{R}_\odot {}$, and age $t=3.07\pm 0.39\, \mathrm{Gyr}{}$. Our results confirm that HD 38529 has a mass near the higher end of the range that can be found in the literature and also demonstrate that precise stellar properties can be measured given shorter timeseries than produced by CoRoT, Kepler, or K2. Title: A Layered Approach to Robust Determination of Asteroseismic Parameters Authors: Elsworth, Yvonne; Themeßl, Nathalie; Hekker, Saskia; Chaplin, William Bibcode: 2020RNAAS...4..177E Altcode: We describe here a layered approach to the robust determination of the broad characteristics of the asteroseismic signal from red-giant stars. No single stringent test can exclude all false results. The use of multiple, weak tests not only provides robust results but also avoids over-constraining the parameter space. Title: The TESS light curve of AI Phoenicis Authors: Maxted, P. F. L.; Gaulme, Patrick; Graczyk, D.; Hełminiak, K. G.; Johnston, C.; Orosz, Jerome A.; Prša, Andrej; Southworth, John; Torres, Guillermo; Davies, Guy R.; Ball, Warrick; Chaplin, William J. Bibcode: 2020MNRAS.498..332M Altcode: 2020arXiv200309295M; 2020MNRAS.tmp.1795M Accurate masses and radii for normal stars derived from observations of detached eclipsing binary stars are of fundamental importance for testing stellar models and may be useful for calibrating free parameters in these model if the masses and radii are sufficiently precise and accurate. We aim to measure precise masses and radii for the stars in the bright eclipsing binary AI Phe, and to quantify the level of systematic error in these estimates. We use several different methods to model the Transiting Exoplanet Survey Satellite (TESS) light curve of AI Phe combined with spectroscopic orbits from multiple sources to estimate precisely the stellar masses and radii together with robust error estimates. We find that the agreement between different methods for the light-curve analysis is very good but some methods underestimate the errors on the model parameters. The semi-amplitudes of the spectroscopic orbits derived from spectra obtained with modern échelle spectrographs are consistent to within 0.1 per cent. The masses of the stars in AI Phe are $M_1 = 1.1938 \pm 0.0008\, \rm M_{\odot }$ and $M_2 = 1.2438 \pm 0.0008\, \rm M_{\odot }$ , and the radii are $R_1 = 1.8050 \pm 0.0022\, \rm R_{\odot }$ and $R_2 = 2.9332 \pm 0.0023\, \rm R_{\odot }$ . We conclude that it is possible to measure accurate masses and radii for stars in bright eclipsing binary stars to a precision of 0.2 per cent or better using photometry from TESS and spectroscopy obtained with modern échelle spectrographs. We provide recommendations for publishing masses and radii of eclipsing binary stars at this level of precision. Title: TESS asteroseismology of the known planet host star λ2 Fornacis Authors: Nielsen, M. B.; Ball, W. H.; Standing, M. R.; Triaud, A. H. M. J.; Buzasi, D.; Carboneau, L.; Stassun, K. G.; Kane, S. R.; Chaplin, W. J.; Bellinger, E. P.; Mosser, B.; Roxburgh, I. W.; Çelik Orhan, Z.; Yıldız, M.; Örtel, S.; Vrard, M.; Mazumdar, A.; Ranadive, P.; Deal, M.; Davies, G. R.; Campante, T. L.; García, R. A.; Mathur, S.; González-Cuesta, L.; Serenelli, A. Bibcode: 2020A&A...641A..25N Altcode: 2020arXiv200700497N Context. The Transiting Exoplanet Survey Satellite (TESS) is observing bright known planet-host stars across almost the entire sky. These stars have been subject to extensive ground-based observations, providing a large number of radial velocity measurements.
Aims: The objective of this work is to use the new TESS photometric observations to characterize the star λ2 Fornacis, and following this to update the parameters of the orbiting planet λ2 For b.
Methods: We measured the frequencies of the p-mode oscillations in λ2 For, and in combination with non-seismic parameters estimated the stellar fundamental properties using stellar models. Using the revised stellar properties and a time series of archival radial velocities from the UCLES, HIRES and HARPS instruments spanning almost 20 years, we refit the orbit of λ2 For b and searched the residual radial velocities for remaining variability.
Results: We find that λ2 For has a mass of 1.16 ± 0.03 M⊙ and a radius of 1.63 ± 0.04 R⊙, with an age of 6.3 ± 0.9 Gyr. This and the updated radial velocity measurements suggest a mass of λ2 For b of 16.8-1.3+1.2 M⊕, which is ∼5M⊕ less than literature estimates. We also detect an additional periodicity at 33 days in the radial velocity measurements, which is likely due to the rotation of the host star.
Conclusions: While previous literature estimates of the properties of λ2 For are ambiguous, the asteroseismic measurements place the star firmly at the early stage of its subgiant evolutionary phase. Typically only short time series of photometric data are available from TESS, but by using asteroseismology it is still possible to provide tight constraints on the properties of bright stars that until now have only been observed from the ground. This prompts a reexamination of archival radial velocity data that have been accumulated in the past few decades in order to update the characteristics of the planet hosting systems observed by TESS for which asteroseismology is possible. Title: VizieR Online Data Catalog: RAVE 6th data release (Steinmetz+, 2020) Authors: Steinmetz, M.; Matijevic, G.; Enke, H.; Zwitter, T.; Guiglion, G.; McMillan, P. J.; Kordopatis, G.; Valentini, M.; Chiappini, C.; Casagrande, L.; Wojno, J.; Anguiano, B.; Bienayme, O.; Bijaoui, A.; Binney, J.; Burton, D.; Cass, P.; de Laverny, P.; Fiegert, K.; Freeman, K.; Fulbright, J. P.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Kunder, A.; Munari, U.; Navarro, J. F.; Parker, Q.; Ruchti, G. R.; Recio-Blanco, A.; Reid, W.; Seabroke, G. M.; Siviero, A.; Siebert, A.; Stupar, M.; Watson, F.; Williams, M. E. K.; Wyse, R. F. G.; Anders, F.; Antoja, T.; Birko, D.; Bland-Hawthorn, J.; Bossini, D.; Garcia, R. A.; Carrillo, I.; Chaplin, W. J.; Elsworth, Y.; Famaey, B.; Gerhard, O.; Jofre, P.; Just, A.; Mathur, S.; Miglio, A.; Minchev, I.; Monari, G.; Mosser, B.; Ritter, A.; Rodrigues, T. S.; Scholz, R. -D.; Sharma, S.; Sysoliatina, K. Bibcode: 2020yCat.3283....0S Altcode: The Radial Velocity Experiment (RAVE) is a magnitude-limited (9<I<12) spectroscopic survey of Galactic stars randomly selected in the southern hemisphere. The RAVE medium resolution spectra (R~7500) cover the Ca-triplet region (8410-8795Å) and span the complete time frame from the start of RAVE observations on 12 April 2003 to their completion on 4 April 2013. Wavelength-calibrated and flux-normalized spectra for 518387 observations of 451783 unique stars are presented. The final data release 6 consists of spectra, error spectra, spectral classification, derived radial velocities, and cross matches with other relevant catalogs.

Further data products are using a suite of advanced reduction pipelines focusing on stellar atmospheric parameters, in particular purely spectroscopically derived stellar atmospheric parameters (Teff, logg, and the overall metallicity), enhanced stellar parameters inferred via a Bayesian pipeline using Gaia DR2 astrometric priors, and asteroseismically calibrated stellar parameters for giant stars based on asteroseismic observations for 699 K2 stars. In addition, we provide abundances of the elements Fe, Al, and Ni, as well as an overall [alpha/Fe] ratio obtained using a new pipeline based on the GAUGUIN optimization method that is able to deal with variable signal-to-noise ratios. The Rave DR6 catalogs are cross matched with relevant astrometric and photometric catalogs, and are complemented by orbital parameters and effective temperatures based on the infrared flux method.

(22 data files). Title: The Evolution of Rotation and Magnetic Activity in 94 Aqr Aa from Asteroseismology with TESS Authors: Metcalfe, Travis S.; van Saders, Jennifer L.; Basu, Sarbani; Buzasi, Derek; Chaplin, William J.; Egeland, Ricky; Garcia, Rafael A.; Gaulme, Patrick; Huber, Daniel; Reinhold, Timo; Schunker, Hannah; Stassun, Keivan G.; Appourchaux, Thierry; Ball, Warrick H.; Bedding, Timothy R.; Deheuvels, Sébastien; González-Cuesta, Lucía; Handberg, Rasmus; Jiménez, Antonio; Kjeldsen, Hans; Li, Tanda; Lund, Mikkel N.; Mathur, Savita; Mosser, Benoit; Nielsen, Martin B.; Noll, Anthony; Çelik Orhan, Zeynep; Örtel, Sibel; Santos, Ângela R. G.; Yildiz, Mutlu; Baliunas, Sallie; Soon, Willie Bibcode: 2020ApJ...900..154M Altcode: 2020arXiv200712755M Most previous efforts to calibrate how rotation and magnetic activity depend on stellar age and mass have relied on observations of clusters, where isochrones from stellar evolution models are used to determine the properties of the ensemble. Asteroseismology employs similar models to measure the properties of an individual star by matching its normal modes of oscillation, yielding the stellar age and mass with high precision. We use 27 days of photometry from the Transiting Exoplanet Survey Satellite to characterize solar-like oscillations in the G8 subgiant of the 94 Aqr triple system. The resulting stellar properties, when combined with a reanalysis of 35 yr of activity measurements from the Mount Wilson HK project, allow us to probe the evolution of rotation and magnetic activity in the system. The asteroseismic age of the subgiant agrees with a stellar isochrone fit, but the rotation period is much shorter than expected from standard models of angular momentum evolution. We conclude that weakened magnetic braking may be needed to reproduce the stellar properties, and that evolved subgiants in the hydrogen shell-burning phase can reinvigorate large-scale dynamo action and briefly sustain magnetic activity cycles before ascending the red giant branch. Title: The Sixth Data Release of the Radial Velocity Experiment (RAVE). I. Survey Description, Spectra, and Radial Velocities Authors: Steinmetz, Matthias; Matijevič, Gal; Enke, Harry; Zwitter, Tomaž; Guiglion, Guillaume; McMillan, Paul J.; Kordopatis, Georges; Valentini, Marica; Chiappini, Cristina; Casagrande, Luca; Wojno, Jennifer; Anguiano, Borja; Bienaymé, Olivier; Bijaoui, Albert; Binney, James; Burton, Donna; Cass, Paul; de Laverny, Patrick; Fiegert, Kristin; Freeman, Kenneth; Fulbright, Jon P.; Gibson, Brad K.; Gilmore, Gerard; Grebel, Eva K.; Helmi, Amina; Kunder, Andrea; Munari, Ulisse; Navarro, Julio F.; Parker, Quentin; Ruchti, Gregory R.; Recio-Blanco, Alejandra; Reid, Warren; Seabroke, George M.; Siviero, Alessandro; Siebert, Arnaud; Stupar, Milorad; Watson, Fred; Williams, Mary E. K.; Wyse, Rosemary F. G.; Anders, Friedrich; Antoja, Teresa; Birko, Danijela; Bland-Hawthorn, Joss; Bossini, Diego; García, Rafael A.; Carrillo, Ismael; Chaplin, William J.; Elsworth, Yvonne; Famaey, Benoit; Gerhard, Ortwin; Jofre, Paula; Just, Andreas; Mathur, Savita; Miglio, Andrea; Minchev, Ivan; Monari, Giacomo; Mosser, Benoit; Ritter, Andreas; Rodrigues, Thaise S.; Scholz, Ralf-Dieter; Sharma, Sanjib; Sysoliatina, Kseniia; RAVE Collaboration Bibcode: 2020AJ....160...82S Altcode: 2020arXiv200204377S The Radial Velocity Experiment (RAVE) is a magnitude-limited (9 < I < 12) spectroscopic survey of Galactic stars randomly selected in Earth's southern hemisphere. The RAVE medium-resolution spectra (R ∼ 7500) cover the Ca-triplet region (8410-8795 Å). The sixth and final data release (DR6) is based on 518,387 observations of 451,783 unique stars. RAVE observations were taken between 2003 April 12 and 2013 April 4. Here we present the genesis, setup, and data reduction of RAVE as well as wavelength-calibrated and flux-normalized spectra and error spectra for all observations in RAVE DR6. Furthermore, we present derived spectral classification and radial velocities for the RAVE targets, complemented by cross-matches with Gaia DR2 and other relevant catalogs. A comparison between internal error estimates, variances derived from stars with more than one observing epoch, and a comparison with radial velocities of Gaia DR2 reveals consistently that 68% of the objects have a velocity accuracy better than 1.4 km s-1, while 95% of the objects have radial velocities better than 4.0 km s-1. Stellar atmospheric parameters, abundances and distances are presented in a subsequent publication. The data can be accessed via the RAVE website (http://rave-survey.org) or the Vizier database. Title: The Sixth Data Release of the Radial Velocity Experiment (RAVE). II. Stellar Atmospheric Parameters, Chemical Abundances, and Distances Authors: Steinmetz, Matthias; Guiglion, Guillaume; McMillan, Paul J.; Matijevič, Gal; Enke, Harry; Kordopatis, Georges; Zwitter, Tomaž; Valentini, Marica; Chiappini, Cristina; Casagrande, Luca; Wojno, Jennifer; Anguiano, Borja; Bienaymé, Olivier; Bijaoui, Albert; Binney, James; Burton, Donna; Cass, Paul; de Laverny, Patrick; Fiegert, Kristin; Freeman, Kenneth; Fulbright, Jon P.; Gibson, Brad K.; Gilmore, Gerard; Grebel, Eva K.; Helmi, Amina; Kunder, Andrea; Munari, Ulisse; Navarro, Julio F.; Parker, Quentin; Ruchti, Gregory R.; Recio-Blanco, Alejandra; Reid, Warren; Seabroke, George M.; Siviero, Alessandro; Siebert, Arnaud; Stupar, Milorad; Watson, Fred; Williams, Mary E. K.; Wyse, Rosemary F. G.; Anders, Friedrich; Antoja, Teresa; Birko, Danijela; Bland-Hawthorn, Joss; Bossini, Diego; García, Rafael A.; Carrillo, Ismael; Chaplin, William J.; Elsworth, Yvonne; Famaey, Benoit; Gerhard, Ortwin; Jofre, Paula; Just, Andreas; Mathur, Savita; Miglio, Andrea; Minchev, Ivan; Monari, Giacomo; Mosser, Benoit; Ritter, Andreas; Rodrigues, Thaise S.; Scholz, Ralf-Dieter; Sharma, Sanjib; Sysoliatina, Kseniia; RAVE Collaboration Bibcode: 2020AJ....160...83S Altcode: 2020arXiv200204512S We present part 2 of the sixth and final Data Release (DR6) of the Radial Velocity Experiment (RAVE), a magnitude-limited ( $9\lt I\lt 12$ ) spectroscopic survey of Galactic stars randomly selected in Earth's southern hemisphere. The RAVE medium-resolution spectra (R ∼ 7500) cover the Ca triplet region (8410-8795 Å) and span the complete time frame from the start of RAVE observations on 2003 April 12 to their completion on 2013 April 4. In the second of two publications, we present the data products derived from 518,387 observations of 451,783 unique stars using a suite of advanced reduction pipelines focusing on stellar atmospheric parameters, in particular purely spectroscopically derived stellar atmospheric parameters ( ${T}_{\mathrm{eff}}$ , $\mathrm{log}g$ , and the overall metallicity), enhanced stellar atmospheric parameters inferred via a Bayesian pipeline using Gaia DR2 astrometric priors, and asteroseismically calibrated stellar atmospheric parameters for giant stars based on asteroseismic observations for 699 K2 stars. In addition, we provide abundances of the elements Fe, Al, and Ni, as well as an overall [α/Fe] ratio obtained using a new pipeline based on the GAUGUIN optimization method that is able to deal with variable signal-to-noise ratios. The RAVE DR6 catalogs are cross-matched with relevant astrometric and photometric catalogs, and are complemented by orbital parameters and effective temperatures based on the infrared flux method. The data can be accessed via the RAVE website (http://rave-survey.org) or the Vizier database. Title: The 16th Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra Authors: Ahumada, Romina; Prieto, Carlos Allende; Almeida, Andrés; Anders, Friedrich; Anderson, Scott F.; Andrews, Brett H.; Anguiano, Borja; Arcodia, Riccardo; Armengaud, Eric; Aubert, Marie; Avila, Santiago; Avila-Reese, Vladimir; Badenes, Carles; Balland, Christophe; Barger, Kat; Barrera-Ballesteros, Jorge K.; Basu, Sarbani; Bautista, Julian; Beaton, Rachael L.; Beers, Timothy C.; Benavides, B. Izamar T.; Bender, Chad F.; Bernardi, Mariangela; Bershady, Matthew; Beutler, Florian; Bidin, Christian Moni; Bird, Jonathan; Bizyaev, Dmitry; Blanc, Guillermo A.; Blanton, Michael R.; Boquien, Médéric; Borissova, Jura; Bovy, Jo; Brandt, W. N.; Brinkmann, Jonathan; Brownstein, Joel R.; Bundy, Kevin; Bureau, Martin; Burgasser, Adam; Burtin, Etienne; Cano-Díaz, Mariana; Capasso, Raffaella; Cappellari, Michele; Carrera, Ricardo; Chabanier, Solène; Chaplin, William; Chapman, Michael; Cherinka, Brian; Chiappini, Cristina; Doohyun Choi, Peter; Chojnowski, S. Drew; Chung, Haeun; Clerc, Nicolas; Coffey, Damien; Comerford, Julia M.; Comparat, Johan; da Costa, Luiz; Cousinou, Marie-Claude; Covey, Kevin; Crane, Jeffrey D.; Cunha, Katia; Ilha, Gabriele da Silva; Dai, Yu Sophia; Damsted, Sanna B.; Darling, Jeremy; Davidson, James W., Jr.; Davies, Roger; Dawson, Kyle; De, Nikhil; de la Macorra, Axel; De Lee, Nathan; Queiroz, Anna Bárbara de Andrade; Deconto Machado, Alice; de la Torre, Sylvain; Dell'Agli, Flavia; du Mas des Bourboux, Hélion; Diamond-Stanic, Aleksandar M.; Dillon, Sean; Donor, John; Drory, Niv; Duckworth, Chris; Dwelly, Tom; Ebelke, Garrett; Eftekharzadeh, Sarah; Davis Eigenbrot, Arthur; Elsworth, Yvonne P.; Eracleous, Mike; Erfanianfar, Ghazaleh; Escoffier, Stephanie; Fan, Xiaohui; Farr, Emily; Fernández-Trincado, José G.; Feuillet, Diane; Finoguenov, Alexis; Fofie, Patricia; Fraser-McKelvie, Amelia; Frinchaboy, Peter M.; Fromenteau, Sebastien; Fu, Hai; Galbany, Lluís; Garcia, Rafael A.; García-Hernández, D. A.; Oehmichen, Luis Alberto Garma; Ge, Junqiang; Maia, Marcio Antonio Geimba; Geisler, Doug; Gelfand, Joseph; Goddy, Julian; Gonzalez-Perez, Violeta; Grabowski, Kathleen; Green, Paul; Grier, Catherine J.; Guo, Hong; Guy, Julien; Harding, Paul; Hasselquist, Sten; Hawken, Adam James; Hayes, Christian R.; Hearty, Fred; Hekker, S.; Hogg, David W.; Holtzman, Jon A.; Horta, Danny; Hou, Jiamin; Hsieh, Bau-Ching; Huber, Daniel; Hunt, Jason A. S.; Chitham, J. Ider; Imig, Julie; Jaber, Mariana; Angel, Camilo Eduardo Jimenez; Johnson, Jennifer A.; Jones, Amy M.; Jönsson, Henrik; Jullo, Eric; Kim, Yerim; Kinemuchi, Karen; Kirkpatrick, Charles C., IV; Kite, George W.; Klaene, Mark; Kneib, Jean-Paul; Kollmeier, Juna A.; Kong, Hui; Kounkel, Marina; Krishnarao, Dhanesh; Lacerna, Ivan; Lan, Ting-Wen; Lane, Richard R.; Law, David R.; Le Goff, Jean-Marc; Leung, Henry W.; Lewis, Hannah; Li, Cheng; Lian, Jianhui; Lin, Lihwai; Long, Dan; Longa-Peña, Penélope; Lundgren, Britt; Lyke, Brad W.; Ted Mackereth, J.; MacLeod, Chelsea L.; Majewski, Steven R.; Manchado, Arturo; Maraston, Claudia; Martini, Paul; Masseron, Thomas; Masters, Karen L.; Mathur, Savita; McDermid, Richard M.; Merloni, Andrea; Merrifield, Michael; Mészáros, Szabolcs; Miglio, Andrea; Minniti, Dante; Minsley, Rebecca; Miyaji, Takamitsu; Mohammad, Faizan Gohar; Mosser, Benoit; Mueller, Eva-Maria; Muna, Demitri; Muñoz-Gutiérrez, Andrea; Myers, Adam D.; Nadathur, Seshadri; Nair, Preethi; Nandra, Kirpal; do Nascimento, Janaina Correa; Nevin, Rebecca Jean; Newman, Jeffrey A.; Nidever, David L.; Nitschelm, Christian; Noterdaeme, Pasquier; O'Connell, Julia E.; Olmstead, Matthew D.; Oravetz, Daniel; Oravetz, Audrey; Osorio, Yeisson; Pace, Zachary J.; Padilla, Nelson; Palanque-Delabrouille, Nathalie; Palicio, Pedro A.; Pan, Hsi-An; Pan, Kaike; Parker, James; Paviot, Romain; Peirani, Sebastien; Ramŕez, Karla Peña; Penny, Samantha; Percival, Will J.; Perez-Fournon, Ismael; Pérez-Ràfols, Ignasi; Petitjean, Patrick; Pieri, Matthew M.; Pinsonneault, Marc; Poovelil, Vijith Jacob; Povick, Joshua Tyler; Prakash, Abhishek; Price-Whelan, Adrian M.; Raddick, M. Jordan; Raichoor, Anand; Ray, Amy; Rembold, Sandro Barboza; Rezaie, Mehdi; Riffel, Rogemar A.; Riffel, Rogério; Rix, Hans-Walter; Robin, Annie C.; Roman-Lopes, A.; Román-Zúñiga, Carlos; Rose, Benjamin; Ross, Ashley J.; Rossi, Graziano; Rowlands, Kate; Rubin, Kate H. R.; Salvato, Mara; Sánchez, Ariel G.; Sánchez-Menguiano, Laura; Sánchez-Gallego, José R.; Sayres, Conor; Schaefer, Adam; Schiavon, Ricardo P.; Schimoia, Jaderson S.; Schlafly, Edward; Schlegel, David; Schneider, Donald P.; Schultheis, Mathias; Schwope, Axel; Seo, Hee-Jong; Serenelli, Aldo; Shafieloo, Arman; Shamsi, Shoaib Jamal; Shao, Zhengyi; Shen, Shiyin; Shetrone, Matthew; Shirley, Raphael; Aguirre, Víctor Silva; Simon, Joshua D.; Skrutskie, M. F.; Slosar, Anže; Smethurst, Rebecca; Sobeck, Jennifer; Sodi, Bernardo Cervantes; Souto, Diogo; Stark, David V.; Stassun, Keivan G.; Steinmetz, Matthias; Stello, Dennis; Stermer, Julianna; Storchi-Bergmann, Thaisa; Streblyanska, Alina; Stringfellow, Guy S.; Stutz, Amelia; Suárez, Genaro; Sun, Jing; Taghizadeh-Popp, Manuchehr; Talbot, Michael S.; Tayar, Jamie; Thakar, Aniruddha R.; Theriault, Riley; Thomas, Daniel; Thomas, Zak C.; Tinker, Jeremy; Tojeiro, Rita; Toledo, Hector Hernandez; Tremonti, Christy A.; Troup, Nicholas W.; Tuttle, Sarah; Unda-Sanzana, Eduardo; Valentini, Marica; Vargas-González, Jaime; Vargas-Magaña, Mariana; Vázquez-Mata, Jose Antonio; Vivek, M.; Wake, David; Wang, Yuting; Weaver, Benjamin Alan; Weijmans, Anne-Marie; Wild, Vivienne; Wilson, John C.; Wilson, Robert F.; Wolthuis, Nathan; Wood-Vasey, W. M.; Yan, Renbin; Yang, Meng; Yèche, Christophe; Zamora, Olga; Zarrouk, Pauline; Zasowski, Gail; Zhang, Kai; Zhao, Cheng; Zhao, Gongbo; Zheng, Zheng; Zheng, Zheng; Zhu, Guangtun; Zou, Hu Bibcode: 2020ApJS..249....3A Altcode: 2019arXiv191202905A This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17). Title: TESS Asteroseismic Analysis of the Known Exoplanet Host Star HD 222076 Authors: Jiang, Chen; Bedding, Timothy R.; Stassun, Keivan G.; Veras, Dimitri; Corsaro, Enrico; Buzasi, Derek L.; Mikołajczyk, Przemysław; Zhang, Qian-sheng; Ou, Jian-wen; Campante, Tiago L.; Rodrigues, Thaíise S.; Nsamba, Benard; Bossini, Diego; Kane, Stephen R.; Ong, Jia Mian Joel; Yıldız, Mutlu; Çelik Orhan, Zeynep; Örtel, Sibel; Wu, Tao; Zhang, Xinyi; Li, Tanda; Basu, Sarbani; Cunha, Margarida S.; Christensen-Dalsgaard, Jørgen; Chaplin, William J. Bibcode: 2020ApJ...896...65J Altcode: 2020arXiv200500272J The Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission aiming to search for exoplanets that transit bright stars. The high-quality photometric data of TESS are excellent for the asteroseismic study of solar-like stars. In this work, we present an asteroseismic analysis of the red-giant star HD 222076 hosting a long-period (2.4 yr) giant planet discovered through radial velocities. Solar-like oscillations of HD 222076 are detected around 203 μHz by TESS for the first time. Asteroseismic modeling, using global asteroseismic parameters as inputs, yields a determination of the stellar mass ( ${M}_{\star }=1.12\pm 0.12\,{M}_{\odot }$ ), radius ( ${R}_{\star }=4.34\pm 0.21\,{R}_{\odot }$ ), and age (7.4 ± 2.7 Gyr), with precisions greatly improved from previous studies. The period spacing of the dipolar mixed modes extracted from the observed power spectrum reveals that the star is on the red-giant branch burning hydrogen in a shell surrounding the core. We find that the planet will not escape the tidal pull of the star and will be engulfed into it within about 800 Myr, before the tip of the red-giant branch is reached. Title: VizieR Online Data Catalog: APOGEE-2 data from DR16 (Majewski+, 2017) Authors: Majewski, S. R.; Schiavon, R. P.; Frinchaboy, P. M.; Allende Prieto, C.; Barkhouser, R.; Bizyaev, D.; Blank, B.; Brunner, S.; Burton, A.; Carrera, R.; Chojnowski, S. D.; Cunha, K.; Epstein, C.; Fitzgerald, G.; Garcia Perez, A. E.; Hearty, F. R.; Henderson, C.; Holtzman, J. A.; Johnson, J. A.; Lam, C. R.; Lawler, J. E.; Maseman, P.; Meszaros, S.; Nelson, M.; Nguyen, D. C.; Nidever, D. L.; Pinsonneault, M.; Shetrone, M.; Smee, S.; Smith, V. V.; Stolberg, T.; Skrutskie, M. F.; Walker, E.; Wilson, J. C.; Zasowski, G.; Anders, F.; Basu, S.; Beland, S.; Blanton, M. R.; Bovy, J.; Brownstein, J. R.; Carlberg, J.; Chaplin, W.; Chiappini, C.; Eisenstein, D. J.; Elsworth, Y.; Feuillet, D.; Fleming, S. W.; Galbraith-Frew, J.; Garcia, R. A.; Garcia-Hernandez, D. A.; Gillespie, B. A.; Girardi, L.; Gunn, J. E.; Hasselquist, S.; Hayden, M. R.; Hekker, S.; Ivans, I.; Kinemuchi, K.; Klaene, M.; Mahadevan, S.; Mathur, S.; Mosser, B.; Muna, D.; Munn, J. A.; Nichol, R. C.; O'Connell, R. W.; Parejko, J. K.; Robin, A. C.; Rocha-Pinto, H.; Schultheis, M.; Serenelli, A. M.; Shane, N.; Silva Aguirre, E. V.; Sob Eck, J. S.; Thompson, B.; Troup, N. W.; Weinberg, D. H.; Zamora, O. Bibcode: 2020yCat..51540094M Altcode: The second generation of the Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) observes the "archaeological" record embedded in hundreds of thousands of stars to explore the assembly history and evolution of the Milky Way Galaxy.

APOGEE-2 maps the dynamical and chemical patterns of Milky Way stars with data from the 1-meter NMSU Telescope and the 2.5-meter Sloan Foundation Telescope at the Apache Point Observatory in New Mexico (APOGEE-2N), and the 2.5-meter du Pont Telescope at Las Campanas Observatory in Chile (APOGEE-2S).

(2 data files). Title: VizieR Online Data Catalog: APOGEE-2 data from DR16 (Majewski+, 2017) Authors: Majewski, S. R.; Schiavon, R. P.; Frinchaboy, P. M.; Allende Prieto, C.; Barkhouser, R.; Bizyaev, D.; Blank, B.; Brunner, S.; Burton, A.; Carrera, R.; Chojnowski, S. D.; Cunha, K.; Epstein, C.; Fitzgerald, G.; Garcia Perez, A. E.; Hearty, F. R.; Henderson, C.; Holtzman, J. A.; Johnson, J. A.; Lam, C. R.; Lawler, J. E.; Maseman, P.; Meszaros, S.; Nelson, M.; Nguyen, D. C.; Nidever, D. L.; Pinsonneault, M.; Shetrone, M.; Smee, S.; Smith, V. V.; Stolberg, T.; Skrutskie, M. F.; Walker, E.; Wilson, J. C.; Zasowski, G.; Anders, F.; Basu, S.; Beland, S.; Blanton, M. R.; Bovy, J.; Brownstein, J. R.; Carlberg, J.; Chaplin, W.; Chiappini, C.; Eisenstein, D. J.; Elsworth, Y.; Feuillet, D.; Fleming, S. W.; Galbraith-Frew, J.; Garcia, R. A.; Garcia-Hernandez, D. A.; Gillespie, B. A.; Girardi, L.; Gunn, J. E.; Hasselquist, S.; Hayden, M. R.; Hekker, S.; Ivans, I.; Kinemuchi, K.; Klaene, M.; Mahadevan, S.; Mathur, S.; Mosser, B.; Muna, D.; Munn, J. A.; Nichol, R. C.; O'Connell, R. W.; Parejko, J. K.; Robin, A. C.; Rocha-Pinto, H.; Schultheis, M.; Serenelli, A. M.; Shane, N.; Silva Aguirre, E. V.; Sob Eck, J. S.; Thompson, B.; Troup, N. W.; Weinberg, D. H.; Zamora, O. Bibcode: 2020yCat.3284....0M Altcode: The second generation of the Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) observes the "archaeological" record embedded in hundreds of thousands of stars to explore the assembly history and evolution of the Milky Way Galaxy.

APOGEE-2 maps the dynamical and chemical patterns of Milky Way stars with data from the 1-meter NMSU Telescope and the 2.5-meter Sloan Foundation Telescope at the Apache Point Observatory in New Mexico (APOGEE-2N), and the 2.5-meter du Pont Telescope at Las Campanas Observatory in Chile (APOGEE-2S).

(2 data files). Title: Very regular high-frequency pulsation modes in young intermediate-mass stars Authors: Bedding, Timothy R.; Murphy, Simon J.; Hey, Daniel R.; Huber, Daniel; Li, Tanda; Smalley, Barry; Stello, Dennis; White, Timothy R.; Ball, Warrick H.; Chaplin, William J.; Colman, Isabel L.; Fuller, Jim; Gaidos, Eric; Harbeck, Daniel R.; Hermes, J. J.; Holdsworth, Daniel L.; Li, Gang; Li, Yaguang; Mann, Andrew W.; Reese, Daniel R.; Sekaran, Sanjay; Yu, Jie; Antoci, Victoria; Bergmann, Christoph; Brown, Timothy M.; Howard, Andrew W.; Ireland, Michael J.; Isaacson, Howard; Jenkins, Jon M.; Kjeldsen, Hans; McCully, Curtis; Rabus, Markus; Rains, Adam D.; Ricker, George R.; Tinney, Christopher G.; Vanderspek, Roland K. Bibcode: 2020Natur.581..147B Altcode: 2020arXiv200506157B Asteroseismology probes the internal structures of stars by using their natural pulsation frequencies1. It relies on identifying sequences of pulsation modes that can be compared with theoretical models, which has been done successfully for many classes of pulsators, including low-mass solar-type stars2, red giants3, high-mass stars4 and white dwarfs5. However, a large group of pulsating stars of intermediate mass—the so-called δ Scuti stars—have rich pulsation spectra for which systematic mode identification has not hitherto been possible6,7. This arises because only a seemingly random subset of possible modes are excited and because rapid rotation tends to spoil regular patterns8-10. Here we report the detection of remarkably regular sequences of high-frequency pulsation modes in 60 intermediate-mass main-sequence stars, which enables definitive mode identification. The space motions of some of these stars indicate that they are members of known associations of young stars, as confirmed by modelling of their pulsation spectra. Title: Measurement of Atmospheric Scintillation during a Period of Saharan Dust (Calima) at Observatorio del Teide, Iz∼ana, Tenerife, and the Impact on Photometric Exposure Times Authors: Hale, S. J.; Chaplin, W. J.; Davies, G. R.; Elsworth, Y. P.; Howe, R.; Pallé, P. L. Bibcode: 2020PASP..132c4501H Altcode: We present scintillation noise profiles captured at the Observatorio del Teide, Izaña, Tenerife, over a one-week period in 2017 September. Contemporaneous data from the Birmingham Solar Oscillations Network (BiSON) and the Stellar Activity (STELLA) robotic telescopes provides estimates of daily atmospheric extinction allowing the scintillation noise to be placed within the context of overall atmospheric conditions. We discuss the results both in terms of the impact on BiSON spectrophotometer design, and for astronomical observations more generally. We find that scintillation noise power reduces by half at about 5 Hz, and is reduced to one tenth between 20 and 30 Hz even during periods of mild Calima, where visibility is reduced due to high concentrations of mineral dust in the atmosphere. We show that the common accepted exposure time of <10 ms for limiting the effect of scintillation noise in ground based photometry may be increased, and that depending on the application there may be little benefit to achieving exposure times shorter than 50 ms, relaxing constraints on detector gain and bandwidth. Title: Solar cycle variation of νmax in helioseismic data and its implications for asteroseismology Authors: Howe, Rachel; Chaplin, William J.; Basu, Sarbani; Ball, Warrick H.; Davies, Guy R.; Elsworth, Yvonne; Hale, Steven J.; Miglio, Andrea; Nielsen, Martin Bo; Viani, Lucas S. Bibcode: 2020MNRAS.493L..49H Altcode: 2020MNRAS.tmpL...4H; 2020arXiv200110949C; 2020arXiv200110949H The frequency, νmax, at which the envelope of pulsation power peaks for solar-like oscillators is an important quantity in asteroseismology. We measure νmax for the Sun using 25 yr of Sun-as-a-star Doppler velocity observations with the Birmingham Solar-Oscillations Network (BiSON), by fitting a simple model to binned power spectra of the data. We also apply the fit to Sun-as-a-star Doppler velocity data from Global Oscillation Network Group and Global Oscillations at Low Frequency, and photometry data from VIRGO/SPM on the ESA/NASA SOHO spacecraft. We discover a weak but nevertheless significant positive correlation of the solar νmax with solar activity. The uncovered shift between low and high activity, of ∼eq 25 μ Hz, translates to an uncertainty of 0.8 per cent in radius and 2.4 per cent in mass, based on direct use of asteroseismic scaling relations calibrated to the Sun. The mean νmax in the different data sets is also clearly offset in frequency. Our results flag the need for caution when using νmax in asteroseismology. Title: Modelling stochastic signatures in classical pulsators Authors: Avelino, P. P.; Cunha, M. S.; Chaplin, W. J. Bibcode: 2020MNRAS.492.4477A Altcode: 2020arXiv200104558A; 2020MNRAS.tmp..118A We consider the impact of stochastic perturbations on otherwise coherent oscillations of classical pulsators. The resulting dynamics are modelled by a driven damped harmonic oscillator subject to either an external or an internal forcing and white noise velocity perturbations. We characterize the phase and relative amplitude variations using analytical and numerical tools. When the forcing is internal the phase variation displays a random walk behaviour and a red noise power spectrum with a ragged erratic appearance. We determine the dependence of the root mean square phase and relative amplitude variations (σΔφ and σΔA/A, respectively) on the amplitude of the stochastic perturbations, the damping constant η, and the total observation time tobs for this case, under the assumption that the relative amplitude variations remain small, showing that σΔφ increases with t_obs^{1/2} becoming much larger than σΔA/A for tobs ≫ η-1. In the case of an external forcing the phase and relative amplitude variations remain of the same order, independent of the observing time. In the case of an internal forcing, we find that σΔφ does not depend on η. Hence, the damping time cannot be inferred from fitting the power of the signal, as done for solar-like pulsators, but the amplitude of the stochastic perturbations may be constrained from the observations. Our results imply that, given sufficient time, the variation of the phase associated with the stochastic perturbations in internally driven classical pulsators will become sufficiently large to be probed observationally. Title: Detection and Characterization of Oscillating Red Giants: First Results from the TESS Satellite Authors: Silva Aguirre, Víctor; Stello, Dennis; Stokholm, Amalie; Mosumgaard, Jakob R.; Ball, Warrick H.; Basu, Sarbani; Bossini, Diego; Bugnet, Lisa; Buzasi, Derek; Campante, Tiago L.; Carboneau, Lindsey; Chaplin, William J.; Corsaro, Enrico; Davies, Guy R.; Elsworth, Yvonne; García, Rafael A.; Gaulme, Patrick; Hall, Oliver J.; Handberg, Rasmus; Hon, Marc; Kallinger, Thomas; Kang, Liu; Lund, Mikkel N.; Mathur, Savita; Mints, Alexey; Mosser, Benoit; Çelik Orhan, Zeynep; Rodrigues, Thaíse S.; Vrard, Mathieu; Yıldız, Mutlu; Zinn, Joel C.; Örtel, Sibel; Beck, Paul G.; Bell, Keaton J.; Guo, Zhao; Jiang, Chen; Kuszlewicz, James S.; Kuehn, Charles A.; Li, Tanda; Lundkvist, Mia S.; Pinsonneault, Marc; Tayar, Jamie; Cunha, Margarida S.; Hekker, Saskia; Huber, Daniel; Miglio, Andrea; F. G. Monteiro, Mario J. P.; Slumstrup, Ditte; Winther, Mark L.; Angelou, George; Benomar, Othman; Bódi, Attila; De Moura, Bruno L.; Deheuvels, Sébastien; Derekas, Aliz; Di Mauro, Maria Pia; Dupret, Marc-Antoine; Jiménez, Antonio; Lebreton, Yveline; Matthews, Jaymie; Nardetto, Nicolas; do Nascimento, Jose D., Jr.; Pereira, Filipe; Rodríguez Díaz, Luisa F.; Serenelli, Aldo M.; Spitoni, Emanuele; Stonkutė, Edita; Suárez, Juan Carlos; Szabó, Robert; Van Eylen, Vincent; Ventura, Rita; Verma, Kuldeep; Weiss, Achim; Wu, Tao; Barclay, Thomas; Christensen-Dalsgaard, Jørgen; Jenkins, Jon M.; Kjeldsen, Hans; Ricker, George R.; Seager, Sara; Vanderspek, Roland Bibcode: 2020ApJ...889L..34S Altcode: 2019arXiv191207604S; 2020ApJ...889L..34A Since the onset of the "space revolution" of high-precision high-cadence photometry, asteroseismology has been demonstrated as a powerful tool for informing Galactic archeology investigations. The launch of the NASA Transiting Exoplanet Survey Satellite (TESS) mission has enabled seismic-based inferences to go full sky—providing a clear advantage for large ensemble studies of the different Milky Way components. Here we demonstrate its potential for investigating the Galaxy by carrying out the first asteroseismic ensemble study of red giant stars observed by TESS. We use a sample of 25 stars for which we measure their global asteroseimic observables and estimate their fundamental stellar properties, such as radius, mass, and age. Significant improvements are seen in the uncertainties of our estimates when combining seismic observables from TESS with astrometric measurements from the Gaia mission compared to when the seismology and astrometry are applied separately. Specifically, when combined we show that stellar radii can be determined to a precision of a few percent, masses to 5%-10%, and ages to the 20% level. This is comparable to the precision typically obtained using end-of-mission Kepler data. Title: Modelling the response of potassium vapour in resonance scattering spectroscopy Authors: Hale, S J; Chaplin, W J; Davies, G R; Elsworth, Y P Bibcode: 2020arXiv200204546H Altcode: Resonance scattering techniques are often used to study the properties of atoms and molecules. The Birmingham Solar Oscillations Network (BiSON) makes use of Resonance Scattering Spectroscopy by applying the known properties of potassium vapour to achieve ultra-precise Doppler velocity observations of oscillations of the Sun. We present a model of the resonance scattering properties of potassium vapour which can be used to determine the ideal operating vapour temperature and detector parameters within a spectrophotometer. The model is validated against a typical BiSON vapour cell using a tunable diode laser, where the model is fitted to observed absorption profiles at a range of temperatures. Finally we demonstrate using the model to determine the effects of varying scattering detector aperture size, and vapour temperature, and again validate against observed scattering profiles. Such information is essential when designing the next generation of BiSON spectrophotometers (BiSON:NG), where the aim is to make use of off-the-shelf components to simplify and miniaturise the instrumentation as much as practical. Title: Michael Thompson's Legacy in Solar and Stellar Physics Authors: Chaplin, William J. Bibcode: 2020ASSP...57....3C Altcode: Professor Michael J. Thompson died on 15 October 2018. Michael made long-lasting contributions to the international research community as both a research pioneer in the field of solar and stellar astrophysics and as an administrator who held major leadership positions in the UK and the USA. In this review we summarize his outstanding contributions to research. Title: Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi Authors: Chaplin, William J.; Serenelli, Aldo M.; Miglio, Andrea; Morel, Thierry; Mackereth, J. Ted; Vincenzo, Fiorenzo; Kjeldsen, Hans; Basu, Sarbani; Ball, Warrick H.; Stokholm, Amalie; Verma, Kuldeep; Mosumgaard, Jakob Rørsted; Silva Aguirre, Victor; Mazumdar, Anwesh; Ranadive, Pritesh; Antia, H. M.; Lebreton, Yveline; Ong, Joel; Appourchaux, Thierry; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen; Creevey, Orlagh; García, Rafael A.; Handberg, Rasmus; Huber, Daniel; Kawaler, Steven D.; Lund, Mikkel N.; Metcalfe, Travis S.; Stassun, Keivan G.; Bazot, Michäel; Beck, Paul G.; Bell, Keaton J.; Bergemann, Maria; Buzasi, Derek L.; Benomar, Othman; Bossini, Diego; Bugnet, Lisa; Campante, Tiago L.; Orhan, Zeynep çelik; Corsaro, Enrico; González-Cuesta, Lucía; Davies, Guy R.; Di Mauro, Maria Pia; Egeland, Ricky; Elsworth, Yvonne P.; Gaulme, Patrick; Ghasemi, Hamed; Guo, Zhao; Hall, Oliver J.; Hasanzadeh, Amir; Hekker, Saskia; Howe, Rachel; Jenkins, Jon M.; Jiménez, Antonio; Kiefer, René; Kuszlewicz, James S.; Kallinger, Thomas; Latham, David W.; Lundkvist, Mia S.; Mathur, Savita; Montalbán, Josefina; Mosser, Benoit; Bedón, Andres Moya; Nielsen, Martin Bo; Örtel, Sibel; Rendle, Ben M.; Ricker, George R.; Rodrigues, Thaíse S.; Roxburgh, Ian W.; Safari, Hossein; Schofield, Mathew; Seager, Sara; Smalley, Barry; Stello, Dennis; Szabó, Róbert; Tayar, Jamie; Themeßl, Nathalie; Thomas, Alexandra E. L.; Vanderspek, Roland K.; van Rossem, Walter E.; Vrard, Mathieu; Weiss, Achim; White, Timothy R.; Winn, Joshua N.; Yıldız, Mutlu Bibcode: 2020NatAs...4..382C Altcode: 2020NatAs.tmp....7C; 2020arXiv200104653C Over the course of its history, the Milky Way has ingested multiple smaller satellite galaxies1. Although these accreted stellar populations can be forensically identified as kinematically distinct structures within the Galaxy, it is difficult in general to date precisely the age at which any one merger occurred. Recent results have revealed a population of stars that were accreted via the collision of a dwarf galaxy, called Gaia-Enceladus1, leading to substantial pollution of the chemical and dynamical properties of the Milky Way. Here we identify the very bright, naked-eye star ν Indi as an indicator of the age of the early in situ population of the Galaxy. We combine asteroseismic, spectroscopic, astrometric and kinematic observations to show that this metal-poor, alpha-element-rich star was an indigenous member of the halo, and we measure its age to be 11.0 ±0.7 ? (stat) ±0.8 ? (sys) billion years. The star bears hallmarks consistent with having been kinematically heated by the Gaia-Enceladus collision. Its age implies that the earliest the merger could have begun was 11.6 and 13.2 billion years ago, at 68% and 95% confidence, respectively. Computations based on hierarchical cosmological models slightly reduce the above limits. Title: The K2 Galactic Caps Project - going beyond the Kepler field and ageing the Galactic disc Authors: Rendle, B. M.; Miglio, A.; Chiappini, C.; Valentini, M.; Davies, G. R.; Mosser, B.; Elsworth, Y.; García, R. A.; Mathur, S.; Jofré, P.; Worley, C. C.; Casagrande, L.; Girardi, L.; Lund, M. N.; Feuillet, D. K.; Gavel, A.; Magrini, L.; Khan, S.; Rodrigues, T. S.; Johnson, J. A.; Cunha, K.; Lane, R. L.; Nitschelm, C.; Chaplin, W. J. Bibcode: 2019MNRAS.490.4465R Altcode: 2019MNRAS.tmp.2643R; 2019arXiv190607489R Analyses of data from spectroscopic and astrometric surveys have led to conflicting results concerning the vertical characteristics of the Milky Way. Ages are often used to provide clarity, but typical uncertainties of >40 per cent from photometry restrict the validity of the inferences made. Using the Kepler APOKASC sample for context, we explore the global population trends of two K2 campaign fields (3 and 6), which extend further vertically out of the Galactic plane than APOKASC. We analyse the properties of red giant stars utilizing three asteroseismic data analysis methods to cross-check and validate detections. The Bayesian inference tool PARAM is used to determine the stellar masses, radii, and ages. Evidence of a pronounced red giant branch bump and an [α/Fe] dependence on the position of the red clump is observed from the K2 fields radius distribution. Two peaks in the age distribution centred at ∼5 and ∼12 Gyr are found using a sample with σage < 35 per cent. In comparison with Kepler, we find the older peak to be more prominent for K2. This age bimodality is also observed based on a chemical selection of low-[α/Fe] (≤0.1) and high-[α/Fe] (>0.1) stars. As a function of vertical distance from the Galactic mid-plane (|Z|), the age distribution shows a transition from a young to old stellar population with increasing |Z| for the K2 fields. Further coverage of campaign targets with high-resolution spectroscopy is required to increase the yield of precise ages achievable with asteroseismology. Title: Measurement of atmospheric scintillation during a period of Saharan dust (Calima) at Observatorio del Teide, Izaña, Tenerife, and the impact on photometric exposure times Authors: Hale, S J; Chaplin, W J; Davies, G R; Elsworth, Y P; Howe, R; Pallé, P L Bibcode: 2019arXiv191212237H Altcode: We present scintillation noise profiles captured at the Observatorio del Teide, Izaña, Tenerife, over a one-week period in September 2017. Contemporaneous data from the Birmingham Solar Oscillations Network (BiSON) and the Stellar Activity (STELLA) robotic telescopes provides estimates of daily atmospheric extinction allowing the scintillation noise to be placed within the context of overall atmospheric conditions. We discuss the results both in terms of the impact on BiSON spectrophotometer design, and for astronomical observations more generally. We find that scintillation noise power reduces by half at about~\SI{5}{\hertz}, and is reduced to one tenth between~\SIrange{20}{30}{\hertz} even during periods of mild Calima, where visibility is reduced due to high concentrations of mineral dust in the atmosphere. We show that the common accepted exposure time of~\SI{<10}{\milli\second} for limiting the effect of scintillation noise in ground based photometry may be increased, and that depending on the application there may be little benefit to achieving exposure times shorter than~\SI{50}{\milli\second}, relaxing constraints on detector gain and bandwidth. Title: Asteroseismology of the Multiplanet System K2-93 Authors: Lund, Mikkel N.; Knudstrup, Emil; Silva Aguirre, Víctor; Basu, Sarbani; Chontos, Ashley; Von Essen, Carolina; Chaplin, William J.; Bieryla, Allyson; Casagrande, Luca; Vanderburg, Andrew; Huber, Daniel; Kane, Stephen R.; Albrecht, Simon; Latham, David W.; Davies, Guy R.; Becker, Juliette C.; Rodriguez, Joseph E. Bibcode: 2019AJ....158..248L Altcode: 2019arXiv191107519L We revisit the analysis of the bright multiplanet system K2-93, discovered with data taken by the K2 mission. This system contains five identified planets ranging in size from sub-Neptune to Jupiter size. The K2 data available at the discovery of the system only showed single transits for the three outer planets, which allowed weak constraints to be put on their periods. As these planets are interesting candidates for future atmospheric studies, a better characterization of the host star and tighter constraints on their orbital periods are essential. Using new data from the K2 mission taken after the discovery of the system, we perform an asteroseismic characterization of the host star. We are able to place strong constraints on the stellar parameters and obtain a value for the stellar mass of {1.22}-0.02+0.03 {M}⊙ , a stellar radius of 1.30 ± 0.01 R ⊙, and an age of {2.07}-0.27+0.36 Gyr. Put together with the additional transits identified for two of the three outer planets, we constrain the orbital periods of the outer planets and provide updated estimates for the stellar reflex velocities induced by the planets. Title: TESS Asteroseismology of the Known Red-giant Host Stars HD 212771 and HD 203949 Authors: Campante, Tiago L.; Corsaro, Enrico; Lund, Mikkel N.; Mosser, Benoît; Serenelli, Aldo; Veras, Dimitri; Adibekyan, Vardan; Antia, H. M.; Ball, Warrick; Basu, Sarbani; Bedding, Timothy R.; Bossini, Diego; Davies, Guy R.; Delgado Mena, Elisa; García, Rafael A.; Handberg, Rasmus; Hon, Marc; Kane, Stephen R.; Kawaler, Steven D.; Kuszlewicz, James S.; Lucas, Miles; Mathur, Savita; Nardetto, Nicolas; Nielsen, Martin B.; Pinsonneault, Marc H.; Reffert, Sabine; Silva Aguirre, Víctor; Stassun, Keivan G.; Stello, Dennis; Stock, Stephan; Vrard, Mathieu; Yıldız, Mutlu; Chaplin, William J.; Huber, Daniel; Bean, Jacob L.; Çelik Orhan, Zeynep; Cunha, Margarida S.; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Metcalfe, Travis S.; Miglio, Andrea; Monteiro, Mário J. P. F. G.; Nsamba, Benard; Örtel, Sibel; Pereira, Filipe; Sousa, Sérgio G.; Tsantaki, Maria; Turnbull, Margaret C. Bibcode: 2019ApJ...885...31C Altcode: 2019arXiv190905961C The Transiting Exoplanet Survey Satellite (TESS) is performing a near all-sky survey for planets that transit bright stars. In addition, its excellent photometric precision enables asteroseismology of solar-type and red-giant stars, which exhibit convection-driven, solar-like oscillations. Simulations predict that TESS will detect solar-like oscillations in nearly 100 stars already known to host planets. In this paper, we present an asteroseismic analysis of the known red-giant host stars HD 212771 and HD 203949, both systems having a long-period planet detected through radial velocities. These are the first detections of oscillations in previously known exoplanet-host stars by TESS, further showcasing the mission’s potential to conduct asteroseismology of red-giant stars. We estimate the fundamental properties of both stars through a grid-based modeling approach that uses global asteroseismic parameters as input. We discuss the evolutionary state of HD 203949 in depth and note the large discrepancy between its asteroseismic mass (M * = 1.23 ± 0.15 M ⊙ if on the red-giant branch or M * = 1.00 ± 0.16 M ⊙ if in the clump) and the mass quoted in the discovery paper (M * = 2.1 ± 0.1 M ⊙), implying a change >30% in the planet’s mass. Assuming HD 203949 to be in the clump, we investigate the planet’s past orbital evolution and discuss how it could have avoided engulfment at the tip of the red-giant branch. Finally, HD 212771 was observed by K2 during its Campaign 3, thus allowing for a preliminary comparison of the asteroseismic performances of TESS and K2. We estimate the ratio of the observed oscillation amplitudes for this star to be {A}\max {TESS}/{A}\max K2=0.75+/- 0.14, consistent with the expected ratio of ∼0.85 due to the redder bandpass of TESS. Title: Dynamical heating across the Milky Way disc using APOGEE and Gaia Authors: Mackereth, J. Ted; Bovy, Jo; Leung, Henry W.; Schiavon, Ricardo P.; Trick, Wilma H.; Chaplin, William J.; Cunha, Katia; Feuillet, Diane K.; Majewski, Steven R.; Martig, Marie; Miglio, Andrea; Nidever, David; Pinsonneault, Marc H.; Aguirre, Victor Silva; Sobeck, Jennifer; Tayar, Jamie; Zasowski, Gail Bibcode: 2019MNRAS.489..176M Altcode: 2019arXiv190104502M The kinematics of the Milky Way disc as a function of age are well measured at the solar radius, but have not been studied over a wider range of Galactocentric radii. Here, we measure the kinematics of mono-age, mono-[Fe/H] populations in the low and high [α/Fe] discs between 4 ≲ R ≲ 13 kpc and |z| ≲ 2 kpc using 65 719 stars in common between APOGEE DR14 and Gaia DR2 for which we estimate ages using a Bayesian neural network model trained on asteroseismic ages. We determine the vertical and radial velocity dispersions, finding that the low and high [α/Fe] discs display markedly different age-velocity dispersion relations (AVRs) and shapes σz/σR. The high [α/Fe] disc has roughly flat AVRs and constant σz/σR = 0.64 ± 0.04, whereas the low [α/Fe] disc has large variations in this ratio that positively correlate with the mean orbital radius of the population at fixed age. The high [α/Fe] disc component's flat AVRs and constant σz/σR clearly indicate an entirely different heating history. Outer disc populations also have flatter radial AVRs than those in the inner disc, likely due to the waning effect of spiral arms. Our detailed measurements of AVRs and σz/σR across the disc indicate that low [α/Fe], inner disc (R ≲ 10 kpc) stellar populations are likely dynamically heated by both giant molecular clouds and spiral arms, while the observed trends for outer disc populations require a significant contribution from another heating mechanism such as satellite perturbations. We also find that outer disc populations have slightly positive mean vertical and radial velocities likely because they are part of the warped disc. Title: Sensitivity of low-degree solar p modes to active and ephemeral regions: frequency shifts back to the Maunder minimum Authors: Chaplin, William J.; Howe, Rachel; Basu, Sarbani; Elsworth, Yvonne; Milbourne, Timothy W.; Haywood, Raphaëlle D.; Davies, Guy R.; Hale, Steven J.; Miglio, Andrea; Ross, Eddie Bibcode: 2019MNRAS.489L..86C Altcode: 2019arXiv190808755C We explore the sensitivity of the frequencies of low-degree solar p modes to near-surface magnetic flux on different spatial scales and strengths, specifically to active regions with strong magnetic fields and ephemeral regions with weak magnetic fields. We also use model reconstructions from the literature to calculate average frequency offsets back to the end of the Maunder minimum. We find that the p-mode frequencies are at least 3 times less sensitive (at 95 per cent confidence) to the ephemeral-region field than they are to the active-region field. Frequency shifts between activity cycle minima and maxima are controlled predominantly by the change of active region flux. Frequency shifts at cycle minima (with respect to a magnetically quiet Sun) are determined largely by the ephemeral flux, and are estimated to have been 0.1 μ Hz or less over the last few minima. We conclude that at epochs of cycle minimum, frequency shifts due to near-surface magnetic activity are negligible compared to the offsets between observed and model frequencies that arise from inaccurate modelling of the near-surface layers (the so-called surface term). The implication is that this will be the case for other Sun-like stars with similar activity, which has implications for asteroseismic modelling of stars. Title: Bayesian hierarchical inference of asteroseismic inclination angles Authors: Kuszlewicz, James S.; Chaplin, William J.; North, Thomas S. H.; Farr, Will M.; Bell, Keaton J.; Davies, Guy R.; Campante, Tiago L.; Hekker, Saskia Bibcode: 2019MNRAS.488..572K Altcode: 2019MNRAS.tmp.1650K; 2019arXiv190701565K; 2019MNRAS.tmp.1602K The stellar inclination angle - the angle between the rotation axis of a star and our line of sight - provides valuable information in many different areas, from the characterization of the geometry of exoplanetary and eclipsing binary systems to the formation and evolution of those systems. We propose a method based on asteroseismology and a Bayesian hierarchical scheme for extracting the inclination angle of a single star. This hierarchical method therefore provides a means to both accurately and robustly extract inclination angles from red giant stars. We successfully apply this technique to an artificial data set with an underlying isotropic inclination angle distribution to verify the method. We also apply this technique to 123 red giant stars observed with Kepler. We also show the need for a selection function to account for possible population-level biases, which are not present in individual star-by-star cases, in order to extend the hierarchical method towards inferring underlying population inclination angle distributions. Title: Signatures of Magnetic Activity: On the Relation between Stellar Properties and p-mode Frequency Variations Authors: Santos, A. R. G.; Campante, T. L.; Chaplin, W. J.; Cunha, M. S.; van Saders, J. L.; Karoff, C.; Metcalfe, T. S.; Mathur, S.; García, R. A.; Lund, M. N.; Kiefer, R.; Silva Aguirre, V.; Davies, G. R.; Howe, R.; Elsworth, Y. Bibcode: 2019ApJ...883...65S Altcode: 2019arXiv190802897S In the Sun, the properties of acoustic modes are sensitive to changes in the magnetic activity. In particular, mode frequencies are observed to increase with increasing activity level. Thanks to CoRoT and Kepler, such variations have been found in other solar-type stars and encode information on the activity-related changes in their interiors. Thus, the unprecedented long-term Kepler photometric observations provide a unique opportunity to study stellar activity through asteroseismology. The goal of this work is to investigate the dependencies of the observed mode frequency variations on the stellar parameters and whether those are consistent with an activity-related origin. We select the solar-type oscillators with highest signal-to-noise ratio, in total, 75 targets. Using the temporal frequency variations determined in Santos et al., we study the relation between those variations and the fundamental stellar properties. We also compare the observed frequency shifts with chromospheric and photometric activity indexes, which are only available for a subset of the sample. We find that frequency shifts increase with increasing chromospheric activity, which is consistent with an activity-related origin of the observed frequency shifts. Frequency shifts are also found to increase with effective temperature, which is in agreement with the theoretical predictions for the activity-related frequency shifts by Metcalfe et al. Frequency shifts are largest for fast rotating and young stars, which is consistent with those being more active than slower rotators and older stars. Finally, we find evidence for frequency shifts increasing with stellar metallicity. Title: VizieR Online Data Catalog: Radial velocities and transit times for KOI 4 (Chontos+, 2019) Authors: Chontos, A.; Huber, D.; Latham, D. W.; Bieryla, A.; van Eylen, V.; Bedding, T. R.; Berger, T.; Buchhave, L. A.; Campante, T. L.; Chaplin, W. J.; Colman, I. L.; Coughlin, J. L.; Davies, G.; Hirano, T.; Howard, A. W.; Isaacson, H. Bibcode: 2019yCat..51570192C Altcode: Following the asteroseismic reclassification of the host star, we initiated an intensive radial velocity (RV) follow-up program using the Tillinghast Reflector Echelle Spectrograph (TRES), a fiber-fed echelle spectrograph spanning the spectral range of 3900-9100 Å with a resolving power of R~44000. We obtained 23 spectra with TRES between UT 2009 November 8 and 2017 September 13 using the medium 2.3" fiber. The spectra were reduced and extracted as outlined in Buchhave et al. (2010, J/ApJ/720/1118). The average exposure time of ~1800 s, corresponding to a mean signal-to-noise ratio (S/N) per resolution element of ~53 at the peak of the continuum near the Mg b triplet at 519 nm. We used the strongest S/N spectrum as a template to derive relative RVs by cross-correlating the remaining spectra order-by-order against the template, which is given a relative velocity of 0 km/s, by definition.

(2 data files). Title: New light on the Gaia DR2 parallax zero-point: influence of the asteroseismic approach, in and beyond the Kepler field Authors: Khan, S.; Miglio, A.; Mosser, B.; Arenou, F.; Belkacem, K.; Brown, A. G. A.; Katz, D.; Casagrande, L.; Chaplin, W. J.; Davies, G. R.; Rendle, B. M.; Rodrigues, T. S.; Bossini, D.; Cantat-Gaudin, T.; Elsworth, Y. P.; Girardi, L.; North, T. S. H.; Vallenari, A. Bibcode: 2019A&A...628A..35K Altcode: 2019arXiv190405676K The importance of studying the Gaia DR2 parallax zero-point by external means was underlined by the articles that accompanied the release, and initiated by several works making use of Cepheids, eclipsing binaries, and asteroseismology. Despite a very efficient elimination of basic-angle variations, a small fluctuation remains and shows up as a small offset in the Gaia DR2 parallaxes. By combining astrometric, asteroseismic, spectroscopic, and photometric constraints, we undertake a new analysis of the Gaia parallax offset for nearly 3000 red-giant branch (RGB) and 2200 red clump (RC) stars observed by Kepler, as well as about 500 and 700 red giants (all either in the RGB or RC phase) selected by the K2 Galactic Archaeology Program in campaigns 3 and 6. Engaging in a thorough comparison of the astrometric and asteroseismic parallaxes, we are able to highlight the influence of the asteroseismic method, and measure parallax offsets in the Kepler field that are compatible with independent estimates from literature and open clusters. Moreover, adding the K2 fields to our investigation allows us to retrieve a clear illustration of the positional dependence of the zero-point, in general agreement with the information provided by quasars. Lastly, we initiate a two-step methodology to make progress in the simultaneous calibration of the asteroseismic scaling relations and of the Gaia DR2 parallax offset, which will greatly benefit from the gain in precision with the third data release of Gaia. Title: VizieR Online Data Catalog: High-precision radial velocities for HD 221416 (Huber+, 2019) Authors: Huber, D.; Chaplin, W. J.; Chontos, A.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Bedding, T. R.; Ball, W.; Brahm, R.; Espinoza, N.; Henning, T.; Jordan, A.; Sarkis, P.; Knudstrup, E.; Albrecht, S.; Grundahl, F.; Andersen, M. F.; Palle, P. L.; Crossfield, I.; Fulton, B.; Howard, A. W.; Isaacson, H. T.; Weiss, L. M.; Handberg, R.; Lund, M. N.; Serenelli, A. M.; Rorsted Mosumgaard, J.; Stokholm, A.; Bieryla, A.; Buchhave, L. A.; Latham, D. W.; Quinn, S. N.; Gaidos, E.; Hirano, T.; Ricker, G. R.; Vanderspek, R. K.; Seager, S.; Jenkins, J. M.; Winn, J. N.; Antia, H. M.; Appourchaux, T.; Basu, S.; Bell, K. J.; Benomar, O.; Bonanno, A.; Buzasi, D. L.; Campante, T. L.; Celik Orhan, Z.; Corsaro, E.; Cunha, M. S.; Davies, G. R.; Deheuvels, S.; Grunblatt, S. K.; Hasanzadeh, A.; di Mauro, M. P.; Garcia, R. A.; Gaulme, P.; Girardi, L.; Guzik, J. A.; Hon, M.; Jiang, C.; Kallinger, T.; Kawaler, S. D.; Kuszlewicz, J. S.; Lebreton, Y.; Li, T.; Lucas, M.; Lundkvist, M. S.; Mann, A. W.; Mathis, S.; Mathur, S.; Mazumdar, A.; Metcalfe, T. S.; Miglio, A.; Monteiro, M. J. P. F. G.; Mosser, B.; Noll, A.; Nsamba, B.; Ong, J. M. J.; Ortel, S.; Pereira, F.; Ranadive, P.; Regulo, C.; Rodrigues, T. S.; Roxburgh, I. W.; Aguirre, V. S.; Smalley, B.; Schofield, M.; Sousa, S. G.; Stassun, K. G.; Stello, D.; Tayar, J.; White, T. R.; Verma, K.; Vrard, M.; Yildiz, M.; Baker, D.; Bazot, M.; Beichmann, C.; Bergmann, C.; Bugnet, L.; Cale, B.; Carlino, R.; Cartwright, S. M.; Christiansen, J. L.; Ciardi, D. R.; Creevey, O.; Dittmann, J. A.; Do Nascimento, J. -D., Jr.; van Eylen, V.; Furesz, G.; Gagne, J.; Gao, P.; Gazeas, K.; Giddens, F.; Hall, O. J.; Hekker, S.; Ireland, M. J.; Latouf, N.; Lebrun, D.; Levine, A. M.; Matzko, W.; Natinsky, E.; Page, E.; Plavchan, P.; Mansouri-Samani, M.; McCauliff, S.; Mullally, S. E.; Orenstein, B.; Soto, A. G.; Paegert, M.; van Saders, J. L.; Schnaible, C.; Soderblom, D. R.; Szabo, R.; Tanner, A.; Tinney, C. G.; Teske, J.; Thomas, A.; Trampedach, R.; Wright, D.; Yuan, T. T.; Zohrabi, F. Bibcode: 2019yCat..51570245H Altcode: We obtained high-resolution spectra of HD 221416 using several facilities within the TESS Follow-up Observation Program (TFOP), including HIRES (Vogt et al. 1994SPIE.2198..362V) on the 10 m telescope at Keck Observatory (Maunakea, Hawai'i); the Hertzsprung SONG Telescope at Teide Observatory (Tenerife; Grundahl et al. 2017ApJ...836..142G); HARPS (Mayor et al. 2003Msngr.114...20M), FEROS (Kaufer et al. 1999Msngr..95....8K), Coralie (Queloz et al. 2001Msngr.105....1Q), and FIDEOS (Vanzi et al. 2018MNRAS.477.5041V) on the MPG/ESO 3.6 m, 2.2 m, 1.2 m, and 1 m telescopes at La Silla Observatory (Chile); Veloce (Gilbert et al. 2018SPIE10702E..0YG) on the 3.9 m Anglo-Australian Telescope at Siding Spring Observatory (Australia); TRES (Furesz 2008, PhD thesis Univ. Szeged) on the 1.5 m Tillinghast reflector at the F. L. Whipple Observatory (Mt. Hopkins, Arizona); and iSHELL (Rayner et al. 2012SPIE.8446E..2CR) on the NASA IRTF Telescope (Maunakea, Hawai'i). All spectra used in this paper were obtained between 2018 November 11 and December 30 and have a minimum spectral resolution of R~44000.

(1 data file). Title: KOI-3890: a high-mass-ratio asteroseismic red giant+M-dwarf eclipsing binary undergoing heartbeat tidal interactions Authors: Kuszlewicz, James S.; North, Thomas S. H.; Chaplin, William J.; Bieryla, Allyson; Latham, David W.; Miglio, Andrea; Bell, Keaton J.; Davies, Guy R.; Hekker, Saskia; Campante, Tiago L.; Deheuvels, Sebastien; Lund, Mikkel N. Bibcode: 2019MNRAS.487...14K Altcode: 2019arXiv190500040K; 2019MNRAS.tmp.1136K KOI-3890 is a highly eccentric, 153-d period eclipsing, single-lined spectroscopic binary system containing a red giant star showing solar-like oscillations alongside tidal interactions. The combination of transit photometry, radial velocity observations, and asteroseismology has enabled the detailed characterization of both the red giant primary and the M-dwarf companion, along with the tidal interaction and the geometry of the system. The stellar parameters of the red giant primary are determined through the use of asteroseismology and grid-based modelling to give a mass and radius of M_{\star }=1.04± 0.06 M_{⊙} and R_{\star }=5.8± 0.2 R_{⊙}, respectively. When combined with transit photometry, the M-dwarf companion is found to have a mass and radius of Mc=0.23± 0.01 M_{⊙} and Rc=0.256± 0.007 R_{⊙}. Moreover, through asteroseismology we constrain the age of the system through the red giant primary to be 9.1^{+2.4}_{-1.7} Gyr. This provides a constraint on the age of the M-dwarf secondary, which is difficult to do for other M-dwarf binary systems. In addition, the asteroseismic analysis yields an estimate of the inclination angle of the rotation axis of the red giant star of i=87.6^{+2.4}_{-1.2} degrees. The obliquity of the system - the angle between the stellar rotation axis and the angle normal to the orbital plane - is also derived to give ψ =4.2^{+2.1}_{-4.2} degrees, showing that the system is consistent with alignment. We observe no radius inflation in the M-dwarf companion when compared to current low-mass stellar models. Title: Testing asteroseismology with Gaia DR2: hierarchical models of the Red Clump Authors: Hall, Oliver J.; Davies, Guy R.; Elsworth, Yvonne P.; Miglio, Andrea; Bedding, Timothy R.; Brown, Anthony G. A.; Khan, Saniya; Hawkins, Keith; García, Rafael A.; Chaplin, William J.; North, Thomas S. H. Bibcode: 2019MNRAS.486.3569H Altcode: 2019MNRAS.tmp.1036H; 2019arXiv190407919H Asteroseismology provides fundamental stellar parameters independent of distance, but subject to systematics under calibration. Gaia DR2 has provided parallaxes for a billion stars, which are offset by a parallax zero-point (ϖzp). Red Clump (RC) stars have a narrow spread in luminosity, thus functioning as standard candles to calibrate these systematics. This work measures how the magnitude and spread of the RC in the Kepler field are affected by changes to temperature and scaling relations for seismology, and changes to the parallax zero-point for Gaia. We use a sample of 5576 RC stars classified through asteroseismology. We apply hierarchical Bayesian latent variable models, finding the population-level properties of the RC with seismology, and use those as priors on Gaia parallaxes to find ϖzp. We then find the position of the RC, using published values for ϖzp. We find a seismic temperature-insensitive spread of the RC of {∼ }0.03 mag in the 2MASS K band and a larger and slightly temperature-dependent spread of {∼ }0.13 mag in the Gaia G band. This intrinsic dispersion in the K band provides a distance precision of {∼ } 1{{ per cent}} for RC stars. Using Gaia data alone, we find a mean zero-point of -41± 10 μ as. This offset yields RC absolute magnitudes of -1.634 ± 0.018 in K and 0.546 ± 0.016 in G. Obtaining these same values through seismology would require a global temperature shift of {∼ }-70 K, which is compatible with known systematics in spectroscopy. Title: Determining the Best Method of Calculating the Large Frequency Separation For Stellar Models Authors: Viani, Lucas S.; Basu, Sarbani; Corsaro, Enrico; Ball, Warrick H.; Chaplin, William J. Bibcode: 2019ApJ...879...33V Altcode: 2019arXiv190508333V Asteroseismology of solar-like oscillators often relies on the comparisons between stellar models and stellar observations in order to determine the properties of stars. The values of the global seismic parameters, ν max (the frequency where the smoothed amplitude of the oscillations peak) and Δν (the large frequency separation), are frequently used in grid-based modeling searches. However, the methods by which Δν is calculated from observed data and how Δν is calculated from stellar models are not the same. Typically for observed stars, especially for those with low signal-to-noise data, Δν is calculated by taking the power spectrum of a power spectrum, or with autocorrelation techniques. However, for stellar models, the actual individual mode frequencies are calculated and the average spacing between them directly determined. In this work we try to determine the best way to combine model frequencies in order to obtain Δν that can be compared with observations. For this we use stars with high signal-to-noise observations from Kepler as well as simulated Transiting Exoplanet Survey Satellite data of Ball et al. We find that when determining Δν from individual mode frequencies the best method is to use the ℓ = 0 modes with either no weighting or with a Gaussian weighting around ν max. Title: Sounding stellar cycles with Kepler - III. Comparative analysis of chromospheric, photometric, and asteroseismic variability Authors: Karoff, C.; Metcalfe, T. S.; Montet, B. T.; Jannsen, N. E.; Santos, A. R. G.; Nielsen, M. B.; Chaplin, W. J. Bibcode: 2019MNRAS.485.5096K Altcode: 2019arXiv190202172K; 2019MNRAS.tmp..751K By combining ground-based spectrographic observations of variability in the chromospheric emission from Sun-like stars with the variability seen in their eigenmode frequencies, it is possible to relate the changes observed at the surfaces of these stars to the changes taking place in the interior. By further comparing this variability to changes in the relative flux from the stars, one can obtain an expression for how these activity indicators relate to the energy output from the stars. Such studies become very pertinent when the variability can be related to stellar cycles as they can then be used to improve our understanding of the solar cycle and its effect on the energy output from the Sun. Here, we present observations of chromospheric emission in 20 Sun-like stars obtained over the course of the nominal 4 yr Kepler mission. Even though 4 yr is too short to detect stellar equivalents of the 11 yr solar cycle, observations from the Kepler mission can still be used to analyse the variability of the different activity indicators thereby obtaining information of the physical mechanism generating the variability. The analysis reveals no strong correlation between the different activity indicators, except in very few cases. We suggest that this is due to the sparse sampling of our ground-based observations on the one hand and that we are likely not tracing cyclic variability on the other hand. We also discuss how to improve the situation. Title: A Hot Saturn Orbiting an Oscillating Late Subgiant Discovered by TESS Authors: Huber, Daniel; Chaplin, William J.; Chontos, Ashley; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Bedding, Timothy R.; Ball, Warrick; Brahm, Rafael; Espinoza, Nestor; Henning, Thomas; Jordán, Andrés; Sarkis, Paula; Knudstrup, Emil; Albrecht, Simon; Grundahl, Frank; Fredslund Andersen, Mads; Pallé, Pere L.; Crossfield, Ian; Fulton, Benjamin; Howard, Andrew W.; Isaacson, Howard T.; Weiss, Lauren M.; Handberg, Rasmus; Lund, Mikkel N.; Serenelli, Aldo M.; Rørsted Mosumgaard, Jakob; Stokholm, Amalie; Bieryla, Allyson; Buchhave, Lars A.; Latham, David W.; Quinn, Samuel N.; Gaidos, Eric; Hirano, Teruyuki; Ricker, George R.; Vanderspek, Roland K.; Seager, Sara; Jenkins, Jon M.; Winn, Joshua N.; Antia, H. M.; Appourchaux, Thierry; Basu, Sarbani; Bell, Keaton J.; Benomar, Othman; Bonanno, Alfio; Buzasi, Derek L.; Campante, Tiago L.; Çelik Orhan, Z.; Corsaro, Enrico; Cunha, Margarida S.; Davies, Guy R.; Deheuvels, Sebastien; Grunblatt, Samuel K.; Hasanzadeh, Amir; Di Mauro, Maria Pia; García, Rafael A.; Gaulme, Patrick; Girardi, Léo; Guzik, Joyce A.; Hon, Marc; Jiang, Chen; Kallinger, Thomas; Kawaler, Steven D.; Kuszlewicz, James S.; Lebreton, Yveline; Li, Tanda; Lucas, Miles; Lundkvist, Mia S.; Mann, Andrew W.; Mathis, Stéphane; Mathur, Savita; Mazumdar, Anwesh; Metcalfe, Travis S.; Miglio, Andrea; Monteiro, Mário J. P. F. G.; Mosser, Benoit; Noll, Anthony; Nsamba, Benard; Ong, Jia Mian Joel; Örtel, S.; Pereira, Filipe; Ranadive, Pritesh; Régulo, Clara; Rodrigues, Thaíse S.; Roxburgh, Ian W.; Silva Aguirre, Victor; Smalley, Barry; Schofield, Mathew; Sousa, Sérgio G.; Stassun, Keivan G.; Stello, Dennis; Tayar, Jamie; White, Timothy R.; Verma, Kuldeep; Vrard, Mathieu; Yıldız, M.; Baker, David; Bazot, Michaël; Beichmann, Charles; Bergmann, Christoph; Bugnet, Lisa; Cale, Bryson; Carlino, Roberto; Cartwright, Scott M.; Christiansen, Jessie L.; Ciardi, David R.; Creevey, Orlagh; Dittmann, Jason A.; Do Nascimento, Jose-Dias, Jr.; Van Eylen, Vincent; Fürész, Gabor; Gagné, Jonathan; Gao, Peter; Gazeas, Kosmas; Giddens, Frank; Hall, Oliver J.; Hekker, Saskia; Ireland, Michael J.; Latouf, Natasha; LeBrun, Danny; Levine, Alan M.; Matzko, William; Natinsky, Eva; Page, Emma; Plavchan, Peter; Mansouri-Samani, Masoud; McCauliff, Sean; Mullally, Susan E.; Orenstein, Brendan; Garcia Soto, Aylin; Paegert, Martin; van Saders, Jennifer L.; Schnaible, Chloe; Soderblom, David R.; Szabó, Róbert; Tanner, Angelle; Tinney, C. G.; Teske, Johanna; Thomas, Alexandra; Trampedach, Regner; Wright, Duncan; Yuan, Thomas T.; Zohrabi, Farzaneh Bibcode: 2019AJ....157..245H Altcode: 2019arXiv190101643H We present the discovery of HD 221416 b, the first transiting planet identified by the Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology of the host star is possible. HD 221416 b (HIP 116158, TOI-197) is a bright (V = 8.2 mag), spectroscopically classified subgiant that oscillates with an average frequency of about 430 μHz and displays a clear signature of mixed modes. The oscillation amplitude confirms that the redder TESS bandpass compared to Kepler has a small effect on the oscillations, supporting the expected yield of thousands of solar-like oscillators with TESS 2 minute cadence observations. Asteroseismic modeling yields a robust determination of the host star radius (R ⋆ = 2.943 ± 0.064 R ⊙), mass (M ⋆ = 1.212 ± 0.074 M ⊙), and age (4.9 ± 1.1 Gyr), and demonstrates that it has just started ascending the red-giant branch. Combining asteroseismology with transit modeling and radial-velocity observations, we show that the planet is a “hot Saturn” (R p = 9.17 ± 0.33 R ⊕) with an orbital period of ∼14.3 days, irradiance of F = 343 ± 24 F ⊕, and moderate mass (M p = 60.5 ± 5.7 M ⊕) and density (ρ p = 0.431 ± 0.062 g cm-3). The properties of HD 221416 b show that the host-star metallicity-planet mass correlation found in sub-Saturns (4-8 R ⊕) does not extend to larger radii, indicating that planets in the transition between sub-Saturns and Jupiters follow a relatively narrow range of densities. With a density measured to ∼15%, HD 221416 b is one of the best characterized Saturn-size planets to date, augmenting the small number of known transiting planets around evolved stars and demonstrating the power of TESS to characterize exoplanets and their host stars using asteroseismology. Title: The Curious Case of KOI 4: Confirming Kepler’s First Exoplanet Detection Authors: Chontos, Ashley; Huber, Daniel; Latham, David W.; Bieryla, Allyson; Van Eylen, Vincent; Bedding, Timothy R.; Berger, Travis; Buchhave, Lars A.; Campante, Tiago L.; Chaplin, William J.; Colman, Isabel L.; Coughlin, Jeff L.; Davies, Guy; Hirano, Teruyuki; Howard, Andrew W.; Isaacson, Howard Bibcode: 2019AJ....157..192C Altcode: 2019arXiv190301591C The discovery of thousands of planetary systems by Kepler has demonstrated that planets are ubiquitous. However, a major challenge has been the confirmation of Kepler planet candidates, many of which still await confirmation. One of the most enigmatic examples is KOI 4.01, Kepler’s first discovered planet candidate detection (as KOI 1.01, 2.01, and 3.01 were known prior to launch). Here we present the confirmation and characterization of KOI 4.01 (now Kepler-1658), using a combination of asteroseismology and radial velocities. Kepler-1658 is a massive, evolved subgiant (M ⋆ = 1.45 ± 0.06 M ⊙, R ⋆ = 2.89 ± 0.12 R ⊙) hosting a massive ({M}{{p}} = 5.88 ± 0.47 {M}{{J}}, {R}{{p}} = 1.07 ± 0.05 {R}{{J}}) hot Jupiter that orbits every 3.85 days. Kepler-1658 joins a small population of evolved hosts with short-period (≤100 days) planets and is now the closest known planet in terms of orbital period to an evolved star. Because of its uniqueness and short orbital period, Kepler-1658 is a new benchmark system for testing tidal dissipation and hot Jupiter formation theories. Using all four years of the Kepler data, we constrain the orbital decay rate to be \dot{P} ≤ -0.42 s yr-1, corresponding to a strong observational limit of {Q}\star {\prime } ≥ 4.826 × {10}3 for the tidal quality factor in evolved stars. With an effective temperature of {T}eff} ∼ 6200 K, Kepler-1658 sits close to the spin-orbit misalignment boundary at ∼6250 K, making it a prime target for follow-up observations to better constrain its obliquity and to provide insight into theories for hot Jupiter formation and migration. Title: Asteroseismic constraints on active latitudes of solar-type stars: HD 173701 has active bands at higher latitudes than the Sun Authors: Thomas, Alexandra E. L.; Chaplin, William J.; Davies, Guy R.; Howe, Rachel; Santos, Ángela R. G.; Elsworth, Yvonne; Miglio, Andrea; Campante, Tiago; Cunha, Margarida S. Bibcode: 2019MNRAS.485.3857T Altcode: 2019arXiv190304998T; 2019MNRAS.tmp..736T We present a new method for determining the location of active bands of latitude on solar-type stars, which uses stellar-cycle-induced frequency shifts of detectable solar-like oscillations. When near-surface activity is distributed in a non-homogeneous manner, oscillation modes of different angular degree and azimuthal order will have their frequencies shifted by different amounts. We use this simple concept, coupled to a model for the spatial distribution of the near-surface activity, to develop two methods that use the frequency shifts to infer minimum and maximum latitudes for the active bands. Our methods respond to the range in latitude over which there is significant magnetic flux present, over and above weak basal ephemeral flux levels. We verify that we are able to draw accurate inferences in the solar case, using Sun-as-a-star helioseismic data and artificial data. We then apply our methods to Kepler data on the solar analogue HD 173701, and find that its active bands straddle a much wider range in latitude than do the bands on the Sun. Title: Stellar Physics and Galactic Archaeology using Asteroseismology in the 2020's Authors: Huber, Daniel; Basu, Sarbani; Beck, Paul; Bedding, Timothy R.; Buzasi, Derek; Cantiello, Matteo; Chaplin, William J.; Christiansen, Jessie L.; Cunha, Katia; Egeland, Ricky; Fuller, Jim; Garcia, Rafael A.; Gies, Douglas R.; Guzik, Joyce; Hekker, Saskia; Hermes, JJ; Jackiewicz, Jason; Johnson, Jennifer; Kawaler, Steve; Metcalfe, Travis; Mosser, Benoit; Ness, Melissa; Pinsonneault, Marc; Piro, Anthony L.; Aguirre, Victor Silva; Soderblom, David; Stassun, Keivan; Tayar, Jamie; ten Brummelaar, Theo; Roettenbacher, Rachael; Trampedach, Regner; van Belle, Gerard; van Saders, Jennifer; Stello, Dennis Bibcode: 2019BAAS...51c.488H Altcode: 2019astro2020T.488H; 2019arXiv190308188H Asteroseismology is the only observational tool in astronomy that can probe the interiors of stars, and is a benchmark method for deriving fundamental properties of stars and exoplanets. In this white paper, we describe key science questions and necessary facilities to continue the asteroseismology revolution into the 2020's. Title: Filtering Solar-Like Oscillations for Exoplanet Detection in Radial Velocity Observations Authors: Chaplin, W. J.; Cegla, H. M.; Watson, C. A.; Davies, G. R.; Ball, W. H. Bibcode: 2019AJ....157..163C Altcode: 2019arXiv190300657C Cool main-sequence, subgiant, and red giant stars all show solar-like oscillations, pulsations that are excited and intrinsically damped by near-surface convection. Many overtones are typically excited to observable amplitudes, giving a rich spectrum of detectable modes. These modes provide a wealth of information on fundamental stellar properties. However, the radial velocity (RV) shifts induced by these oscillations can also be problematic when searching for low-mass, long-period planets; this is because their amplitudes are large enough to completely mask such minute planetary signals. Here we show how fine-tuning exposure times to the stellar parameters can help efficiently average out the solar-like, oscillation-induced shifts. To reduce the oscillation signal to the RV precision commensurate with an Earth analog, we find that for cool, low-mass stars (near spectral type K), the necessary exposure times may be as short as ∼4 minutes, while for hotter, higher-mass stars (near spectral type F, or slightly evolved), the required exposure times can be longer than 100 minutes. We provide guideline exposure durations required to suppress the total observed amplitude due to oscillations to a level of 0.1 m s-1, and a level corresponding to the Earth-analog reflex amplitude for the star. Owing to the intrinsic stochastic variability of the oscillations, we recommend in practice choosing short exposure durations at the telescope and then averaging over those exposures later, as guided by our predictions. To summarize, as we enter an era of 0.1 m s-1 instrumental precision, it is critical to tailor our observing strategies to the stellar properties. Title: VizieR Online Data Catalog: Masses and ages of 1059 HARPS-GTO stars (Delgado Mena+, 2019) Authors: Delgado Mena, E.; Moya, A.; Adibekyan, V.; Tsantaki, M.; Gonzalez Hernandez, J. I.; Israelian, G.; Davies, G. R.; Chaplin, W. J.; Sousa, S. G.; Ferreira, A.; Santos, N. C. Bibcode: 2019yCat..36240078D Altcode: The baseline sample used in this work consist of 1111 FGK stars observed within the context of the HARPS-GTO planet search programs (Mayor et al., 2003Msngr.114...20M; Lo Curto et al., 2010, Cat. J/A+A/512/A48; Santos et al., 2011, Cat. J/A+A/526/A112). The final spectra have a resolution of R~115000 and high signal-to-noise ratio (45% of the spectra have 100<S/N<300, 40% of the spectra have S/N>300 and the mean S/N is 380). Precise stellar parameters for the full sample of 1111 stars within the HARPS-GTO program were homogeneously derived in Sousa et al. (2008, Cat. J/A+A/487/373, 2011a, Cat.J/A+A/526/A99, 2011b, Cat. J/A+A/533/A141). The parameters for cool stars were revised by Tsantaki et al. (2013, Cat. J/A+A/555/A150) using a special list of iron lines which was later applied to the full sample in Delgado Mena et al. (2017, Cat. J/A+A/606/A94), also correcting the spectroscopic gravities. From the 1111 stars in the original sample, the derivation of parameters converged to a solution for 1059 of them.

(1 data file). Title: The Detailed Science Case for the Maunakea Spectroscopic Explorer, 2019 edition Authors: The MSE Science Team; Babusiaux, Carine; Bergemann, Maria; Burgasser, Adam; Ellison, Sara; Haggard, Daryl; Huber, Daniel; Kaplinghat, Manoj; Li, Ting; Marshall, Jennifer; Martell, Sarah; McConnachie, Alan; Percival, Will; Robotham, Aaron; Shen, Yue; Thirupathi, Sivarani; Tran, Kim-Vy; Yeche, Christophe; Yong, David; Adibekyan, Vardan; Silva Aguirre, Victor; Angelou, George; Asplund, Martin; Balogh, Michael; Banerjee, Projjwal; Bannister, Michele; Barría, Daniela; Battaglia, Giuseppina; Bayo, Amelia; Bechtol, Keith; Beck, Paul G.; Beers, Timothy C.; Bellinger, Earl P.; Berg, Trystyn; Bestenlehner, Joachim M.; Bilicki, Maciej; Bitsch, Bertram; Bland-Hawthorn, Joss; Bolton, Adam S.; Boselli, Alessandro; Bovy, Jo; Bragaglia, Angela; Buzasi, Derek; Caffau, Elisabetta; Cami, Jan; Carleton, Timothy; Casagrande, Luca; Cassisi, Santi; Catelan, Márcio; Chang, Chihway; Cortese, Luca; Damjanov, Ivana; Davies, Luke J. M.; de Grijs, Richard; de Rosa, Gisella; Deason, Alis; di Matteo, Paola; Drlica-Wagner, Alex; Erkal, Denis; Escorza, Ana; Ferrarese, Laura; Fleming, Scott W.; Font-Ribera, Andreu; Freeman, Ken; Gänsicke, Boris T.; Gabdeev, Maksim; Gallagher, Sarah; Gandolfi, Davide; García, Rafael A.; Gaulme, Patrick; Geha, Marla; Gennaro, Mario; Gieles, Mark; Gilbert, Karoline; Gordon, Yjan; Goswami, Aruna; Greco, Johnny P.; Grillmair, Carl; Guiglion, Guillaume; Hénault-Brunet, Vincent; Hall, Patrick; Handler, Gerald; Hansen, Terese; Hathi, Nimish; Hatzidimitriou, Despina; Haywood, Misha; Hernández Santisteban, Juan V.; Hillenbrand, Lynne; Hopkins, Andrew M.; Howlett, Cullan; Hudson, Michael J.; Ibata, Rodrigo; Ilić, Dragana; Jablonka, Pascale; Ji, Alexander; Jiang, Linhua; Juneau, Stephanie; Karakas, Amanda; Karinkuzhi, Drisya; Kim, Stacy Y.; Kong, Xu; Konstantopoulos, Iraklis; Krogager, Jens-Kristian; Lagos, Claudia; Lallement, Rosine; Laporte, Chervin; Lebreton, Yveline; Lee, Khee-Gan; Lewis, Geraint F.; Lianou, Sophia; Liu, Xin; Lodieu, Nicolas; Loveday, Jon; Mészáros, Szabolcs; Makler, Martin; Mao, Yao-Yuan; Marchesini, Danilo; Martin, Nicolas; Mateo, Mario; Melis, Carl; Merle, Thibault; Miglio, Andrea; Gohar Mohammad, Faizan; Molaverdikhani, Karan; Monier, Richard; Morel, Thierry; Mosser, Benoit; Nataf, David; Necib, Lina; Neilson, Hilding R.; Newman, Jeffrey A.; Nierenberg, A. M.; Nord, Brian; Noterdaeme, Pasquier; O'Dea, Chris; Oshagh, Mahmoudreza; Pace, Andrew B.; Palanque-Delabrouille, Nathalie; Pandey, Gajendra; Parker, Laura C.; Pawlowski, Marcel S.; Peter, Annika H. G.; Petitjean, Patrick; Petric, Andreea; Placco, Vinicius; Popović, Luka Č.; Price-Whelan, Adrian M.; Prsa, Andrej; Ravindranath, Swara; Rich, R. Michael; Ruan, John; Rybizki, Jan; Sakari, Charli; Sanderson, Robyn E.; Schiavon, Ricardo; Schimd, Carlo; Serenelli, Aldo; Siebert, Arnaud; Siudek, Malgorzata; Smiljanic, Rodolfo; Smith, Daniel; Sobeck, Jennifer; Starkenburg, Else; Stello, Dennis; Szabó, Gyula M.; Szabo, Robert; Taylor, Matthew A.; Thanjavur, Karun; Thomas, Guillaume; Tollerud, Erik; Toonen, Silvia; Tremblay, Pier-Emmanuel; Tresse, Laurence; Tsantaki, Maria; Valentini, Marica; Van Eck, Sophie; Variu, Andrei; Venn, Kim; Villaver, Eva; Walker, Matthew G.; Wang, Yiping; Wang, Yuting; Wilson, Michael J.; Wright, Nicolas; Xu, Siyi; Yildiz, Mutlu; Zhang, Huawei; Zwintz, Konstanze; Anguiano, Borja; Bedell, Megan; Chaplin, William; Collet, Remo; Cuillandre, Jean-Charles; Duc, Pierre-Alain; Flagey, Nicolas; Hermes, JJ; Hill, Alexis; Kamath, Devika; Laychak, Mary Beth; Małek, Katarzyna; Marley, Mark; Sheinis, Andy; Simons, Doug; Sousa, Sérgio G.; Szeto, Kei; Ting, Yuan-Sen; Vegetti, Simona; Wells, Lisa; Babas, Ferdinand; Bauman, Steve; Bosselli, Alessandro; Côté, Pat; Colless, Matthew; Comparat, Johan; Courtois, Helene; Crampton, David; Croom, Scott; Davies, Luke; de Grijs, Richard; Denny, Kelly; Devost, Daniel; di Matteo, Paola; Driver, Simon; Fernandez-Lorenzo, Mirian; Guhathakurta, Raja; Han, Zhanwen; Higgs, Clare; Hill, Vanessa; Ho, Kevin; Hopkins, Andrew; Hudson, Mike; Ibata, Rodrigo; Isani, Sidik; Jarvis, Matt; Johnson, Andrew; Jullo, Eric; Kaiser, Nick; Kneib, Jean-Paul; Koda, Jun; Koshy, George; Mignot, Shan; Murowinski, Rick; Newman, Jeff; Nusser, Adi; Pancoast, Anna; Peng, Eric; Peroux, Celine; Pichon, Christophe; Poggianti, Bianca; Richard, Johan; Salmon, Derrick; Seibert, Arnaud; Shastri, Prajval; Smith, Dan; Sutaria, Firoza; Tao, Charling; Taylor, Edwar; Tully, Brent; van Waerbeke, Ludovic; Vermeulen, Tom; Walker, Matthew; Willis, Jon; Willot, Chris; Withington, Kanoa Bibcode: 2019arXiv190404907T Altcode: (Abridged) The Maunakea Spectroscopic Explorer (MSE) is an end-to-end science platform for the design, execution and scientific exploitation of spectroscopic surveys. It will unveil the composition and dynamics of the faint Universe and impact nearly every field of astrophysics across all spatial scales, from individual stars to the largest scale structures in the Universe. Major pillars in the science program for MSE include (i) the ultimate Gaia follow-up facility for understanding the chemistry and dynamics of the distant Milky Way, including the outer disk and faint stellar halo at high spectral resolution (ii) galaxy formation and evolution at cosmic noon, via the type of revolutionary surveys that have occurred in the nearby Universe, but now conducted at the peak of the star formation history of the Universe (iii) derivation of the mass of the neutrino and insights into inflationary physics through a cosmological redshift survey that probes a large volume of the Universe with a high galaxy density. MSE is positioned to become a critical hub in the emerging international network of front-line astronomical facilities, with scientific capabilities that naturally complement and extend the scientific power of Gaia, the Large Synoptic Survey Telescope, the Square Kilometer Array, Euclid, WFIRST, the 30m telescopes and many more. Title: New light on the Gaia DR2 parallax zero-point: influence of the asteroseismic approach, in and beyond the Kepler field Authors: Khan, Saniya; Miglio, Andrea; Mosser, Benoît; Arenou, Frédéric; Belkacem, Kévin; Brown, Anthony G. A.; Katz, David; Casagrande, Luca; Chaplin, William J.; Davies, Guy R.; Rendle, Ben M.; Rodrigues, Thaíse S.; Bossini, Diego; Cantat-Gaudin, Tristan; Elsworth, Yvonne P.; Girardi, Leo; North, Thomas S. H.; Vallenari, Antonella Bibcode: 2019gaia.confE..13K Altcode: The importance of studying the Gaia DR2 parallax zero-point by external means was underlined by Lindegren et al. (2018), and initiated by several works making use of Cepheids, eclipsing binaries, and asteroseismology. Despite a very efficient elimination of basic-angle variations, a small fluctuation remains and shows up as a small offset in the Gaia DR2 parallaxes.

By combining astrometric, asteroseismic, spectroscopic, and photometric constraints, we undertake a new analysis of the Gaia parallax offset for nearly 3000 red-giant branch (RGB) and 2200 red clump (RC) stars observed by Kepler, as well as about 500 and 700 red giants (both RGB and RC) selected by the K2 Galactic Archaeology Program in campaigns 3 and 6. Engaging into a thorough comparison of the astrometric and asteroseismic parallaxes, we are able to highlight the influence of the asteroseismic method, and measure parallax offsets in the Kepler field that are compatible with independent estimates from literature and open clusters.

Moreover, adding the K2 fields to our investigation allows us to retrieve a clear illustration of the positional dependence of the zero-point, in general agreement with the information provided by quasars.

Lastly, we initiate a two-step methodology to make progress in the simultaneous calibration of the asteroseismic scaling relations and of the Gaia DR2 parallax offset, which will greatly benefit from the gain in precision with the third Data Release of Gaia. Title: Abundance to age ratios in the HARPS-GTO sample with Gaia DR2. Chemical clocks for a range of [Fe/H] Authors: Delgado Mena, E.; Moya, A.; Adibekyan, V.; Tsantaki, M.; González Hernández, J. I.; Israelian, G.; Davies, G. R.; Chaplin, W. J.; Sousa, S. G.; Ferreira, A. C. S.; Santos, N. C. Bibcode: 2019A&A...624A..78D Altcode: 2019arXiv190202127D; 2019A&A...624A..78M
Aims: The purpose of this work is to evaluate how several elements produced by different nucleosynthesis processes behave with stellar age and provide empirical relations to derive stellar ages from chemical abundances.
Methods: We derived different sets of ages using Padova and Yonsei-Yale isochrones and HIPPARCOS and Gaia parallaxes for a sample of more than 1000 FGK dwarf stars for which he have high-resolution (R 115 000) and high-quality spectra from the HARPS-GTO program. We analyzed the temporal evolution of different abundance ratios to find the best chemical clocks. We applied multivariable linear regressions to our sample of stars with a small uncertainty on age to obtain empirical relations of age as a function of stellar parameters and different chemical clocks.
Results: We find that [α/Fe] ratio (average of Mg, Si, and Ti), [O/Fe] and [Zn/Fe] are good age proxies with a lower dispersion than the age-metallicity dispersion. Several abundance ratios present a significant correlation with age for chemically separated thin disk stars (i.e., low-α) but in the case of the chemically defined thick disk stars (i.e., high-α) only the elements Mg, Si, Ca, and Ti II show a clear correlation with age. We find that the thick disk stars are more enriched in light-s elements than thin disk stars of similar age. The maximum enrichment of s-process elements in the thin disk occurs in the youngest stars which in turn have solar metallicity. The slopes of the [X/Fe]-age relations are quite constant for O, Mg, Si, Ti, Zn, Sr, and Eu regardless of the metallicity. However, this is not the case for Al, Ca, Cu and most of the s-process elements, which display very different trends depending on the metallicity. This demonstrates the limitations of using simple linear relations based on certain abundance ratios to obtain ages for stars of different metallicities. Finally, we show that by using 3D relations with a chemical clock and two stellar parameters (either Teff, [Fe/H] or stellar mass) we can explain up to 89% of age variance in a star. A similar result is obtained when using 2D relations with a chemical clock and one stellar parameter, explaining up to a 87% of the variance.
Conclusions: The complete understanding of how the chemical elements were produced and evolved in the Galaxy requires the knowledge of stellar ages and precise chemical abundances. We show how the temporal evolution of some chemical species change with metallicity, with remarkable variations at super-solar metallicities, which will help to better constrain the yields of different nucleosynthesis processes along the history of the Galaxy.

Full Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A78Based on observations collected at the La Silla Observatory, ESO (Chile), with the HARPS spectrograph at the 3.6 m ESO telescope (ESO runs ID 72.C-0488, 082.C-0212, and 085.C-0063). Title: VizieR Online Data Catalog: Mixing-length parameter for a sample of KIC stars (Viani+, 2018) Authors: Viani, L. S.; Basu, S.; J. O., J. M.; Bonaca, A.; Chaplin, W. J. Bibcode: 2019yCat..18580028V Altcode: Stellar models typically use the mixing-length approximation as a way to implement convection in a simplified manner. While conventionally the value of the mixing-length parameter, α, used is the solar-calibrated value, many studies have shown that other values of α are needed to properly model stars. This uncertainty in the value of the mixing-length parameter is a major source of error in stellar models and isochrones. Using asteroseismic data, we determine the value of the mixing-length parameter required to properly model a set of about 450 stars ranging in logg, Teff, and [Fe/H]. The relationship between the value of α required and the properties of the star is then investigated. For Eddington atmosphere, non-diffusion models, we find that the value of α can be approximated by a linear model, in the form of α/αȯ=5.426-0.101, log(g)-1.071, log(Teff)+0.437([Fe/H]). This process is repeated using a variety of model physics, as well as compared with previous studies and results from 3D convective simulations.

(1 data file). Title: The Asteroseismic Target List for Solar-like Oscillators Observed in 2 minute Cadence with the Transiting Exoplanet Survey Satellite Authors: Schofield, Mathew; Chaplin, William J.; Huber, Daniel; Campante, Tiago L.; Davies, Guy R.; Miglio, Andrea; Ball, Warrick H.; Appourchaux, Thierry; Basu, Sarbani; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen; Creevey, Orlagh; García, Rafael A.; Handberg, Rasmus; Kawaler, Steven D.; Kjeldsen, Hans; Latham, David W.; Lund, Mikkel N.; Metcalfe, Travis S.; Ricker, George R.; Serenelli, Aldo; Silva Aguirre, Victor; Stello, Dennis; Vanderspek, Roland Bibcode: 2019ApJS..241...12S Altcode: 2019arXiv190110148S We present the target list of solar-type stars to be observed in short-cadence (2 minute) for asteroseismology by the NASA Transiting Exoplanet Survey Satellite (TESS) during its 2 year nominal survey mission. The solar-like Asteroseismic Target List (ATL) is comprised of bright, cool main-sequence and subgiant stars and forms part of the larger target list of the TESS Asteroseismic Science Consortium. The ATL uses the Gaia Data Release 2 and the Extended Hipparcos Compilation (XHIP) to derive fundamental stellar properties, to calculate detection probabilities, and to produce a rank-ordered target list. We provide a detailed description of how the ATL was produced and calculate expected yields for solar-like oscillators based on the nominal photometric performance by TESS. We also provide a publicly available source code that can be used to reproduce the ATL, thereby enabling comparisons of asteroseismic results from TESS with predictions from synthetic stellar populations. Title: AIMS - a new tool for stellar parameter determinations using asteroseismic constraints Authors: Rendle, Ben M.; Buldgen, Gaël; Miglio, Andrea; Reese, Daniel; Noels, Arlette; Davies, Guy R.; Campante, Tiago L.; Chaplin, William J.; Lund, Mikkel N.; Kuszlewicz, James S.; Scott, Laura J. A.; Scuflaire, Richard; Ball, Warrick H.; Smetana, Jiri; Nsamba, Benard Bibcode: 2019MNRAS.484..771R Altcode: 2019MNRAS.tmp...36R; 2019arXiv190102663R A key aspect in the determination of stellar properties is the comparison of observational constraints with predictions from stellar models. Asteroseismic Inference on a Massive Scale (AIMS) is an open source code that uses Bayesian statistics and a Markov Chain Monte Carlo approach to find a representative set of models that reproduce a given set of classical and asteroseismic constraints. These models are obtained by interpolation on a pre-calculated grid, thereby increasing computational efficiency. We test the accuracy of the different operational modes within AIMS for grids of stellar models computed with the Liège stellar evolution code (main sequence and red giants) and compare the results to those from another asteroseismic analysis pipeline, PARAM. Moreover, using artificial inputs generated from models within the grid (assuming the models to be correct), we focus on the impact on the precision of the code when considering different combinations of observational constraints (individual mode frequencies, period spacings, parallaxes, photospheric constraints,...). Our tests show the absolute limitations of precision on parameter inferences using synthetic data with AIMS, and the consistency of the code with expected parameter uncertainty distributions. Interpolation testing highlights the significance of the underlying physics to the analysis performance of AIMS and provides caution as to the upper limits in parameter step size. All tests demonstrate the flexibility and capability of AIMS as an analysis tool and its potential to perform accurate ensemble analysis with current and future asteroseismic data yields. Title: VizieR Online Data Catalog: APOKASC-2 catalog of Kepler evolved stars (Pinsonneault+, 2018) Authors: Pinsonneault, M. H.; Elsworth, Y. P.; Tayar, J.; Serenelli, A.; Stello, D.; Zinn, J.; Mathur, S.; Garcia, R. A.; Johnson, J. A.; Hekker, S.; Huber, D.; Kallinger, T.; Meszaros, S.; Mosser, B.; Stassun, K.; Girardi, L.; Rodrigues, T. S.; Aguirre, V. S.; An, D.; Basu, S.; Chaplin, W. J.; Corsaro, E.; Cunha, K.; Garcia-Hernandez, D. A.; Holtzman, J.; Jonsson, H.; Shetrone, M.; Smith, V. V.; Sobeck, J. S.; Stringfellow, G. S.; Zamora, O.; Beers, T. C.; Fernandez-Trincado, J. G.; Frinchaboy, P. M.; Hearty, F. R.; Nitschelm, C. Bibcode: 2019yCat..22390032P Altcode: Our 6676 targets have high-resolution (R~22000) H-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) project (Majewski+ 2017AJ....154...94M), which were obtained during the third Sloan Digital Sky Survey, hereafter SDSS-III (Eisenstein+ 2011AJ....142...72E), and analyzed during the fourth Sloan Digital Sky Survey, hereafter SDSS-IV (Blanton+ 2017AJ....154...28B). Our asteroseismic data were obtained by the Kepler mission (Borucki+ 2010Sci...327..977B), analyzed by members of the Kepler Asteroseismology Science Consortium (KASC), and interpreted by the team using both asteroseismic and spectroscopic data.

(2 data files). Title: The Behaviour of Galactic Cosmic-Ray Intensity During Solar Activity Cycle 24 Authors: Ross, Eddie; Chaplin, William J. Bibcode: 2019SoPh..294....8R Altcode: We have studied long-term variations of galactic cosmic-ray (GCR) intensity in relation to the sunspot number (SSN) during the most recent solar cycles. This study analyses the time lag between the GCR intensity and SSN, and hysteresis plots of the GCR count rate against SSN for Solar Cycles 20 - 23, to validate a methodology against previous results in the literature, before applying the method to provide a timely update on the behaviour of Cycle 24. Plots of SSN versus GCR show a clear difference between the odd- and even-numbered cycles. Linear and elliptical models have been fit to the data, with the linear fit and elliptical model proving the more suitable model for even- and odd-numbered solar-activity cycles, respectively, in agreement with previous literature. Through the application of these methods for Solar Cycle 24, it has been shown that Cycle 24 experienced a lag of two to four months between the GCR intensity and SSN, and this follows the trend of the preceding activity cycles, albeit with a slightly longer lag than previous even-numbered cycles. It has been shown through the hysteresis analysis that the linear fit is a better representative model for Cycle 24, as the ellipse model does not show a significant improvement, which is also in agreement with previous even-numbered cycles. Title: Chapter 4 - Helioseismic Inferences on the Internal Structure and Dynamics of the Sun Authors: Basu, Sarbani; Chaplin, William J. Bibcode: 2019sgsp.book...87B Altcode: Helioseismology has made it possible to peel back the outer layers of the Sun to allow inferences to be made about its internal structure, dynamics, and solar cycle-related changes. In this chapter, we introduce helioseismic analyses, in particular inversion methods, and then discuss knowledge that has been acquired through the application of these analysis techniques to what is now an observational data archive stretching back over a few solar cycles. Title: Combining multiple structural inversions to constrain the solar modelling problem Authors: Buldgen, G.; Salmon, S. J. A. J.; Noels, A.; Scuflaire, R.; Montalban, J.; Baturin, V. A.; Eggenberger, P.; Gryaznov, V. K.; Iosilevskiy, I. L.; Meynet, G.; Chaplin, W. J.; Miglio, A.; Oreshina, A. V.; Richard, O.; Starostin, A. N. Bibcode: 2019A&A...621A..33B Altcode: 2018arXiv180908958B Context. The Sun is the most studied of all stars, which serves as a reference for all other observed stars in the Universe. Furthermore, it also serves the role of a privileged laboratory of fundamental physics and can help us better understand processes occuring in conditions irreproducible on Earth. However, our understanding of our star is currently lessened by the so-called solar modelling problem, resulting from comparisons of theoretical solar models to helioseismic constraints. These discrepancies can stem from various causes, such as the radiative opacities, the equation of state as well as the mixing of the chemical elements.
Aims: By analysing the potential of combining information from multiple seismic inversions, our aim is to help disentangle the origins of the solar modelling problem.
Methods: We combined inversions of the adiabatic sound speed, an entropy proxy and the Ledoux discriminant with other constraints such as the position of the base of the convective zone and the photospheric helium abundance. First, we tested various combinations of standard ingredients available for solar modelling such as abundance tables, equation of state, formalism for convection and diffusion and opacity tables. Second, we studied the diagnostic potential of the inversions on models including ad hoc modifications of the opacity profile and additional mixing below the convective envelope.
Results: We show that combining inversions provides stringent constraints on the required modifications to the solar ingredients, far beyond what can be achieved from sound speed inversions alone. We constrain the form and amplitude of the opacity increase required in solar models and show that a 15% increase at log T = 6.35 provides a significant improvement, but is insufficient on its own. A more global increase in the opacity, within the uncertainties of the current tables, coupled with a localized additional mixing at the bottom of the convective zone provides the best agreement for low-metallicity models. We show that high-metallicity models do not satisfy all the inversion results. We conclude that the solar modelling problem likely occurs from multiple small contributors, as other ingredients such as the equation of state or the formalism of convection can induce small but significant changes in the models and that using phase shift analyses combined with our approach is the next step for a better understanding of the inaccuracies of solar models just below the convective envelope. Title: The behaviour of galactic cosmic ray intensity during solar activity cycle 24 Authors: Ross, Eddie; Chaplin, William J. Bibcode: 2018arXiv181202125R Altcode: We have studied long-term variations of galactic cosmic ray (GCR) intensity in relation to the sunspot number (SSN) during the most recent solar cycles. This study analyses the time-lag between the GCR intensity and SSN, and hysteresis plots of the GCR count rate against SSN for solar activity cycles 20-23 to validate a methodology against previous results in the literature, before applying the method to provide a timely update on the behaviour of cycle 24. Cross-plots of SSN vs GCR show a clear difference between the odd-numbered and even-numbered cycles. Linear and elliptical models have been fit to the data with the linear fit and elliptical model proving the more suitable model for even-numbered and odd-numbered solar activity cycles respectively, in agreement with previous literature. Through the application of these methods for the 24th solar activity cycle, it has been shown that cycle 24 experienced a lag of 2-4 months and follows the trend of the preceding activity cycles albeit with a slightly longer lag than previous even-numbered cycles. It has been shown through the hysteresis analysis that the linear fit is a better representative model for cycle 24, as the ellipse model doesn't show a significant improvement, which is also in agreement with previous even-numbered cycles. Title: The Second APOKASC Catalog: The Empirical Approach Authors: Pinsonneault, Marc H.; Elsworth, Yvonne P.; Tayar, Jamie; Serenelli, Aldo; Stello, Dennis; Zinn, Joel; Mathur, Savita; García, Rafael A.; Johnson, Jennifer A.; Hekker, Saskia; Huber, Daniel; Kallinger, Thomas; Mészáros, Szabolcs; Mosser, Benoit; Stassun, Keivan; Girardi, Léo; Rodrigues, Thaíse S.; Silva Aguirre, Victor; An, Deokkeun; Basu, Sarbani; Chaplin, William J.; Corsaro, Enrico; Cunha, Katia; García-Hernández, D. A.; Holtzman, Jon; Jönsson, Henrik; Shetrone, Matthew; Smith, Verne V.; Sobeck, Jennifer S.; Stringfellow, Guy S.; Zamora, Olga; Beers, Timothy C.; Fernández-Trincado, J. G.; Frinchaboy, Peter M.; Hearty, Fred R.; Nitschelm, Christian Bibcode: 2018ApJS..239...32P Altcode: 2018arXiv180409983P We present a catalog of stellar properties for a large sample of 6676 evolved stars with Apache Point Observatory Galactic Evolution Experiment spectroscopic parameters and Kepler asteroseismic data analyzed using five independent techniques. Our data include evolutionary state, surface gravity, mean density, mass, radius, age, and the spectroscopic and asteroseismic measurements used to derive them. We employ a new empirical approach for combining asteroseismic measurements from different methods, calibrating the inferred stellar parameters, and estimating uncertainties. With high statistical significance, we find that asteroseismic parameters inferred from the different pipelines have systematic offsets that are not removed by accounting for differences in their solar reference values. We include theoretically motivated corrections to the large frequency spacing (Δν) scaling relation, and we calibrate the zero-point of the frequency of the maximum power (ν max) relation to be consistent with masses and radii for members of star clusters. For most targets, the parameters returned by different pipelines are in much better agreement than would be expected from the pipeline-predicted random errors, but 22% of them had at least one method not return a result and a much larger measurement dispersion. This supports the usage of multiple analysis techniques for asteroseismic stellar population studies. The measured dispersion in mass estimates for fundamental calibrators is consistent with our error model, which yields median random and systematic mass uncertainties for RGB stars of order 4%. Median random and systematic mass uncertainties are at the 9% and 8% level, respectively, for red clump stars. Title: A Synthetic Sample of Short-cadence Solar-like Oscillators for TESS Authors: Ball, Warrick H.; Chaplin, William J.; Schofield, Mathew; Miglio, Andrea; Bossini, Diego; Davies, Guy R.; Girardi, Léo Bibcode: 2018ApJS..239...34B Altcode: 2018arXiv180909108B NASA’s Transiting Exoplanet Survey Satellite (TESS) has begun a two-year survey of most of the sky, which will include light curves for thousands of solar-like oscillators sampled at a cadence of two minutes. To prepare for this steady stream of data, we present a mock catalog of light curves, designed to realistically mimic the properties of the TESS sample. In the process, we also present the first public release of the asteroFLAG Artificial DataSet Generator, which simulates light curves of solar-like oscillators based on input mode properties. The targets are drawn from a simulation of the Milky Way’s populations and are selected in the same way as TESS’s true Asteroseismic Target List. The light curves are produced by combining stellar models, pulsation calculations and semi-empirical models of solar-like oscillators. We describe the details of the catalog and provide several examples. We provide pristine light curves to which noise can be added easily. This mock catalog will be valuable in testing asteroseismology pipelines for TESS and our methods can be applied in preparation and planning for other observatories and observing campaigns. Title: Stellar Surface Magneto-convection as a Source of Astrophysical Noise. II. Center-to-limb Parameterization of Absorption Line Profiles and Comparison to Observations Authors: Cegla, H. M.; Watson, C. A.; Shelyag, S.; Chaplin, W. J.; Davies, G. R.; Mathioudakis, M.; Palumbo, M. L., III; Saar, S. H.; Haywood, R. D. Bibcode: 2018ApJ...866...55C Altcode: 2018arXiv180711423C Manifestations of stellar activity (such as star-spots, plage/faculae, and convective flows) are well-known to induce spectroscopic signals often referred to as astrophysical noise by exoplanet hunters. For example, setting an ultimate goal of detecting true Earth analogs demands reaching radial velocity (RV) precisions of ∼9 cm s-1. While this is becoming technically feasible with the latest generation of highly stabilized spectrographs, it is astrophysical noise that sets the true fundamental barrier on attainable RV precisions. In this paper, we parameterize the impact of solar surface magneto-convection on absorption line profiles, and extend the analysis from the solar disk center (Paper I) to the solar limb. Off disk-center, the plasma flows orthogonal to the granule tops begin to lie along the line of sight, and those parallel to the granule tops are no longer completely aligned with the observer. Moreover, the granulation is corrugated and the granules can block other granules, as well as the intergranular lane components. Overall, the visible plasma flows and geometry of the corrugated surface significantly impact the resultant line profiles and induce center-to-limb variations in shape and net position. We detail these herein, and compare to various solar observations. We find our granulation parameterization can recreate realistic line profiles and induced radial velocity shifts, across the stellar disk, indicative of both those found in computationally heavy radiative 3D magnetohydrodynamical simulations and empirical solar observations. Title: Changes in the sensitivity of solar p-mode frequency shifts to activity over three solar cycles Authors: Howe, R.; Chaplin, W. J.; Davies, G. R.; Elsworth, Y.; Basu, S.; Broomhall, A. -M. Bibcode: 2018MNRAS.480L..79H Altcode: 2018arXiv180701504H; 2018MNRAS.tmpL.128H Low-degree solar p-mode observations from the long-lived Birmingham Solar-Oscillations Network (BiSON) stretch back further than any other single helioseismic data set. Results from BiSON have suggested that the response of the mode frequency to solar activity levels may be different in different cycles. In order to check whether such changes can also be seen at higher degrees, we compare the response of medium-degree solar p modes to activity levels across three solar cycles using data from Big Bear Solar Observatory, Global Oscillation Network Group, Michelson Doppler Imager, and Helioseismic and Magnetic Imager, by examining the shifts in the mode frequencies and their sensitivity to solar activity levels. We compare these shifts and sensitivities with those from radial modes from BiSON. We find that the medium-degree data show small but significant systematic differences between the cycles, with solar Cycle 24 showing a frequency shift about 10 per cent larger than Cycle 23 for the same change in activity as determined by the 10.7 cm radio flux. This may support the idea that there have been changes in the magnetic properties of the shallow subsurface layers of the Sun that have the strongest influence on the frequency shifts. Title: VizieR Online Data Catalog: Temporal frequency shifts in 87 Kepler stars (Santos+, 2018) Authors: Santos, A. R. G.; Campante, T. L.; Chaplin, W. J.; Cunha, M. S.; Lund, M. N.; Kiefer, R.; Salabert, D.; Garcia, R. A.; Davies, G. R.; Elsworth, Y.; Howe, R. Bibcode: 2018yCat..22370017S Altcode: In the Sun, the frequencies of the acoustic modes are observed to vary in phase with the magnetic activity level. These frequency variations are expected to be common in solar-type stars and contain information about the activity-related changes that take place in their interiors. The unprecedented duration of Kepler photometric time-series provides a unique opportunity to detect and characterize stellar magnetic cycles through asteroseismology. In this work, we analyze a sample of 87 solar-type stars, measuring their temporal frequency shifts over segments of 90 days. For each segment, the individual frequencies are obtained through a Bayesian peak-bagging tool. The mean frequency shifts are then computed and compared with: (1) those obtained from a cross-correlation method; (2) the variation in the mode heights; (3) a photometric activity proxy; and (4) the characteristic timescale of the granulation. For each star and 90-day sub-series, we provide mean frequency shifts, mode heights, and characteristic timescales of the granulation. Interestingly, more than 60% of the stars show evidence for (quasi-)periodic variations in the frequency shifts. In the majority of the cases, these variations are accompanied by variations in other activity proxies. About 20% of the stars show mode frequencies and heights varying approximately in phase, in opposition to what is observed for the Sun.

(2 data files). Title: Synergy between asteroseismology and exoplanet science: an outlook Authors: Campante, Tiago L.; Barros, Susana C. C.; Demangeon, Olivier; da Nóbrega, Hugo J.; Kuszlewicz, James S.; Pereira, Filipe; Chaplin, William J.; Huber, Daniel Bibcode: 2018phos.confE..50C Altcode: 2018arXiv181206150C Space-based asteroseismology has been playing an important role in the characterization of exoplanet-host stars and their planetary systems. The future looks even brighter, with space missions such as NASA's TESS and ESA's PLATO ready to take on this legacy. In this contribution, we provide an outlook on the synergy between asteroseismology and exoplanet science, namely, on the prospect of conducting a populational study of giant planets around oscillating evolved stars with the TESS mission. Title: HD 89345: a bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2 Authors: Van Eylen, V.; Dai, F.; Mathur, S.; Gandolfi, D.; Albrecht, S.; Fridlund, M.; García, R. A.; Guenther, E.; Hjorth, M.; Justesen, A. B.; Livingston, J.; Lund, M. N.; Pérez Hernández, F.; Prieto-Arranz, J.; Regulo, C.; Bugnet, L.; Everett, M. E.; Hirano, T.; Nespral, D.; Nowak, G.; Palle, E.; Silva Aguirre, V.; Trifonov, T.; Winn, J. N.; Barragán, O.; Beck, P. G.; Chaplin, W. J.; Cochran, W. D.; Csizmadia, S.; Deeg, H.; Endl, M.; Heeren, P.; Grziwa, S.; Hatzes, A. P.; Hidalgo, D.; Korth, J.; Mathis, S.; Montañes Rodriguez, P.; Narita, N.; Patzold, M.; Persson, C. M.; Rodler, F.; Smith, A. M. S. Bibcode: 2018MNRAS.478.4866V Altcode: 2018arXiv180501860V; 2018MNRAS.tmp.1339V We report the discovery and characterization of HD 89345b (K2-234b; EPIC 248777106b), a Saturn-sized planet orbiting a slightly evolved star. HD 89345 is a bright star (V = 9.3 mag) observed by the K2 mission with 1 min time sampling. It exhibits solar-like oscillations. We conducted asteroseismology to determine the parameters of the star, finding the mass and radius to be 1.12^{+0.04}_{-0.01} M_⊙ and 1.657^{+0.020}_{-0.004} R_⊙, respectively. The star appears to have recently left the main sequence, based on the inferred age, 9.4^{+0.4}_{-1.3} Gyr, and the non-detection of mixed modes. The star hosts a `warm Saturn' (P = 11.8 d, Rp = 6.86 ± 0.14 R⊕). Radial-velocity follow-up observations performed with the FIbre-fed Echelle Spectrograph, HARPS, and HARPS-N spectrographs show that the planet has a mass of 35.7 ± 3.3 M⊕. The data also show that the planet's orbit is eccentric (e ≈ 0.2). An investigation of the rotational splitting of the oscillation frequencies of the star yields no conclusive evidence on the stellar inclination angle. We further obtained Rossiter-McLaughlin observations, which result in a broad posterior of the stellar obliquity. The planet seems to confirm to the same patterns that have been observed for other sub-Saturns regarding planet mass and multiplicity, orbital eccentricity, and stellar metallicity. Title: VizieR Online Data Catalog: Kepler planetary cand. VIII. DR25 reliability (Thompson+, 2018) Authors: Thompson, S. E.; Coughlin, J. L.; Hoffman, K.; Mullally, F.; Christiansen, J. L.; Burke, C. J.; Bryson, S.; Batalha, N.; Haas, M. R.; Catanzarite, J.; Rowe, J. F.; Barentsen, G.; Caldwell, D. A.; Clarke, B. D.; Jenkins, J. M.; Li, J.; Latham, D. W.; Lissauer, J. J.; Mathur, S.; Morris, R. L.; Seader, S. E.; Smith, J. C.; Klaus, T. C.; Twicken, J. D.; van Cleve, J. E.; Wohler, B.; Akeson, R.; Ciardi, D. R.; Cochran, W. D.; Henze, C. E.; Howell, S. B.; Huber, D.; Prsa, A.; Ramirez, S. V.; Morton, T. D.; Barclay, T.; Campbell, J. R.; Chaplin, W. J.; Charbonneau, D.; Christensen-Dalsgaard, J.; Dotson, J. L.; Doyle, L.; Dunham, E. W.; Dupree, A. K.; Ford, E. B.; Geary, J. C.; Girouard, F. R.; Isaacson, H.; Kjeldsen, H.; Quintana, E. V.; Ragozzine, D.; Shabram, M.; Shporer, A.; Aguirre, V. S.; Steffen, J. H.; Still, M.; Tenenbaum, P.; Welsh, W. F.; Wolfgang, A.; Zamudio, K. A.; Koch, D. G.; Borucki, W. J. Bibcode: 2018yCat..22350038T Altcode: We present the Kepler Object of Interest (KOI) catalog of transiting exoplanets based on searching 4yr of Kepler time series photometry (Data Release 25, Q1-Q17: Twicken+, 2016, J/AJ/152/158). The catalog contains 8054 KOIs, of which 4034 are planet candidates with periods between 0.25 and 632 days. Of these candidates, 219 are new, including two in multiplanet systems (KOI-82.06 and KOI-2926.05) and 10 high-reliability, terrestrial-size, habitable zone candidates. This catalog was created using a tool called the Robovetter, which automatically vets the DR25 threshold crossing events (TCEs). The Robovetter also vetted simulated data sets and measured how well it was able to separate TCEs caused by noise from those caused by low signal-to-noise transits. We discuss the Robovetter and the metrics it uses to sort TCEs. For orbital periods less than 100 days the Robovetter completeness (the fraction of simulated transits that are determined to be planet candidates) across all observed stars is greater than 85%. For the same period range, the catalog reliability (the fraction of candidates that are not due to instrumental or stellar noise) is greater than 98%. However, for low signal-to-noise candidates between 200 and 500 days around FGK-dwarf stars, the Robovetter is 76.7% complete and the catalog is 50.5% reliable.

(6 data files). Title: Empirical Relations for the Accurate Estimation of Stellar Masses and Radii Authors: Moya, Andy; Zuccarino, Federico; Chaplin, William J.; Davies, Guy R. Bibcode: 2018ApJS..237...21M Altcode: 2018arXiv180606574M In this work, we have taken advantage of the most recent accurate stellar characterizations carried out using asteroseismology, eclipsing binaries and interferometry to evaluate a comprehensive set of empirical relations for the estimation of stellar masses and radii. We have gathered a total of 934 stars—of which around two-thirds are on the main sequence—that are characterized with different levels of precision, most of them having estimates of M, R, T eff, L, g, ρ, and [Fe/H]. We have deliberately used a heterogeneous sample (in terms of characterizing techniques and spectroscopic types) to reduce the influence of possible biases coming from the observation, reduction, and analysis methods used to obtain the stellar parameters. We have studied a total of 576 linear combinations of T eff, L, g, ρ, and [Fe/H] (and their logarithms) to be used as independent variables to estimate M or R. We have used an error-in-variables linear regression algorithm to extract the relations and to ensure the fair treatment of the uncertainties. We present a total of 38 new or revised relations that have an adj-R 2 regression statistic higher than 0.85, and a relative accuracy and precision better than 10% for almost all the cases. The relations cover almost all the possible combinations of observables, ensuring that, whatever list of observables is available, there is at least one relation for estimating the stellar mass and radius. Title: Signatures of Magnetic Activity in the Seismic Data of Solar-type Stars Observed by Kepler Authors: Santos, A. R. G.; Campante, T. L.; Chaplin, W. J.; Cunha, M. S.; Lund, M. N.; Kiefer, R.; Salabert, D.; García, R. A.; Davies, G. R.; Elsworth, Y.; Howe, R. Bibcode: 2018ApJS..237...17S Altcode: 2018arXiv180600136S In the Sun, the frequencies of the acoustic modes are observed to vary in phase with the magnetic activity level. These frequency variations are expected to be common in solar-type stars and contain information about the activity-related changes that take place in their interiors. The unprecedented duration of Kepler photometric time-series provides a unique opportunity to detect and characterize stellar magnetic cycles through asteroseismology. In this work, we analyze a sample of 87 solar-type stars, measuring their temporal frequency shifts over segments of 90 days. For each segment, the individual frequencies are obtained through a Bayesian peak-bagging tool. The mean frequency shifts are then computed and compared with: (1) those obtained from a cross-correlation method; (2) the variation in the mode heights; (3) a photometric activity proxy; and (4) the characteristic timescale of the granulation. For each star and 90-day sub-series, we provide mean frequency shifts, mode heights, and characteristic timescales of the granulation. Interestingly, more than 60% of the stars show evidence for (quasi-)periodic variations in the frequency shifts. In the majority of the cases, these variations are accompanied by variations in other activity proxies. About 20% of the stars show mode frequencies and heights varying approximately in phase, in opposition to what is observed for the Sun. Title: Signatures of Solar Cycle 25 in Subsurface Zonal Flows Authors: Howe, R.; Hill, F.; Komm, R.; Chaplin, W. J.; Elsworth, Y.; Davies, G. R.; Schou, J.; Thompson, M. J. Bibcode: 2018ApJ...862L...5H Altcode: 2018arXiv180702398H The pattern of migrating zonal flow bands associated with the solar cycle, known as the torsional oscillation, has been monitored with continuous global helioseismic observations by the Global Oscillations Network Group (GONG), together with those made by the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO) and its successor, the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO), since 1995, giving us nearly two full solar cycles of observations. We report that the flows now show traces of the mid-latitude acceleration that is expected to become the main equatorward-moving branch of the zonal flow pattern for Cycle 25. Based on the current position of this branch, we speculate that the onset of widespread activity for Cycle 25 is unlikely to be earlier than the middle of 2019. Title: Establishing the accuracy of asteroseismic mass and radius estimates of giant stars - I. Three eclipsing systems at [Fe/H] ∼ -0.3 and the need for a large high-precision sample Authors: Brogaard, K.; Hansen, C. J.; Miglio, A.; Slumstrup, D.; Frandsen, S.; Jessen-Hansen, J.; Lund, M. N.; Bossini, D.; Thygesen, A.; Davies, G. R.; Chaplin, W. J.; Arentoft, T.; Bruntt, H.; Grundahl, F.; Handberg, R. Bibcode: 2018MNRAS.476.3729B Altcode: 2018arXiv180108167B; 2018MNRAS.tmp..262B We aim to establish and improve the accuracy level of asteroseismic estimates of mass, radius, and age of giant stars. This can be achieved by measuring independent, accurate, and precise masses, radii, effective temperatures and metallicities of long period eclipsing binary stars with a red giant component that displays solar-like oscillations. We measured precise properties of the three eclipsing binary systems KIC 7037405, KIC 9540226, and KIC 9970396 and estimated their ages be 5.3 ± 0.5, 3.1 ± 0.6, and 4.8 ± 0.5 Gyr. The measurements of the giant stars were compared to corresponding measurements of mass, radius, and age using asteroseismic scaling relations and grid modelling. We found that asteroseismic scaling relations without corrections to Δν systematically overestimate the masses of the three red giants by 11.7 per cent, 13.7 per cent, and 18.9 per cent, respectively. However, by applying theoretical correction factors fΔν according to Rodrigues et al. (2017), we reached general agreement between dynamical and asteroseismic mass estimates, and no indications of systematic differences at the precision level of the asteroseismic measurements. The larger sample investigated by Gaulme et al. (2016) showed a much more complicated situation, where some stars show agreement between the dynamical and corrected asteroseismic measures while others suggest significant overestimates of the asteroseismic measures. We found no simple explanation for this, but indications of several potential problems, some theoretical, others observational. Therefore, an extension of the present precision study to a larger sample of eclipsing systems is crucial for establishing and improving the accuracy of asteroseismology of giant stars. Title: Investigating the Metallicity-Mixing-length Relation Authors: Viani, Lucas S.; Basu, Sarbani; Ong J., M. Joel; Bonaca, Ana; Chaplin, William J. Bibcode: 2018ApJ...858...28V Altcode: 2018arXiv180305924V Stellar models typically use the mixing-length approximation as a way to implement convection in a simplified manner. While conventionally the value of the mixing-length parameter, α, used is the solar-calibrated value, many studies have shown that other values of α are needed to properly model stars. This uncertainty in the value of the mixing-length parameter is a major source of error in stellar models and isochrones. Using asteroseismic data, we determine the value of the mixing-length parameter required to properly model a set of about 450 stars ranging in log g, {T}eff}, and [{Fe}/{{H}}]. The relationship between the value of α required and the properties of the star is then investigated. For Eddington atmosphere, non-diffusion models, we find that the value of α can be approximated by a linear model, in the form of α /{α }⊙ =5.426{--}0.101 {log}(g)-1.071 {log}({T}eff}) +0.437([{Fe}/{{H}}]). This process is repeated using a variety of model physics, as well as compared with previous studies and results from 3D convective simulations. Title: Using asteroseismology to characterise exoplanet host stars Authors: Lundkvist, Mia S.; Huber, Daniel; Silva Aguirre, Victor; Chaplin, William J. Bibcode: 2018arXiv180402214L Altcode: The last decade has seen a revolution in the field of asteroseismology - the study of stellar pulsations. It has become a powerful method to precisely characterise exoplanet host stars, and as a consequence also the exoplanets themselves. This synergy between asteroseismology and exoplanet science has flourished in large part due to space missions such as $\textit{Kepler}$, which have provided high-quality data that can be used for both types of studies. Perhaps the primary contribution from asteroseismology to the research on transiting exoplanets is the determination of very precise stellar radii that translate into precise planetary radii, but asteroseismology has also proven useful in constraining eccentricities of exoplanets as well as the dynamical architecture of planetary systems. In this contribution, we introduce some basic principles of asteroseismology and review current synergies between the two fields. Title: Planetary Candidates Observed by Kepler. VIII. A Fully Automated Catalog with Measured Completeness and Reliability Based on Data Release 25 Authors: Thompson, Susan E.; Coughlin, Jeffrey L.; Hoffman, Kelsey; Mullally, Fergal; Christiansen, Jessie L.; Burke, Christopher J.; Bryson, Steve; Batalha, Natalie; Haas, Michael R.; Catanzarite, Joseph; Rowe, Jason F.; Barentsen, Geert; Caldwell, Douglas A.; Clarke, Bruce D.; Jenkins, Jon M.; Li, Jie; Latham, David W.; Lissauer, Jack J.; Mathur, Savita; Morris, Robert L.; Seader, Shawn E.; Smith, Jeffrey C.; Klaus, Todd C.; Twicken, Joseph D.; Van Cleve, Jeffrey E.; Wohler, Bill; Akeson, Rachel; Ciardi, David R.; Cochran, William D.; Henze, Christopher E.; Howell, Steve B.; Huber, Daniel; Prša, Andrej; Ramírez, Solange V.; Morton, Timothy D.; Barclay, Thomas; Campbell, Jennifer R.; Chaplin, William J.; Charbonneau, David; Christensen-Dalsgaard, Jørgen; Dotson, Jessie L.; Doyle, Laurance; Dunham, Edward W.; Dupree, Andrea K.; Ford, Eric B.; Geary, John C.; Girouard, Forrest R.; Isaacson, Howard; Kjeldsen, Hans; Quintana, Elisa V.; Ragozzine, Darin; Shabram, Megan; Shporer, Avi; Silva Aguirre, Victor; Steffen, Jason H.; Still, Martin; Tenenbaum, Peter; Welsh, William F.; Wolfgang, Angie; Zamudio, Khadeejah A.; Koch, David G.; Borucki, William J. Bibcode: 2018ApJS..235...38T Altcode: 2017arXiv171006758T We present the Kepler Object of Interest (KOI) catalog of transiting exoplanets based on searching 4 yr of Kepler time series photometry (Data Release 25, Q1-Q17). The catalog contains 8054 KOIs, of which 4034 are planet candidates with periods between 0.25 and 632 days. Of these candidates, 219 are new, including two in multiplanet systems (KOI-82.06 and KOI-2926.05) and 10 high-reliability, terrestrial-size, habitable zone candidates. This catalog was created using a tool called the Robovetter, which automatically vets the DR25 threshold crossing events (TCEs). The Robovetter also vetted simulated data sets and measured how well it was able to separate TCEs caused by noise from those caused by low signal-to-noise transits. We discuss the Robovetter and the metrics it uses to sort TCEs. For orbital periods less than 100 days the Robovetter completeness (the fraction of simulated transits that are determined to be planet candidates) across all observed stars is greater than 85%. For the same period range, the catalog reliability (the fraction of candidates that are not due to instrumental or stellar noise) is greater than 98%. However, for low signal-to-noise candidates between 200 and 500 days around FGK-dwarf stars, the Robovetter is 76.7% complete and the catalog is 50.5% reliable. The KOI catalog, the transit fits, and all of the simulated data used to characterize this catalog are available at the NASA Exoplanet Archive. Title: VizieR Online Data Catalog: KIC star parallaxes from asteroseismology vs Gaia (Huber+, 2017) Authors: Huber, D.; Zinn, J.; Bojsen-Hansen, M.; Pinsonneault, M.; Sahlholdt, C.; Serenelli, A.; Aguirre, V. S.; Stassun, K.; Stello, D.; Tayar, J.; Bastien, F.; Bedding, T. R.; Buchhave, L. A.; Chaplin, W. J.; Davies, G. R.; Garcia, R. A.; Latham, D. W.; Mathur, S.; Mosser, B.; Sharma, S. Bibcode: 2018yCat..18440102H Altcode: Our sample consists of dwarfs, subgiants, and red giants from the APOGEE-Kepler Asteroseismic Science Consortium (APOKASC, Pinsonneault+ J/ApJS/215/19), supplemented with seismic detections using Kepler short-cadence data from Chaplin+ (2014MNRAS.445..946C) and Huber+ (2013, J/ApJ/767/127).

(2 data files). Title: VizieR Online Data Catalog: APOKASC catalog of KIC dwarfs and subgiants (Serenelli+, 2017) Authors: Serenelli, A.; Johnson, J.; Huber, D.; Pinsonneault, M.; Ball, W. H.; Tayar, J.; Aguirre, V. S.; Basu, S.; Troup, N.; Hekker, S.; Kallinger, T.; Stello, D.; Davies, G. R.; Lund, M. N.; Mathur, S.; Mosser, B.; Stassun, K. G.; Chaplin, W. J.; Elsworth, Y.; Garcia, R. A.; Handberg, R.; Holtzman, J.; Hearty, F.; Garcia-Hernandez, D. A.; Gaulme, P.; Zamora, O. Bibcode: 2018yCat..22330023S Altcode: The catalog consists of stars with detected solar-like oscillations in Kepler short-cadence data as reported in Chaplin+ (2011Sci...332..213C) and with spectroscopic observations from the APOGEE-1 survey (Majewski+ 2017AJ....154...94M). APOGEE spectra cover the H band, between 1.51 and 1.7um, at a resolution R=22500.

This work extends the first APOKASC red giants catalog presented in Pinsonneault+ (2014, J/ApJS/215/19) to include 415 dwarf and subgiant stars. It is based on global seismic parameters Δν and νmax obtained from Kepler short-cadence asteroseismic data with length of light curves spanning from 30 up to 1055 days.

(3 data files). Title: Seismic signatures of magnetic activity in solar-type stars observed by Kepler Authors: Santos, A. R. G.; Campante, T. L.; Chaplin, W. J.; Cunha, M. S.; Lund, M. N.; Kiefer, R.; Salabert, D.; García, R. A.; Davies, G. R.; Elsworth, Y.; Howe, R. Bibcode: 2018IAUS..340..225S Altcode: 2018arXiv180604263S The properties of the acoustic modes are sensitive to magnetic activity. The unprecedented long-term Kepler photometry, thus, allows stellar magnetic cycles to be studied through asteroseismology. We search for signatures of magnetic cycles in the seismic data of Kepler solar-type stars. We find evidence for periodic variations in the acoustic properties of about half of the 87 analysed stars. In these proceedings, we highlight the results obtained for two such stars, namely KIC 8006161 and KIC 5184732. Title: Characterizing Host Stars Using Asteroseismology Authors: Lundkvist, Mia Sloth; Huber, Daniel; Aguirre, Víctor Silva; Chaplin, William J. Bibcode: 2018haex.bookE.177L Altcode: The last decade has seen a revolution in the field of asteroseismology - the study of stellar pulsations. It has become a powerful method to precisely characterize exoplanet host stars and as a consequence also the exoplanets themselves. This synergy between asteroseismology and exoplanet science has flourished in large part due to space missions such as Kepler, which have provided high-quality data that can be used for both types of studies. Perhaps the primary contribution from asteroseismology to the research on transiting exoplanets is the determination of very precise stellar radii that translate into precise planetary radii, but asteroseismology has also proven useful in constraining eccentricities of exoplanets as well as the dynamical architecture of planetary systems. In this chapter, we introduce some basic principles of asteroseismology and review current synergies between the two fields. Title: The Influence of Metallicity on Stellar Differential Rotation and Magnetic Activity Authors: Karoff, Christoffer; Metcalfe, Travis S.; Santos, Ângela R. G.; Montet, Benjamin T.; Isaacson, Howard; Witzke, Veronika; Shapiro, Alexander I.; Mathur, Savita; Davies, Guy R.; Lund, Mikkel N.; Garcia, Rafael A.; Brun, Allan S.; Salabert, David; Avelino, Pedro P.; van Saders, Jennifer; Egeland, Ricky; Cunha, Margarida S.; Campante, Tiago L.; Chaplin, William J.; Krivova, Natalie; Solanki, Sami K.; Stritzinger, Maximilian; Knudsen, Mads F. Bibcode: 2018ApJ...852...46K Altcode: 2017arXiv171107716K Observations of Sun-like stars over the past half-century have improved our understanding of how magnetic dynamos, like that responsible for the 11 yr solar cycle, change with rotation, mass, and age. Here we show for the first time how metallicity can affect a stellar dynamo. Using the most complete set of observations of a stellar cycle ever obtained for a Sun-like star, we show how the solar analog HD 173701 exhibits solar-like differential rotation and a 7.4 yr activity cycle. While the duration of the cycle is comparable to that generated by the solar dynamo, the amplitude of the brightness variability is substantially stronger. The only significant difference between HD 173701 and the Sun is its metallicity, which is twice the solar value. Therefore, this provides a unique opportunity to study the effect of the higher metallicity on the dynamo acting in this star and to obtain a comprehensive understanding of the physical mechanisms responsible for the observed photometric variability. The observations can be explained by the higher metallicity of the star, which is predicted to foster a deeper outer convection zone and a higher facular contrast, resulting in stronger variability. Title: Empirically Calibrated Asteroseismic Masses and Radii for Red Giants in the Kepler Fields Authors: Pinsonneault, Marc; Elsworth, Yvonne; Silva Aguirre, Victor; Chaplin, William J.; Garcia, Rafael A.; Hekker, Saskia; Holtzman, Jon; Huber, Daniel; Johnson, Jennifer; Kallinger, Thomas; Mosser, Benoit; Mathur, Savita; Serenelli, Aldo; Shetrone, Matthew; Stello, Dennis; Tayar, Jamie; Zinn, Joel; APOGEE Team, KASC Team, APOKASC Team Bibcode: 2018AAS...23145013P Altcode: We report on the joint asteroseismic and spectroscopic properties of a sample of 6048 evolved stars in the fields originally observed by the Kepler satellite. We use APOGEE spectroscopic data taken from Data Release 13 of the Sloan Digital Sky Survey, combined with asteroseismic data analyzed by members of the Kepler Asteroseismic Science Consortium. With high statistical significance, the different pipelines do not have relative zero points that are the same as the solar values, and red clump stars do not have the same empirical relative zero points as red giants. We employ theoretically motivated corrections to the scaling relation for the large frequency spacing, and adjust the zero point of the frequency of maximum power scaling relation to be consistent with masses and radii for members of star clusters. The scatter in calibrator masses is consistent with our error estimation. Systematic and random mass errors are explicitly separated and identified. The measurement scatter, and random uncertainties, are three times larger for red giants where one or more technique failed to return a value than for targets where all five methods could do so, and this is a substantial fraction of the sample (20% of red giants and 25% of red clump stars). Overall trends and future prospects are discussed. Title: Spatial incoherence of solar granulation: a global analysis using BiSON 2B data Authors: Lund, Mikkel N.; Chaplin, William J.; Hale, Steven J.; Davies, Guy R.; Elsworth, Yvonne P.; Howe, Rachel Bibcode: 2017MNRAS.472.3256L Altcode: 2017arXiv170901329L A poor understanding of the impact of convective turbulence in the outer layers of the Sun and Sun-like stars challenges the advance towards an improved understanding of their internal structure and dynamics. Assessing and calibrating these effects is therefore of great importance. Here, we study the spatial coherence of granulation noise and oscillation modes in the Sun, with the aim of exploiting any incoherence to beat down observed granulation noise, hence improving the detection of low-frequency p modes. Using data from the BiSON 2B instrument, we assess the coherence between different atmospheric heights and between different surface regions. We find that granulation noise from the different atmospheric heights probed is largely incoherent; frequency regions dominated by oscillations are almost fully coherent. We find a randomized phase difference for the granulation noise, and a near zero difference for the evanescent oscillations. A reduction of the incoherent granulation noise is shown by application of the cross-spectrum. Title: The masses of retired A stars with asteroseismology: Kepler and K2 observations of exoplanet hosts Authors: North, Thomas S. H.; Campante, Tiago L.; Miglio, Andxsrea; Davies, Guy R.; Grunblatt, Samuel K.; Huber, Daniel; Kuszlewicz, James S.; Lund, Mikkel N.; Cooke, Benjamin F.; Chaplin, William J. Bibcode: 2017MNRAS.472.1866N Altcode: 2017arXiv170800716N We investigate the masses of 'retired A stars' using asteroseismic detections on seven low-luminosity red-giant and sub-giant stars observed by the NASA Kepler and K2 missions. Our aim is to explore whether masses derived from spectroscopy and isochrone fitting may have been systematically overestimated. Our targets have all previously been subject to long-term radial velocity observations to detect orbiting bodies, and satisfy the criteria used by Johnson et al. to select survey stars which may have had A-type (or early F-type) main-sequence progenitors. The sample actually spans a somewhat wider range in mass, from ≈ 1 M⊙ up to ≈ 1.7 M⊙. Whilst for five of the seven stars the reported discovery mass from spectroscopy exceeds the mass estimated using asteroseismology, there is no strong evidence for a significant, systematic bias across the sample. Moreover, comparisons with other masses from the literature show that the absolute scale of any differences is highly sensitive to the chosen reference literature mass, with the scatter between different literature masses significantly larger than reported error bars. We find that any mass difference can be explained through use of different constraints during the recovery process. We also conclude that underestimated uncertainties on the input parameters can significantly bias the recovered stellar masses, which may have contributed to the controversy on the mass scale for retired A stars. Title: Seeing Double with K2: Testing Re-inflation with Two Remarkably Similar Planets around Red Giant Branch Stars Authors: Grunblatt, Samuel K.; Huber, Daniel; Gaidos, Eric; Lopez, Eric D.; Howard, Andrew W.; Isaacson, Howard T.; Sinukoff, Evan; Vanderburg, Andrew; Nofi, Larissa; Yu, Jie; North, Thomas S. H.; Chaplin, William; Foreman-Mackey, Daniel; Petigura, Erik; Ansdell, Megan; Weiss, Lauren; Fulton, Benjamin; Lin, Douglas N. C. Bibcode: 2017AJ....154..254G Altcode: 2017arXiv170605865G Despite more than 20 years since the discovery of the first gas giant planet with an anomalously large radius, the mechanism for planet inflation remains unknown. Here, we report the discovery of K2-132b, an inflated gas giant planet found with the NASA K2 Mission, and a revised mass for another inflated planet, K2-97b. These planets orbit on ≍9 day orbits around host stars that recently evolved into red giants. We constrain the irradiation history of these planets using models constrained by asteroseismology and Keck/High Resolution Echelle Spectrometer spectroscopy and radial velocity measurements. We measure planet radii of 1.31 ± 0.11 RJ and 1.30 ± 0.07 RJ, respectively. These radii are typical for planets receiving the current irradiation, but not the former, zero age main-sequence irradiation of these planets. This suggests that the current sizes of these planets are directly correlated to their current irradiation. Our precise constraints of the masses and radii of the stars and planets in these systems allow us to constrain the planetary heating efficiency of both systems as 0.03 %-0.02%0.03%. These results are consistent with a planet re-inflation scenario, but suggest that the efficiency of planet re-inflation may be lower than previously theorized. Finally, we discuss the agreement within 10% of the stellar masses and radii, and the planet masses, radii, and orbital periods of both systems, and speculate that this may be due to selection bias in searching for planets around evolved stars. Title: The First APOKASC Catalog of Kepler Dwarf and Subgiant Stars Authors: Serenelli, Aldo; Johnson, Jennifer; Huber, Daniel; Pinsonneault, Marc; Ball, Warrick H.; Tayar, Jamie; Silva Aguirre, Victor; Basu, Sarbani; Troup, Nicholas; Hekker, Saskia; Kallinger, Thomas; Stello, Dennis; Davies, Guy R.; Lund, Mikkel N.; Mathur, Savita; Mosser, Benoit; Stassun, Keivan G.; Chaplin, William J.; Elsworth, Yvonne; García, Rafael A.; Handberg, Rasmus; Holtzman, Jon; Hearty, Fred; García-Hernández, D. A.; Gaulme, Patrick; Zamora, Olga Bibcode: 2017ApJS..233...23S Altcode: 2017arXiv171006858S We present the first APOKASC catalog of spectroscopic and asteroseismic data for dwarfs and subgiants. Asteroseismic data for our sample of 415 objects have been obtained by the Kepler mission in short (58.5 s) cadence, and light curves span from 30 up to more than 1000 days. The spectroscopic parameters are based on spectra taken as part of the Apache Point Observatory Galactic Evolution Experiment and correspond to Data Release 13 of the Sloan Digital Sky Survey. We analyze our data using two independent {T}{eff} scales, the spectroscopic values from DR13 and those derived from SDSS griz photometry. We use the differences in our results arising from these choices as a test of systematic temperature uncertainties and find that they can lead to significant differences in the derived stellar properties. Determinations of surface gravity ({log}g), mean density (< ρ > ), radius (R), mass (M), and age (τ) for the whole sample have been carried out by means of (stellar) grid-based modeling. We have thoroughly assessed random and systematic error sources in the spectroscopic and asteroseismic data, as well as in the grid-based modeling determination of the stellar quantities provided in the catalog. We provide stellar properties determined for each of the two {T}{eff} scales. The median combined (random and systematic) uncertainties are 2% (0.01 dex; {log}g), 3.4% (< ρ > ), 2.6% (R), 5.1% (M), and 19% (τ) for the photometric {T}{eff} scale and 2% ({log}g), 3.5% (< ρ > ), 2.7% (R), 6.3% (M), and 23% (τ) for the spectroscopic scale. We present comparisons with stellar quantities in the asteroseismic catalog by Chaplin et al. that highlight the importance of having metallicity measurements for determining stellar parameters accurately. Finally, we compare our results with those coming from a variety of sources, including stellar radii determined from TGAS parallaxes and asteroseismic analyses based on individual frequencies. We find a very good agreement for all inferred quantities. The latter comparison, in particular, gives strong support to the determination of stellar quantities based on global seismology, a relevant result for future missions such as TESS and PLATO. Title: VizieR Online Data Catalog: 61 main-sequence and subgiant oscillations (Appourchaux+, 2012) Authors: Appourchaux, T.; Chaplin, W. J.; Garcia, R. A.; Gruberbauer, M.; Verner, G. A.; Antia, H. M.; Benomar, O.; Campante, T. L.; Davies, G. R.; Deheuvels, S.; Handberg, R.; Hekker, S.; Howe, R.; Regulo, C.; Salabert, D.; Bedding, T. R.; White, T. R.; Ballot, J.; Mathur, S.; Silva Aguirre, V.; Elsworth, Y. P.; Basu, S.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Uddin, K.; Stumpe, M. C.; Barclay, T. Bibcode: 2017yCat..35430054A Altcode: Kepler observations are obtained in two different operating modes: long cadence (LC) and short cadence (SC) (Gilliland et al., 2010ApJ...713L.160G; Jenkins et al., 2010ApJ...713L..87J). This work is based on SC data. For the brightest stars (down to Kepler magnitude, Kp~=12), SC observations can be obtained for a limited number of stars (up to 512 at any given time) with a faster sampling cadence of 58.84876s (Nyquist frequency of ~8.5mHz), which permits a more precise transit timing and the performance of asteroseismology. Kepler observations are divided into three-month-long quarters (Q). A subset of 61 solar-type stars observed during quarters Q5-Q7 (March 22, 2010 to December 22, 2010) were chosen because they have oscillation modes with high signal-to-noise ratios. This length of data gives a frequency resolution of about 0.04uHz.

(2 data files). Title: Erratum: “Standing on the Shoulders of Dwarfs: The Kepler Asteroseismic LEGACY Sample. I. Oscillation Mode Parameters” (2017, ApJ, 835, 172) Authors: Lund, Mikkel N.; Silva Aguirre, Víctor; Davies, Guy R.; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Houdek, Günter; White, Timothy R.; Bedding, Timothy R.; Ball, Warrick H.; Huber, Daniel; Antia, H. M.; Lebreton, Yveline; Latham, David W.; Handberg, Rasmus; Verma, Kuldeep; Basu, Sarbani; Casagrande, Luca; Justesen, Anders B.; Kjeldsen, Hans; Mosumgaard, Jakob R. Bibcode: 2017ApJ...850..110L Altcode: No abstract at ADS Title: VizieR Online Data Catalog: Asterosismology for solar analogues 16 Cyg A/B (Davies+, 2015) Authors: Davies, G. R.; Chaplin, W. J.; Farr, W. M.; Garcia, R. A.; Lund, M. N.; Mathis, S.; Metcalfe, T. S.; Appourchaux, T.; Basu, S.; Benomar, O.; Campante, T. L.; Ceillier, T.; Elsworth, Y.; Handberg, R.; Salabert, D.; Stello, D. Bibcode: 2017yCat..74462959D Altcode: Both 16 Cyg A and B are brighter (V~6) than the saturation limit for which Kepler observations were designed. However, it was possible to capture the full stellar flux by using custom photometric aperture masks. Thus, 928 d of short-cadence observations (Gilliland et al. 2010ApJ...713L.160G) - from Quarter 7 to 16 - were generated using simple aperture photometry (Jenkins et al. 2010ApJ...713L..87J) and then corrected for instrumental perturbations following the methods described by Garcia et al. (2011MNRAS.414L...6G). The final light curves used for asteroseismic analyses were high-pass filtered using a triangular smooth of 4 d width and have a duty cycle of 90.5 per cent. The power density spectra were computed using a Lomb-Scargle algorithm.

(2 data files). Title: NGC 6819: testing the asteroseismic mass scale, mass loss and evidence for products of non-standard evolution Authors: Handberg, R.; Brogaard, K.; Miglio, A.; Bossini, D.; Elsworth, Y.; Slumstrup, D.; Davies, G. R.; Chaplin, W. J. Bibcode: 2017MNRAS.472..979H Altcode: 2017arXiv170708223H We present an extensive peakbagging effort on Kepler data of ∼50 red giant stars in the open star cluster NGC 6819. By employing sophisticated pre-processing of the time series and Markov chain Monte Carlo techniques we extracted individual frequencies, heights and line widths for hundreds of oscillation modes. We show that the 'average' asteroseismic parameter δν02, derived from these, can be used to distinguish the stellar evolutionary state between the red giant branch (RGB) stars and red clump (RC) stars. Masses and radii are estimated using asteroseismic scaling relations, both empirically corrected to obtain self-consistency and agreement with independent measures of distance, and using updated theoretical corrections. Remarkable agreement is found, allowing the evolutionary state of the giants to be determined exclusively from the empirical correction to the scaling relations. We find a mean mass of the RGB stars and RC stars in NGC 6819 to be 1.61 ± 0.02 and 1.64 ± 0.02 M⊙, respectively. The difference ΔM = -0.03 ± 0.01 M⊙ is almost insensitive to systematics, suggesting very little RGB mass loss, if any. Stars that are outliers relative to the ensemble reveal overmassive members that likely evolved via mass transfer in a blue straggler phase. We suggest that KIC 4937011, a low-mass Li-rich giant, is a cluster member in the RC phase that experienced very high mass loss during its evolution. Such over- and undermassive stars need to be considered when studying field giants, since the true age of such stars cannot be known and there is currently no way to distinguish them from normal stars. Title: Data preparation for asteroseismology with TESS Authors: Lund, Mikkel N.; Handberg, Rasmus; Kjeldsen, Hans; Chaplin, William J.; Christensen-Dalsgaard, Jørgen Bibcode: 2017EPJWC.16001005L Altcode: 2016arXiv161002702L The Transiting Exoplanet Survey Satellite (TESS) is a NASA Astrophysics Explorer mission. Following its scheduled launch in 2017, TESS will focus on detecting exoplanets around the nearest and brightest stars in the sky, for which detailed follow-up observations are possible. TESS will, as the NASA Kepler mission, include a asteroseismic program that will be organized within the TESS Asteroseismic Science Consortium (TASC), building on the success of the Kepler Asteroseismic Science Consortium (KASC). Within TASC data for asteroseismic analysis will be prepared by the TASC Working Group 0 (WG-0), who will facilitate data to the community via the TESS Asteroseismic Science Operations Center (TASOC), again building on the success of the corresponding KASOC platform for Kepler. Here, we give an overview of the steps being taken within WG-0 to prepare for the upcoming TESS mission. Title: The more the merrier: grid based modelling of Kepler dwarfs with 5-dimensional stellar grids Authors: Serenelli, Aldo; Chaplin, William J.; Huber, Daniel Bibcode: 2017EPJWC.16003011S Altcode: 2017arXiv170600503S We present preliminary results of our grid based modelling (GBM) of the dwarf/subgiant sample of stars observed with Kepler including global asteroseismic parameters. GBM analysis in this work is based on a large grid of stellar models that is characterized by five independent parameters: model mass and age, initial metallicity (Zini), initial helium (Yini), and mixing length parameter (αMLT). Using this grid relaxes assumptions used in all previous GBM work where the initial composition is determined by a single parameter and that αMLT is fixed to a solar-calibrated value. The new grid allows us to study, for example, the impact of different galactic chemical enrichment models on the determination of stellar parameters such as mass radius and age. Also, it allows to include new results from stellar atmosphere models on αMLT in the GBM analysis in a simple manner. Alternatively, it can be tested if global asteroseismology is a useful tool to constraint our ignorance on quantities such as Yini and αMLT. Initial findings show that mass determination is robust with respect to freedom in the latter quantities, with a 4.4% maximum deviation for extreme assumptions regarding prior information on Yini - Zini relations and aMLT. On the other hand, tests carried out so far seem to indicate that global seismology does not have much power to constrain Yini - Zni relations of αMLT values without resourcing to additional information. Title: On the relation between activity-related frequency shifts and the sunspot distribution over the solar cycle 23 Authors: Santos, Ângela R. G.; Cunha, Margarida S.; Avelino, Pedro P.; Chaplin, William J.; Campante, Tiago L. Bibcode: 2017EPJWC.16002013S Altcode: 2016arXiv161107475S The activity-related variations in the solar acoustic frequencies have been known for 30 years. However, the importance of the different contributions is still not well established. With this in mind, we developed an empirical model to estimate the spot-induced frequency shifts, which takes into account the sunspot properties, such as area and latitude. The comparison between the model frequency shifts obtained from the daily sunspot records and those observed suggests that the contribution from a stochastic component to the total frequency shifts is about 30%. The remaining 70% is related to a global, long-term variation. We also propose a new observable to investigate the short-and mid-term variations of the frequency shifts, which is insensitive to the long-term variations contained in the data. On the shortest time scales the variations in the frequency shifts are strongly correlated with the variations in the total area covered by sunspots. However, a significant loss of correlation is still found, which cannot be fully explained by ignoring the invisible side of the Sun when accounting for the total sunspot area. We also verify that the times when the frequency shifts and the sunspot areas do not vary in a similar way tend to coincide with the times of the maximum amplitude of the quasi-biennial variations found in the seismic data. Title: The Sun in transition? Persistence of near-surface structural changes through Cycle 24 Authors: Howe, R.; Davies, G. R.; Chaplin, W. J.; Elsworth, Y.; Basu, S.; Hale, S. J.; Ball, W. H.; Komm, R. W. Bibcode: 2017MNRAS.470.1935H Altcode: 2017arXiv170509099H We examine the frequency shifts in low-degree helioseismic modes from the Birmingham Solar-Oscillations Network covering the period from 1985 to 2016, and compare them with a number of global activity proxies well as a latitudinally resolved magnetic index. As well as looking at frequency shifts in different frequency bands, we look at a parametrization of the shift as a cubic function of frequency. While the shifts in the medium- and high-frequency bands are very well correlated with all of the activity indices (with the best correlation being with the 10.7-cm radio flux), we confirm earlier findings that there appears to have been a change in the frequency response to activity during solar Cycle 23, and the low-frequency shifts are less correlated with activity in the last two cycles than they were in Cycle 22. At the same time, the more recent cycles show a slight increase in their sensitivity to activity levels at medium and higher frequencies, perhaps because a greater proportion of activity is composed of weaker or more ephemeral regions. This lends weight to the speculation that a fundamental change in the nature of the solar dynamo may be in progress. Title: Atmospheric Extinction Coefficients in the Ic Band for Several Major International Observatories: Results from the BiSON Telescopes, 1984-2016 Authors: Hale, S. J.; Chaplin, W. J.; Davies, G. R.; Elsworth, Y. P.; Howe, R.; Lund, M. N.; Moxon, E. Z.; Thomas, A.; Pallé, P. L.; Rhodes, E. J., Jr. Bibcode: 2017AJ....154...89H Altcode: 2017arXiv170706647H Over 30 years of solar data have been acquired by the Birmingham Solar Oscillations Network (BiSON), an international network of telescopes used to study oscillations of the Sun. Five of the six BiSON telescopes are located at major observatories. The observational sites are, in order of increasing longitude: Mount Wilson (Hale) Observatory (MWO), California, USA; Las Campanas Observatory, Chile; Observatorio del Teide, Izaña, Tenerife, Canary Islands; the South African Astronomical Observatory, Sutherland, South Africa; Carnarvon, Western Australia; and the Paul Wild Observatory, Narrabri, New South Wales, Australia. The BiSON data may be used to measure atmospheric extinction coefficients in the {{{I}}}{{c}} band (approximately 700-900 nm), and presented here are the derived atmospheric extinction coefficients from each site over the years 1984-2016. Title: The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Authors: Majewski, Steven R.; Schiavon, Ricardo P.; Frinchaboy, Peter M.; Allende Prieto, Carlos; Barkhouser, Robert; Bizyaev, Dmitry; Blank, Basil; Brunner, Sophia; Burton, Adam; Carrera, Ricardo; Chojnowski, S. Drew; Cunha, Kátia; Epstein, Courtney; Fitzgerald, Greg; García Pérez, Ana E.; Hearty, Fred R.; Henderson, Chuck; Holtzman, Jon A.; Johnson, Jennifer A.; Lam, Charles R.; Lawler, James E.; Maseman, Paul; Mészáros, Szabolcs; Nelson, Matthew; Nguyen, Duy Coung; Nidever, David L.; Pinsonneault, Marc; Shetrone, Matthew; Smee, Stephen; Smith, Verne V.; Stolberg, Todd; Skrutskie, Michael F.; Walker, Eric; Wilson, John C.; Zasowski, Gail; Anders, Friedrich; Basu, Sarbani; Beland, Stephane; Blanton, Michael R.; Bovy, Jo; Brownstein, Joel R.; Carlberg, Joleen; Chaplin, William; Chiappini, Cristina; Eisenstein, Daniel J.; Elsworth, Yvonne; Feuillet, Diane; Fleming, Scott W.; Galbraith-Frew, Jessica; García, Rafael A.; García-Hernández, D. Aníbal; Gillespie, Bruce A.; Girardi, Léo; Gunn, James E.; Hasselquist, Sten; Hayden, Michael R.; Hekker, Saskia; Ivans, Inese; Kinemuchi, Karen; Klaene, Mark; Mahadevan, Suvrath; Mathur, Savita; Mosser, Benoît; Muna, Demitri; Munn, Jeffrey A.; Nichol, Robert C.; O'Connell, Robert W.; Parejko, John K.; Robin, A. C.; Rocha-Pinto, Helio; Schultheis, Matthias; Serenelli, Aldo M.; Shane, Neville; Silva Aguirre, Victor; Sobeck, Jennifer S.; Thompson, Benjamin; Troup, Nicholas W.; Weinberg, David H.; Zamora, Olga Bibcode: 2017AJ....154...94M Altcode: 2015arXiv150905420M The Apache Point Observatory Galactic Evolution Experiment (APOGEE), one of the programs in the Sloan Digital Sky Survey III (SDSS-III), has now completed its systematic, homogeneous spectroscopic survey sampling all major populations of the Milky Way. After a three-year observing campaign on the Sloan 2.5 m Telescope, APOGEE has collected a half million high-resolution (R ∼ 22,500), high signal-to-noise ratio (>100), infrared (1.51-1.70 μm) spectra for 146,000 stars, with time series information via repeat visits to most of these stars. This paper describes the motivations for the survey and its overall design—hardware, field placement, target selection, operations—and gives an overview of these aspects as well as the data reduction, analysis, and products. An index is also given to the complement of technical papers that describe various critical survey components in detail. Finally, we discuss the achieved survey performance and illustrate the variety of potential uses of the data products by way of a number of science demonstrations, which span from time series analysis of stellar spectral variations and radial velocity variations from stellar companions, to spatial maps of kinematics, metallicity, and abundance patterns across the Galaxy and as a function of age, to new views of the interstellar medium, the chemistry of star clusters, and the discovery of rare stellar species. As part of SDSS-III Data Release 12 and later releases, all of the APOGEE data products are publicly available. Title: VizieR Online Data Catalog: Kepler asteroseismic LEGACY sample. I. Oscillations (Lund+, 2017) Authors: Lund, M. N.; Silva Aguirre, V.; Davies, G. R.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Houdek, G.; White, T. R.; Bedding, T. R.; Ball, W. H.; Huber, D.; Antia, H. M.; Lebreton, Y.; Latham, D. W.; Handberg, R.; Verma, K.; Basu, S.; Casagrande, L.; Justesen, A. B.; Kjeldsen, H.; Mosumgaard, J. R. Bibcode: 2017yCat..18350172L Altcode: The advent of space-based missions like Kepler has revolutionized the study of solar-type stars, particularly through the measurement and modeling of their resonant modes of oscillation. Here we analyze a sample of 66 Kepler main-sequence stars showing solar-like oscillations as part of the Kepler seismic LEGACY project. We use Kepler short-cadence data, of which each star has at least 12 months, to create frequency-power spectra optimized for asteroseismology. For each star, we identify its modes of oscillation and extract parameters such as frequency, amplitude, and line width using a Bayesian Markov chain Monte Carlo "peak-bagging" approach. We report the extracted mode parameters for all 66 stars, as well as derived quantities such as frequency difference ratios, the large and small separations Δν and δν02; the behavior of line widths with frequency and line widths at νmax with Teff, for which we derive parametrizations; and behavior of mode visibilities. These average properties can be applied in future peak-bagging exercises to better constrain the parameters of the stellar oscillation spectra. The frequencies and frequency ratios can tightly constrain the fundamental parameters of these solar-type stars, and mode line widths and amplitudes can test models of mode damping and excitation.

(4 data files). Title: VizieR Online Data Catalog: Kepler asteroseismic LEGACY sample. II. (Silva Aguirre+, 2017) Authors: Silva Aguirre, V.; Lund, M. N.; Antia, H. M.; Ball, W. H.; Basu, S.; Christensen-Dalsgaard, J.; Lebreton, Y.; Reese, D. R.; Verma, K.; Casagrande, L.; Justesen, A. B.; Mosumgaard, J. R.; Chaplin, W. J.; Bedding, T. R.; Davies, G. R.; Handberg, R.; Houdek, G.; Huber, D.; Kjeldsen, H.; Latham, D. W.; White, T. R.; Coelho, H. R.; Miglio, A.; Rendle, B. Bibcode: 2017yCat..18350173S Altcode: The 66 stars comprising the LEGACY sample were chosen from more than 500 main-sequence and subgiant targets in which Kepler detected oscillations (Chaplin+ 2014, J/ApJS/210/1). We selected all targets that had more than one year of short-cadence observations, and where inspection of the power spectrum did not reveal any clear signature of bumped l=1 modes.

(3 data files). Title: VizieR Online Data Catalog: K2 GAP data release. I. Campaign 1 (Stello+, 2017) Authors: Stello, D.; Zinn, J.; Elsworth, Y.; Garcia, R. A.; Kallinger, T.; Mathur, S.; Mosser, B.; Sharma, S.; Chaplin, W. J.; Davies, G.; Huber, D.; Jones, C. D.; Miglio, A.; Silva Aguirre, V. Bibcode: 2017yCat..18350083S Altcode: All K2 Galactic Archaeology Program (GAP; Stello+ 2015ApJ...809L...3S) targets were observed with Kepler for about 80 days from 2014 May 30 to August 21.

(2 data files). Title: Asteroseismology and Gaia: Testing Scaling Relations Using 2200 Kepler Stars with TGAS Parallaxes Authors: Huber, Daniel; Zinn, Joel; Bojsen-Hansen, Mathias; Pinsonneault, Marc; Sahlholdt, Christian; Serenelli, Aldo; Silva Aguirre, Victor; Stassun, Keivan; Stello, Dennis; Tayar, Jamie; Bastien, Fabienne; Bedding, Timothy R.; Buchhave, Lars A.; Chaplin, William J.; Davies, Guy R.; García, Rafael A.; Latham, David W.; Mathur, Savita; Mosser, Benoit; Sharma, Sanjib Bibcode: 2017ApJ...844..102H Altcode: 2017arXiv170504697H We present a comparison of parallaxes and radii from asteroseismology and Gaia DR1 (TGAS) for 2200 Kepler stars spanning from the main sequence to the red-giant branch. We show that previously identified offsets between TGAS parallaxes and distances derived from asteroseismology and eclipsing binaries have likely been overestimated for parallaxes ≲ 5{--}10 mas (≈90%-98% of the TGAS sample). The observed differences in our sample can furthermore be partially compensated by adopting a hotter {T}{eff} scale (such as the infrared flux method) instead of spectroscopic temperatures for dwarfs and subgiants. Residual systematic differences are at the ≈2% level in parallax across three orders of magnitude. We use TGAS parallaxes to empirically demonstrate that asteroseismic radii are accurate to ≈5% or better for stars between ≈ 0.8{--}8 {R}⊙ . We find no significant offset for main-sequence (≲ 1.5 {R}⊙ ) and low-luminosity RGB stars (≈3-8 {R}⊙ ), but seismic radii appear to be systematically underestimated by ≈5% for subgiants (≈1.5-3 {R}⊙ ). We find no systematic errors as a function of metallicity between [{Fe}/{{H}}]≈ -0.8 to +0.4 dex, and show tentative evidence that corrections to the scaling relation for the large frequency separation ({{Δ }}ν ) improve the agreement with TGAS for RGB stars. Finally, we demonstrate that beyond ≈ 3 {kpc} asteroseismology will provide more precise distances than end-of-mission Gaia data, highlighting the synergy and complementary nature of Gaia and asteroseismology for studying galactic stellar populations. Title: Weighing in on the masses of retired A stars with asteroseismology: K2 observations of the exoplanet-host star HD 212771 Authors: Campante, Tiago L.; Veras, Dimitri; North, Thomas S. H.; Miglio, Andrea; Morel, Thierry; Johnson, John A.; Chaplin, William J.; Davies, Guy R.; Huber, Daniel; Kuszlewicz, James S.; Lund, Mikkel N.; Cooke, Benjamin F.; Elsworth, Yvonne P.; Rodrigues, Thaíse S.; Vanderburg, Andrew Bibcode: 2017MNRAS.469.1360C Altcode: 2017arXiv170401794C Doppler-based planet surveys point to an increasing occurrence rate of giant planets with stellar mass. Such surveys rely on evolved stars for a sample of intermediate-mass stars (so-called retired A stars), which are more amenable to Doppler observations than their main-sequence progenitors. However, it has been hypothesized that the masses of subgiant and low-luminosity red-giant stars targeted by these surveys - typically derived from a combination of spectroscopy and isochrone fitting - may be systematically overestimated. Here, we test this hypothesis for the particular case of the exoplanet-host star HD 212771 using K2 asteroseismology. The benchmark asteroseismic mass (1.45^{+0.10}_{-0.09} M_{⊙) is significantly higher than the value reported in the discovery paper (1.15 ± 0.08 M⊙), which has been used to inform the stellar mass-planet occurrence relation. This result, therefore, does not lend support to the above hypothesis. Implications for the fates of planetary systems are sensitively dependent on stellar mass. Based on the derived asteroseismic mass, we predict the post-main-sequence evolution of the Jovian planet orbiting HD 212771 under the effects of tidal forces and stellar mass-loss. Title: VizieR Online Data Catalog: Broadband photometry of Neptune from K2 (Rowe+, 2017) Authors: Rowe, J. F.; Gaulme, P.; Lissauer, J. J.; Marley, M. S.; Simon, A. A.; Hammel, H. B.; Silva Aguirre, V.; Barclay, T.; Benomar, O.; Boumier, P.; Caldwell, D. A.; Casewell, S. L.; Chaplin, W. J.; Colon, K. D.; Corsaro, E.; Davies, G. R.; Fortney, J. J.; Garcia, R. A.; Gizis, J. E.; Haas, M. R.; Mosser, B.; Schmider, F. -X. Bibcode: 2017yCat..51530149R Altcode: The K2 C3 field provided the first opportunity to observe the planet Neptune for up to 80 days with short-cadence (1 minute) sampling (the C3 campaign had an actual duration of 69.2 days, limited by on-board data storage). We were awarded sufficient pixel allocation from Guest Observer Programs GO3060 (PI: Rowe) and GO3057 (PI: Gaulme) to continuously monitor Neptune for 49 days.

Short-cadence target pixel files were obtained from Mikulski Archive for Space Telescopes (MAST). The Neptune short-cadence subraster was spread across 161 FITS files. Each file contained 1 column of time-series pixel data. Each target pixel file contains observations starting on 2014 November 15 and finishing on 2015 January 18.

(1 data file). Title: Changing the ν max Scaling Relation: The Need for a Mean Molecular Weight Term Authors: Viani, Lucas S.; Basu, Sarbani; Chaplin, William J.; Davies, Guy R.; Elsworth, Yvonne Bibcode: 2017ApJ...843...11V Altcode: 2017arXiv170503472V The scaling relations that relate the average asteroseismic parameters {{Δ }}ν and {ν }\max to the global properties of stars are used quite extensively to determine stellar properties. While the {{Δ }}ν scaling relation has been examined carefully and the deviations from the relation have been well documented, the {ν }\max scaling relation has not been examined as extensively. In this paper, we examine the {ν }\max scaling relation using a set of stellar models constructed to have a wide range of mass, metallicity, and age. We find that as with {{Δ }}ν , {ν }\max does not follow the simple scaling relation. The most visible deviation is because of a mean molecular weight term and a {{{Γ }}}1 term that are commonly ignored. The remaining deviation is more difficult to address. We find that the influence of the scaling relation errors on asteroseismically derived values of {log}g are well within uncertainties. The influence of the errors on mass and radius estimates is small for main sequence and subgiants, but can be quite large for red giants. Title: PLATO as it is : A legacy mission for Galactic archaeology Authors: Miglio, A.; Chiappini, C.; Mosser, B.; Davies, G. R.; Freeman, K.; Girardi, L.; Jofré, P.; Kawata, D.; Rendle, B. M.; Valentini, M.; Casagrande, L.; Chaplin, W. J.; Gilmore, G.; Hawkins, K.; Holl, B.; Appourchaux, T.; Belkacem, K.; Bossini, D.; Brogaard, K.; Goupil, M. -J.; Montalbán, J.; Noels, A.; Anders, F.; Rodrigues, T.; Piotto, G.; Pollacco, D.; Rauer, H.; Prieto, C. Allende; Avelino, P. P.; Babusiaux, C.; Barban, C.; Barbuy, B.; Basu, S.; Baudin, F.; Benomar, O.; Bienaymé, O.; Binney, J.; Bland-Hawthorn, J.; Bressan, A.; Cacciari, C.; Campante, T. L.; Cassisi, S.; Christensen-Dalsgaard, J.; Combes, F.; Creevey, O.; Cunha, M. S.; Jong, R. S.; Laverny, P.; Degl'Innocenti, S.; Deheuvels, S.; Depagne, É.; Ridder, J.; Matteo, P. Di; Mauro, M. P. Di; Dupret, M. -A.; Eggenberger, P.; Elsworth, Y.; Famaey, B.; Feltzing, S.; García, R. A.; Gerhard, O.; Gibson, B. K.; Gizon, L.; Haywood, M.; Handberg, R.; Heiter, U.; Hekker, S.; Huber, D.; Ibata, R.; Katz, D.; Kawaler, S. D.; Kjeldsen, H.; Kurtz, D. W.; Lagarde, N.; Lebreton, Y.; Lund, M. N.; Majewski, S. R.; Marigo, P.; Martig, M.; Mathur, S.; Minchev, I.; Morel, T.; Ortolani, S.; Pinsonneault, M. H.; Plez, B.; Moroni, P. G. Prada; Pricopi, D.; Recio-Blanco, A.; Reylé, C.; Robin, A.; Roxburgh, I. W.; Salaris, M.; Santiago, B. X.; Schiavon, R.; Serenelli, A.; Sharma, S.; Aguirre, V. Silva; Soubiran, C.; Steinmetz, M.; Stello, D.; Strassmeier, K. G.; Ventura, P.; Ventura, R.; Walton, N. A.; Worley, C. C. Bibcode: 2017AN....338..644M Altcode: 2017arXiv170603778M Deciphering the assembly history of the Milky Way is a formidable task, which becomes possible only if one can produce high-resolution chrono-chemo-kinematical maps of the Galaxy. Data from large-scale astrometric and spectroscopic surveys will soon provide us with a well-defined view of the current chemo-kinematical structure of the Milky Way, but will only enable a blurred view on the temporal sequence that led to the present-day Galaxy. As demonstrated by the (ongoing) exploitation of data from the pioneering photometric missions CoRoT, Kepler, and K2, asteroseismology provides the way forward: solar-like oscillating giants are excellent evolutionary clocks thanks to the availability of seismic constraints on their mass and to the tight age-initial-mass relation they adhere to. In this paper we identify five key outstanding questions relating to the formation and evolution of the Milky Way that will need precise and accurate ages for large samples of stars to be addressed, and we identify the requirements in terms of number of targets and the precision on the stellar properties that are needed to tackle such questions. By quantifying the asteroseismic yields expected from PLATO for red-giant stars, we demonstrate that these requirements are within the capabilities of the current instrument design, provided that observations are sufficiently long to identify the evolutionary state and allow robust and precise determination of acoustic-mode frequencies. This will allow us to harvest data of sufficient quality to reach a 10% precision in age. This is a fundamental pre-requisite to then reach the more ambitious goal of a similar level of accuracy, which will only be possible if we have to hand a careful appraisal of systematic uncertainties on age deriving from our limited understanding of stellar physics, a goal which conveniently falls within the main aims of PLATO's core science. Title: Kepler observations of the asteroseismic binary HD 176465 Authors: White, T. R.; Benomar, O.; Silva Aguirre, V.; Ball, W. H.; Bedding, T. R.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Garcia, R. A.; Gizon, L.; Stello, D.; Aigrain, S.; Antia, H. M.; Appourchaux, T.; Bazot, M.; Campante, T. L.; Creevey, O. L.; Davies, G. R.; Elsworth, Y. P.; Gaulme, P.; Handberg, R.; Hekker, S.; Houdek, G.; Howe, R.; Huber, D.; Karoff, C.; Marques, J. P.; Mathur, S.; McQuillan, A.; Metcalfe, T. S.; Mosser, B.; Nielsen, M. B.; Régulo, C.; Salabert, D.; Stahn, T. Bibcode: 2017A&A...601A..82W Altcode: 2016arXiv160909581W; 2016A&A...601A..82W Binary star systems are important for understanding stellar structure and evolution, and are especially useful when oscillations can be detected and analysed with asteroseismology. However, only four systems are known in which solar-like oscillations are detected in both components. Here, we analyse the fifth such system, HD 176465, which was observed by Kepler. We carefully analysed the system's power spectrum to measure individual mode frequencies, adapting our methods where necessary to accommodate the fact that both stars oscillate in a similar frequency range. We also modelled the two stars independently by fitting stellar models to the frequencies and complementaryparameters. We are able to cleanly separate the oscillation modes in both systems. The stellar models produce compatible ages and initial compositions for the stars, as is expected from their common and contemporaneous origin. Combining the individual ages, the system is about 3.0 ± 0.5 Gyr old. The two components of HD 176465 are young physically-similar oscillating solar analogues, the first such system to be found, and provide important constraints for stellar evolution and asteroseismology. Title: RAVE stars in K2. I. Improving RAVE red giants spectroscopy using asteroseismology from K2 Campaign 1 Authors: Valentini, M.; Chiappini, C.; Davies, G. R.; Elsworth, Y. P.; Mosser, B.; Lund, M. N.; Miglio, A.; Chaplin, W. J.; Rodrigues, T. S.; Boeche, C.; Steinmetz, M.; Matijevič, G.; Kordopatis, G.; Bland-Hawthorn, J.; Munari, U.; Bienaymé, O.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Kunder, A.; McMillan, P.; Navarro, J.; Parker, Q. A.; Reid, W.; Seabroke, G.; Sharma, S.; Siviero, A.; Watson, F.; Wyse, R. F. G.; Zwitter, T.; Mott, A. Bibcode: 2017A&A...600A..66V Altcode: 2016arXiv160903826V We present a set of 87 RAVE stars with detected solar like oscillations, observed during Campaign 1 of the K2 mission (RAVE K2-C1 sample). This data set provides a useful benchmark for testing the gravities provided in RAVE data release 4 (DR4), and is key for the calibration of the RAVE data release 5 (DR5). The RAVE survey collected medium-resolution spectra (R = 7500) centred in the Ca II triplet(8600 Å) wavelength interval, which although being very useful for determining radial velocity and metallicity, even at low S/N, is known be affected by a log (g)-Teff degeneracy. This degeneracy is the cause of the large spread in the RAVE DR4 gravities for giants. The understanding of the trends and offsets that affects RAVE atmospheric parameters, and in particular log (g), is a crucial step in obtaining not only improved abundance measurements, but also improved distances and ages. In the present work, we use two different pipelines, GAUFRE and Sp_Ace, to determine atmospheric parameters and abundances by fixing log (g) to the seismic one. Our strategy ensures highly consistent values among all stellar parameters, leading to more accurate chemical abundances. A comparison of the chemical abundances obtained here with and without the use of seismic log (g) information has shown that an underestimated (overestimated) gravity leads to an underestimated (overestimated) elemental abundance (e.g. [Mg/H] is underestimated by 0.25 dex when the gravity is underestimated by 0.5 dex). We then perform a comparison between the seismic gravities and the spectroscopic gravities presented in the RAVE DR4 catalogue, extracting a calibration for log (g) of RAVE giants in the colour interval 0.50 < (J-KS) < 0.85. Finally, we show a comparison of the distances, temperatures, extinctions (and ages) derived here for our RAVE K2-C1 sample with those derived in RAVE DR4 and DR5. DR5 performs better than DR4 thanks to the seismic calibration, although discrepancies can still be important for objects for which the difference between DR4/DR5 and seismic gravities differ by more than 0.5 dex. The method illustrated in this work will be used for analysing RAVE targets present in the other K2 campaigns, in the framework of Galactic Archaeology investigations.

Data (atmospheric parameters, abundances, distances, ages and reddening) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/600/A66 Title: Time-series Analysis of Broadband Photometry of Neptune from K2 Authors: Rowe, Jason F.; Gaulme, Patrick; Lissauer, Jack J.; Marley, Mark S.; Simon, Amy A.; Hammel, Heidi B.; Silva Aguirre, Víctor; Barclay, Thomas; Benomar, Othman; Boumier, Patrick; Caldwell, Douglas A.; Casewell, Sarah L.; Chaplin, William J.; Colón, Knicole D.; Corsaro, Enrico; Davies, G. R.; Fortney, Jonathan J.; Garcia, Rafael A.; Gizis, John E.; Haas, Michael R.; Mosser, Benoît; Schmider, François-Xavier Bibcode: 2017AJ....153..149R Altcode: 2017arXiv170202943R We report here on our search for excess power in photometry of Neptune collected by the K2 mission that may be due to intrinsic global oscillations of the planet Neptune. To conduct this search, we developed new methods to correct for instrumental effects such as intrapixel variability and gain variations. We then extracted and analyzed the time-series photometry of Neptune from 49 days of nearly continuous broadband photometry of the planet. We find no evidence of global oscillations and place an upper limit of ∼5 ppm at 1000 μ {Hz} for the detection of a coherent signal. With an observed cadence of 1 minute and a point-to-point scatter of less than 0.01%, the photometric signal is dominated by reflected light from the Sun, which is in turn modulated by atmospheric variability of Neptune at the 2% level. A change in flux is also observed due to the increasing distance between Neptune and the K2 spacecraft and the solar variability with convection-driven solar p modes present. Title: VizieR Online Data Catalog: RAVE 5th data release (Kunder+, 2017) Authors: Kunder, A.; Kordopatis, G.; Steinmetz, M.; Zwitter, T.; McMillan, P.; Casagrande, L.; Enke, H.; Wojno, J.; Valentini, M.; Chiappini, C.; Matijevic, G.; Siviero, A.; de Laverny, P.; Recio-Blanco, A.; Bijaoui, A.; Wyse, R. F. G.; Binney, J.; Grebel, E. K.; Helmi, A.; Jofre, P.; Gilmore, G.; Siebert, A.; Famaey, B.; Bienayme, O.; Gibson, B. K.; Freeman, K. C.; Navarro, J. F.; Munari, U.; Seabroke, G.; Anguiano Jimenez, B.; Reid, W.; Bland-Hawthorn, J.; Watson, F.; Gerhard, O.; Davies, G. R.; Elsworth, Y. P.; Lund, M.; Miglio, A.; Chaplin, W. J.; Mosser, B. Bibcode: 2017yCat.3279....0K Altcode: Spectroscopic radial velocities for 457588 stars in the Milky-Way southern hemisphere using the 6dF instrument at the AAO.

(4 data files). Title: A thorough analysis of the short- and mid-term activity-related variations in the solar acoustic frequencies Authors: Santos, A. R. G.; Cunha, M. S.; Avelino, P. P.; Chaplin, W. J.; Campante, T. L. Bibcode: 2017MNRAS.464.4408S Altcode: 2016arXiv161006872S The frequencies of the solar acoustic oscillations vary over the activity cycle. The variations in other activity proxies are found to be well correlated with the variations in the acoustic frequencies. However, each proxy has a slightly different time behaviour. Our goal is to characterize the differences between the time behaviour of the frequency shifts and of two other activity proxies, namely the area covered by sunspots and the 10.7-cm flux. We define a new observable that is particularly sensitive to the short-term frequency variations. We then compare the observable when computed from model frequency shifts and from observed frequency shifts obtained with the Global Oscillation Network Group (GONG) for cycle 23. Our analysis shows that on the shortest time-scales, the variations in the frequency shifts seen in the GONG observations are strongly correlated with the variations in the area covered by sunspots. However, a significant loss of correlation is still found. We verify that the times when the frequency shifts and the sunspot area do not vary in a similar way tend to coincide with the times of the maxima of the quasi-biennial variations seen in the solar seismic data. A similar analysis of the relation between the 10.7-cm flux and the frequency shifts reveals that the short-time variations in the frequency shifts follow even more closely those of the 10.7-cm flux than those of the sunspot area. However, a loss of correlation between frequency shifts and 10.7-cm flux variations is still found around the same times. Title: Using red clump stars to correct the Gaia DR1 parallaxes Authors: Davies, Guy R.; Lund, Mikkel N.; Miglio, Andrea; Elsworth, Yvonne; Kuszlewicz, James S.; North, Thomas S. H.; Rendle, Ben; Chaplin, William J.; Rodrigues, Thaíse S.; Campante, Tiago L.; Girardi, Léo; Hale, Steven J.; Hall, Oliver; Jones, Caitlin D.; Kawaler, Steven D.; Roxburgh, Ian; Schofield, Mathew Bibcode: 2017A&A...598L...4D Altcode: 2017arXiv170102506D Recent results have suggested that there is tension between the Gaia DR1 TGAS distances and the distances obtained using luminosities determined by eclipsing binaries or asteroseismology on red giant stars. We use the Ks-band luminosities of red clump stars, identified and characterized by asteroseismology, to make independent distance estimates. Our results suggest that Gaia TGAS distances contain a systematic error that decreases with increasing distance. We propose a correction to mitigate this offset as a function of parallax that is valid for the Kepler field and values of parallax that are less than 1.6 mas. For parallaxes greater than this, we find agreement with previously published values. We note that the TGAS distances to the red clump stars of the open cluster M67 show a high level of disagreement that is difficult to correct for. Title: A simple model to describe intrinsic stellar noise for exoplanet detection around red giants Authors: North, Thomas S. H.; Chaplin, William J.; Gilliland, Ronald L.; Huber, Daniel; Campante, Tiago L.; Handberg, Rasmus; Lund, Mikkel N.; Veras, Dimitri; Kuszlewicz, James S.; Farr, Will M. Bibcode: 2017MNRAS.465.1308N Altcode: 2016arXiv161008688N In spite of the huge advances in exoplanet research provided by the NASA Kepler Mission, there remain only a small number of transit detections around evolved stars. Here, we present a reformulation of the noise properties of red-giant stars, where the intrinsic stellar granulation and the stellar oscillations described by asteroseismology play a key role. The new noise model is a significant improvement on the current Kepler results for evolved stars. Our noise model may be used to help understand planet detection thresholds for the ongoing K2 and upcoming TESSmissions, and serve as a predictor of stellar noise for these missions. As an application of our noise model, we explore the minimum detectable planet radii for red giant stars, and find that Neptune-sized planets should be detectable around low-luminosity red giant branch stars. Title: Standing on the Shoulders of Dwarfs: the Kepler Asteroseismic LEGACY Sample. I. Oscillation Mode Parameters Authors: Lund, Mikkel N.; Silva Aguirre, Víctor; Davies, Guy R.; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Houdek, Günter; White, Timothy R.; Bedding, Timothy R.; Ball, Warrick H.; Huber, Daniel; Antia, H. M.; Lebreton, Yveline; Latham, David W.; Handberg, Rasmus; Verma, Kuldeep; Basu, Sarbani; Casagrande, Luca; Justesen, Anders B.; Kjeldsen, Hans; Mosumgaard, Jakob R. Bibcode: 2017ApJ...835..172L Altcode: 2016arXiv161200436L The advent of space-based missions like Kepler has revolutionized the study of solar-type stars, particularly through the measurement and modeling of their resonant modes of oscillation. Here we analyze a sample of 66 Kepler main-sequence stars showing solar-like oscillations as part of the Kepler seismic LEGACY project. We use Kepler short-cadence data, of which each star has at least 12 months, to create frequency-power spectra optimized for asteroseismology. For each star, we identify its modes of oscillation and extract parameters such as frequency, amplitude, and line width using a Bayesian Markov chain Monte Carlo “peak-bagging” approach. We report the extracted mode parameters for all 66 stars, as well as derived quantities such as frequency difference ratios, the large and small separations {{Δ }}ν and δ {ν }02; the behavior of line widths with frequency and line widths at {ν }\max with {T}{eff}, for which we derive parametrizations; and behavior of mode visibilities. These average properties can be applied in future peak-bagging exercises to better constrain the parameters of the stellar oscillation spectra. The frequencies and frequency ratios can tightly constrain the fundamental parameters of these solar-type stars, and mode line widths and amplitudes can test models of mode damping and excitation. Title: Parametrizing the time variation of the `surface term' of stellar p-mode frequencies: application to helioseismic data Authors: Howe, R.; Basu, S.; Davies, G. R.; Ball, W. H.; Chaplin, W. J.; Elsworth, Y.; Komm, R. Bibcode: 2017MNRAS.464.4777H Altcode: 2016arXiv161004113H The solar-cycle variation of acoustic mode frequencies has a frequency dependence related to the inverse mode inertia. The discrepancy between model predictions and measured oscillation frequencies for solar and solar-type stellar acoustic modes includes a significant frequency-dependent term known as the surface term, which is also related to the inverse mode inertia. We parametrize both the surface term and the frequency variations for low-degree solar data from Birmingham Solar-Oscillations Network (BiSON) and medium-degree data from the Global Oscillations Network Group (GONG) using the mode inertia together with cubic and inverse frequency terms. We find that for the central frequency of rotationally split multiplets, the cubic term dominates both the average surface term and the temporal variation, but for the medium-degree case, the inverse term improves the fit to the temporal variation. We also examine the variation of the even-order splitting coefficients for the medium-degree data and find that, as for the central frequency, the latitude-dependent frequency variation, which reflects the changing latitudinal distribution of magnetic activity over the solar cycle, can be described by the combination of a cubic and an inverse function of frequency scaled by inverse mode inertia. The results suggest that this simple parametrization could be used to assess the activity-related frequency variation in solar-like asteroseismic targets. Title: The Radial Velocity Experiment (RAVE): Fifth Data Release Authors: Kunder, Andrea; Kordopatis, Georges; Steinmetz, Matthias; Zwitter, Tomaž; McMillan, Paul J.; Casagrande, Luca; Enke, Harry; Wojno, Jennifer; Valentini, Marica; Chiappini, Cristina; Matijevič, Gal; Siviero, Alessandro; de Laverny, Patrick; Recio-Blanco, Alejandra; Bijaoui, Albert; Wyse, Rosemary F. G.; Binney, James; Grebel, E. K.; Helmi, Amina; Jofre, Paula; Antoja, Teresa; Gilmore, Gerard; Siebert, Arnaud; Famaey, Benoit; Bienaymé, Olivier; Gibson, Brad K.; Freeman, Kenneth C.; Navarro, Julio F.; Munari, Ulisse; Seabroke, George; Anguiano, Borja; Žerjal, Maruša; Minchev, Ivan; Reid, Warren; Bland-Hawthorn, Joss; Kos, Janez; Sharma, Sanjib; Watson, Fred; Parker, Quentin A.; Scholz, Ralf-Dieter; Burton, Donna; Cass, Paul; Hartley, Malcolm; Fiegert, Kristin; Stupar, Milorad; Ritter, Andreas; Hawkins, Keith; Gerhard, Ortwin; Chaplin, W. J.; Davies, G. R.; Elsworth, Y. P.; Lund, M. N.; Miglio, A.; Mosser, B. Bibcode: 2017AJ....153...75K Altcode: 2016arXiv160903210K Data Release 5 (DR5) of the Radial Velocity Experiment (RAVE) is the fifth data release from a magnitude-limited (9< I< 12) survey of stars randomly selected in the Southern Hemisphere. The RAVE medium-resolution spectra (R∼ 7500) covering the Ca-triplet region (8410-8795 Å) span the complete time frame from the start of RAVE observations in 2003 to their completion in 2013. Radial velocities from 520,781 spectra of 457,588 unique stars are presented, of which 255,922 stellar observations have parallaxes and proper motions from the Tycho-Gaia astrometric solution in Gaia DR1. For our main DR5 catalog, stellar parameters (effective temperature, surface gravity, and overall metallicity) are computed using the RAVE DR4 stellar pipeline, but calibrated using recent K2 Campaign 1 seismic gravities and Gaia benchmark stars, as well as results obtained from high-resolution studies. Also included are temperatures from the Infrared Flux Method, and we provide a catalog of red giant stars in the dereddened color {(J-{Ks})}0 interval (0.50, 0.85) for which the gravities were calibrated based only on seismology. Further data products for subsamples of the RAVE stars include individual abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni, and distances found using isochrones. Each RAVE spectrum is complemented by an error spectrum, which has been used to determine uncertainties on the parameters. The data can be accessed via the RAVE Web site or the VizieR database. Title: Standing on the Shoulders of Dwarfs: the Kepler Asteroseismic LEGACY Sample. II.Radii, Masses, and Ages Authors: Silva Aguirre, Víctor; Lund, Mikkel N.; Antia, H. M.; Ball, Warrick H.; Basu, Sarbani; Christensen-Dalsgaard, Jørgen; Lebreton, Yveline; Reese, Daniel R.; Verma, Kuldeep; Casagrande, Luca; Justesen, Anders B.; Mosumgaard, Jakob R.; Chaplin, William J.; Bedding, Timothy R.; Davies, Guy R.; Handberg, Rasmus; Houdek, Günter; Huber, Daniel; Kjeldsen, Hans; Latham, David W.; White, Timothy R.; Coelho, Hugo R.; Miglio, Andrea; Rendle, Ben Bibcode: 2017ApJ...835..173S Altcode: 2016arXiv161108776S We use asteroseismic data from the Kepler satellite to determine fundamental stellar properties of the 66 main-sequence targets observed for at least one full year by the mission. We distributed tens of individual oscillation frequencies extracted from the time series of each star among seven modeling teams who applied different methods to determine radii, masses, and ages for all stars in the sample. Comparisons among the different results reveal a good level of agreement in all stellar properties, which is remarkable considering the variety of codes, input physics, and analysis methods employed by the different teams. Average uncertainties are of the order of ∼2% in radius, ∼4% in mass, and ∼10% in age, making this the best-characterized sample of main-sequence stars available to date. Our predicted initial abundances and mixing-length parameters are checked against inferences from chemical enrichment laws ΔY/ΔZ and predictions from 3D atmospheric simulations. We test the accuracy of the determined stellar properties by comparing them to the Sun, angular diameter measurements, Gaia parallaxes, and binary evolution, finding excellent agreement in all cases and further confirming the robustness of asteroseismically determined physical parameters of stars when individual frequencies of oscillation are available. Baptised as the Kepler dwarfs LEGACY sample, these stars are the solar-like oscillators with the best asteroseismic properties available for at least another decade. All data used in this analysis and the resulting stellar parameters are made publicly available for the community. Title: First Results from the Hertzsprung SONG Telescope: Asteroseismology of the G5 Subgiant Star μ Herculis Authors: Grundahl, F.; Fredslund Andersen, M.; Christensen-Dalsgaard, J.; Antoci, V.; Kjeldsen, H.; Handberg, R.; Houdek, G.; Bedding, T. R.; Pallé, P. L.; Jessen-Hansen, J.; Silva Aguirre, V.; White, T. R.; Frandsen, S.; Albrecht, S.; Andersen, M. I.; Arentoft, T.; Brogaard, K.; Chaplin, W. J.; Harpsøe, K.; Jørgensen, U. G.; Karovicova, I.; Karoff, C.; Kjærgaard Rasmussen, P.; Lund, M. N.; Sloth Lundkvist, M.; Skottfelt, J.; Norup Sørensen, A.; Tronsgaard, R.; Weiss, E. Bibcode: 2017ApJ...836..142G Altcode: 2017arXiv170103365G We report the first asteroseismic results obtained with the Hertzsprung Stellar Observations Network Group Telescope from an extensive high-precision radial-velocity observing campaign of the subgiant μ Herculis. The data set was collected during 215 nights in 2014 and 2015. We detected a total of 49 oscillation modes with l values from zero to three, including some l = 1 mixed modes. Based on the rotational splitting observed in l = 1 modes, we determine a rotational period of 52 days and a stellar inclination angle of 63°. The parameters obtained through modeling of the observed oscillation frequencies agree very well with independent observations and imply a stellar mass between 1.11 and 1.15 M ⊙ and an age of {7.8}-0.4+0.3 Gyr. Furthermore, the high-quality data allowed us to determine the acoustic depths of the He II ionization layer and the base of the convection zone.

Based on observations made with the Hertzsprung SONG telescope operated on the Spanish Observatorio del Teide on the island of Tenerife by the Aarhus and Copenhagen Universities and by the Instituto de Astrofísica de Canarias. Title: Asteroseismic Data Analysis: Foundations and Techniques Authors: Basu, Sarbani; Chaplin, William J. Bibcode: 2017asda.book.....B Altcode: No abstract at ADS Title: The K2 Galactic Archaeology Program Data Release. I. Asteroseismic Results from Campaign 1 Authors: Stello, Dennis; Zinn, Joel; Elsworth, Yvonne; Garcia, Rafael A.; Kallinger, Thomas; Mathur, Savita; Mosser, Benoit; Sharma, Sanjib; Chaplin, William J.; Davies, Guy; Huber, Daniel; Jones, Caitlin D.; Miglio, Andrea; Silva Aguirre, Victor Bibcode: 2017ApJ...835...83S Altcode: 2016arXiv161109852S NASA's K2 mission is observing tens of thousands of stars along the ecliptic, providing data suitable for large-scale asteroseismic analyses to inform galactic archaeology studies. Its first campaign covered a field near the north Galactic cap, a region never covered before by large asteroseismic-ensemble investigations, and was therefore of particular interest for exploring this part of our Galaxy. Here we report the asteroseismic analysis of all stars selected by the K2 Galactic Archaeology Program during the mission's “north Galactic cap” campaign 1. Our consolidated analysis uses six independent methods to measure the global seismic properties, in particular the large frequency separation and the frequency of maximum power. From the full target sample of 8630 stars we find about 1200 oscillating red giants, a number comparable with estimates from galactic synthesis modeling. Thus, as a valuable by-product we find roughly 7500 stars to be dwarfs, which provide a sample well suited for galactic exoplanet occurrence studies because they originate from our simple and easily reproducible selection function. In addition, to facilitate the full potential of the data set for galactic archaeology, we assess the detection completeness of our sample of oscillating red giants. We find that the sample is at least nearly complete for stars with 40 ≲ {ν }\max /μHz ≲ 270 and {ν }\max ,{detect}< 2.6× {10}6\cdot {2}-{\text{Kp}} μHz. There is a detection bias against helium core burning stars with {ν }\max ∼ 30 μHz, affecting the number of measurements of {{Δ }}ν and possibly also {ν }\max . Although we can detect oscillations down to {\text{Kp}} = 15, our campaign 1 sample lacks enough faint giants to assess the detection completeness for stars fainter than {\text{Kp}} ∼ 14.5. Title: Asteroseismology of the Hyades with K2: first detection of main-sequence solar-like oscillations in an open cluster Authors: Lund, Mikkel N.; Basu, Sarbani; Silva Aguirre, Víctor; Chaplin, William J.; Serenelli, Aldo M.; García, Rafael A.; Latham, David W.; Casagrande, Luca; Bieryla, Allyson; Davies, Guy R.; Viani, Lucas S.; Buchhave, Lars A.; Miglio, Andrea; Soderblom, David R.; Valenti, Jeff A.; Stefanik, Robert P.; Handberg, Rasmus Bibcode: 2016MNRAS.463.2600L Altcode: 2016arXiv160807290L; 2016MNRAS.tmp.1271L The Hyades open cluster was targeted during Campaign 4 (C4) of the NASA K2 mission, and short-cadence data were collected on a number of cool main-sequence stars. Here, we report results on two F-type stars that show detectable oscillations of a quality that allows asteroseismic analyses to be performed. These are the first ever detections of solar-like oscillations in main-sequence stars in an open cluster. Title: A Distant Mirror: Solar Oscillations Observed on Neptune by the Kepler K2 Mission Authors: Gaulme, P.; Rowe, J. F.; Bedding, T. R.; Benomar, O.; Corsaro, E.; Davies, G. R.; Hale, S. J.; Howe, R.; Garcia, R. A.; Huber, D.; Jiménez, A.; Mathur, S.; Mosser, B.; Appourchaux, T.; Boumier, P.; Jackiewicz, J.; Leibacher, J.; Schmider, F. -X.; Hammel, H. B.; Lissauer, J. J.; Marley, M. S.; Simon, A. A.; Chaplin, W. J.; Elsworth, Y.; Guzik, J. A.; Murphy, N.; Silva Aguirre, V. Bibcode: 2016ApJ...833L..13G Altcode: 2016arXiv161204287G Starting in 2014 December, Kepler K 2 observed Neptune continuously for 49 days at a 1 minute cadence. The goals consisted of studying its atmospheric dynamics, detecting its global acoustic oscillations, and those of the Sun, which we report on here. We present the first indirect detection of solar oscillations in intensity measurements. Beyond the remarkable technical performance, it indicates how Kepler would see a star like the Sun. The result from the global asteroseismic approach, which consists of measuring the oscillation frequency at maximum amplitude ν max and the mean frequency separation between mode overtones Δν, is surprising as the ν max measured from Neptune photometry is larger than the accepted value. Compared to the usual reference ν max,⊙ = 3100 μHz, the asteroseismic scaling relations therefore make the solar mass and radius appear larger by 13.8 ± 5.8% and 4.3 ± 1.9%, respectively. The higher ν max is caused by a combination of the value of ν max,⊙, being larger at the time of observations than the usual reference from SOHO/VIRGO/SPM data (3160 ± 10 μHz), and the noise level of the K 2 time series, being 10 times larger than VIRGO’s. The peak-bagging method provides more consistent results: despite a low signal-to-noise ratio (S/N), we model 10 overtones for degrees ℓ = 0, 1, 2. We compare the K 2 data with simultaneous SOHO/VIRGO/SPM photometry and BiSON velocity measurements. The individual frequencies, widths, and amplitudes mostly match those from VIRGO and BiSON within 1σ, except for the few peaks with the lowest S/N. Title: Asteroseismic Properties of Solar-type Stars Observed with the NASA K2 Mission: Results from Campaigns 1-3 and Prospects for Future Observations Authors: Lund, Mikkel N.; Chaplin, William J.; Casagrande, Luca; Silva Aguirre, Víctor; Basu, Sarbani; Bieryla, Allyson; Christensen-Dalsgaard, Jørgen; Latham, David W.; White, Timothy R.; Davies, Guy R.; Huber, Daniel; Buchhave, Lars A.; Handberg, Rasmus Bibcode: 2016PASP..128l4204L Altcode: 2016arXiv160807292L We present an asteroseismic analysis of 33 solar-type stars observed in short cadence (SC) during Campaigns (C) 1-3 of the NASA K2 mission. We were able to extract both average seismic parameters and individual mode frequencies for stars with dominant frequencies up to ∼3300 μHz, and we find that data for some targets are good enough to allow for a measurement of the rotational splitting. Modeling of the extracted parameters is performed by using grid-based methods using average parameters and individual frequencies together with spectroscopic parameters. For the target selection in C3, stars were chosen as in C1 and C2 to cover a wide range in parameter space to better understand the performance and noise characteristics. For C3 we still detected oscillations in 73% of the observed stars that we proposed. Future K2 campaigns hold great promise for the study of nearby clusters and the chemical evolution and age-metallicity relation of nearby field stars in the solar neighborhood. We expect oscillations to be detected in ∼388 SC targets if the K2 mission continues until C18, which will greatly complement the ∼500 detections of solar-like oscillations made for SC targets during the nominal Kepler mission. For ∼30-40 of these, including several members of the Hyades open cluster, we furthermore expect that inference from interferometry should be possible. Title: Detection of Solar-like Oscillations, Observational Constraints, and Stellar Models for θ Cyg, the Brightest Star Observed By the Kepler Mission Authors: Guzik, J. A.; Houdek, G.; Chaplin, W. J.; Smalley, B.; Kurtz, D. W.; Gilliland, R. L.; Mullally, F.; Rowe, J. F.; Bryson, S. T.; Still, M. D.; Antoci, V.; Appourchaux, T.; Basu, S.; Bedding, T. R.; Benomar, O.; Garcia, R. A.; Huber, D.; Kjeldsen, H.; Latham, D. W.; Metcalfe, T. S.; Pápics, P. I.; White, T. R.; Aerts, C.; Ballot, J.; Boyajian, T. S.; Briquet, M.; Bruntt, H.; Buchhave, L. A.; Campante, T. L.; Catanzaro, G.; Christensen-Dalsgaard, J.; Davies, G. R.; Doğan, G.; Dragomir, D.; Doyle, A. P.; Elsworth, Y.; Frasca, A.; Gaulme, P.; Gruberbauer, M.; Handberg, R.; Hekker, S.; Karoff, C.; Lehmann, H.; Mathias, P.; Mathur, S.; Miglio, A.; Molenda-Żakowicz, J.; Mosser, B.; Murphy, S. J.; Régulo, C.; Ripepi, V.; Salabert, D.; Sousa, S. G.; Stello, D.; Uytterhoeven, K. Bibcode: 2016ApJ...831...17G Altcode: 2016arXiv160701035G θ Cygni is an F3 spectral type magnitude V = 4.48 main-sequence star that was the brightest star observed by the original Kepler spacecraft mission. Short-cadence (58.8 s) photometric data using a custom aperture were first obtained during Quarter 6 (2010 June-September) and subsequently in Quarters 8 and 12-17. We present analyses of solar-like oscillations based on Q6 and Q8 data, identifying angular degree l = 0, 1, and 2 modes with frequencies of 1000-2700 μHz, a large frequency separation of 83.9 ± 0.4 μHz, and maximum oscillation amplitude at frequency ν max = 1829 ± 54 μHz. We also present analyses of new ground-based spectroscopic observations, which, combined with interferometric angular diameter measurements, give T eff = 6697 ± 78 K, radius 1.49 ± 0.03 R ⊙, [Fe/H] = -0.02 ± 0.06 dex, and log g = 4.23 ± 0.03. We calculate stellar models matching these constraints using the Yale Rotating Evolution Code and the Asteroseismic Modeling Portal. The best-fit models have masses of 1.35-1.39 M ⊙ and ages of 1.0-1.6 Gyr. θ Cyg’s T eff and log g place it cooler than the red edge of the γ Doradus instability region established from pre-Kepler ground-based observations, but just at the red edge derived from pulsation modeling. The pulsation models show γ Dor gravity modes driven by the convective blocking mechanism, with frequencies of 1-3 cycles per day (11 to 33 μHz). However, gravity modes were not seen in Kepler data; one signal at 1.776 cycles per day (20.56 μHz) may be attributable to a faint, possibly background, binary. Title: Oscillation mode linewidths and heights of 23 main-sequence stars observed by Kepler (Corrigendum) Authors: Appourchaux, T.; Antia, H. M.; Benomar, O.; Campante, T. L.; Davies, G. R.; Handberg, R.; Howe, R.; Régulo, C.; Belkacem, K.; Houdek, G.; García, R. A.; Chaplin, W. J. Bibcode: 2016A&A...595C...2A Altcode: No abstract at ADS Title: The Asteroseismic Potential of TESS: Exoplanet-host Stars Authors: Campante, T. L.; Schofield, M.; Kuszlewicz, J. S.; Bouma, L.; Chaplin, W. J.; Huber, D.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Bossini, D.; North, T. S. H.; Appourchaux, T.; Latham, D. W.; Pepper, J.; Ricker, G. R.; Stassun, K. G.; Vanderspek, R.; Winn, J. N. Bibcode: 2016ApJ...830..138C Altcode: 2016arXiv160801138C New insights on stellar evolution and stellar interior physics are being made possible by asteroseismology. Throughout the course of the Kepler mission, asteroseismology has also played an important role in the characterization of exoplanet-host stars and their planetary systems. The upcoming NASA Transiting Exoplanet Survey Satellite (TESS) will be performing a near all-sky survey for planets that transit bright nearby stars. In addition, its excellent photometric precision, combined with its fine time sampling and long intervals of uninterrupted observations, will enable asteroseismology of solar-type and red-giant stars. Here we develop a simple test to estimate the detectability of solar-like oscillations in TESS photometry of any given star. Based on an all-sky stellar and planetary synthetic population, we go on to predict the asteroseismic yield of the TESS mission, placing emphasis on the yield of exoplanet-host stars for which we expect to detect solar-like oscillations. This is done for both the target stars (observed at a 2-minute cadence) and the full-frame-image stars (observed at a 30-minute cadence). A similar exercise is also conducted based on a compilation of known host stars. We predict that TESS will detect solar-like oscillations in a few dozen target hosts (mainly subgiant stars but also in a smaller number of F dwarfs), in up to 200 low-luminosity red-giant hosts, and in over 100 solar-type and red-giant known hosts, thereby leading to a threefold improvement in the asteroseismic yield of exoplanet-host stars when compared to Kepler's. Title: On the contribution of sunspots to the observed frequency shifts of solar acoustic modes Authors: Santos, A. R. G.; Cunha, M. S.; Avelino, P. P.; Chaplin, W. J.; Campante, T. L. Bibcode: 2016MNRAS.461..224S Altcode: 2016arXiv160602133S; 2016MNRAS.tmp.1003S Activity-related variations in the solar oscillation properties have been known for 30 years. However, the relative importance of the different contributions to the observed variations is not yet fully understood. Our goal is to estimate the relative contribution from sunspots to the observed activity-related variations in the frequencies of the acoustic modes. We use a variational principle to relate the phase differences induced by sunspots on the acoustic waves to the corresponding changes in the frequencies of the global acoustic oscillations. From the sunspot properties (area and latitude as a function of time), we are able to estimate the spot-induced frequency shifts. These are then combined with a smooth frequency shift component, associated with long-term solar-cycle variations, and the results compared with the frequency shifts derived from the Global Oscillation Network Group data. The result of this comparison is consistent with a sunspot contribution to the observed frequency shifts of roughly 30 per cent, with the remaining 70 per cent resulting mostly from a global, non-stochastic variation, possibly related to the changes in the overall magnetic field. Moreover, analysis of the residuals obtained after the subtraction of the model frequency shifts from the observations indicates the presence of a 1.5-yr periodicity in the data in phase with the quasi-biennial variations reported in the literature. Title: Detection of solar-like oscillations in relics of the Milky Way: asteroseismology of K giants in M4 using data from the NASA K2 mission Authors: Miglio, A.; Chaplin, W. J.; Brogaard, K.; Lund, M. N.; Mosser, B.; Davies, G. R.; Handberg, R.; Milone, A. P.; Marino, A. F.; Bossini, D.; Elsworth, Y. P.; Grundahl, F.; Arentoft, T.; Bedin, L. R.; Campante, T. L.; Jessen-Hansen, J.; Jones, C. D.; Kuszlewicz, J. S.; Malavolta, L.; Nascimbeni, V.; Sandquist, E. L. Bibcode: 2016MNRAS.461..760M Altcode: 2016arXiv160602115M Asteroseismic constraints on K giants make it possible to infer radii, masses and ages of tens of thousands of field stars. Tests against independent estimates of these properties are however scarce, especially in the metal-poor regime. Here, we report the detection of solar-like oscillations in eight stars belonging to the red-giant branch (RGB) and red-horizontal branch (RHB) of the globular cluster M4. The detections were made in photometric observations from the K2 Mission during its Campaign 2. Making use of independent constraints on the distance, we estimate masses of the eight stars by utilizing different combinations of seismic and non-seismic inputs. When introducing a correction to the Δν scaling relation as suggested by stellar models, for RGB stars we find excellent agreement with the expected masses from isochrone fitting, and with a distance modulus derived using independent methods. The offset with respect to independent masses is lower, or comparable with, the uncertainties on the average RGB mass (4-10 per cent, depending on the combination of constraints used). Our results lend confidence to asteroseismic masses in the metal-poor regime. We note that a larger sample will be needed to allow more stringent tests to be made of systematic uncertainties in all the observables (both seismic and non-seismic), and to explore the properties of RHB stars, and of different populations in the cluster. Title: SpaceInn hare-and-hounds exercise: Estimation of stellar properties using space-based asteroseismic data Authors: Reese, D. R.; Chaplin, W. J.; Davies, G. R.; Miglio, A.; Antia, H. M.; Ball, W. H.; Basu, S.; Buldgen, G.; Christensen-Dalsgaard, J.; Coelho, H. R.; Hekker, S.; Houdek, G.; Lebreton, Y.; Mazumdar, A.; Metcalfe, T. S.; Silva Aguirre, V.; Stello, D.; Verma, K. Bibcode: 2016A&A...592A..14R Altcode: 2016arXiv160408404R Context. Detailed oscillation spectra comprising individual frequencies for numerous solar-type stars and red giants are either currently available, e.g. courtesy of the CoRoT, Kepler, and K2 missions, or will become available with the upcoming NASA TESS and ESA PLATO 2.0 missions. The data can lead to a precise characterisation of these stars thereby improving our understanding of stellar evolution, exoplanetary systems, and the history of our galaxy.
Aims: Our goal is to test and compare different methods for obtaining stellar properties from oscillation frequencies and spectroscopic constraints. Specifically, we would like to evaluate the accuracy of the results and reliability of the associated error bars, and to see where there is room for improvement.
Methods: In the context of the SpaceInn network, we carried out a hare-and-hounds exercise in which one group, the hares, simulated observations of oscillation spectra for a set of ten artificial solar-type stars, and a number of hounds applied various methods for characterising these stars based on the data produced by the hares. Most of the hounds fell into two main groups. The first group used forward modelling (I.e. applied various search/optimisation algorithms in a stellar parameter space) whereas the second group relied on acoustic glitch signatures.
Results: Results based on the forward modelling approach were accurate to 1.5% (radius), 3.9% (mass), 23% (age), 1.5% (surface gravity), and 1.8% (mean density), as based on the root mean square difference. Individual hounds reached different degrees of accuracy, some of which were substantially better than the above average values. For the two 1M⊙ stellar targets, the accuracy on the age is better than 10% thereby satisfying the requirements for the PLATO 2.0 mission. High stellar masses and atomic diffusion (which in our models does not include the effects of radiative accelerations) proved to be sources of difficulty. The average accuracies for the acoustic radii of the base of the convection zone, the He II ionisation, and the Γ1 peak located between the two He ionisation zones were 17%, 2.4%, and 1.9%, respectively. The results from the forward modelling were on average more accurate than those from the glitch fitting analysis as the latter seemed to be affected by aliasing problems for some of the targets.
Conclusions: Our study indicates that forward modelling is the most accurate way of interpreting the pulsation spectra of solar-type stars. However, given its model-dependent nature, this method needs to be complemented by model-independent results from, e.g. glitch analysis. Furthermore, our results indicate that global rather than local optimisation algorithms should be used in order to obtain robust error bars. Title: That's How We Roll: The NASA K2 Mission Science Products and Their Performance Metrics Authors: Van Cleve, Jeffrey E.; Howell, Steve B.; Smith, Jeffrey C.; Clarke, Bruce D.; Thompson, Susan E.; Bryson, Stephen T.; Lund, Mikkel N.; Handberg, Rasmus; Chaplin, William J. Bibcode: 2016PASP..128g5002V Altcode: 2015arXiv151206162V NASA's exoplanet Discovery mission Kepler was reconstituted as the K2 mission a year after the failure of the second of Kepler's four reaction wheels in 2013 May. Fine control of the spacecraft pointing is now accomplished through the use of the two remaining well-functioning reaction wheels and balancing the pressure of sunlight on the solar panels, which constrains K2 observations to fields in the ecliptic for up to approximately 80 days each. This pseudo-stable mechanism gives typical roll motion in the focal plane of 1.0 pixels peak-to-peak over 6 hr at the edges of the field, two orders of magnitude greater than typical 6 hr pointing errors in the Kepler primary mission. Despite these roll errors, the joint performance of the flight system and its modified science data processing pipeline restores much of the photometric precision of the primary mission while viewing a wide variety of targets, thus turning adversity into diversity. We define K2 performance metrics for data compression and pixel budget available in each campaign; the photometric noise on exoplanet transit and stellar activity timescales; residual correlations in corrected long-cadence light curves; and the protection of test sinusoidal signals from overfitting in the systematic error removal process. We find that data compression and noise both increase linearly with radial distance from the center of the field of view, with the data compression proportional to star count as well. At the center, where roll motion is nearly negligible, the limiting 6 hr photometric precision for a quiet 12th magnitude star can be as low as 30 ppm, only 25% higher than that of Kepler. This noise performance is achieved without sacrificing signal fidelity; test sinusoids injected into the data are attenuated by less than 10% for signals with periods upto 15 days, so that a wide range of stellar rotation and variability signatures are preserved by the K2 pipeline. At timescales relevant to asteroseismology, light curves derived from K2 archive calibrated pixels have high-frequency noise amplitude within 40% of that achieved by Kepler. The improvements in K2 operations and science data analysis resulting from 1.5 years of experience with this new mission concept, and quantified by the metrics in this paper, will support continuation of K2's already high level of scientific productivity in an extended K2 mission. Title: That's How We Roll - The NASA K2 Mission Science Planning, Products, and Performance Metrics Authors: Van Cleve, Jeffrey E.; Howell, Steve B.; Smith, Jeffrey C.; Clarke, Bruce; Thompson, Susan E.; Bryson, Steve; Lund, Mikkel N.; Handberg, Rasmus; Chaplin, William J.; Kepler Science Office, Kepler Science Operations Center, Ball Aerospace, U. Colorado LASP Bibcode: 2016AAS...22810209V Altcode: NASA’s exoplanet Discovery mission Kepler was reconstituted as the K2 mission a year after the failure of the 2nd of Kepler’s 4 reaction wheels in May 2013. The new spacecraft pointing method now gives typical roll motion of 1.0 pixels peak-to-peak over 6 hours at the edges of the field, two orders of magnitude greater than for Kepler. Despite these roll errors, the flight system and its modified data processing pipeline restores much of the photometric precision of the primary mission while viewing a wide variety of targets, thus turning adversity into diversity. We define metrics for data compression and pixel budget available in each campaign; the photometric noise on exoplanet transit and stellar activity time scales; residual correlations in corrected long cadence light curves; and the protection of test sinusoidal signals from overfitting in the systematic error removal process. We find that data compression and noise both increase linearly with radial distance from the center of the field of view, while the data compression also increases as the square root of star count. For sufficiently dense star fields, such as the Galactic Center, the data entropy so high that Huffman compression is ineffective and only requantization is used. At the FOV center, where roll motion is nearly negligible, the limiting 6 hour photometric precision for a quiet 12th magnitude star can be as low as 30 ppm, only 25% higher than that of Kepler. This noise performance is achieved without sacrificing signal fidelity; test sinusoids injected into the data are attenuated by less than 10% for signals with periods up 15 days. At time scales relevant to asteroseismology, light curves derived from K2 archive calibrated pixels have high-frequency noise amplitude within 40% of that achieved by Kepler. These improvements follow from the data analysis efforts of Kepler Science Operation Center and Kepler Science Office, and from the operational improvements developed by Ball Aerospace and LASP, during the first 1.5 yr of K2. Our results through December 2015 are shown in detail in http://arxiv.org/abs/1512.06162; in this talk, we will emphasize what we have learned in the last 6 month. Title: VizieR Online Data Catalog: Surface gravity for 220 Kepler stars (Campante+, 2014) Authors: Campante, T. L.; Chaplin, W. J.; Lund, M. N.; Huber, D.; Hekker, S.; Garcia, R. A.; Corsaro, E.; Handberg, R.; Miglio, A.; Arentoft, T.; Basu, S.; Bedding, T. R.; Christensen-Dalsgaard, J.; Davies, G. R.; Elsworth, Y. P.; Gilliland, R. L.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M.; Metcalfe, T. S.; Silva Aguirre, V.; Stello, D. Bibcode: 2016yCat..17830123C Altcode: We propose lower-limit surface gravity estimates for Kepler solar-type planet-candidate host stars with no detected oscillations, as given in Table4.

(1 data file). Title: Hot super-Earths stripped by their host stars Authors: Lundkvist, M. S.; Kjeldsen, H.; Albrecht, S.; Davies, G. R.; Basu, S.; Huber, D.; Justesen, A. B.; Karoff, C.; Silva Aguirre, V.; van Eylen, V.; Vang, C.; Arentoft, T.; Barclay, T.; Bedding, T. R.; Campante, T. L.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Elsworth, Y. P.; Gilliland, R. L.; Handberg, R.; Hekker, S.; Kawaler, S. D.; Lund, M. N.; Metcalfe, T. S.; Miglio, A.; Rowe, J. F.; Stello, D.; Tingley, B.; White, T. R. Bibcode: 2016NatCo...711201L Altcode: 2016arXiv160405220L Simulations predict that hot super-Earth sized exoplanets can have their envelopes stripped by photoevaporation, which would present itself as a lack of these exoplanets. However, this absence in the exoplanet population has escaped a firm detection. Here we demonstrate, using asteroseismology on a sample of exoplanets and exoplanet candidates observed during the Kepler mission that, while there is an abundance of super-Earth sized exoplanets with low incident fluxes, none are found with high incident fluxes. We do not find any exoplanets with radii between 2.2 and 3.8 Earth radii with incident flux above 650 times the incident flux on Earth. This gap in the population of exoplanets is explained by evaporation of volatile elements and thus supports the predictions. The confirmation of a hot-super-Earth desert caused by evaporation will add an important constraint on simulations of planetary systems, since they must be able to reproduce the dearth of close-in super-Earths. Title: Spin-Orbit Alignment of Exoplanet Systems: Ensemble Analysis Using Asteroseismology Authors: Campante, T. L.; Lund, M. N.; Kuszlewicz, J. S.; Davies, G. R.; Chaplin, W. J.; Albrecht, S.; Winn, J. N.; Bedding, T. R.; Benomar, O.; Bossini, D.; Handberg, R.; Santos, A. R. G.; Van Eylen, V.; Basu, S.; Christensen-Dalsgaard, J.; Elsworth, Y. P.; Hekker, S.; Hirano, T.; Huber, D.; Karoff, C.; Kjeldsen, H.; Lundkvist, M. S.; North, T. S. H.; Silva Aguirre, V.; Stello, D.; White, T. R. Bibcode: 2016ApJ...819...85C Altcode: 2016arXiv160106052C The angle ψ between a planet’s orbital axis and the spin axis of its parent star is an important diagnostic of planet formation, migration, and tidal evolution. We seek empirical constraints on ψ by measuring the stellar inclination Is via asteroseismology for an ensemble of 25 solar-type hosts observed with NASA’s Kepler satellite. Our results for Is are consistent with alignment at the 2σ level for all stars in the sample, meaning that the system surrounding the red-giant star Kepler-56 remains as the only unambiguous misaligned multiple-planet system detected to date. The availability of a measurement of the projected spin-orbit angle λ for two of the systems allows us to estimate ψ. We find that the orbit of the hot Jupiter HAT-P-7b is likely to be retrograde (\psi =116\buildrel{\circ}\over{.} {4}-14.7+30.2), whereas that of Kepler-25c seems to be well aligned with the stellar spin axis (\psi =12\buildrel{\circ}\over{.} {6}-11.0+6.7). While the latter result is in apparent contradiction with a statement made previously in the literature that the multi-transiting system Kepler-25 is misaligned, we show that the results are consistent, given the large associated uncertainties. Finally, we perform a hierarchical Bayesian analysis based on the asteroseismic sample in order to recover the underlying distribution of ψ. The ensemble analysis suggests that the directions of the stellar spin and planetary orbital axes are correlated, as conveyed by a tendency of the host stars to display large values of inclination. Title: VizieR Online Data Catalog: Fundamental parameters of Kepler stars (Silva Aguirre+, 2015) Authors: Silva Aguirre, V.; Davies, G. R.; Basu, S.; Christensen-Dalsgaard, J.; Creevey, O.; Metcalfe, T. S.; Bedding, T. R.; Casagrande, L.; Handberg, R.; Lund, M. N.; Nissen, P. E.; Chaplin, W. J.; Huber, D.; Serenelli, A. M.; Stello, D.; van Eylen, V.; Campante, T. L.; Elsworth, Y.; Gilliland, R. L.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M. S. Bibcode: 2016yCat..74522127S Altcode: Our sample has been extracted from the 77 exoplanet host stars presented in Huber et al. (2013, Cat. J/ApJ/767/127).

We have made use of the full time-base of observations from the Kepler satellite to uniformly determine precise fundamental stellar parameters, including ages, for a sample of exoplanet host stars where high-quality asteroseismic data were available. We devised a Bayesian procedure flexible in its input and applied it to different grids of models to study systematics from input physics and extract statistically robust properties for all stars.

(4 data files). Title: Oscillation frequencies for 35 Kepler solar-type planet-hosting stars using Bayesian techniques and machine learning Authors: Davies, G. R.; Silva Aguirre, V.; Bedding, T. R.; Handberg, R.; Lund, M. N.; Chaplin, W. J.; Huber, D.; White, T. R.; Benomar, O.; Hekker, S.; Basu, S.; Campante, T. L.; Christensen-Dalsgaard, J.; Elsworth, Y.; Karoff, C.; Kjeldsen, H.; Lundkvist, M. S.; Metcalfe, T. S.; Stello, D. Bibcode: 2016MNRAS.456.2183D Altcode: 2015arXiv151102105D Kepler has revolutionized our understanding of both exoplanets and their host stars. Asteroseismology is a valuable tool in the characterization of stars and Kepler is an excellent observing facility to perform asteroseismology. Here we select a sample of 35 Kepler solar-type stars which host transiting exoplanets (or planet candidates) with detected solar-like oscillations. Using available Kepler short cadence data up to Quarter 16 we create power spectra optimized for asteroseismology of solar-type stars. We identify modes of oscillation and estimate mode frequencies by `peak bagging' using a Bayesian Markov Chain Monte Carlo framework. In addition, we expand the methodology of quality assurance using a Bayesian unsupervised machine learning approach. We report the measured frequencies of the modes of oscillation for all 35 stars and frequency ratios commonly used in detailed asteroseismic modelling. Due to the high correlations associated with frequency ratios we report the covariance matrix of all frequencies measured and frequency ratios calculated. These frequencies, frequency ratios, and covariance matrices can be used to obtain tight constraint on the fundamental parameters of these planet-hosting stars. Title: Performance of the Birmingham Solar-Oscillations Network (BiSON) Authors: Hale, S. J.; Howe, R.; Chaplin, W. J.; Davies, G. R.; Elsworth, Y. P. Bibcode: 2016SoPh..291....1H Altcode: 2015arXiv151007085H; 2015SoPh..tmp..172H The Birmingham Solar-Oscillations Network (BiSON) has been operating with a full complement of six stations since 1992. Over 20 years later, we look back on the network history. The meta-data from the sites have been analysed to assess performance in terms of site insolation, with a brief look at the challenges that have been encountered over the years. We explain how the international community can gain easy access to the ever-growing dataset produced by the network, and finally look to the future of the network and the potential impact of nearly 25 years of technology miniaturisation. Title: The Kepler-454 System: A Small, Not-rocky Inner Planet, a Jovian World, and a Distant Companion Authors: Gettel, Sara; Charbonneau, David; Dressing, Courtney D.; Buchhave, Lars A.; Dumusque, Xavier; Vanderburg, Andrew; Bonomo, Aldo S.; Malavolta, Luca; Pepe, Francesco; Collier Cameron, Andrew; Latham, David W.; Udry, Stéphane; Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.; Davies, Guy R.; Silva Aguirre, Victor; Kjeldsen, Hans; Bedding, Timothy R.; Lopez, Eric; Affer, Laura; Cosentino, Rosario; Figueira, Pedro; Fiorenzano, Aldo F. M.; Harutyunyan, Avet; Johnson, John Asher; Lopez-Morales, Mercedes; Lovis, Christophe; Mayor, Michel; Micela, Giusi; Molinari, Emilio; Motalebi, Fatemeh; Phillips, David F.; Piotto, Giampaolo; Queloz, Didier; Rice, Ken; Sasselov, Dimitar; Ségransan, Damien; Sozzetti, Alessandro; Watson, Chris; Basu, Sarbani; Campante, Tiago L.; Christensen-Dalsgaard, Jørgen; Kawaler, Steven D.; Metcalfe, Travis S.; Handberg, Rasmus; Lund, Mikkel N.; Lundkvist, Mia S.; Huber, Daniel; Chaplin, William J. Bibcode: 2016ApJ...816...95G Altcode: 2015arXiv151109097G Kepler-454 (KOI-273) is a relatively bright (V = 11.69 mag), Sun-like star that hosts a transiting planet candidate in a 10.6 day orbit. From spectroscopy, we estimate the stellar temperature to be 5687 ± 50 K, its metallicity to be [m/H] = 0.32 ± 0.08, and the projected rotational velocity to be v sin I < 2.4 km s-1. We combine these values with a study of the asteroseismic frequencies from short cadence Kepler data to estimate the stellar mass to be {1.028}-0.03+0.04{M}⊙ , the radius to be 1.066 ± 0.012 R⊙, and the age to be {5.25}-1.39+1.41 Gyr. We estimate the radius of the 10.6 day planet as 2.37 ± 0.13 R⊕. Using 63 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 36 observations made with the HIRES spectrograph at the Keck Observatory, we measure the mass of this planet to be 6.8 ± 1.4 M⊕. We also detect two additional non-transiting companions, a planet with a minimum mass of 4.46 ± 0.12 MJ in a nearly circular 524 day orbit and a massive companion with a period >10 years and mass >12.1 MJ. The 12 exoplanets with radii <2.7 R⊕ and precise mass measurements appear to fall into two populations, with those <1.6 R⊕ following an Earth-like composition curve and larger planets requiring a significant fraction of volatiles. With a density of 2.76 ± 0.73 g cm-3, Kepler-454b lies near the mass transition between these two populations and requires the presence of volatiles and/or H/He gas. Title: Asteroseismology of Red-Giant Stars as a Novel Approach in the Search for Gravitational Waves Authors: Campante, Tiago L.; Lopes, Ilídio; Bossini, D.; Miglio, A.; Chaplin, W. J. Bibcode: 2016IAUFM..29B.363C Altcode: Stars are massive resonators that may be used as gravitational-wave (GW) detectors with isotropic sensitivity. New insights on stellar physics are being made possible by asteroseismology, the study of stars by the observation of their natural oscillations. The continuous monitoring of oscillation modes in stars of different masses and sizes (e.g., as carried out by NASA's Kepler mission) opens the possibility of surveying the local Universe for GW radiation. Red-giant stars are of particular interest in this regard. Since the mean separation between red giants in open clusters is small (a few light years), this can in principle be used to look for the same GW imprint on the oscillation modes of different stars as a GW propagates across the cluster. Furthermore, the frequency range probed by oscillations in red giants complements the capabilities of the planned eLISA space interferometer. We propose asteroseismology of red giants as a novel approach in the search for gravitational waves. Title: Asteroseismology of Exoplanet-Host Stars in the TESS Era Authors: Campante, Tiago L.; Schofield, Mathew; Chaplin, William J.; Huber, Daniel; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Latham, David W.; Ricker, George R.; Winn, Joshua Bibcode: 2015ESS.....350303C Altcode: New insights on stellar evolution and stellar interiors physics are being made possible by asteroseismology, the study of stars by the observation of their natural, resonant oscillations. Throughout the duration of the Kepler mission, asteroseismology has also played an important role in the characterization of host stars and their planetary systems. Examples include the precise estimation of the fundamental properties of stellar hosts, the obliquity determination of planetary systems, or the orbital eccentricity determination via asterodensity profiling. The Transiting Exoplanet Survey Satellite (TESS) will perform a wide-field survey for planets that transit bright host stars. Its excellent photometric precision and long intervals of uninterrupted observations will enable asteroseismology of solar-type stars and their evolved counterparts. Based on existing all-sky simulations of the stellar and planetary populations, we investigate the asteroseismic yield of the mission, placing particular emphasis on the yield of exoplanet-host stars for which we expect to detect solar-like oscillations. This is done both for the cohort of target stars (observed at a 2-min cadence), which will mainly involve low-mass main-sequence hosts, as well as for the cohort of “full-frame image” stars (observed at a 30-min cadence). The latter cohort offers the exciting prospect of conducting asteroseismology on a significant number of evolved hosts. Also, the brightest solar-type hosts with asteroseismology will become some of the best characterized planetary systems known to date. Finally, we discuss the impact of the detected oscillations on the accuracy/precision of the derived properties of the host stars and their planetary systems. Title: Validation of solar-cycle changes in low-degree helioseismic parameters from the Birmingham Solar-Oscillations Network Authors: Howe, R.; Davies, G. R.; Chaplin, W. J.; Elsworth, Y. P.; Hale, S. J. Bibcode: 2015MNRAS.454.4120H Altcode: 2015arXiv150906894H We present a new and up-to-date analysis of the solar low-degree p-mode parameter shifts from the Birmingham Solar-Oscillations Network over the past 22 years, up to the end of 2014. We aim to demonstrate that they are not dominated by changes in the asymmetry of the resonant peak profiles of the modes and that the previously published results on the solar-cycle variations of mode parameters are reliable. We compare the results obtained using a conventional maximum-likelihood estimation algorithm and a new one based on the Markov Chain Monte Carlo (MCMC) technique, both taking into account mode asymmetry. We assess the reliability of the solar-cycle trends seen in the data by applying the same analysis to artificially generated spectra. We find that the two methods are in good agreement. Both methods accurately reproduce the input frequency shifts in the artificial data and underestimate the amplitude and width changes by a small amount, around 10 per cent. We confirm earlier findings that the frequency and line width are positively correlated, and the mode amplitude anticorrelated, with the level of solar activity, with the energy supplied to the modes remaining essentially unchanged. For the mode asymmetry the correlation with activity is marginal, but the MCMC algorithm gives more robust results than the MLE (Maximum-Likelihood Estimate). The magnitude of the parameter shifts is consistent with earlier work. There is no evidence that the frequency changes we see arise from changes in the asymmetry, which would need to be much larger than those observed in order to give the observed frequency shift. Title: VizieR Online Data Catalog: Stellar noise for 4529 Kepler solar-type dwarfs (Gilliland+, 2015) Authors: Gilliland, R. L.; Chaplin, W. J.; Jenkins, J. M.; Ramsey, L. W.; Smith, J. C. Bibcode: 2015yCat..51500133G Altcode: The NASA Kepler Mission has left an indelible imprint on the research of exoplanet and stellar properties for a large number of stars (~150000), over four years.

Our earlier study (Gilliland et al., 2011ApJS..197....6G; Paper I) provided a discussion about the Kepler Mission noise properties. The earlier study over the first six quarters of Kepler data is extended to the full four years ultimately comprising the mission.

A total of 4529 stars (see Table3) brighter than Kp=12.5 met the selection criteria for solar-type dwarfs as detailed in Paper I (Gilliland et al., 2011ApJS..197....6G).

(1 data file). Title: A seismic and gravitationally bound double star observed by Kepler. Implication for the presence of a convective core Authors: Appourchaux, T.; Antia, H. M.; Ball, W.; Creevey, O.; Lebreton, Y.; Verma, K.; Vorontsov, S.; Campante, T. L.; Davies, G. R.; Gaulme, P.; Régulo, C.; Horch, E.; Howell, S.; Everett, M.; Ciardi, D.; Fossati, L.; Miglio, A.; Montalbán, J.; Chaplin, W. J.; García, R. A.; Gizon, L. Bibcode: 2015A&A...582A..25A Altcode: Context. Solar-like oscillations have been observed by Kepler and CoRoT in many solar-type stars, thereby providing a way to probe stars using asteroseismology.
Aims: The derivation of stellar parameters has usually been done with single stars. The aim of the paper is to derive the stellar parameters of a double-star system (HIP 93511), for which an interferometric orbit has been observed along with asteroseismic measurements.
Methods: We used a time series of nearly two years of data for the double star to detect the two oscillation-mode envelopes that appear in the power spectrum. Using a new scaling relation based on luminosity, we derived the radius and mass of each star. We derived the age of each star using two proxies: one based upon the large frequency separation and a new one based upon the small frequency separation. Using stellar modelling, the mode frequencies allowed us to derive the radius, the mass, and the age of each component. In addition, speckle interferometry performed since 2006 has enabled us to recover the orbit of the system and the total mass of the system.
Results: From the determination of the orbit, the total mass of the system is 2.34-0.33+0.45 M⊙. The total seismic mass using scaling relations is 2.47 ± 0.07 M⊙. The seismic age derived using the new proxy based upon the small frequency separation is 3.5 ± 0.3 Gyr. Based on stellar modelling, the mean common age of the system is 2.7-3.9 Gyr. The mean total seismic mass of the system is 2.34-2.53 M⊙ consistent with what we determined independently with the orbit. The stellar models provide the mean radius, mass, and age of the stars as RA = 1.82-1.87R⊙, MA = 1.25-1.39 M⊙, AgeA = 2.6-3.5 Gyr; RB = 1.22-1.25 R⊙, MB = 1.08-1.14 M⊙, AgeB = 3.35-4.21 Gyr. The models provide two sets of values for Star A: [1.25-1.27] M⊙ and [1.34-1.39] M⊙. We detect a convective core in Star A, while Star B does not have any. For the metallicity of the binary system of Z ≈ 0.02, we set the limit between stars having a convective core in the range [1.14-1.25] M⊙.

Appendices are available in electronic form at http://www.aanda.org Title: Asteroseismology of Solar-Type Stars with K2: Detection of Oscillations in C1 Data Authors: Chaplin, W. J.; Lund, M. N.; Handberg, R.; Basu, S.; Buchhave, L. A.; Campante, T. L.; Davies, G. R.; Huber, D.; Latham, D. W.; Latham, C. A.; Serenelli, A.; Antia, H. M.; Appourchaux, T.; Ball, W. H.; Benomar, O.; Casagrande, L.; Christensen-Dalsgaard, J.; Coelho, H. R.; Creevey, O. L.; Elsworth, Y.; García, R. A.; Gaulme, P.; Hekker, S.; Kallinger, T.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M. S.; Marcadon, F.; Mathur, S.; Miglio, A.; Mosser, B.; Régulo, C.; Roxburgh, I. W.; Silva Aguirre, V.; Stello, D.; Verma, K.; White, T. R.; Bedding, T. R.; Barclay, T.; Buzasi, D. L.; Dehuevels, S.; Gizon, L.; Houdek, G.; Howell, S. B.; Salabert, D.; Soderblom, D. R. Bibcode: 2015PASP..127.1038C Altcode: 2015arXiv150701827C We present the first detections by the NASA K2 Mission of oscillations in solar-type stars, using short-cadence data collected during K2 Campaign\,1 (C1). We understand the asteroseismic detection thresholds for C1-like levels of photometric performance, and we can detect oscillations in subgiants having dominant oscillation frequencies around $1000\,\rm \mu Hz$. Changes to the operation of the fine-guidance sensors are expected to give significant improvements in the high-frequency performance from C3 onwards. A reduction in the excess high-frequency noise by a factor of two-and-a-half in amplitude would bring main-sequence stars with dominant oscillation frequencies as high as ${\simeq 2500}\,\rm \mu Hz$ into play as potential asteroseismic targets for K2. Title: Kepler Mission Stellar and Instrument Noise Properties Revisited Authors: Gilliland, Ronald L.; Chaplin, William J.; Jenkins, Jon M.; Ramsey, Lawrence W.; Smith, Jeffrey C. Bibcode: 2015AJ....150..133G Altcode: 2015arXiv150805054G An earlier study of the Kepler Mission noise properties on timescales of primary relevance to detection of exoplanet transits found that higher than expected noise followed, to a large extent, from the stars rather than instrument or data analysis performance. The earlier study over the first six quarters of Kepler data is extended to the full four years ultimately comprising the mission. Efforts to improve the pipeline data analysis have been successful in reducing noise levels modestly as evidenced by smaller values derived from the current data products. The new analyses of noise properties on transit timescales show significant changes in the component attributed to instrument and data analysis, with essentially no change in the inferred stellar noise. We also extend the analyses to timescales of several days, instead of several hours to better sample stellar noise that follows from magnetic activity. On the longer timescale there is a shift in stellar noise for solar-type stars to smaller values in comparison to solar values. Title: Using BiSON to detect solar internal g-modes Authors: Kuszlewicz, J.; Davies, G. R.; Chaplin, W. J. Bibcode: 2015EPJWC.10106041K Altcode: The unambiguous detection of individual solar internal g modes continues to elude us. With the aid of new additions to calibration procedures, as well as updated methods to combine multi-site time series more effectively, the noise and signal detection threshold levels in the low-frequency domain (where the g modes are expected to be found) have been greatly improved. In the BiSON 23-year dataset these levels now rival those of GOLF, and with much greater frequency resolution available, due to the long time series, there is an opportunity to place more constraints on the upper limits of individual g mode amplitudes. Here we detail recent work dedicated to the challenges of observing low-frequency oscillations using a ground-based network, including the role of the window function as well as the effect of calibration on the low frequency domain. Title: Testing the νmax scaling relation Authors: Coelho, H. R.; Chaplin, W. J.; Basu, S.; Serenelli, A.; Miglio, A.; Reese, D. Bibcode: 2015EPJWC.10106017C Altcode: Two key global seismic quantities are relevant to estimate the fundamental properties of a star: the frequency of maximum power (νmax) and the large frequency separation (Δν). The focus of this work is to test the νmax scaling relation in order to ascertain it's level of accuracy. Here we report our results using artificial data and real Kepler data, based on a grid-modelling approach. Title: KOI-3158: The oldest known system of terrestrial-size planets Authors: Campante, T. L.; Barclay, T.; Swift, J. J.; Huber, D.; Adibekyan, V. Zh.; Cochran, W.; Burke, C. J.; Isaacson, H.; Quintana, E. V.; Davies, G. R.; Silva Aguirre, V.; Ragozzine, D.; Riddle, R.; Baranec, C.; Basu, S.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Bedding, T. R.; Handberg, R.; Stello, D.; Brewer, J. M.; Hekker, S.; Karoff, C.; Kolbl, R.; Law, N. M.; Lundkvist, M.; Miglio, A.; Rowe, J. F.; Santos, N. C.; Van Laerhoven, C.; Arentoft, T.; Elsworth, Y. P.; Fischer, D. A.; Kawaler, S. D.; Kjeldsen, H.; Lund, M. N.; Marcy, G. W.; Sousa, S. G.; Sozzetti, A.; White, T. R. Bibcode: 2015EPJWC.10102004C Altcode: 2015arXiv150107869C The first discoveries of exoplanets around Sun-like stars have fueled efforts to find ever smaller worlds evocative of Earth and other terrestrial planets in the Solar System. While gas-giant planets appear to form preferentially around metal-rich stars, small planets (with radii less than four Earth radii) can form under a wide range of metallicities. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the Universe's history when metals were far less abundant. We report Kepler spacecraft observations of KOI-3158, a metal-poor Sun-like star from the old population of the Galactic thick disk, which hosts five planets with sizes between Mercury and Venus. We used asteroseismology to directly measure a precise age of 11.2 ± 1.0 Gyr for the host star, indicating that KOI-3158 formed when the Universe was less than 20 % of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the Universe's 13.8-billion-year history, providing scope for the existence of ancient life in the Galaxy. Title: What asteroseismology can do for exoplanets Authors: Van Eylen, Vincent; Lund, Mikkel N.; Silva Aguirre, Victor; Arentoft, Torben; Kjeldsen, Hans; Albrecht, Simon; Chaplin, William J.; Isaacson, Howard; Pedersen, May G.; Jessen-Hansen, Jens; Tingley, Brandon; Christensen-Dalsgaard, Jørgen; Aerts, Conny; Campante, Tiago L.; Bryson, Steve T. Bibcode: 2015EPJWC.10102005V Altcode: 2014arXiv1412.4848V We describe three useful applications of asteroseismology in the context of exoplanet science: (1) the detailed characterisation of exoplanet host stars; (2) the measurement of stellar inclinations; and (3) the determination of orbital eccentricity from transit duration making use of asteroseismic stellar densities. We do so using the example system Kepler-410 [1]. This is one of the brightest (V = 9.4) Kepler exoplanet host stars, containing a small (2.8 R⊕) transiting planet in a long orbit (17.8 days), and one or more additional non-transiting planets as indicated by transit timing variations. The validation of Kepler-410 (KOI-42) was complicated due to the presence of a companion star, and the planetary nature of the system was confirmed after analyzing a Spitzer transit observation as well as ground-based follow-up observations. Title: Asteroseismic estimate of helium abundance of 16 Cyg A, B Authors: Verma, Kuldeep; Faria, João P.; Antia, H. M.; Basu, Sarbani; Mazumdar, Anwesh; Monteiro, Mário J. P. F. G.; Appourchaux, Thierry; Chaplin, William J.; García, Rafael A.; Metcalfe, Travis S. Bibcode: 2015EPJWC.10106066V Altcode: The helium ionization zone in a star leaves a characteristic signature on its oscillation frequencies, which can be used to estimate the helium content in the envelope of the star. We use the oscillation frequencies of 16 Cyg A and B, obtained using 2.5 years of Kepler data, to estimate the envelope helium abundance of these stars. We find the envelope helium abundance to lie in the range 0.231-0.251 for 16 Cyg A and 0.218-0.266 for 16 Cyg B. Title: Ages and fundamental properties of Kepler exoplanet host stars from asteroseismology Authors: Silva Aguirre, V.; Davies, G. R.; Basu, S.; Christensen-Dalsgaard, J.; Creevey, O.; Metcalfe, T. S.; Bedding, T. R.; Casagrande, L.; Handberg, R.; Lund, M. N.; Nissen, P. E.; Chaplin, W. J.; Huber, D.; Serenelli, A. M.; Stello, D.; Van Eylen, V.; Campante, T. L.; Elsworth, Y.; Gilliland, R. L.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M. S. Bibcode: 2015MNRAS.452.2127S Altcode: 2015arXiv150407992S We present a study of 33 Kepler planet-candidate host stars for which asteroseismic observations have sufficiently high signal-to-noise ratio to allow extraction of individual pulsation frequencies. We implement a new Bayesian scheme that is flexible in its input to process individual oscillation frequencies, combinations of them, and average asteroseismic parameters, and derive robust fundamental properties for these targets. Applying this scheme to grids of evolutionary models yields stellar properties with median statistical uncertainties of 1.2 per cent (radius), 1.7 per cent (density), 3.3 per cent (mass), 4.4 per cent (distance), and 14 per cent (age), making this the exoplanet host-star sample with the most precise and uniformly determined fundamental parameters to date. We assess the systematics from changes in the solar abundances and mixing-length parameter, showing that they are smaller than the statistical errors. We also determine the stellar properties with three other fitting algorithms and explore the systematics arising from using different evolution and pulsation codes, resulting in 1 per cent in density and radius, and 2 per cent and 7 per cent in mass and age, respectively. We confirm previous findings of the initial helium abundance being a source of systematics comparable to our statistical uncertainties, and discuss future prospects for constraining this parameter by combining asteroseismology and data from space missions. Finally, we compare our derived properties with those obtained using the global average asteroseismic observables along with effective temperature and metallicity, finding excellent level of agreement. Owing to selection effects, our results show that the majority of the high signal-to-noise ratio asteroseismic Kepler host stars are older than the Sun. Title: Oscillating Red Giants Observed during Campaign 1 of the Kepler K2 Mission: New Prospects for Galactic Archaeology Authors: Stello, Dennis; Huber, Daniel; Sharma, Sanjib; Johnson, Jennifer; Lund, Mikkel N.; Handberg, Rasmus; Buzasi, Derek L.; Silva Aguirre, Victor; Chaplin, William J.; Miglio, Andrea; Pinsonneault, Marc; Basu, Sarbani; Bedding, Tim R.; Bland-Hawthorn, Joss; Casagrande, Luca; Davies, Guy; Elsworth, Yvonne; Garcia, Rafael A.; Mathur, Savita; Di Mauro, Maria Pia; Mosser, Benoit; Schneider, Donald P.; Serenelli, Aldo; Valentini, Marica Bibcode: 2015ApJ...809L...3S Altcode: 2015arXiv150608931S NASA’s re-purposed Kepler mission—dubbed K2—has brought new scientific opportunities that were not anticipated for the original Kepler mission. One science goal that makes optimal use of K2's capabilities, in particular its 360° ecliptic field of view, is galactic archaeology—the study of the evolution of the Galaxy from the fossil stellar record. The thrust of this research is to exploit high-precision, time-resolved photometry from K2 in order to detect oscillations in red giant stars. This asteroseismic information can provide estimates of stellar radius (hence distance), mass, and age of vast numbers of stars across the Galaxy. Here we present the initial analysis of a subset of red giants, observed toward the north galactic gap, during the mission’s first full science campaign. We investigate the feasibility of using K2 data for detecting oscillations in red giants that span a range in apparent magnitude and evolutionary state (hence intrinsic luminosity). We demonstrate that oscillations are detectable for essentially all cool giants within the {log}g range ∼1.9-3.2. Our detection is complete down to {\text{Kp}} ∼ 14.5, which results in a seismic sample with little or no detection bias. This sample is ideally suited to stellar population studies that seek to investigate potential shortcomings of contemporary Galaxy models. Title: Asteroseismology of red-giant stars as a novel approach in the search for gravitational waves Authors: Campante, Tiago L.; Lopes, Ilídio; Bossini, Diego; Miglio, Andrea; Chaplin, William J. Bibcode: 2015IAUGA..2252323C Altcode: 2016arXiv160203667C Stars are massive resonators that may in principle be used as gravitational-wave (GW) detectors with an isotropic sensitivity. New insights on stellar physics have been made possible by asteroseismology, the study of stars by the observation of their natural, resonant oscillations. The continuous monitoring of oscillation modes in stars of different masses and sizes (e.g., as carried out by NASA’s Kepler space telescope) thus opens the possibility of surveying the local Universe for GW radiation. Red-giant stars are of particular interest in this regard. Since the mean separation between red giants in open clusters is small (of a few light years), this can in principle be used to look for the same GW imprint on the oscillation modes of different stars as a GW propagates across the cluster. Furthermore, the frequency range probed by oscillations in red giants overlaps with, and complements, the capabilities of the planned eLISA space interferometer. We propose asteroseismology of red-giant stars as a novel approach in the search for gravitational waves and assess to what extent oscillations in these stars can be excited by a passing, monochromatic GW. Title: The legacy of CoRoT and Kepler on the physics of stellar evolution Authors: Chaplin, William Bibcode: 2015IAUGA..2235114C Altcode: It is a golden era for stellar astrophysics studies, driven by new satellite observations of unprecedented quality and scope. In this talk I will review advances in our understanding that have followed from asteroseismic studies with CoRoT and Kepler data, not only for stellar evolution theory but also in respect of the legacy for exoplanet and Galactic stellar population studies. I will also highlight the huge amount of work that remains to be performed to fully exploit the CoRoT and Kepler databases, and look to ongoing studies with K2, and the future promise of the NASA TESS and ESA PLATO Missions. Title: A test of the asteroseismic νmax scaling relation for solar-like oscillations in main-sequence and subgiant stars Authors: Coelho, H. R.; Chaplin, W. J.; Basu, S.; Serenelli, A.; Miglio, A.; Reese, D. R. Bibcode: 2015MNRAS.451.3011C Altcode: 2015arXiv150506087C Large-scale analyses of stellar samples comprised of cool, solar-like oscillators now commonly utilize the so-called asteroseismic scaling relations to estimate fundamental stellar properties. In this paper, we present a test of the scaling relation for the global asteroseismic parameter νmax, the frequency at which a solar-like oscillator presents its strongest observed pulsation amplitude. The classic relation assumes that this characteristic frequency scales with a particular combination of surface gravity and effective temperature that also describes the dependence of the cut-off frequency for acoustic waves in an isothermal atmosphere, i.e. ν _max ∝ gT_eff^{-1/2}. We test how well the oscillations of cool main-sequence and subgiant stars adhere to this relation, using a sample of asteroseismic targets observed by the NASA Kepler Mission. Our results, which come from a grid-based analysis, rule out departures from the classic gT_eff^{-1/2} scaling dependence at the level of ≃1.5 per cent over the full ≃ 1560 K range in Teff that we tested. There is some uncertainty over the absolute calibration of the scaling. However, any variation with Teff is evidently small, with limits similar to those above. Title: Young α-enriched giant stars in the solar neighbourhood Authors: Martig, Marie; Rix, Hans-Walter; Silva Aguirre, Victor; Hekker, Saskia; Mosser, Benoit; Elsworth, Yvonne; Bovy, Jo; Stello, Dennis; Anders, Friedrich; García, Rafael A.; Tayar, Jamie; Rodrigues, Thaíse S.; Basu, Sarbani; Carrera, Ricardo; Ceillier, Tugdual; Chaplin, William J.; Chiappini, Cristina; Frinchaboy, Peter M.; García-Hernández, D. A.; Hearty, Fred R.; Holtzman, Jon; Johnson, Jennifer A.; Majewski, Steven R.; Mathur, Savita; Mészáros, Szabolcs; Miglio, Andrea; Nidever, David; Pan, Kaike; Pinsonneault, Marc; Schiavon, Ricardo P.; Schneider, Donald P.; Serenelli, Aldo; Shetrone, Matthew; Zamora, Olga Bibcode: 2015MNRAS.451.2230M Altcode: 2014arXiv1412.3453M We derive age constraints for 1639 red giants in the APOKASC sample for which seismic parameters from Kepler, as well as effective temperatures, metallicities and [α/Fe] values from APOGEE DR12 (Apache Point Observatory Galactic Evolution Experiment Data Release 12) are available. We investigate the relation between age and chemical abundances for these stars, using a simple and robust approach to obtain ages. We first derive stellar masses using standard seismic scaling relations, then determine the maximum possible age for each star as function of its mass and metallicity, independently of its evolutionary stage. While the overall trend between maximum age and chemical abundances is a declining fraction of young stars with increasing [α/Fe], at least 14 out of 241 stars with [α/Fe] >0.13 are younger than 6 Gyr. Five stars with [α/Fe] ≥0.2 have ages below 4 Gyr. We examine the effect of modifications in the standard seismic scaling relations, as well as the effect of very low helium fractions, but these changes are not enough to make these stars as old as usually expected for α-rich stars (i.e. ages greater than 8-9 Gyr). Such unusual α-rich young stars have also been detected by other surveys, but defy simple explanations in a galaxy evolution context. Title: Global helioseismology and asteroseismology of solar-type stars Authors: Howe, R.; Chaplin, W. J. Bibcode: 2015exse.book...63H Altcode: No abstract at ADS Title: Rapid Rotation of Low-mass Red Giants Using APOKASC: A Measure of Interaction Rates on the Post-main-sequence Authors: Tayar, Jamie; Ceillier, Tugdual; García-Hernández, D. A.; Troup, Nicholas W.; Mathur, Savita; García, Rafael A.; Zamora, O.; Johnson, Jennifer A.; Pinsonneault, Marc H.; Mészáros, Szabolcs; Allende Prieto, Carlos; Chaplin, William J.; Elsworth, Yvonne; Hekker, Saskia; Nidever, David L.; Salabert, David; Schneider, Donald P.; Serenelli, Aldo; Shetrone, Matthew; Stello, Dennis Bibcode: 2015ApJ...807...82T Altcode: 2015arXiv150503536T We investigate the occurrence rate of rapidly rotating (v{sin}i >10 km s-1), low-mass giant stars in the Apache Point Observatory Galaxy Evolution Experiment-Kepler (APOKASC) fields with asteroseismic mass and surface gravity measurements. Such stars are likely merger products and their frequency places interesting constraints on stellar population models. We also identify anomalous rotators, i.e., stars with 5 km s-1 < v{sin}i < 10 km s-1 that are rotating significantly faster than both angular momentum evolution predictions and the measured rates of similar stars. Our data set contains fewer rapid rotators than one would expect given measurements of the Galactic field star population, which likely indicates that asteroseismic detections are less common in rapidly rotating red giants. The number of low-mass moderate (5-10 km s-1) rotators in our sample gives a lower limit of 7% for the rate at which low-mass stars interact on the upper red giant branch because single stars in this mass range are expected to rotate slowly. Finally, we classify the likely origin of the rapid or anomalous rotation where possible. KIC 10293335 is identified as a merger product and KIC 6501237 is a possible binary system of two oscillating red giants. Title: The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III Authors: Alam, Shadab; Albareti, Franco D.; Allende Prieto, Carlos; Anders, F.; Anderson, Scott F.; Anderton, Timothy; Andrews, Brett H.; Armengaud, Eric; Aubourg, Éric; Bailey, Stephen; Basu, Sarbani; Bautista, Julian E.; Beaton, Rachael L.; Beers, Timothy C.; Bender, Chad F.; Berlind, Andreas A.; Beutler, Florian; Bhardwaj, Vaishali; Bird, Jonathan C.; Bizyaev, Dmitry; Blake, Cullen H.; Blanton, Michael R.; Blomqvist, Michael; Bochanski, John J.; Bolton, Adam S.; Bovy, Jo; Shelden Bradley, A.; Brandt, W. N.; Brauer, D. E.; Brinkmann, J.; Brown, Peter J.; Brownstein, Joel R.; Burden, Angela; Burtin, Etienne; Busca, Nicolás G.; Cai, Zheng; Capozzi, Diego; Carnero Rosell, Aurelio; Carr, Michael A.; Carrera, Ricardo; Chambers, K. C.; Chaplin, William James; Chen, Yen-Chi; Chiappini, Cristina; Chojnowski, S. Drew; Chuang, Chia-Hsun; Clerc, Nicolas; Comparat, Johan; Covey, Kevin; Croft, Rupert A. C.; Cuesta, Antonio J.; Cunha, Katia; da Costa, Luiz N.; Da Rio, Nicola; Davenport, James R. A.; Dawson, Kyle S.; De Lee, Nathan; Delubac, Timothée; Deshpande, Rohit; Dhital, Saurav; Dutra-Ferreira, Letícia; Dwelly, Tom; Ealet, Anne; Ebelke, Garrett L.; Edmondson, Edward M.; Eisenstein, Daniel J.; Ellsworth, Tristan; Elsworth, Yvonne; Epstein, Courtney R.; Eracleous, Michael; Escoffier, Stephanie; Esposito, Massimiliano; Evans, Michael L.; Fan, Xiaohui; Fernández-Alvar, Emma; Feuillet, Diane; Filiz Ak, Nurten; Finley, Hayley; Finoguenov, Alexis; Flaherty, Kevin; Fleming, Scott W.; Font-Ribera, Andreu; Foster, Jonathan; Frinchaboy, Peter M.; Galbraith-Frew, J. G.; García, Rafael A.; García-Hernández, D. A.; García Pérez, Ana E.; Gaulme, Patrick; Ge, Jian; Génova-Santos, R.; Georgakakis, A.; Ghezzi, Luan; Gillespie, Bruce A.; Girardi, Léo; Goddard, Daniel; Gontcho, Satya Gontcho A.; González Hernández, Jonay I.; Grebel, Eva K.; Green, Paul J.; Grieb, Jan Niklas; Grieves, Nolan; Gunn, James E.; Guo, Hong; Harding, Paul; Hasselquist, Sten; Hawley, Suzanne L.; Hayden, Michael; Hearty, Fred R.; Hekker, Saskia; Ho, Shirley; Hogg, David W.; Holley-Bockelmann, Kelly; Holtzman, Jon A.; Honscheid, Klaus; Huber, Daniel; Huehnerhoff, Joseph; Ivans, Inese I.; Jiang, Linhua; Johnson, Jennifer A.; Kinemuchi, Karen; Kirkby, David; Kitaura, Francisco; Klaene, Mark A.; Knapp, Gillian R.; Kneib, Jean-Paul; Koenig, Xavier P.; Lam, Charles R.; Lan, Ting-Wen; Lang, Dustin; Laurent, Pierre; Le Goff, Jean-Marc; Leauthaud, Alexie; Lee, Khee-Gan; Lee, Young Sun; Licquia, Timothy C.; Liu, Jian; Long, Daniel C.; López-Corredoira, Martín; Lorenzo-Oliveira, Diego; Lucatello, Sara; Lundgren, Britt; Lupton, Robert H.; Mack, Claude E., III; Mahadevan, Suvrath; Maia, Marcio A. G.; Majewski, Steven R.; Malanushenko, Elena; Malanushenko, Viktor; Manchado, A.; Manera, Marc; Mao, Qingqing; Maraston, Claudia; Marchwinski, Robert C.; Margala, Daniel; Martell, Sarah L.; Martig, Marie; Masters, Karen L.; Mathur, Savita; McBride, Cameron K.; McGehee, Peregrine M.; McGreer, Ian D.; McMahon, Richard G.; Ménard, Brice; Menzel, Marie-Luise; Merloni, Andrea; Mészáros, Szabolcs; Miller, Adam A.; Miralda-Escudé, Jordi; Miyatake, Hironao; Montero-Dorta, Antonio D.; More, Surhud; Morganson, Eric; Morice-Atkinson, Xan; Morrison, Heather L.; Mosser, Benôit; Muna, Demitri; Myers, Adam D.; Nandra, Kirpal; Newman, Jeffrey A.; Neyrinck, Mark; Nguyen, Duy Cuong; Nichol, Robert C.; Nidever, David L.; Noterdaeme, Pasquier; Nuza, Sebastián E.; O'Connell, Julia E.; O'Connell, Robert W.; O'Connell, Ross; Ogando, Ricardo L. C.; Olmstead, Matthew D.; Oravetz, Audrey E.; Oravetz, Daniel J.; Osumi, Keisuke; Owen, Russell; Padgett, Deborah L.; Padmanabhan, Nikhil; Paegert, Martin; Palanque-Delabrouille, Nathalie; Pan, Kaike; Parejko, John K.; Pâris, Isabelle; Park, Changbom; Pattarakijwanich, Petchara; Pellejero-Ibanez, M.; Pepper, Joshua; Percival, Will J.; Pérez-Fournon, Ismael; Pérez-Ràfols, Ignasi; Petitjean, Patrick; Pieri, Matthew M.; Pinsonneault, Marc H.; Porto de Mello, Gustavo F.; Prada, Francisco; Prakash, Abhishek; Price-Whelan, Adrian M.; Protopapas, Pavlos; Raddick, M. Jordan; Rahman, Mubdi; Reid, Beth A.; Rich, James; Rix, Hans-Walter; Robin, Annie C.; Rockosi, Constance M.; Rodrigues, Thaíse S.; Rodríguez-Torres, Sergio; Roe, Natalie A.; Ross, Ashley J.; Ross, Nicholas P.; Rossi, Graziano; Ruan, John J.; Rubiño-Martín, J. A.; Rykoff, Eli S.; Salazar-Albornoz, Salvador; Salvato, Mara; Samushia, Lado; Sánchez, Ariel G.; Santiago, Basílio; Sayres, Conor; Schiavon, Ricardo P.; Schlegel, David J.; Schmidt, Sarah J.; Schneider, Donald P.; Schultheis, Mathias; Schwope, Axel D.; Scóccola, C. G.; Scott, Caroline; Sellgren, Kris; Seo, Hee-Jong; Serenelli, Aldo; Shane, Neville; Shen, Yue; Shetrone, Matthew; Shu, Yiping; Silva Aguirre, V.; Sivarani, Thirupathi; Skrutskie, M. F.; Slosar, Anže; Smith, Verne V.; Sobreira, Flávia; Souto, Diogo; Stassun, Keivan G.; Steinmetz, Matthias; Stello, Dennis; Strauss, Michael A.; Streblyanska, Alina; Suzuki, Nao; Swanson, Molly E. C.; Tan, Jonathan C.; Tayar, Jamie; Terrien, Ryan C.; Thakar, Aniruddha R.; Thomas, Daniel; Thomas, Neil; Thompson, Benjamin A.; Tinker, Jeremy L.; Tojeiro, Rita; Troup, Nicholas W.; Vargas-Magaña, Mariana; Vazquez, Jose A.; Verde, Licia; Viel, Matteo; Vogt, Nicole P.; Wake, David A.; Wang, Ji; Weaver, Benjamin A.; Weinberg, David H.; Weiner, Benjamin J.; White, Martin; Wilson, John C.; Wisniewski, John P.; Wood-Vasey, W. M.; Ye`che, Christophe; York, Donald G.; Zakamska, Nadia L.; Zamora, O.; Zasowski, Gail; Zehavi, Idit; Zhao, Gong-Bo; Zheng, Zheng; Zhou, Xu; Zhou, Zhimin; Zou, Hu; Zhu, Guangtun Bibcode: 2015ApJS..219...12A Altcode: 2015arXiv150100963A The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg2 of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg2 of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg2; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra. Title: Hubble Space Telescope search for the transit of the Earth-mass exoplanet α Centauri B b Authors: Demory, Brice-Olivier; Ehrenreich, David; Queloz, Didier; Seager, Sara; Gilliland, Ronald; Chaplin, William J.; Proffitt, Charles; Gillon, Michael; Günther, Maximilian N.; Benneke, Björn; Dumusque, Xavier; Lovis, Christophe; Pepe, Francesco; Ségransan, Damien; Triaud, Amaury; Udry, Stéphane Bibcode: 2015MNRAS.450.2043D Altcode: 2015arXiv150307528D Results from exoplanet surveys indicate that small planets (super-Earth size and below) are abundant in our Galaxy. However, little is known about their interiors and atmospheres. There is therefore a need to find small planets transiting bright stars, which would enable a detailed characterization of this population of objects. We present the results of a search for the transit of the Earth-mass exoplanet α Centauri B b with the Hubble Space Telescope (HST). We observed α Centauri B twice in 2013 and 2014 for a total of 40 h. We achieve a precision of 115 ppm per 6-s exposure time in a highly saturated regime, which is found to be consistent across HST orbits. We rule out the transiting nature of α Centauri B b with the orbital parameters published in the literature at 96.6 per cent confidence. We find in our data a single transit-like event that could be associated with another Earth-sized planet in the system, on a longer period orbit. Our programme demonstrates the ability of HST to obtain consistent, high-precision photometry of saturated stars over 26 h of continuous observations. Title: K2P2— A Photometry Pipeline for the K2 Mission Authors: Lund, Mikkel N.; Handberg, Rasmus; Davies, Guy R.; Chaplin, William J.; Jones, Caitlin D. Bibcode: 2015ApJ...806...30L Altcode: 2015arXiv150405199L With the loss of a second reaction wheel, resulting in the inability to point continuously and stably at the same field of view, the NASA Kepler satellite recently entered a new mode of observation known as the K2 mission. The data from this redesigned mission present a specific challenge; the targets systematically drift in position on an ∼6 hr timescale, inducing a significant instrumental signal in the photometric time series—this greatly impacts the ability to detect planetary signals and perform asteroseismic analysis. Here we detail our version of a reduction pipeline for K2 target pixel data, which automatically defines masks for all targets in a given frame; extracts the target’s flux and position time series; corrects the time series based on the apparent movement on the CCD (either in 1D or 2D), combined with the correction of instrumental and/or planetary signals via the Kepler Asteroseismic Science Operations Center (KASOC) filter, thus rendering the time series ready for asteroseismic analysis; computes power spectra for all targets and identifies potential contaminations between targets. From a test of our pipeline on a sample of targets from the K2 campaign 0, the recovery of data for multiple targets increases the amount of potential light curves by a factor of ≥slant 10. Our pipeline could be applied to the upcoming TESS and PLATO 2.0 missions. Title: VizieR Online Data Catalog: KIC giants Bayesian distances and extinctions (Rodrigues+ 2014) Authors: Rodrigues, T. S.; Girardi, L.; Miglio, A.; Bossini, D.; Bovy, J.; Epstein, C.; Pinsonneault, M. H.; Stello, D.; Zasowski, G.; Allende Prieto, C.; Chaplin, W. J.; Hekker, S.; Johnson, J. A.; Meszaros, S.; Mosser, B.; Anders, F.; Basu, S.; Beers, T. C.; Chiappini, C.; da Costa, L. A. N.; Elsworth, Y.; Garcia, R. A.; Garcia Perez, A. E.; Hearty, F. R.; Maia, M. A. G.; Majewski, S. R.; Mathur, S.; Montalban, J.; Nidever, D. L.; Santiago, B.; Schultheis, M.; Serenelli, A.; Shetrone, M. Bibcode: 2015yCat..74452758R Altcode: APOGEE uses a high-resolution infrared spectrograph, mounted at the Apache Point Observatory 2.5m telescope, with a mean resolution of ~22500 in the H band (spectral coverage: 1.51-1.70um). APOGEE has already observed more than 100000 stars selected from 2MASS photometry, at typical signal-to-noise ratios of ~140 per resolution element. The targeted stars are mostly red giant branch (RGB), red clump (RC), and asymptotic giant branch stars (Zasowski et al., 2013AJ....146...81Z), and are spread over all regions of the MW, including the bulge, disc, and halo.

The Kepler space telescope has observed ~196400 stars (Huber et al., 2014ApJS..211....2H, Cat. J/ApJS/211/2) in a field of 105deg2 towards the constellations of Cygnus and Lyra (Borucki et al., 2010Sci...327..977B...327..997B). Apart from the discovery of exoplanets and multiple stellar systems, the high temporal and photometric quality of the data provides the possibility to study red giants by detection of solar-like oscillations (e.g. Huber et al., 2010ApJ...723.1607H; Chaplin et al., 2011Sci...332..213C).

In addition to the spectroscopic and asteroseismic parameters, stars in the APOKASC catalogue have measured apparent magnitudes in SDSS griz and DDO51, as measured by the KIC team (Brown et al., 2011, Cat. J/AJ/142/112), and corrected by Pinsonneault et al. (2012, Cat. J/ApJS/199/30);

JHKs from 2MASS (Cutri et al., 2003, Cat. II/246; Skrutskie et al., 2006, Cat. VII/233);

the Kepler magnitude, Kp, as derived from a combination of the griz magnitudes (Brown et al., 2011, Cat. J/AJ/142/112);

WISE photometry (at 3.35, 4.6, 11.6 and 22.1um, or W1 to W4) from the Preliminary Release Source Catalog (Wright et al., 2010AJ....140.1868W).

(1 data file). Title: VizieR Online Data Catalog: Kepler planetary candidates. VI. 4yr Q1-Q16 (Mullally+, 2015) Authors: Mullally, F.; Coughlin, J. L.; Thompson, S. E.; Rowe, J.; Burke, C.; Latham, D. W.; Batalha, N. M.; Bryson, S. T.; Christiansen, J.; Henze, C. E.; Ofir, A.; Quarles, B.; Shporer, A.; van Eylen, V.; van Laerhoven, C.; Shah, Y.; Wolfgang, A.; Chaplin, W. J.; Xie, J. -W.; Akeson, R.; Argabright, V.; Bachtell, E.; Barclay, T.; Borucki, W. J.; Caldwell, D. A.; Campbell, J. R.; Catanzarite, J. H.; Cochran, W. D.; Duren, R. M.; Fleming, S. W.; Fraquelli, D.; Girouard, F. R.; Haas, M. R.; Helminiak, K. G.; Howell, S. B.; Huber, D.; Larson, K.; Gautier, T. N., III; Jenkins, J. M.; Li, J.; Lissauer, J. J.; McArthur, S.; Miller, C.; Morris, R. L.; Patil-Sabale, A.; Plavchan, P.; Putnam, D.; Quintana, E. V.; Ramirez, S.; Aguirre, V. S.; Seader, S.; Smith, J. C.; Steffen, J. H.; Stewart, C.; Stober, J.; Still, M.; Tenenbaum, P.; Troeltzsch, J.; Twicken, J. D.; Zamudio, K. A. Bibcode: 2015yCat..22170031M Altcode: The Q1-Q16 catalog is based on the analysis of 16 quarters of data obtained by the Kepler spacecraft from 2009 May 13 to 2013 April 8.

(2 data files). Title: Planetary Candidates Observed by Kepler. VI. Planet Sample from Q1--Q16 (47 Months) Authors: Mullally, F.; Coughlin, Jeffrey L.; Thompson, Susan E.; Rowe, Jason; Burke, Christopher; Latham, David W.; Batalha, Natalie M.; Bryson, Stephen T.; Christiansen, Jessie; Henze, Christopher E.; Ofir, Aviv; Quarles, Billy; Shporer, Avi; Van Eylen, Vincent; Van Laerhoven, Christa; Shah, Yash; Wolfgang, Angie; Chaplin, W. J.; Xie, Ji-Wei; Akeson, Rachel; Argabright, Vic; Bachtell, Eric; Barclay, Thomas; Borucki, William J.; Caldwell, Douglas A.; Campbell, Jennifer R.; Catanzarite, Joseph H.; Cochran, William D.; Duren, Riley M.; Fleming, Scott W.; Fraquelli, Dorothy; Girouard, Forrest R.; Haas, Michael R.; Hełminiak, Krzysztof G.; Howell, Steve B.; Huber, Daniel; Larson, Kipp; Gautier, Thomas N., III; Jenkins, Jon M.; Li, Jie; Lissauer, Jack J.; McArthur, Scot; Miller, Chris; Morris, Robert L.; Patil-Sabale, Anima; Plavchan, Peter; Putnam, Dustin; Quintana, Elisa V.; Ramirez, Solange; Silva Aguirre, V.; Seader, Shawn; Smith, Jeffrey C.; Steffen, Jason H.; Stewart, Chris; Stober, Jeremy; Still, Martin; Tenenbaum, Peter; Troeltzsch, John; Twicken, Joseph D.; Zamudio, Khadeejah A. Bibcode: 2015ApJS..217...31M Altcode: 2015arXiv150202038M We present the sixth catalog of Kepler candidate planets based on nearly four years of high precision photometry. This catalog builds on the legacy of previous catalogs released by the Kepler project and includes 1493 new Kepler Objects of Interest (KOIs) of which 554 are planet candidates, and 131 of these candidates have best-fit radii \lt 1.5 {{R}\oplus }. This brings the total number of KOIs and planet candidates to 7348 and 4175 respectively. We suspect that many of these new candidates at the low signal-to-noise ratio limit may be false alarms created by instrumental noise, and discuss our efforts to identify such objects. We re-evaluate all previously published KOIs with orbital periods of \gt 50 days to provide a consistently vetted sample that can be used to improve planet occurrence rate calculations. We discuss the performance of our planet detection algorithms, and the consistency of our vetting products. The full catalog is publicly available at the NASA Exoplanet Archive. Title: Kepler-432: A Red Giant Interacting with One of its Two Long-period Giant Planets Authors: Quinn, Samuel N.; White, Timothy. R.; Latham, David W.; Chaplin, William J.; Handberg, Rasmus; Huber, Daniel; Kipping, David M.; Payne, Matthew J.; Jiang, Chen; Silva Aguirre, Victor; Stello, Dennis; Sliski, David H.; Ciardi, David R.; Buchhave, Lars A.; Bedding, Timothy R.; Davies, Guy R.; Hekker, Saskia; Kjeldsen, Hans; Kuszlewicz, James S.; Everett, Mark E.; Howell, Steve B.; Basu, Sarbani; Campante, Tiago L.; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne P.; Karoff, Christoffer; Kawaler, Steven D.; Lund, Mikkel N.; Lundkvist, Mia; Esquerdo, Gilbert A.; Calkins, Michael L.; Berlind, Perry Bibcode: 2015ApJ...803...49Q Altcode: 2014arXiv1411.4666Q We report the discovery of Kepler-432b, a giant planet ({{M}b}=5.41-0.18+0.32 {{M}Jup}, {{R}b}=1.145-0.039+0.036 {{R}Jup}) transiting an evolved star ({{M}\star }=1.32-0.07+0.10 {{M}⊙ },{{R}\star }=4.06-0.08+0.12 {{R}⊙ }) with an orbital period of {{P}b}=52.501129-0.000053+0.000067 days. Radial velocities (RVs) reveal that Kepler-432b orbits its parent star with an eccentricity of e=0.5134-0.0089+0.0098, which we also measure independently with asterodensity profiling (AP; e=0.507-0.114+0.039), thereby confirming the validity of AP on this particular evolved star. The well-determined planetary properties and unusually large mass also make this planet an important benchmark for theoretical models of super-Jupiter formation. Long-term RV monitoring detected the presence of a non-transiting outer planet (Kepler-432c; {{M}c}sin {{i}c}=2.43-0.24+0.22 {{M}Jup}, {{P}c}=406.2-2.5+3.9 days), and adaptive optics imaging revealed a nearby (0\buildrel{\prime\prime}\over{.} 87), faint companion (Kepler-432B) that is a physically bound M dwarf. The host star exhibits high signal-to-noise ratio asteroseismic oscillations, which enable precise measurements of the stellar mass, radius, and age. Analysis of the rotational splitting of the oscillation modes additionally reveals the stellar spin axis to be nearly edge-on, which suggests that the stellar spin is likely well aligned with the orbit of the transiting planet. Despite its long period, the obliquity of the 52.5 day orbit may have been shaped by star-planet interaction in a manner similar to hot Jupiter systems, and we present observational and theoretical evidence to support this scenario. Finally, as a short-period outlier among giant planets orbiting giant stars, study of Kepler-432b may help explain the distribution of massive planets orbiting giant stars interior to 1 AU. Title: An Ancient Extrasolar System with Five Sub-Earth-size Planets Authors: Campante, T. L.; Barclay, T.; Swift, J. J.; Huber, D.; Adibekyan, V. Zh.; Cochran, W.; Burke, C. J.; Isaacson, H.; Quintana, E. V.; Davies, G. R.; Silva Aguirre, V.; Ragozzine, D.; Riddle, R.; Baranec, C.; Basu, S.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Bedding, T. R.; Handberg, R.; Stello, D.; Brewer, J. M.; Hekker, S.; Karoff, C.; Kolbl, R.; Law, N. M.; Lundkvist, M.; Miglio, A.; Rowe, J. F.; Santos, N. C.; Van Laerhoven, C.; Arentoft, T.; Elsworth, Y. P.; Fischer, D. A.; Kawaler, S. D.; Kjeldsen, H.; Lund, M. N.; Marcy, G. W.; Sousa, S. G.; Sozzetti, A.; White, T. R. Bibcode: 2015ApJ...799..170C Altcode: 2015arXiv150106227C The chemical composition of stars hosting small exoplanets (with radii less than four Earth radii) appears to be more diverse than that of gas-giant hosts, which tend to be metal-rich. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the universe's history when metals were more scarce. We report Kepler spacecraft observations of Kepler-444, a metal-poor Sun-like star from the old population of the Galactic thick disk and the host to a compact system of five transiting planets with sizes between those of Mercury and Venus. We validate this system as a true five-planet system orbiting the target star and provide a detailed characterization of its planetary and orbital parameters based on an analysis of the transit photometry. Kepler-444 is the densest star with detected solar-like oscillations. We use asteroseismology to directly measure a precise age of 11.2 ± 1.0 Gyr for the host star, indicating that Kepler-444 formed when the universe was less than 20% of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the universe's 13.8 billion year history, leaving open the possibility for the existence of ancient life in the Galaxy. The age of Kepler-444 not only suggests that thick-disk stars were among the hosts to the first Galactic planets, but may also help to pinpoint the beginning of the era of planet formation. Title: VizieR Online Data Catalog: APOKASC catalog of Kepler red giants (Pinsonneault+, 2014) Authors: Pinsonneault, M. H.; Elsworth, Y.; Epstein, C.; Hekker, S.; Meszaros, Sz.; Chaplin, W. J.; Johnson, J. A.; Garcia, R. A.; Holtzman, J.; Mathur, S.; Garcia Perez, A.; Silva Aguirre, V.; Girardi, L.; Basu, S.; Shetrone, M.; Stello, D.; Allende Prieto, C.; An, D.; Beck, P.; Beers, T. C.; Bizyaev, D.; Bloemen, S.; Bovy, J.; Cunha, K.; De Ridder, J.; Frinchaboy, P. M.; Garcia-Hernandez, D. A.; Gilliland, R.; Harding, P.; Hearty, F. R.; Huber, D.; Ivans, I.; Kallinger, T.; Majewski, S. R.; Metcalfe, T. S.; Miglio, A.; Mosser, B.; Muna, D.; Nidever, D. L.; Schneider, D. P.; Serenelli, A.; Smith, V. V.; Tayar, J.; Zamora, O.; Zasowski, G. Bibcode: 2015yCat..22150019P Altcode: In this paper we present the first release of the joint APOKASC asteroseismic and spectroscopic survey for targets with both high-resolution Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectra analyzed by members of the third Sloan Digital Sky Survey (SDSS-III) and asteroseismic data obtained by the Kepler mission and analyzed by members of the Kepler Asteroseismology Science Consortium (KASC).

(4 data files). Title: A Pair of Massive Planets Orbiting an Oscillating Kepler Red Giant in a Binary System Authors: Quinn, Samuel Noah; Huber, Daniel; Latham, David W.; Payne, Matthew J.; Kipping, David M.; Sliski, David; Ciardi, David R.; Chaplin, William J.; Handberg, Rasmus; Stello, Dennis; White, Timothy R.; Buchhave, Lars A.; Kepler Science Team; Kepler Asteroseismic Science Consortium Bibcode: 2015AAS...22525704Q Altcode: 2015AAS...22525704N We present the radial-velocity confirmation of a massive planet transiting an evolved Kepler star, as well as the discovery of an outer non-transiting planet and a faint visual stellar companion that may be physically bound. The host star exhibits high S/N asteroseismic oscillations, which enable a measurement of the stellar mass, radius, age, and spin axis inclination. In conjunction with the radial velocities, an N-body simulation and stability analysis help constrain the parameters of the outer planetary orbit. With precisely derived stellar and planetary properties, the system provides a rare opportunity to study giant planet evolution around evolved stars and at long periods. The planets reside inside the ice line (Pb≈52.5 days, Pc≈407 days), which indicates that migration has occurred, and their high eccentricities (eb≈0.51, ec≈0.48) hint that they may have been scattered inward. However, the inclination of the stellar spin axis is nearly edge-on, implying a likely alignment between the stellar spin and the orbit of the inner (transiting) planet. We suggest that despite the long period, the star and planet may have experienced tidal interaction leading to realignment of the stellar spin axis. Title: Erratum: Sounding stellar cycles with Kepler - II. Ground-based observations Authors: Karoff, C.; Metcalfe, T. S.; Chaplin, W. J.; Frandsen, S.; Grundahl, F.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Nielsen, M. B.; Frimann, S.; Thygesen, A. O.; Arentoft, T.; Amby, T. M.; Sousa, S. G.; Buzasi, D. L. Bibcode: 2015MNRAS.446.1139K Altcode: No abstract at ADS Title: Inferences on Stellar Activity and Stellar Cycles from Asteroseismology Authors: Chaplin, William J.; Basu, Sarbani Bibcode: 2015sac..book..437C Altcode: No abstract at ADS Title: Transiting Exoplanet Survey Satellite (TESS) Authors: Ricker, George R.; Winn, Joshua N.; Vanderspek, Roland; Latham, David W.; Bakos, Gáspár Á.; Bean, Jacob L.; Berta-Thompson, Zachory K.; Brown, Timothy M.; Buchhave, Lars; Butler, Nathaniel R.; Butler, R. Paul; Chaplin, William J.; Charbonneau, David; Christensen-Dalsgaard, Jørgen; Clampin, Mark; Deming, Drake; Doty, John; De Lee, Nathan; Dressing, Courtney; Dunham, Edward W.; Endl, Michael; Fressin, Francois; Ge, Jian; Henning, Thomas; Holman, Matthew J.; Howard, Andrew W.; Ida, Shigeru; Jenkins, Jon M.; Jernigan, Garrett; Johnson, John Asher; Kaltenegger, Lisa; Kawai, Nobuyuki; Kjeldsen, Hans; Laughlin, Gregory; Levine, Alan M.; Lin, Douglas; Lissauer, Jack J.; MacQueen, Phillip; Marcy, Geoffrey; McCullough, Peter R.; Morton, Timothy D.; Narita, Norio; Paegert, Martin; Palle, Enric; Pepe, Francesco; Pepper, Joshua; Quirrenbach, Andreas; Rinehart, Stephen A.; Sasselov, Dimitar; Sato, Bun'ei; Seager, Sara; Sozzetti, Alessandro; Stassun, Keivan G.; Sullivan, Peter; Szentgyorgyi, Andrew; Torres, Guillermo; Udry, Stephane; Villasenor, Joel Bibcode: 2015JATIS...1a4003R Altcode: The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its 2-year mission, TESS will employ four wide-field optical charge-coupled device cameras to monitor at least 200,000 main-sequence dwarf stars with IC≈4-13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from 1 month to 1 year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10 to 100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every 4 months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations. Title: Stellar Populations with APOGEE and Kepler Authors: Johnson, Jennifer; Pinsonneault, Marc H.; Elsworth, Yvonne P.; Epstein, Courtney R.; Hekker, Saskia; Meszaros, Szabolcs; Chaplin, William J.; Garcia, Rafael; Holtzman, Jon A.; Mathur, Savita; García Pérez, Ana; Basu, Sarbani; Girardi, Leo; Silva Aguirre, Víctor; Shetrone, Matthew D.; Stello, Dennis; Rodrigues, Thaise; Allende-Prieto, Carlos; An, Deokkeun; Beck, Paul; Bizyaev, Dmitry; Bovy, Jo; Cunha, Katia M. L.; De Ridder, Joris; Garcia-Hernandez, D. Bibcode: 2015AAS...22530202J Altcode: The history of the Milky Way is recorded in its stars, but dissecting stellar populations is not a straighforward process. Key information is gained by analyzing the absorption lines from high-resolution spectroscopy of stellar atmospheres by the APOGEE survey and analyzing the frequencies in power spectra of photometric lightcurves by Kepler Asteroseismic Science Consortium, in particular the large frequency separation and the frequency of maximum power. From spectroscopy, we measure effective temperature, rotation, metallicity and abundance ratios, while seismology provides gravities, rotation,and evolutionary state. Combined, these two techniques yield other fundamental parameters such as mass and radius. I will discuss revolutionary insights into Galactic evolution gained by this extensive dataset. Title: &ldquo;Rapid-Fire&rdquo; Spectroscopy of Kepler Solar-Like Oscillators Authors: Thygesen, Anders O.; Bruntt, Hans; Chaplin, William J.; Basu, Sarbani Bibcode: 2015ASSP...39..105T Altcode: 2014arXiv1402.3794T The NASA Kepler mission has been continuously monitoring the same field of the sky since the successful launch in March 2009, providing high-quality stellar lightcurves that are excellent data for asteroseismology, far superior to any other observations available at the present. In order to make a meaningful analysis and interpretation of the asteroseismic data, accurate fundamental parameters for the observed stars are needed. The currently available parameters are quite uncertain as illustrated by e.g. Thygesen et al. (A&A 543:A160, 2012), who found deviations as extreme as 2 dex in [Fe/H] and logg, compared to catalogue values. Thus, additional follow-up observations for these targets are needed in order to put firm limits on the parameter space investigated by the asteroseismic modellers. Here, we propose a method for deriving accurate metallicities of main sequence and subgiant solar-like oscillators from medium resolution spectra with a moderate S/N. The method takes advantage of the additional constraints on the fundamental parameters, available from asteroseismology and multi-color photometry. The approach enables us to reduce the analysis overhead significantly when doing spectral synthesis, which in turn will increases the efficiency of follow-up observations. Title: Asteroseismic inference on rotation, gyrochronology and planetary system dynamics of 16 Cygni Authors: Davies, G. R.; Chaplin, W. J.; Farr, W. M.; García, R. A.; Lund, M. N.; Mathis, S.; Metcalfe, T. S.; Appourchaux, T.; Basu, S.; Benomar, O.; Campante, T. L.; Ceillier, T.; Elsworth, Y.; Handberg, R.; Salabert, D.; Stello, D. Bibcode: 2015MNRAS.446.2959D Altcode: 2014arXiv1411.1359D The solar analogues 16 Cyg A and B are excellent asteroseismic targets in the Kepler field of view and together with a red dwarf and a Jovian planet form an interesting system. For these more evolved Sun-like stars we cannot detect surface rotation with the current Kepler data but instead use the technique of asteroseimology to determine rotational properties of both 16 Cyg A and B. We find the rotation periods to be 23.8^{+1.5}_{-1.8} and 23.2^{+11.5}_{-3.2} d, and the angles of inclination to be 56^{+6}_{-5}° and 36^{+17}_{-7}°, for A and B, respectively. Together with these results we use the published mass and age to suggest that, under the assumption of a solar-like rotation profile, 16 Cyg A could be used when calibrating gyrochronology relations. In addition, we discuss the known 16 Cyg B star-planet eccentricity and measured low obliquity which is consistent with Kozai cycling and tidal theory. Title: Solar-Like Oscillating Stars as Standard Clocks and Rulers for Galactic Studies Authors: Miglio, Andrea; Girardi, Léo; Rodrigues, Thaíse S.; Stello, Dennis; Chaplin, William J. Bibcode: 2015ASSP...39...11M Altcode: 2014arXiv1409.2267M The CoRoT and Kepler space missions have detected oscillations in hundreds of Sun-like stars and thousands of field red-giant stars. This has opened the door to a new era of stellar population studies in the Milky Way. We report on the current status and future prospects of harvesting space-based photometric data for ensemble asteroseismology, and highlight some of the challenges that need to be faced to use these stars as accurate clocks and rulers for Galactic studies. Title: Mixed modes in red giants: a window on stellar evolution Authors: Mosser, B.; Benomar, O.; Belkacem, K.; Goupil, M. J.; Lagarde, N.; Michel, E.; Lebreton, Y.; Stello, D.; Vrard, M.; Barban, C.; Bedding, T. R.; Deheuvels, S.; Chaplin, W. J.; De Ridder, J.; Elsworth, Y.; Montalban, J.; Noels, A.; Ouazzani, R. M.; Samadi, R.; White, T. R.; Kjeldsen, H. Bibcode: 2014A&A...572L...5M Altcode: 2014arXiv1411.1082M Context. The detection of oscillations with a mixed character in subgiants and red giants allows us to probe the physical conditions in their cores.
Aims: With these mixed modes, we aim at determining seismic markers of stellar evolution.
Methods: Kepler asteroseismic data were selected to map various evolutionary stages and stellar masses. Seismic evolutionary tracks were then drawn with the combination of the frequency and period spacings.
Results: We measured the asymptotic period spacing for 1178 stars at various evolutionary stages. This allows us to monitor stellar evolution from the main sequence to the asymptotic giant branch and draw seismic evolutionary tracks. We present clear quantified asteroseismic definitions that characterize the change in the evolutionary stages, in particular the transition from the subgiant stage to the early red giant branch, and the end of the horizontal branch.
Conclusions: The seismic information is so precise that clear conclusions can be drawn independently of evolution models. The quantitative seismic information can now be used for stellar modeling, especially for studying the energy transport in the helium-burning core or for specifying the inner properties of stars entering the red or asymptotic giant branches. Modeling will also allow us to study stars that are identified to be in the helium-subflash stage, high-mass stars either arriving or quitting the secondary clump, or stars that could be in the blue-loop stage.

Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/572/L5 Title: Inferences on Stellar Activity and Stellar Cycles from Asteroseismology Authors: Chaplin, William J.; Basu, Sarbani Bibcode: 2014SSRv..186..437C Altcode: 2014SSRv..tmp...49C The solar activity cycle can be studied using many different types of observations, such as counting sunspots, measuring emission in the Ca II H&K lines, magnetograms, radio emissions, etc. One of the more recent ways of studying solar activity is to use the changing properties of solar oscillations. Stellar activity cycles are generally studied using the Ca II lines, or sometimes using photometry. Asteroseismology is potentially an exciting means of studying these cycles. In this article we examine whether or not asteroseismic data can be used for this purpose, and what the asteroseismic signatures of stellar activity are. We also examine how asteroseismology may help in more indirect ways. Title: Rotation and magnetism of Kepler pulsating solar-like stars. Towards asteroseismically calibrated age-rotation relations Authors: García, R. A.; Ceillier, T.; Salabert, D.; Mathur, S.; van Saders, J. L.; Pinsonneault, M.; Ballot, J.; Beck, P. G.; Bloemen, S.; Campante, T. L.; Davies, G. R.; do Nascimento, J. -D., Jr.; Mathis, S.; Metcalfe, T. S.; Nielsen, M. B.; Suárez, J. C.; Chaplin, W. J.; Jiménez, A.; Karoff, C. Bibcode: 2014A&A...572A..34G Altcode: 2014arXiv1403.7155G Kepler ultra-high precision photometry of long and continuous observations provides a unique dataset in which surface rotation and variability can be studied for thousands of stars. Because many of these old field stars also have independently measured asteroseismic ages, measurements of rotation and activity are particularly interesting in the context of age-rotation-activity relations. In particular, age-rotation relations generally lack good calibrators at old ages, a problem that this Kepler sample of old-field stars is uniquely suited to address. We study the surface rotation and photometric magnetic activity of a subset of 540 solar-like stars on the main-sequence and the subgiant branch for which stellar pulsations have been measured. The rotation period was determined by comparing the results from two different analysis methods: i) the projection onto the frequency domain of the time-period analysis, and ii) the autocorrelation function of the light curves. Reliable surface rotation rates were then extracted by comparing the results from two different sets of calibrated data and from the two complementary analyses. General photometric levels of magnetic activity in this sample of stars were also extracted by using a photometric activity index, which takes into account the rotation period of the stars. We report rotation periods for 310 out of 540 targets (excluding known binaries and candidate planet-host stars); our measurements span a range of 1 to 100 days. The photometric magnetic activity levels of these stars were computed, and for 61.5% of the dwarfs, this level is similar to the range, from minimum to maximum, of the solar magnetic activity. We demonstrate that hot dwarfs, cool dwarfs, and subgiants have very different rotation-age relationships, highlighting the importance of separating out distinct populations when interpreting stellar rotation periods. Our sample of cool dwarf stars with age and metallicity data of the highest quality is consistent with gyrochronology relations reported in the literature.

Full Table 3 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/572/A34 Title: Bayesian distances and extinctions for giants observed by Kepler and APOGEE Authors: Rodrigues, Thaíse S.; Girardi, Léo; Miglio, Andrea; Bossini, Diego; Bovy, Jo; Epstein, Courtney; Pinsonneault, Marc H.; Stello, Dennis; Zasowski, Gail; Allende Prieto, Carlos; Chaplin, William J.; Hekker, Saskia; Johnson, Jennifer A.; Mészáros, Szabolcs; Mosser, Benoît; Anders, Friedrich; Basu, Sarbani; Beers, Timothy C.; Chiappini, Cristina; da Costa, Luiz A. N.; Elsworth, Yvonne; García, Rafael A.; García Pérez, Ana E.; Hearty, Fred R.; Maia, Marcio A. G.; Majewski, Steven R.; Mathur, Savita; Montalbán, Josefina; Nidever, David L.; Santiago, Basilio; Schultheis, Mathias; Serenelli, Aldo; Shetrone, Matthew Bibcode: 2014MNRAS.445.2758R Altcode: 2014arXiv1410.1350R We present a first determination of distances and extinctions for individual stars in the first release of the APOKASC catalogue, built from the joint efforts of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and the Kepler Asteroseismic Science Consortium (KASC). Our method takes into account the spectroscopic constraints derived from the APOGEE Stellar Parameters and Chemical Abundances Pipeline, together with the asteroseismic parameters from KASC. These parameters are then employed to estimate intrinsic stellar properties, including absolute magnitudes, using the Bayesian tool PARAM. We then find the distance and extinction that best fit the observed photometry in Sloan Digital Sky Survey (SDSS), 2MASS, and WISE passbands. The first 1989 giants targetted by APOKASC are found at typical distances between 0.5 and 5 kpc, with individual uncertainties of just ∼1.8 per cent. Our extinction estimates are systematically smaller than provided in the Kepler Input Catalogue and by the Schlegel et al. maps. Distances to individual stars in the NGC 6791 and NGC 6819 star clusters agree to within their credible intervals. Comparison with the APOGEE red clump and SAGA catalogues provide another useful check, exhibiting agreement with our measurements to within a few per cent. Overall, present methods seem to provide excellent distance and extinction determinations for the bulk of the APOKASC sample. Approximately one third of the stars present broad or multiple-peaked probability density functions and hence increased uncertainties. Uncertainties are expected to be reduced in future releases of the catalogue, when a larger fraction of the stars will have seismically determined evolutionary status classifications. Title: The APOKASC Catalog: An Asteroseismic and Spectroscopic Joint Survey of Targets in the Kepler Fields Authors: Pinsonneault, Marc H.; Elsworth, Yvonne; Epstein, Courtney; Hekker, Saskia; Mészáros, Sz.; Chaplin, William J.; Johnson, Jennifer A.; García, Rafael A.; Holtzman, Jon; Mathur, Savita; García Pérez, Ana; Silva Aguirre, Victor; Girardi, Léo; Basu, Sarbani; Shetrone, Matthew; Stello, Dennis; Allende Prieto, Carlos; An, Deokkeun; Beck, Paul; Beers, Timothy C.; Bizyaev, Dmitry; Bloemen, Steven; Bovy, Jo; Cunha, Katia; De Ridder, Joris; Frinchaboy, Peter M.; García-Hernández, D. A.; Gilliland, Ronald; Harding, Paul; Hearty, Fred R.; Huber, Daniel; Ivans, Inese; Kallinger, Thomas; Majewski, Steven R.; Metcalfe, Travis S.; Miglio, Andrea; Mosser, Benoit; Muna, Demitri; Nidever, David L.; Schneider, Donald P.; Serenelli, Aldo; Smith, Verne V.; Tayar, Jamie; Zamora, Olga; Zasowski, Gail Bibcode: 2014ApJS..215...19P Altcode: 2014arXiv1410.2503P We present the first APOKASC catalog of spectroscopic and asteroseismic properties of 1916 red giants observed in the Kepler fields. The spectroscopic parameters provided from the Apache Point Observatory Galactic Evolution Experiment project are complemented with asteroseismic surface gravities, masses, radii, and mean densities determined by members of the Kepler Asteroseismology Science Consortium. We assess both random and systematic sources of error and include a discussion of sample selection for giants in the Kepler fields. Total uncertainties in the main catalog properties are of the order of 80 K in T eff, 0.06 dex in [M/H], 0.014 dex in log g, and 12% and 5% in mass and radius, respectively; these reflect a combination of systematic and random errors. Asteroseismic surface gravities are substantially more precise and accurate than spectroscopic ones, and we find good agreement between their mean values and the calibrated spectroscopic surface gravities. There are, however, systematic underlying trends with T eff and log g. Our effective temperature scale is between 0 and 200 K cooler than that expected from the infrared flux method, depending on the adopted extinction map, which provides evidence for a lower value on average than that inferred for the Kepler Input Catalog (KIC). We find a reasonable correspondence between the photometric KIC and spectroscopic APOKASC metallicity scales, with increased dispersion in KIC metallicities as the absolute metal abundance decreases, and offsets in T eff and log g consistent with those derived in the literature. We present mean fitting relations between APOKASC and KIC observables and discuss future prospects, strengths, and limitations of the catalog data. Title: Why should we correct reported pulsation frequencies for stellar line-of-sight Doppler velocity shifts? Authors: Davies, G. R.; Handberg, R.; Miglio, A.; Campante, T. L.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2014MNRAS.445L..94D Altcode: 2014arXiv1408.7042D In the age of Kepler and CoRoT, extended observations have provided estimates of stellar pulsation frequencies that have achieved new levels of precision, regularly exceeding fractional levels of a few parts in 104. These high levels of precision now in principle exceed the point where one can ignore the Doppler shift of pulsation frequencies caused by the motion of a star relative to the observer. We present a correction for these Doppler shifts and use previously published pulsation frequencies to demonstrate the significance of the effect. We suggest that reported pulsation frequencies should be routinely corrected for stellar line-of-sight velocity Doppler shifts, or if a line-of-sight velocity estimate is not available, the frame of reference in which the frequencies are reported should be clearly stated. Title: VizieR Online Data Catalog: Evolution state of red giants from seismology (Mosser+, 2014) Authors: Mosser, B.; Benomar, O.; Belkacem, K.; Goupil, M. J.; Lagarde, N.; Michel, E.; Lebreton, Y.; Stello, D.; Vrard, M.; Barban, C.; Bedding, T. R.; Deheuvels, S.; Chaplin, W. J.; De Ridder, J.; Elsworth, Y.; Montalban, J.; Noels, A.; Ouazzani, R. M.; Samadi, R.; White, T. R.; Kjeldsen, H. Bibcode: 2014yCat..35729005M Altcode: Seismic global parameters of the stars listed in the paper. Each star is identified with its KIC number (Kepler Input Catalog).

The asymptotic frequency and period spacing are derived from the fit of the radial and dipole oscillation modes. The stellar mass is derived from the seismic scaling relations. The evolutionary status is derived according to the location of the star in the DPi1 - Dnu diagram (Fig. 1)

(1 data file). Title: Super-Nyquist asteroseismology of solar-like oscillators with Kepler and K2 - expanding the asteroseismic cohort at the base of the red giant branch Authors: Chaplin, W. J.; Elsworth, Y.; Davies, G. R.; Campante, T. L.; Handberg, R.; Miglio, A.; Basu, S. Bibcode: 2014MNRAS.445..946C Altcode: 2014arXiv1409.0696C We consider the prospects for detecting solar-like oscillations in the `super-Nyquist' regime of long-cadence (LC) Kepler photometry, i.e. above the associated Nyquist frequency of ≃ 283 μHz. Targets of interest are cool, evolved subgiants and stars lying at the base of the red giant branch. These stars would ordinarily be studied using the short-cadence (SC) data, since the associated SC Nyquist frequency lies well above the frequencies of the detectable oscillations. However, the number of available SC target slots is quite limited. This imposes a severe restriction on the size of the ensemble available for SC asteroseismic study. We find that archival Kepler LC data from the nominal mission may be utilized for asteroseismic studies of targets whose dominant oscillation frequencies lie as high as ≃ 500 μHz, i.e. about 1.75-times the LC Nyquist frequency. The frequency detection threshold for the shorter duration science campaigns of the re-purposed Kepler mission, K2, is lower. The maximum threshold will probably lie somewhere between ≃400 and 450 μHz. The potential to exploit the archival Kepler and K2 LC data in this manner opens the door to increasing significantly the number of subgiant and low-luminosity red giant targets amenable to asteroseismic analysis, overcoming target limitations imposed by the small number of SC slots. We estimate that around 400 such targets are now available for study in the Kepler LC archive. That number could potentially be a lot higher for K2, since there will be a new target list for each of its campaigns. Title: Determining stellar macroturbulence using asteroseismic rotational velocities from Kepler Authors: Doyle, Amanda P.; Davies, Guy R.; Smalley, Barry; Chaplin, William J.; Elsworth, Yvonne Bibcode: 2014MNRAS.444.3592D Altcode: 2014arXiv1408.3988D The Rossiter-McLaughlin effect observed for transiting exoplanets often requires prior knowledge of the stellar projected equatorial rotational velocity (v sin i). This is usually provided by measuring the broadening of spectral lines, however this method has uncertainties as lines are also broadened by velocity fields in the stellar photosphere known as macroturbulence (vmac). We have estimated accurate v sin i values from asteroseismic analyses of main-sequence stars observed by Kepler. The rotational frequency splittings of the detected solar-like oscillations of these stars are determined largely by the near-surface rotation. These estimates have been used to infer the vmac values for 28 Kepler stars. Out of this sample, 26 stars were used along with the Sun to obtain a new calibration between vmac, effective temperature and surface gravity. The new calibration is valid for the temperature range 5200 to 6400 K and the gravity range 4.0 to 4.6 dex. A comparison is also provided with previous vmac calibrations. As a result of this work, vmac, and thus v sin i, can now be determined with confidence for stars that do not have asteroseismic data available. We present new spectroscopic v sin i values for the WASP planet host stars, using high-resolution HARPS spectra. Title: The PLATO 2.0 mission Authors: Rauer, H.; Catala, C.; Aerts, C.; Appourchaux, T.; Benz, W.; Brandeker, A.; Christensen-Dalsgaard, J.; Deleuil, M.; Gizon, L.; Goupil, M. -J.; Güdel, M.; Janot-Pacheco, E.; Mas-Hesse, M.; Pagano, I.; Piotto, G.; Pollacco, D.; Santos, Ċ.; Smith, A.; Suárez, J. -C.; Szabó, R.; Udry, S.; Adibekyan, V.; Alibert, Y.; Almenara, J. -M.; Amaro-Seoane, P.; Eiff, M. Ammler-von; Asplund, M.; Antonello, E.; Barnes, S.; Baudin, F.; Belkacem, K.; Bergemann, M.; Bihain, G.; Birch, A. C.; Bonfils, X.; Boisse, I.; Bonomo, A. S.; Borsa, F.; Brandão, I. M.; Brocato, E.; Brun, S.; Burleigh, M.; Burston, R.; Cabrera, J.; Cassisi, S.; Chaplin, W.; Charpinet, S.; Chiappini, C.; Church, R. P.; Csizmadia, Sz.; Cunha, M.; Damasso, M.; Davies, M. B.; Deeg, H. J.; Díaz, R. F.; Dreizler, S.; Dreyer, C.; Eggenberger, P.; Ehrenreich, D.; Eigmüller, P.; Erikson, A.; Farmer, R.; Feltzing, S.; de Oliveira Fialho, F.; Figueira, P.; Forveille, T.; Fridlund, M.; García, R. A.; Giommi, P.; Giuffrida, G.; Godolt, M.; Gomes da Silva, J.; Granzer, T.; Grenfell, J. L.; Grotsch-Noels, A.; Günther, E.; Haswell, C. A.; Hatzes, A. P.; Hébrard, G.; Hekker, S.; Helled, R.; Heng, K.; Jenkins, J. M.; Johansen, A.; Khodachenko, M. L.; Kislyakova, K. G.; Kley, W.; Kolb, U.; Krivova, N.; Kupka, F.; Lammer, H.; Lanza, A. F.; Lebreton, Y.; Magrin, D.; Marcos-Arenal, P.; Marrese, P. M.; Marques, J. P.; Martins, J.; Mathis, S.; Mathur, S.; Messina, S.; Miglio, A.; Montalban, J.; Montalto, M.; Monteiro, M. J. P. F. G.; Moradi, H.; Moravveji, E.; Mordasini, C.; Morel, T.; Mortier, A.; Nascimbeni, V.; Nelson, R. P.; Nielsen, M. B.; Noack, L.; Norton, A. J.; Ofir, A.; Oshagh, M.; Ouazzani, R. -M.; Pápics, P.; Parro, V. C.; Petit, P.; Plez, B.; Poretti, E.; Quirrenbach, A.; Ragazzoni, R.; Raimondo, G.; Rainer, M.; Reese, D. R.; Redmer, R.; Reffert, S.; Rojas-Ayala, B.; Roxburgh, I. W.; Salmon, S.; Santerne, A.; Schneider, J.; Schou, J.; Schuh, S.; Schunker, H.; Silva-Valio, A.; Silvotti, R.; Skillen, I.; Snellen, I.; Sohl, F.; Sousa, S. G.; Sozzetti, A.; Stello, D.; Strassmeier, K. G.; Švanda, M.; Szabó, Gy. M.; Tkachenko, A.; Valencia, D.; Van Grootel, V.; Vauclair, S. D.; Ventura, P.; Wagner, F. W.; Walton, N. A.; Weingrill, J.; Werner, S. C.; Wheatley, P. J.; Zwintz, K. Bibcode: 2014ExA....38..249R Altcode: 2014ExA...tmp...41R; 2013arXiv1310.0696R PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s candence) providing a wide field-of-view (2232 deg 2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e.g.: - complete our knowledge of planet diversity for low-mass objects, - correlate the planet mean density-orbital distance distribution with predictions from planet formation theories,- constrain the influence of planet migration and scattering on the architecture of multiple systems, and - specify how planet and system parameters change with host star characteristics, such as type, metallicity and age. The catalogue will allow us to study planets and planetary systems at different evolutionary phases. It will further provide a census for small, low-mass planets. This will serve to identify objects which retained their primordial hydrogen atmosphere and in general the typical characteristics of planets in such low-mass, low-density range. Planets detected by PLATO 2.0 will orbit bright stars and many of them will be targets for future atmosphere spectroscopy exploring their atmosphere. Furthermore, the mission has the potential to detect exomoons, planetary rings, binary and Trojan planets. The planetary science possible with PLATO 2.0 is complemented by its impact on stellar and galactic science via asteroseismology as well as light curves of all kinds of variable stars, together with observations of stellar clusters of different ages. This will allow us to improve stellar models and study stellar activity. A large number of well-known ages from red giant stars will probe the structure and evolution of our Galaxy. Asteroseismic ages of bright stars for different phases of stellar evolution allow calibrating stellar age-rotation relationships. Together with the results of ESA's Gaia mission, the results of PLATO 2.0 will provide a huge legacy to planetary, stellar and galactic science. Title: VizieR Online Data Catalog: Pulsating solar-like stars in Kepler (Garcia+, 2014) Authors: Garcia, R. A.; Ceillier, T.; Salabert, D.; Mathur, S.; van Saders, J. L.; Pinsonneault, M.; Ballot, J.; Beck, P. G.; Bloemen, S.; Campante, T. L.; Davies, G. R.; Do Nascimento, J. -D., Jr.; Mathis, S.; Metcalfe, T. S.; Nielsen, M. B.; Suarez, J. C.; Chaplin, W. J.; Jimenez, A.; Karoff, C. Bibcode: 2014yCat..35720034G Altcode: 2014yCat..35729034G We used data collected by the NASA planet-hunter mission Kepler.

(2 data files). Title: Properties of 42 Solar-type Kepler Targets from the Asteroseismic Modeling Portal Authors: Metcalfe, T. S.; Creevey, O. L.; Doğan, G.; Mathur, S.; Xu, H.; Bedding, T. R.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Karoff, C.; Trampedach, R.; Benomar, O.; Brown, B. P.; Buzasi, D. L.; Campante, T. L.; Çelik, Z.; Cunha, M. S.; Davies, G. R.; Deheuvels, S.; Derekas, A.; Di Mauro, M. P.; García, R. A.; Guzik, J. A.; Howe, R.; MacGregor, K. B.; Mazumdar, A.; Montalbán, J.; Monteiro, M. J. P. F. G.; Salabert, D.; Serenelli, A.; Stello, D.; Ste&şacute; licki, M.; Suran, M. D.; Yıldız, M.; Aksoy, C.; Elsworth, Y.; Gruberbauer, M.; Guenther, D. B.; Lebreton, Y.; Molaverdikhani, K.; Pricopi, D.; Simoniello, R.; White, T. R. Bibcode: 2014ApJS..214...27M Altcode: 2014arXiv1402.3614M Recently the number of main-sequence and subgiant stars exhibiting solar-like oscillations that are resolved into individual mode frequencies has increased dramatically. While only a few such data sets were available for detailed modeling just a decade ago, the Kepler mission has produced suitable observations for hundreds of new targets. This rapid expansion in observational capacity has been accompanied by a shift in analysis and modeling strategies to yield uniform sets of derived stellar properties more quickly and easily. We use previously published asteroseismic and spectroscopic data sets to provide a uniform analysis of 42 solar-type Kepler targets from the Asteroseismic Modeling Portal. We find that fitting the individual frequencies typically doubles the precision of the asteroseismic radius, mass, and age compared to grid-based modeling of the global oscillation properties, and improves the precision of the radius and mass by about a factor of three over empirical scaling relations. We demonstrate the utility of the derived properties with several applications. Title: Asteroseismic inference on the spin-orbit misalignment and stellar parameters of HAT-P-7 Authors: Lund, Mikkel N.; Lundkvist, Mia; Silva Aguirre, Victor; Houdek, Günter; Casagrande, Luca; Van Eylen, Vincent; Campante, Tiago L.; Karoff, Christoffer; Kjeldsen, Hans; Albrecht, Simon; Chaplin, William J.; Nielsen, Martin Bo; Degroote, Pieter; Davies, Guy R.; Handberg, Rasmus Bibcode: 2014A&A...570A..54L Altcode: 2014arXiv1407.7516L Context. The measurement of obliquities - the angle between the orbital and stellar rotation - in star-planet systems is of great importance for understanding planet system formation and evolution. The bright and well-studied HAT-P-7 (Kepler-2) system is intriguing because several Rossiter-McLaughlin (RM) measurements found a high projected obliquity in this system, but it was not possible so far to determine whether the orbit is polar and/or retrograde.
Aims: The goal of this study is to measure the stellar inclination and hereby the full 3D obliquity of the HAT-P-7 system instead of only the 2D projection as measured by the RM effect. In addition, we provide an updated set of stellar parameters for the star.
Methods: We used the full set of available observations from Kepler spanning Q0-Q17 to produce the power spectrum of HAT-P-7. We extracted oscillation-mode frequencies via an Markov chain Monte Carlo peak-bagging routine and used the results from this to estimate the stellar inclination angle. Combining this with the projected obliquity from RM and the inclination of the orbital plane allowed us to determine the stellar obliquity. Furthermore, we used asteroseismology to model the star from the extracted frequencies using two different approaches to the modelling, for which either the stellar evolution codes MESA or GARSTEC were adopted.
Results: Our updated asteroseismic modelling shows, i.a., the following stellar parameters for HAT-P-7: M⋆ = 1.51+ 0.04-0.05 M⊙, R⋆ = 2.00+ 0.01-0.02 R⊙, and age = 2.07+ 0.28-0.23 Gyr. The modelling offers a high precision on the stellar parameters, the uncertainty on age, for instance, is of the order ∼ 11%. For the stellar inclination we estimate i⋆< 36.5°, which translates into an obliquity of 83°<ψ< 111°. The planet HAT-P-7b is likely retrograde in its orbit, and the orbit is close to being polar. The new parameters for the star give an updated planetary density of ρp = 0.65 ± 0.03 g cm-3, which is lower than previous estimates.

Appendices are available in electronic form at http://www.aanda.org Title: Observational Constraints, Stellar Models, and Kepler Data for θ Cyg, the Brightest Star Observable by Kepler Authors: Guzik, J. A.; Houdek, G.; Chaplin, W. J.; Kurtz, D.; Gilliland, R. L.; Mullally, F.; Rowe, J. F.; Haas, M. R.; Bryson, S. T.; Still, M. D.; Boyajian, T. Bibcode: 2014ASPC..487..105G Altcode: The V = 4.48 F4 main-sequence star θ Cyg is the brightest star observable in the Kepler spacecraft field of view. Short-cadence (58.8 s) photometric data were obtained by Kepler during June-September 2010. Preliminary analysis shows solar-like oscillations in the frequency range 1200- 2500 μHz. To interpret these data and to motivate further observations, we use observational constraints from the literature to construct stellar evolution and pulsation models for this star. We compare the observed large frequency separation of the solar-like oscillations with the model predictions and discuss the prospects for γ Doradus-like g-mode pulsations, given the observational constraints. We discuss the value of angular diameter measurements from optical interferometry for constraining stellar properties and the implications for asteroseismology. Title: The APOGEE Red-clump Catalog: Precise Distances, Velocities, and High-resolution Elemental Abundances over a Large Area of the Milky Way's Disk Authors: Bovy, Jo; Nidever, David L.; Rix, Hans-Walter; Girardi, Léo; Zasowski, Gail; Chojnowski, S. Drew; Holtzman, Jon; Epstein, Courtney; Frinchaboy, Peter M.; Hayden, Michael R.; Rodrigues, Thaíse S.; Majewski, Steven R.; Johnson, Jennifer A.; Pinsonneault, Marc H.; Stello, Dennis; Allende Prieto, Carlos; Andrews, Brett; Basu, Sarbani; Beers, Timothy C.; Bizyaev, Dmitry; Burton, Adam; Chaplin, William J.; Cunha, Katia; Elsworth, Yvonne; García, Rafael A.; García-Herńandez, Domingo A.; García Pérez, Ana E.; Hearty, Fred R.; Hekker, Saskia; Kallinger, Thomas; Kinemuchi, Karen; Koesterke, Lars; Mészáros, Szabolcs; Mosser, Benoît; O'Connell, Robert W.; Oravetz, Daniel; Pan, Kaike; Robin, Annie C.; Schiavon, Ricardo P.; Schneider, Donald P.; Schultheis, Mathias; Serenelli, Aldo; Shetrone, Matthew; Silva Aguirre, Victor; Simmons, Audrey; Skrutskie, Michael; Smith, Verne V.; Stassun, Keivan; Weinberg, David H.; Wilson, John C.; Zamora, Olga Bibcode: 2014ApJ...790..127B Altcode: 2014arXiv1405.1032B The Sloan Digital Sky Survey III's Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a high-resolution near-infrared spectroscopic survey covering all of the major components of the Galaxy, including the dust-obscured regions of the inner Milky Way disk and bulge. Here we present a sample of 10,341 likely red-clump stars (RC) from the first two years of APOGEE operations, selected based on their position in color-metallicity-surface-gravity-effective-temperature space using a new method calibrated using stellar evolution models and high-quality asteroseismology data. The narrowness of the RC locus in color-metallicity-luminosity space allows us to assign distances to the stars with an accuracy of 5%-10%. The sample extends to typical distances of about 3 kpc from the Sun, with some stars out to 8 kpc, and spans a volume of approximately 100 kpc3 over 5 kpc <~ R <~ 14 kpc, |Z| <~ 2 kpc, and -15° <~ Galactocentric azimuth <~ 30°. The APOGEE red-clump (APOGEE-RC) catalog contains photometry from the Two Micron All Sky Survey, reddening estimates, distances, line-of-sight velocities, stellar parameters and elemental abundances determined from the high-resolution APOGEE spectra, and matches to major proper motion catalogs. We determine the survey selection function for this data set and discuss how the RC selection samples the underlying stellar populations. We use this sample to limit any azimuthal variations in the median metallicity within the ≈45° azimuthal region covered by the current sample to be <=0.02 dex, which is more than an order of magnitude smaller than the radial metallicity gradient. This result constrains coherent non-axisymmetric flows within a few kiloparsecs from the Sun. Title: Transiting Exoplanet Survey Satellite (TESS) Authors: Ricker, George R.; Winn, Joshua N.; Vanderspek, Roland; Latham, David W.; Bakos, Gáspár. Á.; Bean, Jacob L.; Berta-Thompson, Zachory K.; Brown, Timothy M.; Buchhave, Lars; Butler, Nathaniel R.; Butler, R. Paul; Chaplin, William J.; Charbonneau, David; Christensen-Dalsgaard, Jørgen; Clampin, Mark; Deming, Drake; Doty, John; De Lee, Nathan; Dressing, Courtney; Dunham, E. W.; Endl, Michael; Fressin, Francois; Ge, Jian; Henning, Thomas; Holman, Matthew J.; Howard, Andrew W.; Ida, Shigeru; Jenkins, Jon; Jernigan, Garrett; Johnson, John A.; Kaltenegger, Lisa; Kawai, Nobuyuki; Kjeldsen, Hans; Laughlin, Gregory; Levine, Alan M.; Lin, Douglas; Lissauer, Jack J.; MacQueen, Phillip; Marcy, Geoffrey; McCullough, P. R.; Morton, Timothy D.; Narita, Norio; Paegert, Martin; Palle, Enric; Pepe, Francesco; Pepper, Joshua; Quirrenbach, Andreas; Rinehart, S. A.; Sasselov, Dimitar; Sato, Bun'ei; Seager, Sara; Sozzetti, Alessandro; Stassun, Keivan G.; Sullivan, Peter; Szentgyorgyi, Andrew; Torres, Guillermo; Udry, Stephane; Villasenor, Joel Bibcode: 2014SPIE.9143E..20R Altcode: 2014arXiv1406.0151R The Transiting Exoplanet Survey Satellite (TESS ) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with IC (approximately less than) 13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10-100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every four months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations. Title: Asteroseismic Estimate of Helium Abundance of a Solar Analog Binary System Authors: Verma, Kuldeep; Faria, João P.; Antia, H. M.; Basu, Sarbani; Mazumdar, Anwesh; Monteiro, Mário J. P. F. G.; Appourchaux, Thierry; Chaplin, William J.; García, Rafael A.; Metcalfe, Travis S. Bibcode: 2014ApJ...790..138V Altcode: 2014arXiv1405.7512V 16 Cyg A and B are among the brightest stars observed by Kepler. What makes these stars more interesting is that they are solar analogs. 16 Cyg A and B exhibit solar-like oscillations. In this work we use oscillation frequencies obtained using 2.5 yr of Kepler data to determine the current helium abundance of these stars. For this we use the fact that the helium ionization zone leaves a signature on the oscillation frequencies and that this signature can be calibrated to determine the helium abundance of that layer. By calibrating the signature of the helium ionization zone against models of known helium abundance, the helium abundance in the envelope of 16 Cyg A is found to lie in the range of 0.231 to 0.251 and that of 16 Cyg B lies in the range of 0.218 to 0.266. Title: BiSON data preparation: a correction for differential extinction and the weighted averaging of contemporaneous data Authors: Davies, G. R.; Chaplin, W. J.; Elsworth, Y.; Hale, S. J. Bibcode: 2014MNRAS.441.3009D Altcode: 2014arXiv1405.0160D The Birmingham Solar Oscillations Network (BiSON) has provided high-quality high-cadence observations from as far back in time as 1978. These data must be calibrated from the raw observations into radial velocity and the quality of the calibration has a large impact on the signal-to-noise ratio of the final time series. The aim of this work is to maximize the potential science that can be performed with the BiSON data set by optimizing the calibration procedure. To achieve better levels of signal-to-noise ratio, we perform two key steps in the calibration process: we attempt a correction for terrestrial atmospheric differential extinction; and the resulting improvement in the calibration allows us to perform weighted averaging of contemporaneous data from different BiSON stations. The improvements listed produce significant improvement in the signal-to-noise ratio of the BiSON frequency-power spectrum across all frequency ranges. The reduction of noise in the power spectrum will allow future work to provide greater constraint on changes in the oscillation spectrum with solar activity. In addition, the analysis of the low-frequency region suggests that we have achieved a noise level that may allow us to improve estimates of the upper limit of g-mode amplitudes. Title: Kepler-93b: A Terrestrial World Measured to within 120 km, and a Test Case for a New Spitzer Observing Mode Authors: Ballard, Sarah; Chaplin, William J.; Charbonneau, David; Désert, Jean-Michel; Fressin, Francois; Zeng, Li; Werner, Michael W.; Davies, Guy R.; Silva Aguirre, Victor; Basu, Sarbani; Christensen-Dalsgaard, Jørgen; Metcalfe, Travis S.; Stello, Dennis; Bedding, Timothy R.; Campante, Tiago L.; Handberg, Rasmus; Karoff, Christoffer; Elsworth, Yvonne; Gilliland, Ronald L.; Hekker, Saskia; Huber, Daniel; Kawaler, Steven D.; Kjeldsen, Hans; Lund, Mikkel N.; Lundkvist, Mia Bibcode: 2014ApJ...790...12B Altcode: 2014arXiv1405.3659B We present the characterization of the Kepler-93 exoplanetary system, based on three years of photometry gathered by the Kepler spacecraft. The duration and cadence of the Kepler observations, in tandem with the brightness of the star, enable unusually precise constraints on both the planet and its host. We conduct an asteroseismic analysis of the Kepler photometry and conclude that the star has an average density of 1.652 ± 0.006 g cm-3. Its mass of 0.911 ± 0.033 M ⊙ renders it one of the lowest-mass subjects of asteroseismic study. An analysis of the transit signature produced by the planet Kepler-93b, which appears with a period of 4.72673978 ± 9.7 × 10-7 days, returns a consistent but less precise measurement of the stellar density, 1.72+0.02-0.28 g cm-3. The agreement of these two values lends credence to the planetary interpretation of the transit signal. The achromatic transit depth, as compared between Kepler and the Spitzer Space Telescope, supports the same conclusion. We observed seven transits of Kepler-93b with Spitzer, three of which we conducted in a new observing mode. The pointing strategy we employed to gather this subset of observations halved our uncertainty on the transit radius ratio RP /R sstarf. We find, after folding together the stellar radius measurement of 0.919 ± 0.011 R ⊙ with the transit depth, a best-fit value for the planetary radius of 1.481 ± 0.019 R ⊕. The uncertainty of 120 km on our measurement of the planet's size currently renders it one of the most precisely measured planetary radii outside of the solar system. Together with the radius, the planetary mass of 3.8 ± 1.5 M ⊕ corresponds to a rocky density of 6.3 ± 2.6 g cm-3. After applying a prior on the plausible maximum densities of similarly sized worlds between 1 and 1.5 R ⊕, we find that Kepler-93b possesses an average density within this group. Title: Oscillation mode linewidths and heights of 23 main-sequence stars observed by Kepler Authors: Appourchaux, T.; Antia, H. M.; Benomar, O.; Campante, T. L.; Davies, G. R.; Handberg, R.; Howe, R.; Régulo, C.; Belkacem, K.; Houdek, G.; García, R. A.; Chaplin, W. J. Bibcode: 2014A&A...566A..20A Altcode: 2014arXiv1403.7046A Context. Solar-like oscillations have been observed by Kepler and CoRoT in many solar-type stars, thereby providing a way to probe the stars using asteroseismology.
Aims: We provide the mode linewidths and mode heights of the oscillations of various stars as a function of frequency and of effective temperature.
Methods: We used a time series of nearly two years of data for each star. The 23 stars observed belong to the simple or F-like category. The power spectra of the 23 main-sequence stars were analysed using both maximum likelihood estimators and Bayesian estimators, providing individual mode characteristics such as frequencies, linewidths, and mode heights. We study the source of systematic errors in the mode linewidths and mode heights, and we present a way to correct these errors with respect to a common reference fit.
Results: Using the correction, we can explain all sources of systematic errors, which could be reduced to less than ±15% for mode linewidths and heights, and less than ±5% for amplitude, when compared to the reference fit. The effect of a different estimated stellar background and a different estimated splitting will provide frequency-dependent systematic errors that might affect the comparison with theoretical mode linewidth and mode height, therefore affecting the understanding of the physical nature of these parameters. All other sources of relative systematic errors are less dependent upon frequency. We also provide the dependence of the so-called linewidth dip in the middle of the observed frequency range as a function of effective temperature. We show that the depth of the dip decreases with increasing effective temperature. The dependence of the dip on effective temperature may imply that the mixing length parameter α or the convective flux may increase with effective temperature.

Tables 4-27 and Appendices are available in electronic form at http://www.aanda.org Title: Prospects for asteroseismic inference on the envelope helium abundance in red giant stars Authors: Broomhall, A. -M.; Miglio, A.; Montalbán, J.; Eggenberger, P.; Chaplin, W. J.; Elsworth, Y.; Scuflaire, R.; Ventura, P.; Verner, G. A. Bibcode: 2014MNRAS.440.1828B Altcode: 2014MNRAS.tmp..576B; 2014arXiv1403.7045B Regions of rapid variation in the internal structure of a star are often referred to as acoustic glitches since they create a characteristic periodic signature in the frequencies of p modes. Here we examine the localized disturbance arising from the helium second ionization zone in red giant branch and clump stars. More specifically, we determine how accurately and precisely the parameters of the ionization zone can be obtained from the oscillation frequencies of stellar models. We use models produced by three different generation codes that not only cover a wide range of stages of evolution along the red giant phase but also incorporate different initial helium abundances. To study the acoustic glitch caused by the second ionization zone of helium we have determined the second differences in frequencies of modes with the same angular degree, l, and then we fit the periodic function described by Houdek & Gough to the second differences. We discuss the conditions under which such fits robustly and accurately determine the acoustic radius of the second ionization zone of helium. When the frequency of maximum amplitude of the p-mode oscillations was greater than 40 μHz a robust value for the radius of the ionization zone was recovered for the majority of models. The determined radii of the ionization zones as inferred from the mode frequencies were found to be coincident with the local maximum in the first adiabatic exponent described by the models, which is associated with the outer edge of the second ionization zone of helium. Finally, we consider whether this method can be used to distinguish stars with different helium abundances. Although a definite trend in the amplitude of the signal is observed any distinction would be difficult unless the stars come from populations with vastly different helium abundances or the uncertainties associated with the fitted parameters can be reduced. However, application of our methodology could be useful for distinguishing between different populations of red giant stars in globular clusters, where distinct populations with very different helium abundances have been observed. Title: Amplitude variability in satellite photometry of the non-radially pulsating O9.5 V star ζ Oph Authors: Howarth, Ian D.; Goss, K. J. F.; Stevens, I. R.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2014MNRAS.440.1674H Altcode: 2014MNRAS.tmp..577H; 2014arXiv1402.6551H We report a time series analysis of satellite photometry of the non-radially pulsating Oe star ζ Oph, principally using data from the Solar Mass Ejection Imager obtained during 2003-2008, but augmented with Microvariability and Oscillations of STars and Wide-field InfraRed Explorer results. Amplitudes of the strongest photometric signals, at 5.18, 2.96 and 2.67 d-1, each vary independently over the 51/2-year monitoring period (from ∼50 to ≲2 mmag at 5.18 d-1), on time-scales of hundreds of days. Signals at 7.19 and 5.18 d-1 have persisted (or recurred) for at least two decades. Supplementary spectroscopic observations show an Hα emission episode in 2006; this coincided with small increases in amplitudes of the three strongest photometric signals. Title: Testing the Asteroseismic Mass Scale Using Metal-poor Stars Characterized with APOGEE and Kepler Authors: Epstein, Courtney R.; Elsworth, Yvonne P.; Johnson, Jennifer A.; Shetrone, Matthew; Mosser, Benoît; Hekker, Saskia; Tayar, Jamie; Harding, Paul; Pinsonneault, Marc; Silva Aguirre, Víctor; Basu, Sarbani; Beers, Timothy C.; Bizyaev, Dmitry; Bedding, Timothy R.; Chaplin, William J.; Frinchaboy, Peter M.; García, Rafael A.; García Pérez, Ana E.; Hearty, Fred R.; Huber, Daniel; Ivans, Inese I.; Majewski, Steven R.; Mathur, Savita; Nidever, David; Serenelli, Aldo; Schiavon, Ricardo P.; Schneider, Donald P.; Schönrich, Ralph; Sobeck, Jennifer S.; Stassun, Keivan G.; Stello, Dennis; Zasowski, Gail Bibcode: 2014ApJ...785L..28E Altcode: 2014arXiv1403.1872E Fundamental stellar properties, such as mass, radius, and age, can be inferred using asteroseismology. Cool stars with convective envelopes have turbulent motions that can stochastically drive and damp pulsations. The properties of the oscillation frequency power spectrum can be tied to mass and radius through solar-scaled asteroseismic relations. Stellar properties derived using these scaling relations need verification over a range of metallicities. Because the age and mass of halo stars are well-constrained by astrophysical priors, they provide an independent, empirical check on asteroseismic mass estimates in the low-metallicity regime. We identify nine metal-poor red giants (including six stars that are kinematically associated with the halo) from a sample observed by both the Kepler space telescope and the Sloan Digital Sky Survey-III APOGEE spectroscopic survey. We compare masses inferred using asteroseismology to those expected for halo and thick-disk stars. Although our sample is small, standard scaling relations, combined with asteroseismic parameters from the APOKASC Catalog, produce masses that are systematically higher (<ΔM > =0.17 ± 0.05 M ⊙) than astrophysical expectations. The magnitude of the mass discrepancy is reduced by known theoretical corrections to the measured large frequency separation scaling relationship. Using alternative methods for measuring asteroseismic parameters induces systematic shifts at the 0.04 M ⊙ level. We also compare published asteroseismic analyses with scaling relationship masses to examine the impact of using the frequency of maximum power as a constraint. Upcoming APOKASC observations will provide a larger sample of ~100 metal-poor stars, important for detailed asteroseismic characterization of Galactic stellar populations. Title: The K2 Mission: Characterization and Early Results Authors: Howell, Steve B.; Sobeck, Charlie; Haas, Michael; Still, Martin; Barclay, Thomas; Mullally, Fergal; Troeltzsch, John; Aigrain, Suzanne; Bryson, Stephen T.; Caldwell, Doug; Chaplin, William J.; Cochran, William D.; Huber, Daniel; Marcy, Geoffrey W.; Miglio, Andrea; Najita, Joan R.; Smith, Marcie; Twicken, J. D.; Fortney, Jonathan J. Bibcode: 2014PASP..126..398H Altcode: 2014arXiv1402.5163H The K2 mission will make use of the Kepler spacecraft and its assets to expand upon Kepler's groundbreaking discoveries in the fields of exoplanets and astrophysics through new and exciting observations. K2 will use an innovative way of operating the spacecraft to observe target fields along the ecliptic for the next 2-3 years. Early science commissioning observations have shown an estimated photometric precision near 400 ppm in a single 30 minute observation, and a 6-hour photometric precision of 80 ppm (both at V=12). The K2 mission offers long-term, simultaneous optical observation of thousands of objects at a precision far better than is achievable from ground-based telescopes. Ecliptic fields will be observed for approximately 75-days enabling a unique exoplanet survey which fills the gaps in duration and sensitivity between the Kepler and TESS missions, and offers pre-launch exoplanet target identification for JWST transit spectroscopy. Astrophysics observations with K2 will include studies of young open clusters, bright stars, galaxies, supernovae, and asteroseismology. Title: Seismic analysis of HD 43587Aa, a solar-like oscillator in a multiple system Authors: Boumier, P.; Benomar, O.; Baudin, F.; Verner, G.; Appourchaux, T.; Lebreton, Y.; Gaulme, P.; Chaplin, W.; García, R. A.; Hekker, S.; Regulo, C.; Salabert, D.; Stahn, T.; Elsworth, Y.; Gizon, L.; Hall, M.; Mathur, S.; Michel, E.; Morel, T.; Mosser, B.; Poretti, E.; Rainer, M.; Roxburgh, I.; do Nascimento, J. -D., Jr.; Samadi, R.; Auvergne, M.; Chaintreuil, S.; Baglin, A.; Catala, C. Bibcode: 2014A&A...564A..34B Altcode: 2014arXiv1402.5053B Context. The object HD 43587Aa is a G0V star observed during the 145-day LRa03 run of the COnvection, ROtation and planetary Transits space mission (CoRoT), for which complementary High Accuracy Radial velocity Planet Searcher (HARPS) spectra with S/N > 300 were also obtained. Its visual magnitude is 5.71, and its effective temperature is close to 5950 K. It has a known companion in a highly eccentric orbit and is also coupled with two more distant companions.
Aims: We undertake a preliminary investigation of the internal structure of HD 43587Aa.
Methods: We carried out a seismic analysis of the star, using maximum likelihood estimators and Markov chain Monte Carlo methods.
Results: We established the first table of the eigenmode frequencies, widths, and heights for HD 43587Aa. The star appears to have a mass and a radius slightly larger than the Sun, and is slightly older (5.6 Gyr). Two scenarios are suggested for the geometry of the star: either its inclination angle is very low, or the rotation velocity of the star is very low.
Conclusions: A more detailed study of the rotation and of the magnetic and chromospheric activity for this star is needed, and will be the subject of a further study. New high resolution spectrometric observations should be performed for at least several months in duration. Title: Low-frequency, low-degree solar p-mode properties from 22 years of Birmingham Solar Oscillations Network data Authors: Davies, G. R.; Broomhall, A. M.; Chaplin, W. J.; Elsworth, Y.; Hale, S. J. Bibcode: 2014MNRAS.439.2025D Altcode: 2014MNRAS.tmp..243D The solar low-degree low-frequency modes of oscillation are of particular interest as their frequencies can be measured with very high precision and hence provide good constraints on seismic models. Here we detect and characterize these valuable measures of the solar interior from a 22 yr Birmingham Solar Oscillations Network data set. We report mode frequencies, line widths, heights, amplitudes, and rotational splitting, all with robust uncertainties. The new values of frequency, rotational splitting, amplitude, and line width we provide will help place new constraints on hydrostatic and rotational structure, plus diagnostics of near-surface convection. Further to this, by assuming simple power laws, we extrapolate mode properties to lower frequencies. We demonstrate that the low-l low-frequency p modes have a low signal-to-noise ratio and that this cannot be overcome simply by continued observation. It will be necessary to observe the Sun in novel ways to `beat' the intrinsic granulation noise. Title: VizieR Online Data Catalog: Revised stellar properties of Q1-16 Kepler targets (Huber+, 2014) Authors: Huber, D.; Silva Aguirre, V.; Matthews, J. M.; Pinsonneault, M. H.; Gaidos, E.; Garcia, R. A.; Hekker, S.; Mathur, S.; Mosser, B.; Torres, G.; Bastien, F. A.; Basu, S.; Bedding, T. R.; Chaplin, W. J.; Demory, B. -O.; Fleming, S. W.; Guo, Z.; Mann, A. W.; Rowe, J. F.; Serenelli, A. M.; Smith, M. A.; Stello, D. Bibcode: 2014yCat..22110002H Altcode: We present revised properties for 196468 stars observed by the NASA Kepler mission and used in the analysis of Quarter 1-16 (Q1-16; May 2009 to Dec 2012) data to detect and characterize transiting planets. The catalog is based on a compilation of literature values for atmospheric properties (temperature, surface gravity, and metallicity) derived from different observational techniques (photometry, spectroscopy, asteroseismology, and exoplanet transits), which were then homogeneously fitted to a grid of Dartmouth stellar isochrones. We use broadband photometry and asteroseismology to characterize 11532 Kepler targets which were previously unclassified in the Kepler Input Catalog (KIC). We report the detection of oscillations in 2762 of these targets, classifying them as giant stars and increasing the number of known oscillating giant stars observed by Kepler by ~20% to a total of ~15500 stars. Typical uncertainties in derived radii and masses are ~40% and ~20%, respectively, for stars with photometric constraints only, and 5%-15% and ~10% for stars based on spectroscopy and/or asteroseismology, although these uncertainties vary strongly with spectral type and luminosity class. A comparison with the Q1-Q12 catalog shows a systematic decrease in radii of M dwarfs, while radii for K dwarfs decrease or increase depending on the Q1-Q12 provenance (KIC or Yonsei-Yale isochrones). Radii of F-G dwarfs are on average unchanged, with the exception of newly identified giants. The Q1-Q16 star properties catalog is a first step toward an improved characterization of all Kepler targets to support planet-occurrence studies.

(3 data files). Title: Flicker as a Tool for Characterizing Planets Through Asterodensity Profiling Authors: Kipping, D. M.; Bastien, F. A.; Stassun, K. G.; Chaplin, W. J.; Huber, D.; Buchhave, L. A. Bibcode: 2014ApJ...785L..32K Altcode: 2014arXiv1403.5264K Variability in the time series brightness of a star on a timescale of 8 hr, known as "flicker," has been previously demonstrated to serve as a proxy for the surface gravity of a star by Bastien et al. Although surface gravity is crucial for stellar classification, it is the mean stellar density that is most useful when studying transiting exoplanets, due to its direct impact on the transit light curve shape. Indeed, an accurate and independent measure of the stellar density can be leveraged to infer subtle properties of a transiting system, such as the companion's orbital eccentricity via asterodensity profiling (AP). We here calibrate flicker to the mean stellar density of 439 Kepler targets with asteroseismology, allowing us to derive a new empirical relation given by log10(ρsstarf (kg m-3)) = 5.413 - 1.850log10(F 8 (ppm)). The calibration is valid for stars with 4500 < T eff < 6500 K, KP < 14, and flicker estimates corresponding to stars with 3.25 < log g sstarf < 4.43. Our relation has a model error in the stellar density of 31.7% and so has ~8 times lower precision than that from asteroseismology but is applicable to a sample ~40 times greater. Flicker therefore provides an empirical method to enable AP on hundreds of planetary candidates from present and future missions. Title: VizieR Online Data Catalog: Kepler planetary candidates. IV. 22 months (Burke+, 2014) Authors: Burke, C. J.; Bryson, S. T.; Mullally, F.; Rowe, J. F.; Christiansen, J. L.; Thompson, S. E.; Coughlin, J. L.; Haas, M. R.; Batalha, N. M.; Caldwell, D. A.; Jenkins, J. M.; Still, M.; Barclay, T.; Borucki, W. J.; Chaplin, W. J.; Ciardi, D. R.; Clarke, B. D.; Cochran, W. D.; Demory, B. -O.; Esquerdo, G. A.; Gautier, T. N., III; Gilliland, R. L.; Girouard, F. R.; Havel, M.; Henze, C. E.; Howell, S. B.; Huber, D.; Latham, D. W.; Li, J.; Morehead, R. C.; Morton, T. D.; Pepper, J.; Quintana, E.; Ragozzine, D.; Seader, S. E.; Shah, Y.; Shporer, A.; Tenenbaum, P.; Twicken, J. D.; Wolfgang, A. Bibcode: 2014yCat..22100019B Altcode: In 2011 November, the Q1-Q8 (22 months of data) Kepler pipeline run generated one or more TCEs (threshold crossing events) for ~13400 Kepler targets out of ~191000 targets searched.

(1 data file). Title: VizieR Online Data Catalog: Small Kepler planets radial velocities (Marcy+, 2014) Authors: Marcy, G. W.; Isaacson, H.; Howard, A. W.; Rowe, J. F.; Jenkins, J. M.; Bryson, S. T.; Latham, D. W.; Howell, S. B.; Gautier, T. N., III; Batalha, N. M.; Rogers, L.; Ciardi, D.; Fischer, D. A.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Huber, D.; Chaplin, W. J.; Basu, S.; Buchhave, L. A.; Quinn, S. N.; Borucki, W. J.; Koch, D. G.; Hunter, R.; Caldwell, D. A.; van Cleve, J.; Kolbl, R.; Weiss, L. M.; Petigura, E.; Seager, S.; Morton, T.; Johnson, J. A.; Ballard, S.; Burke, C.; Cochran, W. D.; Endl, M.; MacQueen, P.; Everett, M. E.; Lissauer, J. J.; Ford, E. B.; Torres, G.; Fressin, F.; Brown, T. M.; Steffen, J. H.; Charbonneau, D.; Basri, G. S.; Sasselov, D. D.; Winn, J.; Sanchis-Ojeda, R.; Christiansen, J.; Adams, E.; Henze, C.; Dupree, A.; Fabrycky, D. C.; Fortney, J. J.; Tarter, J.; Holman, M. J.; Tenenbaum, P.; Shporer, A.; Lucas, P. W.; Welsh, W. F.; Orosz, J. A.; Bedding, T. R.; Campante, T. L.; Davies, G. R.; Elsworth, Y.; Handberg, R.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Lund, M. N.; Lundkvist, M.; Metcalfe, T. S.; Miglio, A.; Silva Aguirre, V.; Stello, D.; White, T. R.; Boss, A.; Devore, E.; Gould, A.; Prsa, A.; Agol, E.; Barclay, T.; Coughlin, J.; Brugamyer, E.; Mullally, F.; Quintana, E. V.; Still, M.; Thompson, S. E.; Morrison, D.; Twicken, J. D.; Desert, J. -M.; Carter, J.; Crepp, J. R.; Hebrard, G.; Santerne, A.; Moutou, C.; Sobeck, C.; Hudgins, D.; Haas, M. R.; Robertson, P.; Lillo-Box, J.; Barrado, D. Bibcode: 2014yCat..22100020M Altcode: Here we report measured masses, radii, and densities (or upper limits on those values) for 42 transiting planet candidates contained within 22 bright Kepler Objects of Interest (KOIs) from Batalha et al. (2013, Cat. J/ApJS/204/24). We carried out multiple Doppler-shift measurements of the host stars using the Keck 1 telescope. From the spectroscopy and Doppler measurements, we compute self-consistent measurements of stellar and planet radii, employing either stellar structure models or asteroseismology measurements from the Kepler photometry. We also search for (and report) 7 additional non-transiting planets revealed by the precise radial velocities (RVs), for a total of 49 planets.

We carried out "reconnaissance" high-resolution spectroscopy on ~1000 KOIs with spectral resolution, R~50000, and S/N=20-100 per pixel. The dual goals were searching for false positives and refining the stellar parameters. We obtained one or two such reconnaissance spectra using one of four facilities: the McDonald Observatory 2.7m, the Tillinghast 1.5m on Mt. Hopkins, the Lick Observatory 3m, and the 2.6m Nordic Optical Telescope.

Speckle imaging of each of the selected 22 KOIs was obtained using the two-color DSSI speckle camera at the WIYN 3.5m telescope on Kitt Peak.

All 22 KOIs were observed with the Keck NIRC2-AO system.

(3 data files). Title: Seismic constraints on the radial dependence of the internal rotation profiles of six Kepler subgiants and young red giants Authors: Deheuvels, S.; Doğan, G.; Goupil, M. J.; Appourchaux, T.; Benomar, O.; Bruntt, H.; Campante, T. L.; Casagrande, L.; Ceillier, T.; Davies, G. R.; De Cat, P.; Fu, J. N.; García, R. A.; Lobel, A.; Mosser, B.; Reese, D. R.; Regulo, C.; Schou, J.; Stahn, T.; Thygesen, A. O.; Yang, X. H.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Eggenberger, P.; Gizon, L.; Mathis, S.; Molenda-Żakowicz, J.; Pinsonneault, M. Bibcode: 2014A&A...564A..27D Altcode: 2014arXiv1401.3096D Context. We still do not understand which physical mechanisms are responsible for the transport of angular momentum inside stars. The recent detection of mixed modes that contain the clear signature of rotation in the spectra of Kepler subgiants and red giants gives us the opportunity to make progress on this question.
Aims: Our aim is to probe the radial dependence of the rotation profiles for a sample of Kepler targets. For this purpose, subgiants and early red giants are particularly interesting targets because their rotational splittings are more sensitive to the rotation outside the deeper core than is the case for their more evolved counterparts.
Methods: We first extracted the rotational splittings and frequencies of the modes for six young Kepler red giants. We then performed a seismic modeling of these stars using the evolutionary codes Cesam2k and astec. By using the observed splittings and the rotational kernels of the optimal models, we inverted the internal rotation profiles of the six stars.
Results: We obtain estimates of the core rotation rates for these stars, and upper limits to the rotation in their convective envelope. We show that the rotation contrast between the core and the envelope increases during the subgiant branch. Our results also suggest that the core of subgiants spins up with time, while their envelope spins down. For two of the stars, we show that a discontinuous rotation profile with a deep discontinuity reproduces the observed splittings significantly better than a smooth rotation profile. Interestingly, the depths that are found to be most probable for the discontinuities roughly coincide with the location of the H-burning shell, which separates the layers that contract from those that expand.
Conclusions: We characterized the differential rotation pattern of six young giants with a range of metallicities, and with both radiative and convective cores on the main sequence. This will bring observational constraints to the scenarios of angular momentum transport in stars. Moreover, if the existence of sharp gradients in the rotation profiles of young red giants is confirmed, it is expected to help in distinguishing between the physical processes that could transport angular momentum in the subgiant and red giant branches.

Appendices and Tables 3-9 are available in electronic form at http://www.aanda.org Title: Revised Stellar Properties of Kepler Targets for the Quarter 1-16 Transit Detection Run Authors: Huber, Daniel; Silva Aguirre, Victor; Matthews, Jaymie M.; Pinsonneault, Marc H.; Gaidos, Eric; García, Rafael A.; Hekker, Saskia; Mathur, Savita; Mosser, Benoit; Torres, Guillermo; Bastien, Fabienne A.; Basu, Sarbani; Bedding, Timothy R.; Chaplin, William J.; Demory, Brice-Olivier; Fleming, Scott W.; Guo, Zhao; Mann, Andrew W.; Rowe, Jason F.; Serenelli, Aldo M.; Smith, Myron A.; Stello, Dennis Bibcode: 2014ApJS..211....2H Altcode: 2013arXiv1312.0662H We present revised properties for 196,468 stars observed by the NASA Kepler mission and used in the analysis of Quarter 1-16 (Q1-Q16) data to detect and characterize transiting planets. The catalog is based on a compilation of literature values for atmospheric properties (temperature, surface gravity, and metallicity) derived from different observational techniques (photometry, spectroscopy, asteroseismology, and exoplanet transits), which were then homogeneously fitted to a grid of Dartmouth stellar isochrones. We use broadband photometry and asteroseismology to characterize 11,532 Kepler targets which were previously unclassified in the Kepler Input Catalog (KIC). We report the detection of oscillations in 2762 of these targets, classifying them as giant stars and increasing the number of known oscillating giant stars observed by Kepler by ~20% to a total of ~15,500 stars. Typical uncertainties in derived radii and masses are ~40% and ~20%, respectively, for stars with photometric constraints only, and 5%-15% and ~10% for stars based on spectroscopy and/or asteroseismology, although these uncertainties vary strongly with spectral type and luminosity class. A comparison with the Q1-Q12 catalog shows a systematic decrease in radii of M dwarfs, while radii for K dwarfs decrease or increase depending on the Q1-Q12 provenance (KIC or Yonsei-Yale isochrones). Radii of F-G dwarfs are on average unchanged, with the exception of newly identified giants. The Q1-Q16 star properties catalog is a first step toward an improved characterization of all Kepler targets to support planet-occurrence studies. Title: Prospects for Detecting Asteroseismic Binaries in Kepler Data Authors: Miglio, A.; Chaplin, W. J.; Farmer, R.; Kolb, U.; Girardi, L.; Elsworth, Y.; Appourchaux, T.; Handberg, R. Bibcode: 2014ApJ...784L...3M Altcode: 2014arXiv1402.2480M Asteroseismology may in principle be used to detect unresolved stellar binary systems comprised of solar-type stars and/or red giants. This novel method relies on the detection of the presence of two solar-like oscillation spectra in the frequency spectrum of a single light curve. Here, we make predictions of the numbers of systems that may be detectable in data already collected by the NASA Kepler Mission. Our predictions, which are based upon TRILEGAL and BiSEPS simulations of the Kepler field of view, indicate that as many as 200 or more "asteroseismic binaries" may be detectable in this manner. Most of these binaries should be comprised of two He-core-burning red giants. Owing largely to the limited numbers of targets with the requisite short-cadence Kepler data, we expect only a small number of detected binaries containing solar-type stars. The predicted yield of detections is sensitive to the assumed initial mass ratio distribution (IMRD) of the binary components and therefore represents a sensitive calibration of the much debated IMRD near mass ratio unity. Title: Limits on Surface Gravities of Kepler Planet-candidate Host Stars from Non-detection of Solar-like Oscillations Authors: Campante, T. L.; Chaplin, W. J.; Lund, M. N.; Huber, D.; Hekker, S.; García, R. A.; Corsaro, E.; Handberg, R.; Miglio, A.; Arentoft, T.; Basu, S.; Bedding, T. R.; Christensen-Dalsgaard, J.; Davies, G. R.; Elsworth, Y. P.; Gilliland, R. L.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Lundkvist, M.; Metcalfe, T. S.; Silva Aguirre, V.; Stello, D. Bibcode: 2014ApJ...783..123C Altcode: 2014arXiv1401.6324C We present a novel method for estimating lower-limit surface gravities (log g) of Kepler targets whose data do not allow the detection of solar-like oscillations. The method is tested using an ensemble of solar-type stars observed in the context of the Kepler Asteroseismic Science Consortium. We then proceed to estimate lower-limit log g for a cohort of Kepler solar-type planet-candidate host stars with no detected oscillations. Limits on fundamental stellar properties, as provided by this work, are likely to be useful in the characterization of the corresponding candidate planetary systems. Furthermore, an important byproduct of the current work is the confirmation that amplitudes of solar-like oscillations are suppressed in stars with increased levels of surface magnetic activity. Title: Study of KIC 8561221 observed by Kepler: an early red giant showing depressed dipolar modes Authors: García, R. A.; Pérez Hernández, F.; Benomar, O.; Silva Aguirre, V.; Ballot, J.; Davies, G. R.; Doğan, G.; Stello, D.; Christensen-Dalsgaard, J.; Houdek, G.; Lignières, F.; Mathur, S.; Takata, M.; Ceillier, T.; Chaplin, W. J.; Mathis, S.; Mosser, B.; Ouazzani, R. M.; Pinsonneault, M. H.; Reese, D. R.; Régulo, C.; Salabert, D.; Thompson, M. J.; van Saders, J. L.; Neiner, C.; De Ridder, J. Bibcode: 2014A&A...563A..84G Altcode: 2013arXiv1311.6990G Context. The continuous high-precision photometric observations provided by the CoRoT and Kepler space missions have allowed us to understand the structure and dynamics of red giants better using asteroseismic techniques. A small fraction of these stars show dipole modes with unexpectedly low amplitudes. The reduction in amplitude is more pronounced for stars with a higher frequency of maximum power, νmax.
Aims: In this work we want to characterise KIC 8561221 in order to confirm that it is currently the least evolved star among this peculiar subset and to discuss several hypotheses that could help explain the reduction of the dipole mode amplitudes.
Methods: We used Kepler short- and long-cadence data combined with spectroscopic observations to infer the stellar structure and dynamics of KIC 8561221. We then discussed different scenarios that could contribute to reducing the dipole amplitudes, such as a fast-rotating interior or the effect of a magnetic field on the properties of the modes. We also performed a detailed study of the inertia and damping of the modes.
Results: We have been able to characterise 36 oscillations modes, in particular, a few dipole modes above νmax that exhibit nearly normal amplitudes. The frequencies of all the measured modes were used to determine the overall properties and the internal structure of the star. We have inferred a surface rotation period of ~91 days and uncovered a variation in the surface magnetic activity during the last 4 years. The analysis of the convective background did not reveal any difference compared to "normal" red giants. As expected, the internal regions of the star probed by the ℓ = 2 and 3 modes spin 4 to 8 times faster than the surface.
Conclusions: With our grid of standard models we are able to properly fit the observed frequencies. Our model calculation of mode inertia and damping give no explanation for the depressed dipole modes. A fast-rotating core is also ruled out as a possible explanation. Finally, we do not have any observational evidence of a strong deep magnetic field inside the star.

Table 3 and Appendix A are available in electronic form at http://www.aanda.org Title: Planetary Candidates Observed by Kepler IV: Planet Sample from Q1-Q8 (22 Months) Authors: Burke, Christopher J.; Bryson, Stephen T.; Mullally, F.; Rowe, Jason F.; Christiansen, Jessie L.; Thompson, Susan E.; Coughlin, Jeffrey L.; Haas, Michael R.; Batalha, Natalie M.; Caldwell, Douglas A.; Jenkins, Jon M.; Still, Martin; Barclay, Thomas; Borucki, William J.; Chaplin, William J.; Ciardi, David R.; Clarke, Bruce D.; Cochran, William D.; Demory, Brice-Olivier; Esquerdo, Gilbert A.; Gautier, Thomas N., III; Gilliland, Ronald L.; Girouard, Forrest R.; Havel, Mathieu; Henze, Christopher E.; Howell, Steve B.; Huber, Daniel; Latham, David W.; Li, Jie; Morehead, Robert C.; Morton, Timothy D.; Pepper, Joshua; Quintana, Elisa; Ragozzine, Darin; Seader, Shawn E.; Shah, Yash; Shporer, Avi; Tenenbaum, Peter; Twicken, Joseph D.; Wolfgang, Angie Bibcode: 2014ApJS..210...19B Altcode: 2013arXiv1312.5358B We provide updates to the Kepler planet candidate sample based upon nearly two years of high-precision photometry (i.e., Q1-Q8). From an initial list of nearly 13,400 threshold crossing events, 480 new host stars are identified from their flux time series as consistent with hosting transiting planets. Potential transit signals are subjected to further analysis using the pixel-level data, which allows background eclipsing binaries to be identified through small image position shifts during transit. We also re-evaluate Kepler Objects of Interest (KOIs) 1-1609, which were identified early in the mission, using substantially more data to test for background false positives and to find additional multiple systems. Combining the new and previous KOI samples, we provide updated parameters for 2738 Kepler planet candidates distributed across 2017 host stars. From the combined Kepler planet candidates, 472 are new from the Q1-Q8 data examined in this study. The new Kepler planet candidates represent ~40% of the sample with R P ~ 1 R ⊕ and represent ~40% of the low equilibrium temperature (T eq < 300 K) sample. We review the known biases in the current sample of Kepler planet candidates relevant to evaluating planet population statistics with the current Kepler planet candidate sample. Title: Sounding the solar cycle with helioseismology: Implications for asteroseismology Authors: Chaplin, William J. Bibcode: 2014aste.book....1C Altcode: 2011arXiv1109.4842C My brief for the IAC Winter School was to cover observational results on helioseismology, flagging where possible implications of those results for the asteroseismic study of solar-type stars. My desire to make such links meant that I concentrated largely upon results for low angular-degree (low-l) solar p modes, in particular results derived from "Sun-as-a-star" observations (which are of course most instructive for the transfer of experience from helioseismology to asteroseismology). The lectures covered many aspects of helioseismology - modern helioseismology is a diverse field. In these notes, rather than discuss each aspect to a moderate level of detail, I have instead made the decision to concentrate upon one theme, that of "sounding" the solar activity cycle with helioseismology. I cover the topics from the lectures and I also include some new material, relating both to the lecture topics and other aspects I did not have time to cover. Implications for asteroseismology are developed and discussed throughout. Title: Precision Asteroseismology Authors: Guzik, Joyce A.; Chaplin, William J.; Handler, Gerald; Pigulski, Andrzej Bibcode: 2014IAUS..301.....G Altcode: No abstract at ADS Title: Measurement of Acoustic Glitches in Solar-type Stars from Oscillation Frequencies Observed by Kepler Authors: Mazumdar, A.; Monteiro, M. J. P. F. G.; Ballot, J.; Antia, H. M.; Basu, S.; Houdek, G.; Mathur, S.; Cunha, M. S.; Silva Aguirre, V.; García, R. A.; Salabert, D.; Verner, G. A.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Sanderfer, D. T.; Seader, S. E.; Smith, J. C.; Chaplin, W. J. Bibcode: 2014ApJ...782...18M Altcode: 2013arXiv1312.4907M For the very best and brightest asteroseismic solar-type targets observed by Kepler, the frequency precision is sufficient to determine the acoustic depths of the surface convective layer and the helium ionization zone. Such sharp features inside the acoustic cavity of the star, which we call acoustic glitches, create small oscillatory deviations from the uniform spacing of frequencies in a sequence of oscillation modes with the same spherical harmonic degree. We use these oscillatory signals to determine the acoustic locations of such features in 19 solar-type stars observed by the Kepler mission. Four independent groups of researchers utilized the oscillation frequencies themselves, the second differences of the frequencies and the ratio of the small and large separation to locate the base of the convection zone and the second helium ionization zone. Despite the significantly different methods of analysis, good agreement was found between the results of these four groups, barring a few cases. These results also agree reasonably well with the locations of these layers in representative models of the stars. These results firmly establish the presence of the oscillatory signals in the asteroseismic data and the viability of several techniques to determine the location of acoustic glitches inside stars. Title: What Asteroseismology can do for Exoplanets: Kepler-410A b is a Small Neptune around a Bright Star, in an Eccentric Orbit Consistent with Low Obliquity Authors: Van Eylen, V.; Lund, M. N.; Silva Aguirre, V.; Arentoft, T.; Kjeldsen, H.; Albrecht, S.; Chaplin, W. J.; Isaacson, H.; Pedersen, M. G.; Jessen-Hansen, J.; Tingley, B.; Christensen-Dalsgaard, J.; Aerts, C.; Campante, T. L.; Bryson, S. T. Bibcode: 2014ApJ...782...14V Altcode: 2013arXiv1312.4938V We confirm the Kepler planet candidate Kepler-410A b (KOI-42b) as a Neptune-sized exoplanet on a 17.8 day, eccentric orbit around the bright (K p = 9.4) star Kepler-410A (KOI-42A). This is the third brightest confirmed planet host star in the Kepler field and one of the brightest hosts of all currently known transiting exoplanets. Kepler-410 consists of a blend between the fast rotating planet host star (Kepler-410A) and a fainter star (Kepler-410B), which has complicated the confirmation of the planetary candidate. Employing asteroseismology, using constraints from the transit light curve, adaptive optics and speckle images, and Spitzer transit observations, we demonstrate that the candidate can only be an exoplanet orbiting Kepler-410A. We determine via asteroseismology the following stellar and planetary parameters with high precision; M sstarf = 1.214 ± 0.033 M ⊙, R sstarf = 1.352 ± 0.010 R ⊙, age =2.76 ± 0.54 Gyr, planetary radius (2.838 ± 0.054 R ⊕), and orbital eccentricity (0.17^{+0.07}_{-0.06}). In addition, rotational splitting of the pulsation modes allows for a measurement of Kepler-410A's inclination and rotation rate. Our measurement of an inclination of 82.5^{+7.5}_{-2.5} [°] indicates a low obliquity in this system. Transit timing variations indicate the presence of at least one additional (non-transiting) planet (Kepler-410A c) in the system. Title: Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets Authors: Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.; Rowe, Jason F.; Jenkins, Jon M.; Bryson, Stephen T.; Latham, David W.; Howell, Steve B.; Gautier, Thomas N., III; Batalha, Natalie M.; Rogers, Leslie; Ciardi, David; Fischer, Debra A.; Gilliland, Ronald L.; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Huber, Daniel; Chaplin, William J.; Basu, Sarbani; Buchhave, Lars A.; Quinn, Samuel N.; Borucki, William J.; Koch, David G.; Hunter, Roger; Caldwell, Douglas A.; Van Cleve, Jeffrey; Kolbl, Rea; Weiss, Lauren M.; Petigura, Erik; Seager, Sara; Morton, Timothy; Johnson, John Asher; Ballard, Sarah; Burke, Chris; Cochran, William D.; Endl, Michael; MacQueen, Phillip; Everett, Mark E.; Lissauer, Jack J.; Ford, Eric B.; Torres, Guillermo; Fressin, Francois; Brown, Timothy M.; Steffen, Jason H.; Charbonneau, David; Basri, Gibor S.; Sasselov, Dimitar D.; Winn, Joshua; Sanchis-Ojeda, Roberto; Christiansen, Jessie; Adams, Elisabeth; Henze, Christopher; Dupree, Andrea; Fabrycky, Daniel C.; Fortney, Jonathan J.; Tarter, Jill; Holman, Matthew J.; Tenenbaum, Peter; Shporer, Avi; Lucas, Philip W.; Welsh, William F.; Orosz, Jerome A.; Bedding, T. R.; Campante, T. L.; Davies, G. R.; Elsworth, Y.; Handberg, R.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Lund, M. N.; Lundkvist, M.; Metcalfe, T. S.; Miglio, A.; Silva Aguirre, V.; Stello, D.; White, T. R.; Boss, Alan; Devore, Edna; Gould, Alan; Prsa, Andrej; Agol, Eric; Barclay, Thomas; Coughlin, Jeff; Brugamyer, Erik; Mullally, Fergal; Quintana, Elisa V.; Still, Martin; Thompson, Susan E.; Morrison, David; Twicken, Joseph D.; Désert, Jean-Michel; Carter, Josh; Crepp, Justin R.; Hébrard, Guillaume; Santerne, Alexandre; Moutou, Claire; Sobeck, Charlie; Hudgins, Douglas; Haas, Michael R.; Robertson, Paul; Lillo-Box, Jorge; Barrado, David Bibcode: 2014ApJS..210...20M Altcode: 2014arXiv1401.4195M We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm-3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than ~2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O).

Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Title: Exploring Stellar Populations and Asteroseismology with APOGEE and Kepler Authors: Epstein, Courtney R.; Elsworth, Y. P.; Shetrone, M. D.; Mosser, B.; Tayar, J.; Harding, P.; Pinsonneault, M. H.; Silva Aguirre, V.; Basu, S.; Bizyaev, D.; Bedding, T.; Chaplin, W. J.; Garcia, R.; Garcia Perez, A.; Hearty, F.; Hekker, S.; Huber, D.; Ivans, I. I.; Majewski, S.; Mathur, S.; Serenelli, A.; Schiavon, R. P.; Schoenrich, R.; Sobeck, J.; Zasowski, G. Bibcode: 2014AAS...22340304E Altcode: Accurate measurements of fundamental stellar properties are vital for improving our understanding of stellar populations and galactic evolution. Asteroseismology makes possible precise measurements of stellar mass, radius, and surface gravity. Combining these asteroseismic measurements with spectroscopic temperatures and abundances enables the derivation of precise ages for field stars. To achieve that goal, two complementary surveys, the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and the Kepler Asteroseismic Science Consortium (KASC), are working together to characterize the fundamental properties thousands of red giants in the Kepler field. As a first step toward deriving ages, asteroseismic masses need to be calibrated with independent mass constraints. I will describe how we use a sample of halo stars to test asteroseismic results in the metal-poor regime. The age of halo stars is well constrained by many lines of evidence, including isochrones fits to globular clusters, white dwarf cooling sequence, and the radioactive decay of uranium and thorium. These age constraints translate to a strict prior on halo star masses. I show that the seismic masses are sensitive to the method used to derive seismic parameters and to published, theoretically motivated corrections. The implications of this work for stellar populations are discussed. Title: VizieR Online Data Catalog: Asteroseismic study of solar-type stars (Chaplin+, 2014) Authors: Chaplin, W. J.; Basu, S.; Huber, D.; Serenelli, A.; Casagrande, L.; Silva Aguirre, V.; Ball, W. H.; Creevey, O. L.; Gizon, L.; Handberg, R.; Karoff, C.; Lutz, R.; Marques, J. P.; Miglio, A.; Stello, D.; Suran, M. D.; Pricopi, D.; Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Molenda-Zakowicz, J.; Appourchaux, T.; Christensen-Dalsgaard, J.; Elsworth, Y.; Garcia, R. A.; Houdek, G.; Kjeldsen, H.; Bonanno, A.; Campante, T. L.; Corsaro, E.; Gaulme, P.; Hekker, S.; Mathur, S.; Mosser, B.; Regulo, C.; Salabert, D. Bibcode: 2014yCat..22100001C Altcode: During the first 10 months of science operations more than 2000 solar-type stars were selected by the Kepler Asteroseismic Science Consortium (KASC) to be observed as part of an asteroseismic survey of the Sun-like population in the Kepler field of view. Solar-like oscillations were detected by Kepler in more than 500 stars (Chaplin et al. 2011Sci...332..213C), and from these data robust global or average asteroseismic parameters were determined for all targets in the sample. These asteroseismic parameters allow us to estimate fundamental properties of the stars. In this paper we present stellar properties - namely masses, radii, surface gravities, mean densities and ages - of this asteroseismic sample of main-sequence and subgiant stars.

(5 data files). Title: Asteroseismic Fundamental Properties of Solar-type Stars Observed by the NASA Kepler Mission Authors: Chaplin, W. J.; Basu, S.; Huber, D.; Serenelli, A.; Casagrande, L.; Silva Aguirre, V.; Ball, W. H.; Creevey, O. L.; Gizon, L.; Handberg, R.; Karoff, C.; Lutz, R.; Marques, J. P.; Miglio, A.; Stello, D.; Suran, M. D.; Pricopi, D.; Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Molenda-Żakowicz, J.; Appourchaux, T.; Christensen-Dalsgaard, J.; Elsworth, Y.; García, R. A.; Houdek, G.; Kjeldsen, H.; Bonanno, A.; Campante, T. L.; Corsaro, E.; Gaulme, P.; Hekker, S.; Mathur, S.; Mosser, B.; Régulo, C.; Salabert, D. Bibcode: 2014ApJS..210....1C Altcode: 2013arXiv1310.4001C We use asteroseismic data obtained by the NASA Kepler mission to estimate the fundamental properties of more than 500 main-sequence and sub-giant stars. Data obtained during the first 10 months of Kepler science operations were used for this work, when these solar-type targets were observed for one month each in survey mode. Stellar properties have been estimated using two global asteroseismic parameters and complementary photometric and spectroscopic data. Homogeneous sets of effective temperatures, T eff, were available for the entire ensemble from complementary photometry; spectroscopic estimates of T eff and [Fe/H] were available from a homogeneous analysis of ground-based data on a subset of 87 stars. We adopt a grid-based analysis, coupling six pipeline codes to 11 stellar evolutionary grids. Through use of these different grid-pipeline combinations we allow implicitly for the impact on the results of stellar model dependencies from commonly used grids, and differences in adopted pipeline methodologies. By using just two global parameters as the seismic inputs we are able to perform a homogenous analysis of all solar-type stars in the asteroseismic cohort, including many targets for which it would not be possible to provide robust estimates of individual oscillation frequencies (due to a combination of low signal-to-noise ratio and short dataset lengths). The median final quoted uncertainties from consolidation of the grid-based analyses are for the full ensemble (spectroscopic subset) approximately 10.8% (5.4%) in mass, 4.4% (2.2%) in radius, 0.017 dex (0.010 dex) in log g, and 4.3% (2.8%) in mean density. Around 36% (57%) of the stars have final age uncertainties smaller than 1 Gyr. These ages will be useful for ensemble studies, but should be treated carefully on a star-by-star basis. Future analyses using individual oscillation frequencies will offer significant improvements on up to 150 stars, in particular for estimates of the ages, where having the individual frequency data is most important. Title: Asteroseismic Analysis of the CoRoT Target HD 169392 Authors: Mathur, S.; Bruntt, H.; Catala, C.; Benomar, O.; Davies, G. R.; García, R. A.; Salabert, D.; Ballot, J.; Mosser, B.; Régulo, C.; Chaplin, W. J.; Elsworth, Y.; Handberg, R.; Hekker, S.; Mantegazza, L.; Michel, E.; Poretti, E.; Rainer, M.; Roxburgh, I. W.; Samadi, R.; Steslicki, M.; Uytterhoeven, K.; Verner, G. A.; Auvergne, M.; Baglin, A.; Barceló Forteza, S.; Baudin, F.; Roca Cortés, T. Bibcode: 2013ASPC..479..155M Altcode: 2013arXiv1308.0647M The satellite CoRoT (Convection, Rotation, and planetary Transits) has provided high-quality data for almost six years. We show here the asteroseismic analysis and modeling of HD 169392A, which belongs to a weakly-bound binary system as the distance between the two components is ∼4250 au. The main component, HD 169392A, is a G0 IV star with a magnitude of 7.50 while the second component is a G0 V - G2 IV star with a magnitude of 8.98. This analysis focuses on the main component, as the secondary is too faint for the measurement of seismic parameters. A complete modeling has been possible thanks to complementary spectroscopic observations from HARPS (High Accuracy Radial Velocity Planet Searcher), providing Teff = 5985 ± 60 K, log g = 3.96 ± 0.07, and [Fe/H] = -0.04 ± 0.10. Title: Challenges and Opportunities for Ground-based Helioseismic Observations Authors: Chaplin, W. J. Bibcode: 2013ASPC..478..101C Altcode: I summarize the current status of ground-based helioseismic observations, in particular the two operational networks GONG and BiSON. I then discuss requirements for continued and future ground-based observations based on key science drivers, finishing with a discussion of SPRING, a proposed future high-spatial-resolution network that would provide helioseismic data and a broad range of synoptic data products. Title: Comparing the Internal Structure of the Sun During the Cycle 23 and Cycle 24 Minima Authors: Basu, S.; Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; Davies, G. R.; Schou, J.; Larson, T. P. Bibcode: 2013ASPC..478..161B Altcode: The Birmingham Solar-Oscillations Network (BiSON) has been collecting helioseismic data for the last three solar cycles. We use these data to determine whether the internal properties of the Sun during the minimum preceding cycle 24 was different compared to that preceding cycle 23. Title: Mode Line Widths in Red-Giant Stars Authors: Baudin, F.; Elsworth, Y.; Hekker, S.; Kallinger, T.; Stello, D.; Mosser, B.; Appourchaux, T.; Belkacem, K.; Benomar, O.; Barban, C.; Chaplin, W. J. Bibcode: 2013ASPC..479..179B Altcode: Mode line widths and amplitudes provide valuable information on stellar oscillation excitation and damping, and thus on physical processes such as convection, radiative losses and convection/pulsation coupling. We present preliminary results for mode line widths obtained by fitting mode spectra from Kepler observations. The difficulties of such fitting are discussed as well as these preliminary estimates in the context of models. Title: Calibrations of Atmospheric Parameters Obtained from the First Year of SDSS-III APOGEE Observations Authors: Mészáros, Sz.; Holtzman, J.; García Pérez, A. E.; Allende Prieto, C.; Schiavon, R. P.; Basu, S.; Bizyaev, D.; Chaplin, W. J.; Chojnowski, S. D.; Cunha, K.; Elsworth, Y.; Epstein, C.; Frinchaboy, P. M.; García, R. A.; Hearty, F. R.; Hekker, S.; Johnson, J. A.; Kallinger, T.; Koesterke, L.; Majewski, S. R.; Martell, S. L.; Nidever, D.; Pinsonneault, M. H.; O'Connell, J.; Shetrone, M.; Smith, V. V.; Wilson, J. C.; Zasowski, G. Bibcode: 2013AJ....146..133M Altcode: 2013arXiv1308.6617M The Sloan Digital Sky Survey III (SDSS-III) Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a three-year survey that is collecting 105 high-resolution spectra in the near-IR across multiple Galactic populations. To derive stellar parameters and chemical compositions from this massive data set, the APOGEE Stellar Parameters and Chemical Abundances Pipeline (ASPCAP) has been developed. Here, we describe empirical calibrations of stellar parameters presented in the first SDSS-III APOGEE data release (DR10). These calibrations were enabled by observations of 559 stars in 20 globular and open clusters. The cluster observations were supplemented by observations of stars in NASA's Kepler field that have well determined surface gravities from asteroseismic analysis. We discuss the accuracy and precision of the derived stellar parameters, considering especially effective temperature, surface gravity, and metallicity; we also briefly discuss the derived results for the abundances of the α-elements, carbon, and nitrogen. Overall, we find that ASPCAP achieves reasonably accurate results for temperature and metallicity, but suffers from systematic errors in surface gravity. We derive calibration relations that bring the raw ASPCAP results into better agreement with independently determined stellar parameters. The internal scatter of ASPCAP parameters within clusters suggests that metallicities are measured with a precision better than 0.1 dex, effective temperatures better than 150 K, and surface gravities better than 0.2 dex. The understanding provided by the clusters and Kepler giants on the current accuracy and precision will be invaluable for future improvements of the pipeline. Title: Stellar Spin-Orbit Misalignment in a Multiplanet System Authors: Huber, Daniel; Carter, Joshua A.; Barbieri, Mauro; Miglio, Andrea; Deck, Katherine M.; Fabrycky, Daniel C.; Montet, Benjamin T.; Buchhave, Lars A.; Chaplin, William J.; Hekker, Saskia; Montalbán, Josefina; Sanchis-Ojeda, Roberto; Basu, Sarbani; Bedding, Timothy R.; Campante, Tiago L.; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne P.; Stello, Dennis; Arentoft, Torben; Ford, Eric B.; Gilliland, Ronald L.; Handberg, Rasmus; Howard, Andrew W.; Isaacson, Howard; Johnson, John Asher; Karoff, Christoffer; Kawaler, Steven D.; Kjeldsen, Hans; Latham, David W.; Lund, Mikkel N.; Lundkvist, Mia; Marcy, Geoffrey W.; Metcalfe, Travis S.; Silva Aguirre, Victor; Winn, Joshua N. Bibcode: 2013Sci...342..331H Altcode: 2013arXiv1310.4503H Stars hosting hot Jupiters are often observed to have high obliquities, whereas stars with multiple coplanar planets have been seen to have low obliquities. This has been interpreted as evidence that hot-Jupiter formation is linked to dynamical disruption, as opposed to planet migration through a protoplanetary disk. We used asteroseismology to measure a large obliquity for Kepler-56, a red giant star hosting two transiting coplanar planets. These observations show that spin-orbit misalignments are not confined to hot-Jupiter systems. Misalignments in a broader class of systems had been predicted as a consequence of torques from wide-orbiting companions, and indeed radial velocity measurements revealed a third companion in a wide orbit in the Kepler-56 system. Title: Kepler-63b: A Giant Planet in a Polar Orbit around a Young Sun-like Star Authors: Sanchis-Ojeda, Roberto; Winn, Joshua N.; Marcy, Geoffrey W.; Howard, Andrew W.; Isaacson, Howard; Johnson, John Asher; Torres, Guillermo; Albrecht, Simon; Campante, Tiago L.; Chaplin, William J.; Davies, Guy R.; Lund, Mikkel N.; Carter, Joshua A.; Dawson, Rebekah I.; Buchhave, Lars A.; Everett, Mark E.; Fischer, Debra A.; Geary, John C.; Gilliland, Ronald L.; Horch, Elliott P.; Howell, Steve B.; Latham, David W. Bibcode: 2013ApJ...775...54S Altcode: 2013arXiv1307.8128S We present the discovery and characterization of a giant planet orbiting the young Sun-like star Kepler-63 (KOI-63, m Kp = 11.6, T eff = 5576 K, M sstarf = 0.98 M ⊙). The planet transits every 9.43 days, with apparent depth variations and brightening anomalies caused by large starspots. The planet's radius is 6.1 ± 0.2 R ⊕, based on the transit light curve and the estimated stellar parameters. The planet's mass could not be measured with the existing radial-velocity data, due to the high level of stellar activity, but if we assume a circular orbit, then we can place a rough upper bound of 120 M ⊕ (3σ). The host star has a high obliquity (ψ = 104°), based on the Rossiter-McLaughlin effect and an analysis of starspot-crossing events. This result is valuable because almost all previous obliquity measurements are for stars with more massive planets and shorter-period orbits. In addition, the polar orbit of the planet combined with an analysis of spot-crossing events reveals a large and persistent polar starspot. Such spots have previously been inferred using Doppler tomography, and predicted in simulations of magnetic activity of young Sun-like stars. Title: Tests of the asymptotic large frequency separation of acoustic oscillations in solar-type and red-giant stars Authors: Hekker, S.; Elsworth, Y.; Basu, S.; Mazumdar, A.; Silva Aguirre, V.; Chaplin, W. J. Bibcode: 2013MNRAS.434.1668H Altcode: 2013arXiv1306.4323H; 2013MNRAS.tmp.1776H Asteroseismology, i.e. the study of the internal structures of stars via their global oscillations, is a valuable tool to obtain stellar parameters such as mass, radius, surface gravity and mean density. These parameters can be obtained using certain scaling relations which are based on an asymptotic approximation. Usually the observed oscillation parameters are assumed to follow these scaling relations. Recently, it has been questioned whether this is a valid approach, i.e. whether the order of the observed oscillation modes is high enough to be approximated with an asymptotic theory. In this work, we use stellar models to investigate whether the differences between observable oscillation parameters and their asymptotic estimates are indeed significant. We compute the asymptotic values directly from the stellar models and derive the observable values from adiabatic pulsation calculations of the same models. We find that the extent to which the atmosphere is included in the models is a key parameter. Considering a larger extension of the atmosphere beyond the photosphere reduces the difference between the asymptotic and observable values of the large frequency separation. Therefore, we conclude that the currently suggested discrepancies in the scaling relations might have been overestimated. Hence, based on the results presented here we believe that the suggestions of Mosser et al. should not be followed without careful consideration. Title: Kepler White Paper: Asteroseismology of Solar-Like Oscillators in a 2-Wheel Mission Authors: Chaplin, W. J; Kjeldsen, H.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Basu, S.; De Ridder, J.; Huber, D.; Arentoft, T.; Schou, J.; Garcia, R. A.; Metcalfe, T. S.; Brogaard, K.; Campante, T. L.; Elsworth, Y.; Miglio, A.; Appourchaux, T.; Bedding, T. R.; Hekker, S.; Houdek, G.; Karoff, C.; Molenda-Zakowicz, J.; Monteiro, M. J. P. F. G.; Silva Aguirre, V.; Stello, D.; Ball, W.; Beck, P. G.; Birch, A. C.; Buzasi, D. L.; Casagrande, L.; Cellier, T.; Corsaro, E.; Creevey, O. L.; Davies, G. R.; Deheuvels, S.; Dogan, G.; Gizon, L.; Grundahl, F.; Guzik, J.; Handberg, R.; Jimenez, A.; Kallinger, T.; Lund, M. N.; Lundkvist, M.; Mathis, S.; Mathur, S.; Mazumdar, A.; Mosser, B.; Neiner, C.; Nielsen, M. B.; Palle, P. L.; Pinsonneault, M. H.; Salabert, D.; Serenelli, A. M.; Shunker, H.; White, T. R. Bibcode: 2013arXiv1309.0702C Altcode: We comment on the potential for continuing asteroseismology of solar-type and red-giant stars in a 2-wheel Kepler Mission. Our main conclusion is that by targeting stars in the ecliptic it should be possible to perform high-quality asteroseismology, as long as favorable scenarios for 2-wheel pointing performance are met. Targeting the ecliptic would potentially facilitate unique science that was not possible in the nominal Mission, notably from the study of clusters that are significantly brighter than those in the Kepler field. Our conclusions are based on predictions of 2-wheel observations made by a space photometry simulator, with information provided by the Kepler Project used as input to describe the degraded pointing scenarios. We find that elevated levels of frequency-dependent noise, consistent with the above scenarios, would have a significant negative impact on our ability to continue asteroseismic studies of solar-like oscillators in the Kepler field. However, the situation may be much more optimistic for observations in the ecliptic, provided that pointing resets of the spacecraft during regular desaturations of the two functioning reaction wheels are accurate at the < 1 arcsec level. This would make it possible to apply a post-hoc analysis that would recover most of the lost photometric precision. Without this post-hoc correction---and the accurate re-pointing it requires---the performance would probably be as poor as in the Kepler-field case. Critical to our conclusions for both fields is the assumed level of pointing noise (in the short-term jitter and the longer-term drift). We suggest that further tests will be needed to clarify our results once more detail and data on the expected pointing performance becomes available, and we offer our assistance in this work. Title: Erratum: "A Revised Effective Temperature Scale for the Kepler Input Catalog" (2012, ApJS, 199, 30) Authors: Pinsonneault, Marc H.; An, Deokkeun; Molenda-Żakowicz, Joanna; Chaplin, William J.; Metcalfe, Travis S.; Bruntt, Hans Bibcode: 2013ApJS..208...12P Altcode: No abstract at ADS Title: Asteroseismic surface gravity for evolved stars Authors: Hekker, S.; Elsworth, Y.; Mosser, B.; Kallinger, T.; Basu, S.; Chaplin, W. J.; Stello, D. Bibcode: 2013A&A...556A..59H Altcode: 2013arXiv1305.6586H Context. Asteroseismic surface gravity values can be important for determining spectroscopic stellar parameters. The independent log (g) value from asteroseismology can be used as a fixed value in the spectroscopic analysis to reduce uncertainties because log (g) and effective temperature cannot be determined independently from spectra. Since 2012, a combined analysis of seismically and spectroscopically derived stellar properties has been ongoing for a large survey with SDSS/APOGEE and Kepler. Therefore, knowledge of any potential biases and uncertainties in asteroseismic log (g) values is now becoming important.
Aims: The seismic parameter needed to derive log (g) is the frequency of maximum oscillation power (νmax). Here, we investigate the influence on the derived log (g) values of νmax derived with different methods. The large frequency separation between modes of the same degree and consecutive radial orders (Δν) is often used as an additional constraint for determining log (g). Additionally, we checked the influence of small corrections applied to Δν on the derived values of log (g).
Methods: We use methods extensively described in the literature to determine νmax and Δν together with seismic scaling relations and grid-based modelling to derive log (g).
Results: We find that different approaches to derive oscillation parameters give results for log (g) with small, but different, biases for red-clump and red-giant-branch stars. These biases are well within the quoted uncertainties of ~0.01 dex (cgs). Corrections suggested in the literature to the Δν scaling relation have no significant effect on log (g); however, somewhat unexpectedly, method specific solar reference values induce biases close to the uncertainties, which is not the case when canonical solar reference values are used. Title: Seismic constraints on rotation of Sun-like star and mass of exoplanet Authors: Gizon, L.; Ballot, J.; Michel, E.; Stahn, T.; Vauclair, G.; Bruntt, H.; Quirion, P. -O.; Benomar, O.; Vauclair, S.; Appourchaux, T.; Auvergne, M.; Baglin, A.; Barban, C.; Baudin, F.; Bazot, M.; Campante, T.; Catala, C.; Chaplin, W.; Creevey, O.; Deheuvels, S.; Dolez, N.; Elsworth, Y.; Garcia, R.; Gaulme, P.; Mathis, S.; Mathur, S.; Mosser, B.; Regulo, C.; Roxburgh, I.; Salabert, D.; Samadi, R.; Sato, K.; Verner, G.; Hanasoge, S.; Sreenivasan, K. R. Bibcode: 2013PNAS..11013267G Altcode: 2013arXiv1308.4352G Rotation is thought to drive cyclic magnetic activity in the Sun and Sun-like stars. Stellar dynamos, however, are poorly understood owing to the scarcity of observations of rotation and magnetic fields in stars. Here, inferences are drawn on the internal rotation of a distant Sun-like star by studying its global modes of oscillation. We report asteroseismic constraints imposed on the rotation rate and the inclination of the spin axis of the Sun-like star HD 52265, a principal target observed by the CoRoT satellite that is known to host a planetary companion. These seismic inferences are remarkably consistent with an independent spectroscopic observation (rotational line broadening) and with the observed rotation period of star spots. Furthermore, asteroseismology constrains the mass of exoplanet HD 52265b. Under the standard assumption that the stellar spin axis and the axis of the planetary orbit coincide, the minimum spectroscopic mass of the planet can be converted into a true mass of 1.85 (+0.52,-0.42) M_Jupiter, which implies that it is a planet, not a brown dwarf. Title: Asteroseismology of Solar-Type and Red-Giant Stars Authors: Chaplin, William J.; Miglio, Andrea Bibcode: 2013ARA&A..51..353C Altcode: 2013arXiv1303.1957C We are entering a golden era for stellar physics driven by satellite and telescope observations of unprecedented quality and scope. New insights on stellar evolution and stellar interiors physics are being made possible by asteroseismology, the study of stars by the observation of natural, resonant oscillations. Asteroseismology is proving to be particularly significant for the study of solar-type and red-giant stars. These stars show rich spectra of solar-like oscillations, which are excited and intrinsically damped by turbulence in the outermost layers of the convective envelopes. In this review we discuss the current state of the field, with a particular emphasis on recent advances provided by the Kepler and COROT (Convection, Rotation & Planetary Transits) space missions and the wider significance to astronomy of the results from asteroseismology, such as stellar populations studies and exoplanet studies. Title: Sounding stellar cycles with Kepler - II. Ground-based observations Authors: Karoff, C.; Metcalfe, T. S.; Chaplin, W. J.; Frandsen, S.; Grundahl, F.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Nielsen, M. B.; Frimann, S.; Thygesen, A. O.; Arentoft, T.; Amby, T. M.; Sousa, S. G.; Buzasi, D. L. Bibcode: 2013MNRAS.433.3227K Altcode: 2013arXiv1306.3306K; 2013MNRAS.tmp.1612K We have monitored 20 Sun-like stars in the Kepler field-of-view for excess flux with the Fibre-fed Echelle Spectrograph on the Nordic Optical Telescope since the launch of Kepler spacecraft in 2009. These 20 stars were selected based on their asteroseismic properties to sample the parameter space (effective temperature, surface gravity, activity level, etc.) around the Sun. Though the ultimate goal is to improve stellar dynamo models, we focus the present paper on the combination of space-based and ground-based observations that can be used to test the age-rotation-activity relations. In this paper we describe the considerations behind the selection of these 20 Sun-like stars and present an initial asteroseismic analysis, which includes stellar age estimates. We also describe the observations from the Nordic Optical Telescope and present mean values of measured excess fluxes. These measurements are combined with estimates of the rotation periods obtained from a simple analysis of the modulation in photometric observations from Kepler caused by starspots, and asteroseismic determinations of stellar ages, to test relations between age, rotation and activity. Title: "Rapid Fire" Spectroscopy of Kepler Solar-Like Oscillators Authors: Thygesen, A. O.; Bruntt, H.; Chaplin, W. J.; Basu, S. Bibcode: 2013aspm.confE..25T Altcode: No abstract at ADS Title: Low-degree multi-spectral p-mode fitting Authors: Howe, R.; Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; Jain, K. Bibcode: 2013JPhCS.440a2011H Altcode: We combine unresolved-Sun velocity and intensity observations at multiple wavelengths from the Helioseismic and Magnetic Imager and Atmospheric Imaging Array onboard the Solar Dynamics Observatory to investigate the possibility of multi-spectral mode-frequency estimation at low spherical harmonic degree. We test a simple multi-spectral algorithm using a common line width and frequency for each mode and a separate amplitude, background and asymmetry parameter, and compare the results with those from fits to the individual spectra. The preliminary results suggest that this approach may provide a more stable fit than using the observables separately. Title: Stellar Ages and Convective Cores in Field Main-sequence Stars: First Asteroseismic Application to Two Kepler Targets Authors: Silva Aguirre, V.; Basu, S.; Brandão, I. M.; Christensen-Dalsgaard, J.; Deheuvels, S.; Doğan, G.; Metcalfe, T. S.; Serenelli, A. M.; Ballot, J.; Chaplin, W. J.; Cunha, M. S.; Weiss, A.; Appourchaux, T.; Casagrande, L.; Cassisi, S.; Creevey, O. L.; García, R. A.; Lebreton, Y.; Noels, A.; Sousa, S. G.; Stello, D.; White, T. R.; Kawaler, S. D.; Kjeldsen, H. Bibcode: 2013ApJ...769..141S Altcode: 2013arXiv1304.2772S Using asteroseismic data and stellar evolution models we obtain the first detection of a convective core in a Kepler field main-sequence star, putting a stringent constraint on the total size of the mixed zone and showing that extra mixing beyond the formal convective boundary exists. In a slightly less massive target the presence of a convective core cannot be conclusively discarded, and thus its remaining main-sequence lifetime is uncertain. Our results reveal that best-fit models found solely by matching individual frequencies of oscillations corrected for surface effects do not always properly reproduce frequency combinations. Moreover, slightly different criteria to define what the best-fit model is can lead to solutions with similar global properties but very different interior structures. We argue that the use of frequency ratios is a more reliable way to obtain accurate stellar parameters, and show that our analysis in field main-sequence stars can yield an overall precision of 1.5%, 4%, and 10% in radius, mass, and age, respectively. We compare our results with those obtained from global oscillation properties, and discuss the possible sources of uncertainties in asteroseismic stellar modeling where further studies are still needed. Title: The Sun-as-a-star observations: GOLF & VIRGO on SoHO, and BiSON network Authors: García, R. A.; Davies, G. R.; Jiménez, A.; Ballot, J.; Mathur, S.; Salabert, D.; Chaplin, W. J.; Elsworth, Y.; Régulo, C.; Turck-Chièze, S. Bibcode: 2013JPhCS.440a2040G Altcode: 2013arXiv1301.6934G Sun-as-a-star observations are very important for the study of the conditions within the Sun and in particular for the deep interior where higher degree modes do not penetrate. They are also of significance in this era of dramatic advances in stellar asteroseismology as they are comparable to those measured in other stars by asteroseismic missions such as CoRoT, Kepler, and MOST. More than 17 years of continuous measurements of SoHO and more than 30 years of BiSON observations provide very long data sets of uninterrupted helioseismic observations. In this work, we discuss the present status of all these facilities that continue to provide state-of-the-art measurements and invaluable data to improve our knowledge of the deepest layers of the Sun and its structural changes during the activity cycle. Title: A large sample of calibration stars for Gaia: log g from Kepler and CoRoT fields Authors: Creevey, O. L.; Thévenin, F.; Basu, S.; Chaplin, W. J.; Bigot, L.; Elsworth, Y.; Huber, D.; Monteiro, M. J. P. F. G.; Serenelli, A. Bibcode: 2013MNRAS.431.2419C Altcode: 2013arXiv1302.7158C Asteroseismic data can be used to determine stellar surface gravities with precisions of <0.05 dex by using the global seismic quantities <Δν> and νmax along with standard atmospheric data such as Teff and metallicity. Surface gravity is also one of the four stellar properties to be derived by automatic analyses for one billion stars from Gaia data (workpackage GSP_PHOT). In this paper, we explore seismic data from main-sequence F, G, K stars (solar-like stars) observed by the Kepler spacecraft as a potential calibration source for the methods that Gaia will use for object characterization (log g). We calculate log g for some bright nearby stars for which radii and masses are known (e.g. from interferometry or binaries), and using their global seismic quantities in a grid-based method, we determine an asteroseismic log g to within 0.01 dex of the direct calculation, thus validating the accuracy of our method. We also find that errors in adopted atmospheric parameters (mainly [Fe/H]) can, however, cause systematic errors of the order of 0.02 dex. We then apply our method to a list of 40 stars to deliver precise values of surface gravity, i.e. uncertainties of the order of 0.02 dex, and we find agreement with recent literature values. Finally, we explore the typical precision that we expect in a sample of more than 400 Kepler stars which have their global seismic quantities measured. We find a mean uncertainty (precision) of the order of better than 0.02 dex in log g over the full explored range 3.8 < log g < 4.6, with the mean value varying only with stellar magnitude (0.01-0.02 dex). We study sources of systematic errors in log g and find possible biases of the order of 0.04 dex, independent of log g and magnitude, which accounts for errors in the Teff and [Fe/H] measurements, as well as from using a different grid-based method. We conclude that Kepler stars provide a wealth of reliable information that can help to calibrate methods that Gaia will use, in particular, for source characterization with GSP_PHOT, where excellent precision (small uncertainties) and accuracy in log g is obtained from seismic data. Title: Erratum: A sub-Mercury-sized exoplanet Authors: Barclay, Thomas; Rowe, Jason F.; Lissauer, Jack J.; Huber, Daniel; Fressin, François; Howell, Steve B.; Bryson, Stephen T.; Chaplin, William J.; Désert, Jean-Michel; Lopez, Eric D.; Marcy, Geoffrey W.; Mullally, Fergal; Ragozzine, Darin; Torres, Guillermo; Adams, Elisabeth R.; Agol, Eric; Barrado, David; Basu, Sarbani; Bedding, Timothy R.; Buchhave, Lars A.; Charbonneau, David; Christiansen, Jessie L.; Christensen-Dalsgaard, Jørgen; Ciardi, David; Cochran, William D.; Dupree, Andrea K.; Elsworth, Yvonne; Everett, Mark; Fischer, Debra A.; Ford, Eric B.; Fortney, Jonathan J.; Geary, John C.; Haas, Michael R.; Handberg, Rasmus; Hekker, Saskia; Henze, Christopher E.; Horch, Elliott; Howard, Andrew W.; Hunter, Roger C.; Isaacson, Howard; Jenkins, Jon M.; Karoff, Christoffer; Kawaler, Steven D.; Kjeldsen, Hans; Klaus, Todd C.; Latham, David W.; Li, Jie; Lillo-Box, Jorge; Lund, Mikkel N.; Lundkvist, Mia; Metcalfe, Travis S.; Miglio, Andrea; Morris, Robert L.; Quintana, Elisa V.; Stello, Dennis; Smith, Jeffrey C.; Still, Martin; Thompson, Susan E. Bibcode: 2013Natur.496..252B Altcode: No abstract at ADS Title: Fundamental Properties of Kepler Planet-candidate Host Stars using Asteroseismology Authors: Huber, Daniel; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Gilliland, Ronald L.; Kjeldsen, Hans; Buchhave, Lars A.; Fischer, Debra A.; Lissauer, Jack J.; Rowe, Jason F.; Sanchis-Ojeda, Roberto; Basu, Sarbani; Handberg, Rasmus; Hekker, Saskia; Howard, Andrew W.; Isaacson, Howard; Karoff, Christoffer; Latham, David W.; Lund, Mikkel N.; Lundkvist, Mia; Marcy, Geoffrey W.; Miglio, Andrea; Silva Aguirre, Victor; Stello, Dennis; Arentoft, Torben; Barclay, Thomas; Bedding, Timothy R.; Burke, Christopher J.; Christiansen, Jessie L.; Elsworth, Yvonne P.; Haas, Michael R.; Kawaler, Steven D.; Metcalfe, Travis S.; Mullally, Fergal; Thompson, Susan E. Bibcode: 2013ApJ...767..127H Altcode: 2013arXiv1302.2624H We have used asteroseismology to determine fundamental properties for 66 Kepler planet-candidate host stars, with typical uncertainties of 3% and 7% in radius and mass, respectively. The results include new asteroseismic solutions for four host stars with confirmed planets (Kepler-4, Kepler-14, Kepler-23 and Kepler-25) and increase the total number of Kepler host stars with asteroseismic solutions to 77. A comparison with stellar properties in the planet-candidate catalog by Batalha et al. shows that radii for subgiants and giants obtained from spectroscopic follow-up are systematically too low by up to a factor of 1.5, while the properties for unevolved stars are in good agreement. We furthermore apply asteroseismology to confirm that a large majority of cool main-sequence hosts are indeed dwarfs and not misclassified giants. Using the revised stellar properties, we recalculate the radii for 107 planet candidates in our sample, and comment on candidates for which the radii change from a previously giant-planet/brown-dwarf/stellar regime to a sub-Jupiter size or vice versa. A comparison of stellar densities from asteroseismology with densities derived from transit models in Batalha et al. assuming circular orbits shows significant disagreement for more than half of the sample due to systematics in the modeled impact parameters or due to planet candidates that may be in eccentric orbits. Finally, we investigate tentative correlations between host-star masses and planet-candidate radii, orbital periods, and multiplicity, but caution that these results may be influenced by the small sample size and detection biases. Title: The SOAPS project - Spin-orbit alignment of planetary systems. Exoplanets' evolution histories in systems with different architectures Authors: Faedi, F.; Gómez Maqueo Chew, Y.; Fossati, L.; Pollacco, D.; McQuillan, A.; Hebb, L.; Chaplin, W. J.; Aigrain, S. Bibcode: 2013EPJWC..4702001F Altcode: The wealth of information rendered by Kepler planets and planet candidates is indispensable for statistically significant studies of distinct planet populations, in both single and multiple systems. Empirical evidences suggest that Kepler's planet population shows different physical properties as compared to the bulk of known exoplanets. The SOAPS project, aims to shed light on Kepler's planets formation, their migration and architecture. By measuring v sini accurately for Kepler hosts with rotation periods measured from their high-precision light curves, we will assess the alignment of the planetary orbit with respect to the stellar spin axis. This degree of alignment traces the formation history and evolution of the planetary systems, and thus, allows to distinguish between different proposed migration theories. SOAPS will increase by a factor of 2 the number of spin-orbit alignment measurements pushing the parameters space down to the SuperEarth domain. Here we present our preliminary results. Title: Asteroseismic Determination of Obliquities of the Exoplanet Systems Kepler-50 and Kepler-65 Authors: Chaplin, W. J.; Sanchis-Ojeda, R.; Campante, T. L.; Handberg, R.; Stello, D.; Winn, J. N.; Basu, S.; Christensen-Dalsgaard, J.; Davies, G. R.; Metcalfe, T. S.; Buchhave, L. A.; Fischer, D. A.; Bedding, T. R.; Cochran, W. D.; Elsworth, Y.; Gilliland, R. L.; Hekker, S.; Huber, D.; Isaacson, H.; Karoff, C.; Kawaler, S. D.; Kjeldsen, H.; Latham, D. W.; Lund, M. N.; Lundkvist, M.; Marcy, G. W.; Miglio, A.; Barclay, T.; Lissauer, J. J. Bibcode: 2013ApJ...766..101C Altcode: 2013arXiv1302.3728C Results on the obliquity of exoplanet host stars—the angle between the stellar spin axis and the planetary orbital axis—provide important diagnostic information for theories describing planetary formation. Here we present the first application of asteroseismology to the problem of stellar obliquity determination in systems with transiting planets and Sun-like host stars. We consider two systems observed by the NASA Kepler mission which have multiple transiting small (super-Earth sized) planets: the previously reported Kepler-50 and a new system, Kepler-65, whose planets we validate in this paper. Both stars show rich spectra of solar-like oscillations. From the asteroseismic analysis we find that each host has its rotation axis nearly perpendicular to the line of sight with the sines of the angles constrained at the 1σ level to lie above 0.97 and 0.91, respectively. We use statistical arguments to show that coplanar orbits are favored in both systems, and that the orientations of the planetary orbits and the stellar rotation axis are correlated. Title: Kepler-68: Three Planets, One with a Density between that of Earth and Ice Giants Authors: Gilliland, Ronald L.; Marcy, Geoffrey W.; Rowe, Jason F.; Rogers, Leslie; Torres, Guillermo; Fressin, Francois; Lopez, Eric D.; Buchhave, Lars A.; Christensen-Dalsgaard, Jørgen; Désert, Jean-Michel; Henze, Christopher E.; Isaacson, Howard; Jenkins, Jon M.; Lissauer, Jack J.; Chaplin, William J.; Basu, Sarbani; Metcalfe, Travis S.; Elsworth, Yvonne; Handberg, Rasmus; Hekker, Saskia; Huber, Daniel; Karoff, Christoffer; Kjeldsen, Hans; Lund, Mikkel N.; Lundkvist, Mia; Miglio, Andrea; Charbonneau, David; Ford, Eric B.; Fortney, Jonathan J.; Haas, Michael R.; Howard, Andrew W.; Howell, Steve B.; Ragozzine, Darin; Thompson, Susan E. Bibcode: 2013ApJ...766...40G Altcode: 2013arXiv1302.2596G NASA's Kepler Mission has revealed two transiting planets orbiting Kepler-68. Follow-up Doppler measurements have established the mass of the innermost planet and revealed a third Jovian-mass planet orbiting beyond the two transiting planets. Kepler-68b, in a 5.4 day orbit, has M_P=8.3^{+2.2}_{-2.4} M ⊕, R_P=2.31^{+0.06}_{-0.09} R ⊕, and \rho _P=3.32^{+0.86}_{-0.98} g cm-3, giving Kepler-68b a density intermediate between that of the ice giants and Earth. Kepler-68c is Earth-sized, with a radius R_P=0.953^{+0.037}_{-0.042} R ⊕ and transits on a 9.6 day orbit; validation of Kepler-68c posed unique challenges. Kepler-68d has an orbital period of 580 ± 15 days and a minimum mass of M Psin i = 0.947 ± 0.035MJ . Power spectra of the Kepler photometry at one minute cadence exhibit a rich and strong set of asteroseismic pulsation modes enabling detailed analysis of the stellar interior. Spectroscopy of the star coupled with asteroseismic modeling of the multiple pulsation modes yield precise measurements of stellar properties, notably T eff = 5793 ± 74 K, M sstarf = 1.079 ± 0.051 M ⊙, R sstarf = 1.243 ± 0.019 R ⊙, and ρsstarf = 0.7903 ± 0.0054 g cm-3, all measured with fractional uncertainties of only a few percent. Models of Kepler-68b suggest that it is likely composed of rock and water, or has a H and He envelope to yield its density ~3 g cm-3. Title: Differential population studies using asteroseismology: Solar-like oscillating giants in CoRoT fields LRc01 and LRa01 Authors: Miglio, A.; Chiappini, C.; Morel, T.; Barbieri, M.; Chaplin, W. J.; Girardi, L.; Montalbán, J.; Noels, A.; Valentini, M.; Mosser, B.; Baudin, F.; Casagrande, L.; Fossati, L.; Silva Aguirre, V.; Baglin, A. Bibcode: 2013EPJWC..4303004M Altcode: 2013arXiv1301.1515M Solar-like oscillating giants observed by the space-borne satellites CoRoT and Kepler can be used as key tracers of stellar populations in the Milky Way. When combined with additional photometric/spectroscopic constraints, the pulsation spectra of solar-like oscillating giant stars not only reveal their radii, and hence distances, but also provide well-constrained estimates of their masses, which can be used as proxies for the ages of these evolved stars. In this contribution we provide supplementary material to the comparison we presented in Miglio et al. (2013) between populations of giants observed by CoRoT in the fields designated LRc01 and LRa01. Title: VizieR Online Data Catalog: Abundances of 93 solar-type Kepler targets (Bruntt+, 2012) Authors: Bruntt, H.; Basu, S.; Smalley, B.; Chaplin, W. J.; Verner, G. A.; Bedding, T. R.; Catala, C.; Gazzano, J. -C.; Molenda-Zakowicz, J.; Thygesen, A. O.; Uytterhoeven, K.; Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Mosser, B.; Appourchaux, T.; Campante, T. L.; Elsworth, Y.; Garcia, R. A.; Handberg, R.; Metcalfe, T. S.; Quirion, P. -O.; Regulo, C.; Roxburgh, I. W.; Stello, D.; Christensen-Dalsgaard, J.; Kawaler, S. D.; Kjeldsen, H.; Morris, R. L.; Quintana, E. V.; Sanderfer, D. T. Bibcode: 2013yCat..74230122B Altcode: The spectra were obtained with the ESPaDOnS spectrograph at the 3.6-m Canada-France-Hawaii Telescope (CFHT) in USA and with the NARVAL spectrograph mounted on the 2-m Bernard Lyot Telescope at the Pic du Midi Observatory in France. In both the facilities, the observations were carried out as service observations from May to September in 2010.

(3 data files). Title: A sub-Mercury-sized exoplanet Authors: Barclay, Thomas; Rowe, Jason F.; Lissauer, Jack J.; Huber, Daniel; Fressin, François; Howell, Steve B.; Bryson, Stephen T.; Chaplin, William J.; Désert, Jean-Michel; Lopez, Eric D.; Marcy, Geoffrey W.; Mullally, Fergal; Ragozzine, Darin; Torres, Guillermo; Adams, Elisabeth R.; Agol, Eric; Barrado, David; Basu, Sarbani; Bedding, Timothy R.; Buchhave, Lars A.; Charbonneau, David; Christiansen, Jessie L.; Christensen-Dalsgaard, Jørgen; Ciardi, David; Cochran, William D.; Dupree, Andrea K.; Elsworth, Yvonne; Everett, Mark; Fischer, Debra A.; Ford, Eric B.; Fortney, Jonathan J.; Geary, John C.; Haas, Michael R.; Handberg, Rasmus; Hekker, Saskia; Henze, Christopher E.; Horch, Elliott; Howard, Andrew W.; Hunter, Roger C.; Isaacson, Howard; Jenkins, Jon M.; Karoff, Christoffer; Kawaler, Steven D.; Kjeldsen, Hans; Klaus, Todd C.; Latham, David W.; Li, Jie; Lillo-Box, Jorge; Lund, Mikkel N.; Lundkvist, Mia; Metcalfe, Travis S.; Miglio, Andrea; Morris, Robert L.; Quintana, Elisa V.; Stello, Dennis; Smith, Jeffrey C.; Still, Martin; Thompson, Susan E. Bibcode: 2013Natur.494..452B Altcode: 2013arXiv1305.5587B Since the discovery of the first exoplanets, it has been known that other planetary systems can look quite unlike our own. Until fairly recently, we have been able to probe only the upper range of the planet size distribution, and, since last year, to detect planets that are the size of Earth or somewhat smaller. Hitherto, no planets have been found that are smaller than those we see in the Solar System. Here we report a planet significantly smaller than Mercury. This tiny planet is the innermost of three that orbit the Sun-like host star, which we have designated Kepler-37. Owing to its extremely small size, similar to that of the Moon, and highly irradiated surface, the planet, Kepler-37b, is probably rocky with no atmosphere or water, similar to Mercury. Title: Correlating Photometric Variability and Chromospheric Activity in Kepler Stars Authors: Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua; Chaplin, William; Huber, Daniel Bibcode: 2013noao.prop..218B Altcode: The panoply of photometric variability due to the magnetic activity of Sun-like stars, as revealed by missions like it Kepler, has significantly impacted our understanding of stars, calling for a thorough characterization of this behavior, an important noise source in planet detection. Our work, based on previous WIYN/Hydra observations of it Kepler stars, reveals that many stars that appear ``inactive'' by traditional measures may be highly variable in radial-velocity and/or exhibit complex photometric variations. Our preliminary results, along with recent modeling efforts, suggest promising and testable observational predictors of this behavior. We propose to measure the magnetic activity of 280 stars in the it Kepler field, including asteroseismic targets with precisely determined parameters, via their Ca II H&K emission, over a relatively long time-baseline, in order to link activity and its degree of variation to photometric variability. We will also use these data to test and refine models that seek to predict photometric and radial-velocity variations of potential planet-hosting stars. This analysis will inform theories of the causes of stellar activity and improve the efficiency of planet detection. Title: The solar-stellar connection: Insights from helioseismology Authors: Chaplin, W. J. Bibcode: 2013AN....334..133C Altcode: 2013csss...17..133C In this review we discuss helioseismology as a probe of the solar activity cycle, highlighting in particular results on studies of the recent, unusual solar minimum. We then discuss the solar-stellar connection, in the context of the potential for performing asteroseismic studies of stellar activity cycles of solar-type stars using data from Kepler, CoRoT and ground-based observations. Title: Galactic archaeology: mapping and dating stellar populations with asteroseismology of red-giant stars Authors: Miglio, A.; Chiappini, C.; Morel, T.; Barbieri, M.; Chaplin, W. J.; Girardi, L.; Montalbán, J.; Valentini, M.; Mosser, B.; Baudin, F.; Casagrande, L.; Fossati, L.; Silva Aguirre, V.; Baglin, A. Bibcode: 2013MNRAS.429..423M Altcode: 2012arXiv1211.0146M Our understanding of how the Galaxy was formed and evolves is severely hampered by the lack of precise constraints on basic stellar properties such as distances, masses and ages. Here, we show that solar-like pulsating red giants represent a well-populated class of accurate distance indicators, spanning a large age range, which can be used to map and date the Galactic disc in the regions probed by observations made by the CoRoT and Kepler space telescopes. When combined with photometric constraints, the pulsation spectra of such evolved stars not only reveal their radii, and hence distances, but also provide well-constrained estimates of their masses, which are reliable proxies for the ages of the stars. As a first application, we consider red giants observed by CoRoT in two different parts of the Milky Way, and determine precise distances for ∼2000 stars spread across nearly 15 000 pc of the Galactic disc, exploring regions which are a long way from the solar neighbourhood. We find significant differences in the mass distributions of these two samples which, by comparison with predictions of synthetic models of the Milky Way, we interpret as mainly due to the vertical gradient in the distribution of stellar masses (hence ages) in the disc. In the future, the availability of spectroscopic constraints for this sample of stars will not only improve the age determination, but also provide crucial constraints on age-velocity and age-metallicity relations at different Galactocentric radii and heights from the plane. Title: Determining distances using asteroseismic methods Authors: Silva Aguirre, V.; Casagrande, L.; Basu, S.; Campante, T. L.; Chaplin, W. J.; Huber, D.; Miglio, A.; Serenelli, A. M. Bibcode: 2013AN....334...22S Altcode: 2012arXiv1210.7343S; 2013csss...17...22S Asteroseismology has been extremely successful in determining the properties of stars in different evolutionary stages with a remarkable level of precision. However, to fully exploit its potential, robust methods for estimating stellar parameters are required and independent verification of the results is needed. In this talk, I present a new technique developed to obtain stellar properties by coupling asteroseismic analysis with the infrared flux method. Using two global seismic observables and multi-band photometry, the technique determines masses, radii, effective temperatures, bolometric fluxes, and thus distances for field stars in a self-consistent manner. Applying our method to a sample of solar-like oscillators in the Kepler field that have accurate Hipparcos parallaxes, we find agreement in our distance determinations to better than 5 %. Comparison with measurements of spectroscopic effective temperatures and interferometric radii also validate our results, and show that our technique can be applied to stars evolved beyond the main-sequence phase. Title: Frequency Dependence of Δν of Solar-Like Oscillators Investigated: Influence of HeII Ionization Zone Authors: Hekker, S.; Basu, Sarbani; Elsworth, Y.; Chaplin, W. J. Bibcode: 2013ASSP...31...73H Altcode: 2012arXiv1203.4588H Oscillations in solar-like oscillators tend to follow an approximately regular pattern in which oscillation modes of a certain degree and consecutive order appear at regular intervals in frequency, i.e. the so-called large frequency separation. This is true to first order approximation for acoustic modes. However, to a second order approximation it is evident that the large frequency separation changes as a function of frequency. This frequency dependence has been seen in the Sun and in other main-sequence stars. However, from observations of giant stars, this effect seemed to be less pronounced. We investigate the difference in frequency dependence of the large frequency separation between main-sequence and giant stars using YREC evolutionary models. Title: Study of HD 169392A observed by CoRoT and HARPS Authors: Mathur, S.; Bruntt, H.; Catala, C.; Benomar, O.; Davies, G. R.; García, R. A.; Salabert, D.; Ballot, J.; Mosser, B.; Régulo, C.; Chaplin, W. J.; Elsworth, Y.; Handberg, R.; Hekker, S.; Mantegazza, L.; Michel, E.; Poretti, E.; Rainer, M.; Roxburgh, I. W.; Samadi, R.; Stȩślicki, M.; Uytterhoeven, K.; Verner, G. A.; Auvergne, M.; Baglin, A.; Barceló Forteza, S.; Baudin, F.; Roca Cortés, T. Bibcode: 2013A&A...549A..12M Altcode: 2012arXiv1209.5696M Context. The results obtained by asteroseismology with data from space missions such as CoRoT and Kepler are providing new insights into stellar evolution. After five years of observations, CoRoT is continuing to provide high-quality data and we here present an analysis of the CoRoT observations of the double star HD 169392, complemented by ground-based spectroscopic observations.
Aims: This work aims at characterising the fundamental parameters of the two stars, their chemical composition, the acoustic-mode global parameters including their individual frequencies, and their dynamics.
Methods: We analysed HARPS observations of the two stars to derive their chemical compositions. Several methods were used and compared to determine the global properties of stars' acoustic modes and their individual frequencies from the photometric data of CoRoT.
Results: The new spectroscopic observations and archival astrometric values suggest that HD 169392 is a weakly bound wide binary system. We obtained spectroscopic parameters for both components which suggest that they originate from the same interstellar cloud. However, only the signature of oscillation modes of HD 169392 A was measured; the signal-to-noise ratio of the modes in HD 169392B is too low to allow any confident detection. For HD 169392 A we were able to extract parameters of modes for ℓ = 0, 1, 2, and 3. The analysis of splittings and inclination angle gives two possible solutions: one with with splittings and inclination angles of 0.4-1.0 μHz and 20 - 40°, the other with 0.2-0.5 μHz and 55-86°. Modelling this star using the Asteroseismic Modeling Portal (AMP) gives a mass of 1.15 ± 0.01 M⊙, a radius of 1.88 ± 0.02 R⊙, and an age of 4.33 ± 0.12 Gyr. The uncertainties come from estimated errors on the observables but do not include uncertainties on the surface layer correction or the physics of stellar models.

The CoRoT space mission, launched on December 27 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain.This work is based on ground-based observations made with the ESO 3.6 m-telescope at La Silla Observatory under the ESO Large Programme LP185-D.0056.Tables 5 and 7 are available in electronic form at http://www.aanda.org Title: Characterizing Two Solar-type Kepler Subgiants with Asteroseismology: KIC 10920273 and KIC 11395018 Authors: Doǧan, G.; Metcalfe, T. S.; Deheuvels, S.; Di Mauro, M. P.; Eggenberger, P.; Creevey, O. L.; Monteiro, M. J. P. F. G.; Pinsonneault, M.; Frasca, A.; Karoff, C.; Mathur, S.; Sousa, S. G.; Brandão, I. M.; Campante, T. L.; Handberg, R.; Thygesen, A. O.; Biazzo, K.; Bruntt, H.; Niemczura, E.; Bedding, T. R.; Chaplin, W. J.; Christensen-Dalsgaard, J.; García, R. A.; Molenda-Żakowicz, J.; Stello, D.; Van Saders, J. L.; Kjeldsen, H.; Still, M.; Thompson, S. E.; Van Cleve, J. Bibcode: 2013ApJ...763...49D Altcode: 2012arXiv1211.6650D Determining fundamental properties of stars through stellar modeling has improved substantially due to recent advances in asteroseismology. Thanks to the unprecedented data quality obtained by space missions, particularly CoRoT and Kepler, invaluable information is extracted from the high-precision stellar oscillation frequencies, which provide very strong constraints on possible stellar models for a given set of classical observations. In this work, we have characterized two relatively faint stars, KIC 10920273 and KIC 11395018, using oscillation data from Kepler photometry and atmospheric constraints from ground-based spectroscopy. Both stars have very similar atmospheric properties; however, using the individual frequencies extracted from the Kepler data, we have determined quite distinct global properties, with increased precision compared to that of earlier results. We found that both stars have left the main sequence and characterized them as follows: KIC 10920273 is a one-solar-mass star (M = 1.00 ± 0.04 M ⊙), but much older than our Sun (t = 7.12 ± 0.47 Gyr), while KIC 11395018 is significantly more massive than the Sun (M = 1.27 ± 0.04 M ⊙) with an age close to that of the Sun (t = 4.57 ± 0.23 Gyr). We confirm that the high lithium abundance reported for these stars should not be considered to represent young ages, as we precisely determined them to be evolved subgiants. We discuss the use of surface lithium abundance, rotation, and activity relations as potential age diagnostics. Title: Asteroseismology with NASA's Kepler Mission Authors: Huber, Daniel; Chaplin, W. J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Working Groups of Kepler Asteroseismic Science Consortium (KASC) Bibcode: 2013AAS...22130101H Altcode: The measurement of stellar oscillations - also called asteroseismology - is among the most powerful observational tools to study the structure and evolution of stars. The high precision photometry collected by the Kepler space telescope has revolutionized asteroseismology over the past few years by boosting the number of stars with detected oscillations by nearly two orders of magnitude over ground-based efforts, and delivering data with unprecedented signal-to-noise. In this talk I will highlight some of the recent breakthrough discoveries by the Kepler Mission, focusing in particular on the internal composition and rotation of red giants and the study of fundamental properties in large ensembles of stars throughout the Hertzsprung-Russell diagram. I will furthermore present results for an ensemble of ~80 Kepler Objects of Interest for which accurate host star and planet candidate properties have been determined using asteroseismology. Title: Erratum: A new method to detect solar-like oscillations at very low S/N using statistical significance testing Authors: Lund, Mikkel N.; Chaplin, William J.; Kjeldsen, Hans Bibcode: 2012MNRAS.427.3489L Altcode: No abstract at ADS Title: Acoustic glitches in solar-type stars from Kepler Authors: Mazumdar, A.; Monteiro, M. J. P. F. G.; Ballot, J.; Antia, H. M.; Basu, S.; Houdek, G.; Mathur, S.; Cunha, M. S.; Silva Aguirre, V.; García, R. A.; Salabert, D.; Verner, G. A.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Chaplin, W. J. Bibcode: 2012AN....333.1040M Altcode: We report the measurement of the acoustic locations of layers of sharp variation in sound speed in the interiors of 19 solar-type stars observed by the Kepler mission. The oscillatory signal in the frequencies arising due to the acoustic glitches at the base of the convection zone and the second helium ionisation zone was utilised to determine their location by four independent methods. Despite the significantly different methods of analysis, remarkable agreement was found between the results of these four methods. Further, the extracted locations of these layers were found to be consistent with representative models of the stars. Title: A new method to detect solar-like oscillations at very low S/N using statistical significance testing Authors: Lund, Mikkel N.; Chaplin, William J.; Kjeldsen, Hans Bibcode: 2012MNRAS.427.1784L Altcode: 2012arXiv1209.3792L We introduce a new method to detect solar-like oscillations in frequency power spectra of stellar observations, under conditions of very low signal-to-noise ratio. The Moving-Windowed-Power-Search (MWPS) searches the power spectrum for signatures of excess power, over and above slowly varying (in frequency) background contributions from stellar granulation and shot or instrumental noise. We adopt a false-alarm approach to ascertain whether flagged excess power, which is consistent with the excess expected from solar-like oscillations, is hard to explain by chance alone (and hence a candidate detection).

We apply the method to solar photometry data, whose quality was systematically degraded to test the performance of the MWPS at low signal-to-noise ratios. We also compare the performance of the MWPS against the frequently applied power-spectrum-of-power-spectrum (PS⊗PS) detection method. The MWPS is found to outperform the PS⊗PS method. Title: Fundamental Properties of Stars Using Asteroseismology from Kepler and CoRoT and Interferometry from the CHARA Array Authors: Huber, D.; Ireland, M. J.; Bedding, T. R.; Brandão, I. M.; Piau, L.; Maestro, V.; White, T. R.; Bruntt, H.; Casagrande, L.; Molenda-Żakowicz, J.; Silva Aguirre, V.; Sousa, S. G.; Barclay, T.; Burke, C. J.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Cunha, M. S.; De Ridder, J.; Farrington, C. D.; Frasca, A.; García, R. A.; Gilliland, R. L.; Goldfinger, P. J.; Hekker, S.; Kawaler, S. D.; Kjeldsen, H.; McAlister, H. A.; Metcalfe, T. S.; Miglio, A.; Monteiro, M. J. P. F. G.; Pinsonneault, M. H.; Schaefer, G. H.; Stello, D.; Stumpe, M. C.; Sturmann, J.; Sturmann, L.; ten Brummelaar, T. A.; Thompson, M. J.; Turner, N.; Uytterhoeven, K. Bibcode: 2012ApJ...760...32H Altcode: 2012arXiv1210.0012H We present results of a long-baseline interferometry campaign using the PAVO beam combiner at the CHARA Array to measure the angular sizes of five main-sequence stars, one subgiant and four red giant stars for which solar-like oscillations have been detected by either Kepler or CoRoT. By combining interferometric angular diameters, Hipparcos parallaxes, asteroseismic densities, bolometric fluxes, and high-resolution spectroscopy, we derive a full set of near-model-independent fundamental properties for the sample. We first use these properties to test asteroseismic scaling relations for the frequency of maximum power (νmax) and the large frequency separation (Δν). We find excellent agreement within the observational uncertainties, and empirically show that simple estimates of asteroseismic radii for main-sequence stars are accurate to <~ 4%. We furthermore find good agreement of our measured effective temperatures with spectroscopic and photometric estimates with mean deviations for stars between T eff = 4600-6200 K of -22 ± 32 K (with a scatter of 97 K) and -58 ± 31 K (with a scatter of 93 K), respectively. Finally, we present a first comparison with evolutionary models, and find differences between observed and theoretical properties for the metal-rich main-sequence star HD 173701. We conclude that the constraints presented in this study will have strong potential for testing stellar model physics, in particular when combined with detailed modeling of individual oscillation frequencies. Title: Thinning of the Sun's Magnetic Layer: The Peculiar Solar Minimum Could Have Been Predicted Authors: Basu, Sarbani; Broomhall, Anne-Marie; Chaplin, William J.; Elsworth, Yvonne Bibcode: 2012ApJ...758...43B Altcode: 2012arXiv1208.5493B The solar magnetic activity cycle causes changes in the Sun on timescales that are equivalent to human lifetimes. The minimum solar activity that preceded the current solar cycle (cycle 24) was deeper and quieter than any other recent minimum. Using data from the Birmingham Solar Oscillations Network (BiSON), we show that the structure of the solar sub-surface layers during the descending phase of the preceding cycle (cycle 23) was very different from that during cycle 22. This leads us to believe that a detailed examination of the data would have led to the prediction that the cycle 24 minimum would be out of the ordinary. The behavior of the oscillation frequencies allows us to infer that changes in the Sun that affected the oscillation frequencies in cycle 23 were localized mainly to layers above about 0.996 R ⊙, depths shallower than about 3000 km. In cycle 22, on the other hand, the changes must have also occurred in the deeper-lying layers. Title: Asteroseismology of the Open Clusters NGC 6791, NGC 6811, and NGC 6819 from 19 Months of Kepler Photometry Authors: Corsaro, Enrico; Stello, Dennis; Huber, Daniel; Bedding, Timothy R.; Bonanno, Alfio; Brogaard, Karsten; Kallinger, Thomas; Benomar, Othman; White, Timothy R.; Mosser, Benoit; Basu, Sarbani; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne P.; García, Rafael A.; Hekker, Saskia; Kjeldsen, Hans; Mathur, Savita; Meibom, Søren; Hall, Jennifer R.; Ibrahim, Khadeejah A.; Klaus, Todd C. Bibcode: 2012ApJ...757..190C Altcode: 2012arXiv1205.4023C We studied solar-like oscillations in 115 red giants in the three open clusters, NGC 6791, NGC 6811, and NGC 6819, based on photometric data covering more than 19 months with NASA's Kepler space telescope. We present the asteroseismic diagrams of the asymptotic parameters δν02, δν01, and epsilon, which show clear correlation with fundamental stellar parameters such as mass and radius. When the stellar populations from the clusters are compared, we see evidence for a difference in mass of the red giant branch stars and possibly a difference in structure of the red clump stars, from our measurements of the small separations δν02 and δν01. Ensemble échelle diagrams and upper limits to the linewidths of l = 0 modes as a function of Δν of the clusters NGC 6791 and NGC 6819 are also shown, together with the correlation between the l = 0 ridge width and the T eff of the stars. Lastly, we distinguish between red giant branch and red clump stars through the measurement of the period spacing of mixed dipole modes in 53 stars among all the three clusters to verify the stellar classification from the color-magnitude diagram. These seismic results also allow us to identify a number of special cases, including evolved blue stragglers and binaries, as well as stars in late He-core burning phases, which can be potentially interesting targets for detailed theoretical modeling. Title: Future Prospects for Inference on Solar-type Stars Authors: Chaplin, W. J. Bibcode: 2012ASPC..462..525C Altcode: 2011arXiv1109.6175C We discuss prospects for asteroseismic inference on solar-type stars, in particular opportunities that are being made possible by the large ensemble of exquisite-quality Kepler data. Title: How Different Was the Last Solar Minimum? Authors: Basu, S.; Chaplin, W. J.; Elsworth, Y.; Broomhall, A.; Jarvis, E. Bibcode: 2012ASPC..462..261B Altcode: The activity minimum between solar Cycles 23 and 24 has been exceptional in its quietness. It had the lowest sustained 10.7 cm flux since since observation of this proxy began in 1947. The internal dynamics of the Sun have been found to be very different for the minimum of Cycle 24 compared with that of Cycle 23. There have only been preliminary attempts to determine whether there were differences in the structure of the Sun during the Cycle 24 minimum compared with the Cycle 23 minimum. Early studies have shown differences between solar oscillation frequencies at the two minima. We expand the earlier study and use a hybrid forward-modelling and fitting method to determine whether the frequency differences imply differences in the structure of the Sun between the two minima. Title: Verifying Asteroseismically Determined Parameters of Kepler Stars Using Hipparcos Parallaxes: Self-consistent Stellar Properties and Distances Authors: Silva Aguirre, V.; Casagrande, L.; Basu, S.; Campante, T. L.; Chaplin, W. J.; Huber, D.; Miglio, A.; Serenelli, A. M.; Ballot, J.; Bedding, T. R.; Christensen-Dalsgaard, J.; Creevey, O. L.; Elsworth, Y.; García, R. A.; Gilliland, R. L.; Hekker, S.; Kjeldsen, H.; Mathur, S.; Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Mosser, B.; Pinsonneault, M. H.; Stello, D.; Weiss, A.; Tenenbaum, P.; Twicken, J. D.; Uddin, K. Bibcode: 2012ApJ...757...99S Altcode: 2012arXiv1208.6294S Accurately determining the properties of stars is of prime importance for characterizing stellar populations in our Galaxy. The field of asteroseismology has been thought to be particularly successful in such an endeavor for stars in different evolutionary stages. However, to fully exploit its potential, robust methods for estimating stellar parameters are required and independent verification of the results is mandatory. With this purpose, we present a new technique to obtain stellar properties by coupling asteroseismic analysis with the InfraRed Flux Method. By using two global seismic observables and multi-band photometry, the technique allows us to obtain masses, radii, effective temperatures, bolometric fluxes, and hence distances for field stars in a self-consistent manner. We apply our method to 22 solar-like oscillators in the Kepler short-cadence sample, that have accurate Hipparcos parallaxes. Our distance determinations agree to better than 5%, while measurements of spectroscopic effective temperatures and interferometric radii also validate our results. We briefly discuss the potential of our technique for stellar population analysis and models of Galactic Chemical Evolution. Title: Ensemble Asteroseismology of Red-giant Stars Authors: Hekker, S.; Gilliland, R. L.; Basu, S.; De Ridder, J.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2012ASPC..462..139H Altcode: 2011arXiv1109.0144H The successful launches of the CoRoT and Kepler space missions have led to the detections of solar-like oscillations in large samples of red-giant stars. The large numbers of red giants with observed oscillations make it possible to investigate the properties of the sample as a whole: ensemble asteroseismology. In this article we summarise ensemble asteroseismology results obtained from data released by the Kepler Science Team (∼150 000 field stars) as presented by Hekker et al. (2011b) and for the clusters NGC 6791, NGC 6811 and NGC 6819 (Hekker et al. 2011a); we discuss the importance of such studies. Title: Fast Rotating Solar-like Stars Using Asteroseismic Datasets Authors: García, R. A.; Ceillier, T.; Campante, T. L.; Davies, G. R.; Mathur, S.; Suárez, J. C.; Ballot, J.; Benomar, O.; Bonanno, A.; Brun, A. S.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Deheuvels, S.; Elsworth, Y.; Handberg, R.; Hekker, S.; Jiménez, A.; Karoff, C.; Kjeldsen, H.; Mathis, S.; Mosser, B.; Pallé, P. L.; Pinsonneault, M.; Régulo, C.; Salabert, D.; Silva Aguirre, V.; Stello, D.; Thompson, M. J.; Verner, G.; PE11 Team of Kepler WG#1 Bibcode: 2012ASPC..462..133G Altcode: 2011arXiv1109.6488G The NASA Kepler mission is providing an unprecedented set of asteroseismic data. In particular, short-cadence light-curves (∼ 60 s samplings), allow us to study solar-like stars covering a wide range of masses, spectral types and evolutionary stages. Oscillations have been observed in around 600 out of 2000 stars observed for one month during the survey phase of the Kepler mission. The measured light curves can present features related to the surface magnetic activity (starspots) and, thus we are able to obtain a good estimate of the surface (differential) rotation. In this work we establish the basis of such research and we show a potential method to find stars with fast surface rotation. Title: Seismic Analysis of Four Solar-like Stars Observed during More Than Eight Months by Kepler Authors: Mathur, S.; Campante, T. L.; Handberg, R.; García, R. A.; Appourchaux, T.; Bedding, T. R.; Mosser, B.; Chaplin, W. J.; Ballot, J.; Benomar, O.; Bonanno, A.; Corsaro, E.; Gaulme, P.; Hekker, S.; Régulo, C.; Salabert, D.; Verner, G.; White, T. R.; Brandão, I. M.; Creevey, O. L.; Dogan, G.; Bazot, M.; Cunha, M. S.; Elsworth, Y.; Huber, D.; Hale, S. J.; Houdek, G.; Karoff, C.; Lundkvist, M.; Metcalfe, T. S.; Molenda-Zakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Stello, D.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Clarke, B. D.; Girouard, F. R.; Hall, J. R.; Quintana, E. V.; Sanderfer, D. T.; Seader, S. E. Bibcode: 2012ASPC..462..180M Altcode: 2011arXiv1110.0135M Having started science operations in May 2009, the Kepler photometer has been able to provide exquisite data for solar-like stars. Five out of the 42 stars observed continuously during the survey phase show evidence of oscillations, even though they are rather faint (magnitudes from 10.5 to 12). In this paper, we present an overview of the results of the seismic analysis of 4 of these stars observed during more than eight months. Title: Investigating the Properties of Granulation in the Red Giants Observed by Kepler Authors: Mathur, S.; Hekker, S.; Trampedach, R.; Ballot, J.; Kallinger, T.; Buzasi, D.; García, R. A.; Huber, D.; Jiménez, A.; Mosser, B.; Bedding, T. R.; Elsworth, Y.; Régulo, C.; Stello, D.; Chaplin, W. J.; De Ridder, J.; Hale, S. J.; Kinemuchi, K.; Kjeldsen, H.; Mullally, F.; Thompson, S. E. Bibcode: 2012ASPC..462..375M Altcode: 2011arXiv1110.0117M More than 1000 red giants have been observed by NASA/Kepler mission during a nearly continuous period of ∼ 13 months. The resulting high-frequency resolution (< 0.03 μHz) allows us to study the granulation parameters of these stars. The granulation pattern results from the convection motions leading to upward flows of hot plasma and downward flows of cooler plasma. We fitted Harvey-like functions to the power spectra, to retrieve the timescale and amplitude of granulation. We show that there is an anti-correlation between both of these parameters and the position of maximum power of acoustic modes, while we also find a correlation with the radius, which agrees with the theory. We finally compare our results with 3D models of the convection. Title: Seismic Evidence for a Rapidly Rotating Core in a Lower-giant-branch Star Observed with Kepler Authors: Deheuvels, S.; García, R. A.; Chaplin, W. J.; Basu, S.; Antia, H. M.; Appourchaux, T.; Benomar, O.; Davies, G. R.; Elsworth, Y.; Gizon, L.; Goupil, M. J.; Reese, D. R.; Regulo, C.; Schou, J.; Stahn, T.; Casagrande, L.; Christensen-Dalsgaard, J.; Fischer, D.; Hekker, S.; Kjeldsen, H.; Mathur, S.; Mosser, B.; Pinsonneault, M.; Valenti, J.; Christiansen, J. L.; Kinemuchi, K.; Mullally, F. Bibcode: 2012ApJ...756...19D Altcode: 2012arXiv1206.3312D Rotation is expected to have an important influence on the structure and the evolution of stars. However, the mechanisms of angular momentum transport in stars remain theoretically uncertain and very complex to take into account in stellar models. To achieve a better understanding of these processes, we desperately need observational constraints on the internal rotation of stars, which until very recently was restricted to the Sun. In this paper, we report the detection of mixed modes—i.e., modes that behave both as g modes in the core and as p modes in the envelope—in the spectrum of the early red giant KIC 7341231, which was observed during one year with the Kepler spacecraft. By performing an analysis of the oscillation spectrum of the star, we show that its non-radial modes are clearly split by stellar rotation and we are able to determine precisely the rotational splittings of 18 modes. We then find a stellar model that reproduces very well the observed atmospheric and seismic properties of the star. We use this model to perform inversions of the internal rotation profile of the star, which enables us to show that the core of the star is rotating at least five times faster than the envelope. This will shed new light on the processes of transport of angular momentum in stars. In particular, this result can be used to place constraints on the angular momentum coupling between the core and the envelope of early red giants, which could help us discriminate between the theories that have been proposed over the last few decades. Title: Estimating the p-mode frequencies of the solar twin 18 Scorpii Authors: Bazot, M.; Campante, T. L.; Chaplin, W. J.; Carfantan, H.; Bedding, T. R.; Dumusque, X.; Broomhall, A. -M.; Petit, P.; Théado, S.; Van Grootel, V.; Arentoft, T.; Castro, M.; Christensen-Dalsgaard, J.; do Nascimento, J. -D., Jr.; Dintrans, B.; Kjeldsen, H.; Monteiro, M. J. P. F. G.; Santos, N. C.; Sousa, S.; Vauclair, S. Bibcode: 2012A&A...544A.106B Altcode: 2012arXiv1209.0218B Solar twins have been a focus of attention for more than a decade, because their structure is extremely close to that of the Sun. Today, thanks to high-precision spectrometers, it is possible to use asteroseismology to probe their interiors. Our goal is to use time series obtained from the HARPS spectrometer to extract the oscillation frequencies of 18 Sco, the brightest solar twin. We used the tools of spectral analysis to estimate these quantities. We estimate 52 frequencies using an MCMC algorithm. After examination of their probability densities and comparison with results from direct MAP optimization, we obtain a minimal set of 21 reliable modes. The identification of each pulsation mode is straightforwardly accomplished by comparing to the well-established solar pulsation modes. We also derived some basic seismic indicators using these values. These results offer a good basis to start a detailed seismic analysis of 18 Sco using stellar models.

Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (run ID: 183.D-0729(A)).Results of the MCMC analysis are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/544/A106 Title: Calibrating Convective Properties of Solar-like Stars in the Kepler Field of View Authors: Bonaca, Ana; Tanner, Joel D.; Basu, Sarbani; Chaplin, William J.; Metcalfe, Travis S.; Monteiro, Mário J. P. F. G.; Ballot, Jérôme; Bedding, Timothy R.; Bonanno, Alfio; Broomhall, Anne-Marie; Bruntt, Hans; Campante, Tiago L.; Christensen-Dalsgaard, Jørgen; Corsaro, Enrico; Elsworth, Yvonne; García, Rafael A.; Hekker, Saskia; Karoff, Christoffer; Kjeldsen, Hans; Mathur, Savita; Régulo, Clara; Roxburgh, Ian; Stello, Dennis; Trampedach, Regner; Barclay, Thomas; Burke, Christopher J.; Caldwell, Douglas A. Bibcode: 2012ApJ...755L..12B Altcode: 2012arXiv1207.2765B Stellar models generally use simple parameterizations to treat convection. The most widely used parameterization is the so-called mixing-length theory where the convective eddy sizes are described using a single number, α, the mixing-length parameter. This is a free parameter, and the general practice is to calibrate α using the known properties of the Sun and apply that to all stars. Using data from NASA's Kepler mission we show that using the solar-calibrated α is not always appropriate, and that in many cases it would lead to estimates of initial helium abundances that are lower than the primordial helium abundance. Kepler data allow us to calibrate α for many other stars and we show that for the sample of stars we have studied, the mixing-length parameter is generally lower than the solar value. We studied the correlation between α and stellar properties, and we find that α increases with metallicity. We therefore conclude that results obtained by fitting stellar models or by using population-synthesis models constructed with solar values of α are likely to have large systematic errors. Our results also confirm theoretical expectations that the mixing-length parameter should vary with stellar properties. Title: Solar-like oscillations in red giants observed with Kepler: influence of increased timespan on global oscillation parameters Authors: Hekker, S.; Elsworth, Y.; Mosser, B.; Kallinger, T.; Chaplin, W. J.; De Ridder, J.; García, R. A.; Stello, D.; Clarke, B. D.; Hall, J. R.; Ibrahim, K. A. Bibcode: 2012A&A...544A..90H Altcode: 2012arXiv1207.0615H Context. The length of the asteroseismic timeseries obtained from the Kepler satellite analysed here span 19 months. Kepler provides the longest continuous timeseries currently available, which calls for a study of the influence of the increased timespan on the accuracy and precision of the obtained results.
Aims: We aim to investigate how the increased timespan influences the detectability of the oscillation modes, and the absolute values and uncertainties of the global oscillation parameters, i.e., frequency of maximum oscillation power, νmax, and large frequency separation between modes of the same degree and consecutive orders, ⟨ Δν ⟩ .
Methods: We use published methods to derive νmax and ⟨ Δν ⟩ for timeseries ranging from 50 to 600 days and compare these results as a function of method, timespan and ⟨ Δν ⟩ .
Results: We find that in general a minimum of the order of 400 day long timeseries are necessary to obtain reliable results for the global oscillation parameters in more than 95% of the stars, but this does depend on ⟨ Δν ⟩ . In a statistical sense the quoted uncertainties seem to provide a reasonable indication of the precision of the obtained results in short (50-day) runs, they do however seem to be overestimated for results of longer runs. Furthermore, the different definitions of the global parameters used in the different methods have non-negligible effects on the obtained values. Additionally, we show that there is a correlation between νmax and the flux variance.
Conclusions: We conclude that longer timeseries improve the likelihood to detect oscillations with automated codes (from ~60% in 50 day runs to >95% in 400 day runs with a slight method dependence) and the precision of the obtained global oscillation parameters. The trends suggest that the improvement will continue for even longer timeseries than the 600 days considered here, with a reduction in the median absolute deviation of more than a factor of 10 for an increase in timespan from 50 to 2000 days (the currently foreseen length of the mission). This work shows that global parameters determined with high precision - thus from long datasets - using different definitions can be used to identify the evolutionary state of the stars.

Values of the global oscillation parameters can be obtained from the authors upon request. Title: Kepler-36: A Pair of Planets with Neighboring Orbits and Dissimilar Densities Authors: Carter, Joshua A.; Agol, Eric; Chaplin, William J.; Basu, Sarbani; Bedding, Timothy R.; Buchhave, Lars A.; Christensen-Dalsgaard, Jørgen; Deck, Katherine M.; Elsworth, Yvonne; Fabrycky, Daniel C.; Ford, Eric B.; Fortney, Jonathan J.; Hale, Steven J.; Handberg, Rasmus; Hekker, Saskia; Holman, Matthew J.; Huber, Daniel; Karoff, Christopher; Kawaler, Steven D.; Kjeldsen, Hans; Lissauer, Jack J.; Lopez, Eric D.; Lund, Mikkel N.; Lundkvist, Mia; Metcalfe, Travis S.; Miglio, Andrea; Rogers, Leslie A.; Stello, Dennis; Borucki, William J.; Bryson, Steve; Christiansen, Jessie L.; Cochran, William D.; Geary, John C.; Gilliland, Ronald L.; Haas, Michael R.; Hall, Jennifer; Howard, Andrew W.; Jenkins, Jon M.; Klaus, Todd; Koch, David G.; Latham, David W.; MacQueen, Phillip J.; Sasselov, Dimitar; Steffen, Jason H.; Twicken, Joseph D.; Winn, Joshua N. Bibcode: 2012Sci...337..556C Altcode: 2012arXiv1206.4718C In the solar system, the planets’ compositions vary with orbital distance, with rocky planets in close orbits and lower-density gas giants in wider orbits. The detection of close-in giant planets around other stars was the first clue that this pattern is not universal and that planets’ orbits can change substantially after their formation. Here, we report another violation of the orbit-composition pattern: two planets orbiting the same star with orbital distances differing by only 10% and densities differing by a factor of 8. One planet is likely a rocky “super-Earth,” whereas the other is more akin to Neptune. These planets are 20 times more closely spaced and have a larger density contrast than any adjacent pair of planets in the solar system. Title: Helioseismology - a clear view of the interior Authors: Elsworth, Yvonne; Broomhall, Anne-Marie; Chaplin, William Bibcode: 2012IAUS..286...77E Altcode: Helioseismology is a very powerful tool that allows us to explore the interior of the Sun. Here we give particular emphasis to the justification for the likely location of the zone that is most sensitive to cycle-related changes. For the low degree modes we find that more than one timescale for changes in the oscillations is discovered. We also note the successive cycles have differing sensitivities to the activity. We end with a warning of the risk of being misled with short datasets such as are seen with stellar data. Title: VizieR Online Data Catalog: p-mode frequencies of the solar twin 18 Sco (Bazot+, 2012) Authors: Bazot, M.; Campante, T. L.; Chaplin, W. J.; Carfantan, H.; Bedding, T. R.; Dumusque, X.; Broomhall, A. -M.; Petit, P.; Theado, S.; Van Grootel, V.; Arentoft, T.; Castro, M.; Christensen-Dalsgaard, J.; Do Nascimento, J. -D., Jr.; Dintrans, B.; Kjeldsen, H.; Monteiro, M. J. P. F. G.; Santos, N. C.; Sousa, S.; Vauclair, S. Bibcode: 2012yCat..35440106B Altcode: 2012yCat..35449106B Results from the estimation of the parameter of the spectrum model using the Markov Chain Monte-Carlo (MCMC) algorithm described in Sect.4. A burn-in sequence has been removed. The data is stored in the form of an array [1975001x54] The first 52 columns give the frequencies of the modes order by degree (13 l=0 modes, 13 l=1 modes, 13 l=2 modes, 13 l=3 modes). For each mode, they are sorted in ascending order. The last two columns of each line give the parameters Gamma1 and Gamma2.

(1 data file). Title: Oscillation mode frequencies of 61 main-sequence and subgiant stars observed by Kepler Authors: Appourchaux, T.; Chaplin, W. J.; García, R. A.; Gruberbauer, M.; Verner, G. A.; Antia, H. M.; Benomar, O.; Campante, T. L.; Davies, G. R.; Deheuvels, S.; Handberg, R.; Hekker, S.; Howe, R.; Régulo, C.; Salabert, D.; Bedding, T. R.; White, T. R.; Ballot, J.; Mathur, S.; Silva Aguirre, V.; Elsworth, Y. P.; Basu, S.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Uddin, K.; Stumpe, M. C.; Barclay, T. Bibcode: 2012A&A...543A..54A Altcode: 2012arXiv1204.3147A Context. Solar-like oscillations have been observed by Kepler and CoRoT in several solar-type stars, thereby providing a way to probe the stars using asteroseismology
Aims: We provide the mode frequencies of the oscillations of various stars required to perform a comparison with those obtained from stellar modelling.
Methods: We used a time series of nine months of data for each star. The 61 stars observed were categorised in three groups: simple, F-like, and mixed-mode. The simple group includes stars for which the identification of the mode degree is obvious. The F-like group includes stars for which the identification of the degree is ambiguous. The mixed-mode group includes evolved stars for which the modes do not follow the asymptotic relation of low-degree frequencies. Following this categorisation, the power spectra of the 61 main-sequence and subgiant stars were analysed using both maximum likelihood estimators and Bayesian estimators, providing individual mode characteristics such as frequencies, linewidths, and mode heights. We developed and describe a methodology for extracting a single set of mode frequencies from multiple sets derived by different methods and individual scientists. We report on how one can assess the quality of the fitted parameters using the likelihood ratio test and the posterior probabilities.
Results: We provide the mode frequencies of 61 stars (with their 1-σ error bars), as well as their associated échelle diagrams.

Appendices are available in electronic form at http://www.aanda.org Title: Accurate fundamental parameters and detailed abundance patterns from spectroscopy of 93 solar-type Kepler targets Authors: Bruntt, H.; Basu, S.; Smalley, B.; Chaplin, W. J.; Verner, G. A.; Bedding, T. R.; Catala, C.; Gazzano, J. -C.; Molenda-Żakowicz, J.; Thygesen, A. O.; Uytterhoeven, K.; Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Mosser, B.; Appourchaux, T.; Campante, T. L.; Elsworth, Y.; García, R. A.; Handberg, R.; Metcalfe, T. S.; Quirion, P. -O.; Régulo, C.; Roxburgh, I. W.; Stello, D.; Christensen-Dalsgaard, J.; Kawaler, S. D.; Kjeldsen, H.; Morris, R. L.; Quintana, E. V.; Sanderfer, D. T. Bibcode: 2012MNRAS.423..122B Altcode: 2012arXiv1203.0611B; 2012MNRAS.tmp.3037B We present a detailed spectroscopic study of 93 solar-type stars that are targets of the NASA/Kepler mission and provide detailed chemical composition of each target. We find that the overall metallicity is well represented by Fe lines. Relative abundances of light elements (CNO) and α elements are generally higher for low-metallicity stars. Our spectroscopic analysis benefits from the accurately measured surface gravity from the asteroseismic analysis of the Kepler light curves. The accuracy on the log g parameter is better than 0.03 dex and is held fixed in the analysis. We compare our Teff determination with a recent colour calibration of VT-KS [TYCHO V magnitude minus Two Micron All Sky Survey (2MASS) KS magnitude] and find very good agreement and a scatter of only 80 K, showing that for other nearby Kepler targets, this index can be used. The asteroseismic log g values agree very well with the classical determination using Fe I-Fe II balance, although we find a small systematic offset of 0.08 dex (asteroseismic log g values are lower). The abundance patterns of metals, α elements and the light elements (CNO) show that a simple scaling by [Fe/H] is adequate to represent the metallicity of the stars, except for the stars with metallicity below -0.3, where α-enhancement becomes important. However, this is only important for a very small fraction of the Kepler sample. We therefore recommend that a simple scaling with [Fe/H] be employed in the asteroseismic analyses of large ensembles of solar-type stars. Title: Misleading variations in estimated rotational frequency splittings of solar p modes: consequences for helioseismology and asteroseismology Authors: Broomhall, Anne-Marie; Salabert, David; Chaplin, William J.; García, Rafael A.; Elsworth, Yvonne; Howe, Rachel; Mathur, Savita Bibcode: 2012MNRAS.422.3564B Altcode: 2012arXiv1204.1168B; 2012MNRAS.tmp.2800B The aim of this paper is to investigate whether there are any 11-yr or quasi-biennial solar-cycle-related variations in solar rotational splitting frequencies of low-degree solar p modes. Although no 11-yr signals were observed, variations on a shorter time-scale (∼2 yr) were apparent. We show that the variations arose from complications/artefacts associated with the realization noise in the data and the process by which the data were analysed. More specifically, the realization noise was observed to have a larger effect on the rotational splittings than accounted for by the formal uncertainties. When used to infer the rotation profile of the Sun these variations are not important. The outer regions of the solar interior can be constrained using higher degree modes. While the variations in the low-l splittings do make large differences to the inferred rotation rate of the core, the core rotation rate is so poorly constrained, even by low-l modes, that the different inferred rotation profiles still agree within their respective 1σ uncertainties. By contrast, in asteroseismology, only low-l modes are visible and so higher l modes cannot be used to constrain the rotation profile of stars. Furthermore, we usually only have one data set from which to measure the observed low-l splitting. In such circumstances the inferred internal rotation rate of a main-sequence star could differ significantly from estimates of the surface rotation rate, hence leading to spurious conclusions. Therefore, extreme care must be taken when using only the splittings of low-l modes to draw conclusions about the average internal rotation rate of a star. Title: VizieR Online Data Catalog: Effective temperature scale for KIC stars (Pinsonneault+, 2012) Authors: Pinsonneault, M. H.; An, D.; Molenda-Zakowicz, J.; Chaplin, W. J.; Metcalfe, T. S.; Bruntt, H. Bibcode: 2012yCat..21990030P Altcode: We took griz photometry from long-cadence targets in the Kepler Input Catalog (KIC) (Brown et al. 2011AJ....142..112B, see Cat. V/133); photometric uncertainties were taken as 0.01mag in gri and 0.03mag in z. Errors were taken from the quadrature sum of uncertainties in the individual filters. JHKs photometry was taken from the All Sky Data Release of the 2MASS Point Source Catalog (Skrutskie et al. 2006, Cat. VII/233) and checked against complementary information in the KIC itself.

(2 data files). Title: Solving the Mode Identification Problem in Asteroseismology of F Stars Observed with Kepler Authors: White, Timothy R.; Bedding, Timothy R.; Gruberbauer, Michael; Benomar, Othman; Stello, Dennis; Appourchaux, Thierry; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne P.; García, Rafael A.; Hekker, Saskia; Huber, Daniel; Kjeldsen, Hans; Mosser, Benoît; Kinemuchi, Karen; Mullally, Fergal; Still, Martin Bibcode: 2012ApJ...751L..36W Altcode: 2012arXiv1205.0544W Asteroseismology of F-type stars has been hindered by an ambiguity in identification of their oscillation modes. The regular mode pattern that makes this task trivial in cooler stars is masked by increased line widths. The absolute mode frequencies, encapsulated in the asteroseismic variable epsilon, can help solve this impasse because the values of epsilon implied by the two possible mode identifications are distinct. We find that the correct epsilon can be deduced from the effective temperature and the line widths and we apply these methods to a sample of solar-like oscillators observed with Kepler. Title: Evolutionary influences on the structure of red-giant acoustic oscillation spectra from 600d of Kepler observations Authors: Kallinger, T.; Hekker, S.; Mosser, B.; De Ridder, J.; Bedding, T. R.; Elsworth, Y. P.; Gruberbauer, M.; Guenther, D. B.; Stello, D.; Basu, S.; García, R. A.; Chaplin, W. J.; Mullally, F.; Still, M.; Thompson, S. E. Bibcode: 2012A&A...541A..51K Altcode: 2012arXiv1203.3134K Context. It was recently discovered that the period spacings of mixed pressure/gravity dipole modes in red giants permit a distinction between the otherwise unknown evolutionary stage of these stars. The Kepler space mission is reaching continuous observing times long enough to also start studying the fine structure of the observed pressure-mode spectra.
Aims: In this paper, we aim to study the signature of stellar evolution on the radial and pressure-dominated l = 2 modes in an ensemble of red giants that show solar-type oscillations.
Methods: We use established methods to automatically identify the mode degree of l = 0 and 2 modes and measure the large (Δνc) and small (δν02) frequency separation around the central radial mode. We then determine the phase shift ɛc of the central radial mode, i.e. the linear offset in the asymptotic fit to the acoustic modes. Furthermore we measure the individual frequencies of radial modes and investigate their average curvature.
Results: We find that ɛc is significantly different for red giants at a given Δνc but which burn only H in a shell (RGB) than those that have already ignited core He burning. Even though not directly probing the stellar core the pair of local seismic observables (Δνc, ɛc) can be used as an evolutionary stage discriminator that turned out to be as reliable as the period spacing of the mixed dipole modes. We find a tight correlation between ɛc and Δνc for RGB stars and unlike less evolved stars we find no indication that ɛc depends on other properties of the star. It appears that the difference in ɛc between the two populations becomes smaller and eventually indistinguishable if we use an average of several radial orders, instead of a local, i.e. only around the central radial mode, large separation to determine the phase shift. This indicates that the information on the evolutionary stage is encoded locally, more precisely in the shape of the radial mode sequence. This shape turns out to be approximately symmetric around the central radial mode for RGB stars but asymmetric for core He burning stars. We computed radial mode frequencies for a sequence of red-giant models and find them to qualitatively confirm our findings. We also find that, at least in our models, the local Δν is an at least as good and mostly better proxy for both the asymptotic spacing and the large separation scaled from the model density than the average Δν. Finally, we investigate the signature of the evolutionary stage on δν02 and quantify the mass dependency of this seismic parameter. Title: Kepler Observations and Asteroseismology of θ Cyg, the Brightest StarObservable in the Kepler Field of View Authors: Guzik, Joyce A.; Houdek, G.; Chaplin, W. J.; Kurtz, D.; Gilliland, R. L.; Mullally, F.; Rowe, J. F.; Haas, M. R.; Bryson, S. T.; Still, M. D. Bibcode: 2012AAS...22041905G Altcode: θ Cyg (13 Cyg) is an F4 main sequence star that, at visual magnitude V=4.48, is the brightest star observable by the Kepler spacecraft. Short-cadence photometric data using a custom aperture requiring 1800 pixels were obtained for this star during Quarter 6 (June-Sept 2010) and Quarter 8 (Jan-March 2011).

We present analyses of the solar-like oscillations first discovered in the Q6 data [1, 2]. We use observational constraints from the literature and recent ground-based observations including angular diameters from optical interferometry in conjunction with the frequency data to derive stellar properties (e.g., mass, age, metallicity, extent of convection zones). We also discuss the prospects for detecting longer period gravity-mode pulsations as seen in gamma Doradus variable stars of spectral type A-F, given these constraints.

With an effective temperature near 6500 K and near ‘solar’ element abundances, θ Cyg is near the red edge of the gamma Doradus instability strip, where high-order gravity-mode pulsations with periods of 1 day may be present. If the envelope convection zone of the star is not too deep, these gravity-mode pulsations may be driven by the convective blocking mechanism. The calculated envelope convection zone depth depends on the element abundance mixtures adopted for the stellar models [2]. Asteroseismic studies of θ Cyg therefore have potential to shed light on the solar abundance problem [3, 4], as well as to put constraints on the presence and detectability of g-mode pulsations for main-sequence solar-like stars.

References:

[1] Haas, M.R. et al. 2011, BAAS, 43, No. 2, 140.07.

[2] Guzik, J.A. et al. 2011, in Resolving the Future of Astronomy with Long Baseline Interferometry, Soccoro, NM,

March 2011, ASP, in press.

[3] Guzik, J.A. and Mussack, K. 2010, ApJ 713, 1108.

[4] Basu, S. and Antia, H.M. 2008, Phys. Rep. 457, 217. Title: A Uniform Asteroseismic Analysis of 22 Solar-type Stars Observed by Kepler Authors: Mathur, S.; Metcalfe, T. S.; Woitaszek, M.; Bruntt, H.; Verner, G. A.; Christensen-Dalsgaard, J.; Creevey, O. L.; Doǧan, G.; Basu, S.; Karoff, C.; Stello, D.; Appourchaux, T.; Campante, T. L.; Chaplin, W. J.; García, R. A.; Bedding, T. R.; Benomar, O.; Bonanno, A.; Deheuvels, S.; Elsworth, Y.; Gaulme, P.; Guzik, J. A.; Handberg, R.; Hekker, S.; Herzberg, W.; Monteiro, M. J. P. F. G.; Piau, L.; Quirion, P. -O.; Régulo, C.; Roth, M.; Salabert, D.; Serenelli, A.; Thompson, M. J.; Trampedach, R.; White, T. R.; Ballot, J.; Brandão, I. M.; Molenda-Żakowicz, J.; Kjeldsen, H.; Twicken, J. D.; Uddin, K.; Wohler, B. Bibcode: 2012ApJ...749..152M Altcode: 2012arXiv1202.2844M Asteroseismology with the Kepler space telescope is providing not only an improved characterization of exoplanets and their host stars, but also a new window on stellar structure and evolution for the large sample of solar-type stars in the field. We perform a uniform analysis of 22 of the brightest asteroseismic targets with the highest signal-to-noise ratio observed for 1 month each during the first year of the mission, and we quantify the precision and relative accuracy of asteroseismic determinations of the stellar radius, mass, and age that are possible using various methods. We present the properties of each star in the sample derived from an automated analysis of the individual oscillation frequencies and other observational constraints using the Asteroseismic Modeling Portal (AMP), and we compare them to the results of model-grid-based methods that fit the global oscillation properties. We find that fitting the individual frequencies typically yields asteroseismic radii and masses to ~1% precision, and ages to ~2.5% precision (respectively, 2, 5, and 8 times better than fitting the global oscillation properties). The absolute level of agreement between the results from different approaches is also encouraging, with model-grid-based methods yielding slightly smaller estimates of the radius and mass and slightly older values for the stellar age relative to AMP, which computes a large number of dedicated models for each star. The sample of targets for which this type of analysis is possible will grow as longer data sets are obtained during the remainder of the mission. Title: A Revised Effective Temperature Scale for the Kepler Input Catalog Authors: Pinsonneault, Marc H.; An, Deokkeun; Molenda-Żakowicz, Joanna; Chaplin, William J.; Metcalfe, Travis S.; Bruntt, Hans Bibcode: 2012ApJS..199...30P Altcode: 2011arXiv1110.4456P We present a catalog of revised effective temperatures for stars observed in long-cadence mode in the Kepler Input Catalog (KIC). We use Sloan Digital Sky Survey (SDSS) griz filters tied to the fundamental temperature scale. Polynomials for griz color-temperature relations are presented, along with correction terms for surface gravity effects, metallicity, and statistical corrections for binary companions or blending. We compare our temperature scale to the published infrared flux method (IRFM) scale for VTJKs in both open clusters and the Kepler fields. We find good agreement overall, with some deviations between (J - Ks )-based temperatures from the IRFM and both SDSS filter and other diagnostic IRFM color-temperature relationships above 6000 K. For field dwarfs, we find a mean shift toward hotter temperatures relative to the KIC, of order 215 K, in the regime where the IRFM scale is well defined (4000 K to 6500 K). This change is of comparable magnitude in both color systems and in spectroscopy for stars with T eff below 6000 K. Systematic differences between temperature estimators appear for hotter stars, and we define corrections to put the SDSS temperatures on the IRFM scale for them. When the theoretical dependence on gravity is accounted for, we find a similar temperature scale offset between the fundamental and KIC scales for giants. We demonstrate that statistical corrections to color-based temperatures from binaries are significant. Typical errors, mostly from uncertainties in extinction, are of order 100 K. Implications for other applications of the KIC are discussed. Title: Asteroseismology of the Solar Analogs 16 Cyg A and B from Kepler Observations Authors: Metcalfe, T. S.; Chaplin, W. J.; Appourchaux, T.; García, R. A.; Basu, S.; Brandão, I.; Creevey, O. L.; Deheuvels, S.; Doǧan, G.; Eggenberger, P.; Karoff, C.; Miglio, A.; Stello, D.; Yıldız, M.; Çelik, Z.; Antia, H. M.; Benomar, O.; Howe, R.; Régulo, C.; Salabert, D.; Stahn, T.; Bedding, T. R.; Davies, G. R.; Elsworth, Y.; Gizon, L.; Hekker, S.; Mathur, S.; Mosser, B.; Bryson, S. T.; Still, M. D.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Ibrahim, K. A.; Klaus, T. C.; Li, J. Bibcode: 2012ApJ...748L..10M Altcode: 2012arXiv1201.5966M The evolved solar-type stars 16 Cyg A and B have long been studied as solar analogs, yielding a glimpse into the future of our own Sun. The orbital period of the binary system is too long to provide meaningful dynamical constraints on the stellar properties, but asteroseismology can help because the stars are among the brightest in the Kepler field. We present an analysis of three months of nearly uninterrupted photometry of 16 Cyg A and B from the Kepler space telescope. We extract a total of 46 and 41 oscillation frequencies for the two components, respectively, including a clear detection of octupole (l = 3) modes in both stars. We derive the properties of each star independently using the Asteroseismic Modeling Portal, fitting the individual oscillation frequencies and other observational constraints simultaneously. We evaluate the systematic uncertainties from an ensemble of results generated by a variety of stellar evolution codes and fitting methods. The optimal models derived by fitting each component individually yield a common age (t = 6.8 ± 0.4 Gyr) and initial composition (Z i = 0.024 ± 0.002, Y i = 0.25 ± 0.01) within the uncertainties, as expected for the components of a binary system, bolstering our confidence in the reliability of asteroseismic techniques. The longer data sets that will ultimately become available will allow future studies of differential rotation, convection zone depths, and long-term changes due to stellar activity cycles. Title: Acoustic spectrum fitting for a large set of solar-like pulsators Authors: Benomar, O.; Baudin, F.; Chaplin, W. J.; Elsworth, Y.; Appourchaux, T. Bibcode: 2012MNRAS.420.2178B Altcode: 2011MNRAS.tmp.2149B Asteroseismology provides the means both to constrain the global properties and to probe the internal structures of stars. Asteroseismic data are now available on large numbers of solar-type stars, thanks in particular to the CoRoT and Kepler space missions, and automated data-analysis pipelines are needed to provide efficient and timely results. Here, we present an automated algorithm that is able to extract mode parameters under low signal-to-noise ratio conditions. We use a Bayesian framework to ensure the robustness of the algorithm. We discuss the efficiency of the method and test it using Variability of Solar Irradiance and Gravity Oscillations (VIRGO) Sun-as-a-star photometry data and the artificial Astero Fitting at Low Angular degree Group (asteroFLAG) Kepler ensemble. Analysis of the VIRGO data shows that it is possible to track variations of the individual mode parameters (frequency, height, width) through the solar cycle, using short time series (30 days). The present analysis also revealed a modulation of the degree l = 2 relative height through the solar cycle. Applied on asteroFLAG data, we show that the pipeline extracts accurately the central frequency and the large separation. It is also able to identify the degree of the modes in 78 per cent of stars. Title: Kepler-22b: A 2.4 Earth-radius Planet in the Habitable Zone of a Sun-like Star Authors: Borucki, William J.; Koch, David G.; Batalha, Natalie; Bryson, Stephen T.; Rowe, Jason; Fressin, Francois; Torres, Guillermo; Caldwell, Douglas A.; Christensen-Dalsgaard, Jørgen; Cochran, William D.; DeVore, Edna; Gautier, Thomas N.; Geary, John C.; Gilliland, Ronald; Gould, Alan; Howell, Steve B.; Jenkins, Jon M.; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Sasselov, Dimitar; Boss, Alan; Charbonneau, David; Ciardi, David; Kaltenegger, Lisa; Doyle, Laurance; Dupree, Andrea K.; Ford, Eric B.; Fortney, Jonathan; Holman, Matthew J.; Steffen, Jason H.; Mullally, Fergal; Still, Martin; Tarter, Jill; Ballard, Sarah; Buchhave, Lars A.; Carter, Josh; Christiansen, Jessie L.; Demory, Brice-Olivier; Désert, Jean-Michel; Dressing, Courtney; Endl, Michael; Fabrycky, Daniel; Fischer, Debra; Haas, Michael R.; Henze, Christopher; Horch, Elliott; Howard, Andrew W.; Isaacson, Howard; Kjeldsen, Hans; Johnson, John Asher; Klaus, Todd; Kolodziejczak, Jeffery; Barclay, Thomas; Li, Jie; Meibom, Søren; Prsa, Andrej; Quinn, Samuel N.; Quintana, Elisa V.; Robertson, Paul; Sherry, William; Shporer, Avi; Tenenbaum, Peter; Thompson, Susan E.; Twicken, Joseph D.; Van Cleve, Jeffrey; Welsh, William F.; Basu, Sarbani; Chaplin, William; Miglio, Andrea; Kawaler, Steven D.; Arentoft, Torben; Stello, Dennis; Metcalfe, Travis S.; Verner, Graham A.; Karoff, Christoffer; Lundkvist, Mia; Lund, Mikkel N.; Handberg, Rasmus; Elsworth, Yvonne; Hekker, Saskia; Huber, Daniel; Bedding, Timothy R.; Rapin, William Bibcode: 2012ApJ...745..120B Altcode: 2011arXiv1112.1640B A search of the time-series photometry from NASA's Kepler spacecraft reveals a transiting planet candidate orbiting the 11th magnitude G5 dwarf KIC 10593626 with a period of 290 days. The characteristics of the host star are well constrained by high-resolution spectroscopy combined with an asteroseismic analysis of the Kepler photometry, leading to an estimated mass and radius of 0.970 ± 0.060 M ⊙ and 0.979 ± 0.020 R ⊙. The depth of 492 ± 10 ppm for the three observed transits yields a radius of 2.38 ± 0.13 Re for the planet. The system passes a battery of tests for false positives, including reconnaissance spectroscopy, high-resolution imaging, and centroid motion. A full BLENDER analysis provides further validation of the planet interpretation by showing that contamination of the target by an eclipsing system would rarely mimic the observed shape of the transits. The final validation of the planet is provided by 16 radial velocities (RVs) obtained with the High Resolution Echelle Spectrometer on Keck I over a one-year span. Although the velocities do not lead to a reliable orbit and mass determination, they are able to constrain the mass to a 3σ upper limit of 124 M ⊕, safely in the regime of planetary masses, thus earning the designation Kepler-22b. The radiative equilibrium temperature is 262 K for a planet in Kepler-22b's orbit. Although there is no evidence that Kepler-22b is a rocky planet, it is the first confirmed planet with a measured radius to orbit in the habitable zone of any star other than the Sun. Title: Kepler-21b: A 1.6 R Earth Planet Transiting the Bright Oscillating F Subgiant Star HD 179070 Authors: Howell, Steve B.; Rowe, Jason F.; Bryson, Stephen T.; Quinn, Samuel N.; Marcy, Geoffrey W.; Isaacson, Howard; Ciardi, David R.; Chaplin, William J.; Metcalfe, Travis S.; Monteiro, Mario J. P. F. G.; Appourchaux, Thierry; Basu, Sarbani; Creevey, Orlagh L.; Gilliland, Ronald L.; Quirion, Pierre-Olivier; Stello, Denis; Kjeldsen, Hans; Christensen-Dalsgaard, Jörgen; Elsworth, Yvonne; García, Rafael A.; Houdek, Günter; Karoff, Christoffer; Molenda-Żakowicz, Joanna; Thompson, Michael J.; Verner, Graham A.; Torres, Guillermo; Fressin, Francois; Crepp, Justin R.; Adams, Elisabeth; Dupree, Andrea; Sasselov, Dimitar D.; Dressing, Courtney D.; Borucki, William J.; Koch, David G.; Lissauer, Jack J.; Latham, David W.; Buchhave, Lars A.; Gautier, Thomas N., III; Everett, Mark; Horch, Elliott; Batalha, Natalie M.; Dunham, Edward W.; Szkody, Paula; Silva, David R.; Mighell, Ken; Holberg, Jay; Ballot, Jerôme; Bedding, Timothy R.; Bruntt, Hans; Campante, Tiago L.; Handberg, Rasmus; Hekker, Saskia; Huber, Daniel; Mathur, Savita; Mosser, Benoit; Régulo, Clara; White, Timothy R.; Christiansen, Jessie L.; Middour, Christopher K.; Haas, Michael R.; Hall, Jennifer R.; Jenkins, Jon M.; McCaulif, Sean; Fanelli, Michael N.; Kulesa, Craig; McCarthy, Don; Henze, Christopher E. Bibcode: 2012ApJ...746..123H Altcode: 2011arXiv1112.2165H We present Kepler observations of the bright (V = 8.3), oscillating star HD 179070. The observations show transit-like events which reveal that the star is orbited every 2.8 days by a small, 1.6 R Earth object. Seismic studies of HD 179070 using short cadence Kepler observations show that HD 179070 has a frequency-power spectrum consistent with solar-like oscillations that are acoustic p-modes. Asteroseismic analysis provides robust values for the mass and radius of HD 179070, 1.34 ± 0.06 M ⊙ and 1.86 ± 0.04 R ⊙, respectively, as well as yielding an age of 2.84 ± 0.34 Gyr for this F5 subgiant. Together with ground-based follow-up observations, analysis of the Kepler light curves and image data, and blend scenario models, we conservatively show at the >99.7% confidence level (3σ) that the transit event is caused by a 1.64 ± 0.04 R Earth exoplanet in a 2.785755 ± 0.000032 day orbit. The exoplanet is only 0.04 AU away from the star and our spectroscopic observations provide an upper limit to its mass of ~10 M Earth (2σ). HD 179070 is the brightest exoplanet host star yet discovered by Kepler.

Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology, the Mayall telescope at Kitt Peak National Observatory, and the WIYN Observatory which is a joint facility of NOAO, University of Wisconsin-Madison, Indiana University, and Yale University. Title: Effect of Uncertainties in Stellar Model Parameters on Estimated Masses and Radii of Single Stars Authors: Basu, Sarbani; Verner, Graham A.; Chaplin, William J.; Elsworth, Yvonne Bibcode: 2012ApJ...746...76B Altcode: 2011arXiv1111.6976B Accurate and precise values of radii and masses of stars are needed to correctly estimate properties of extrasolar planets. We examine the effect of uncertainties in stellar model parameters on estimates of the masses, radii, and average densities of solar-type stars. We find that in the absence of seismic data on solar-like oscillations, stellar masses can be determined to a greater accuracy than either stellar radii or densities; but to get reasonably accurate results the effective temperature, log g, and metallicity must be measured to high precision. When seismic data are available, stellar density is the most well-determined property, followed by radius, with mass the least well-determined property. Uncertainties in stellar convection, quantified in terms of uncertainties in the value of the mixing length parameter, cause the most significant errors in the estimates of stellar properties. Title: Quasi-biennial variations in helioseismic frequencies: can the source of the variation be localized? Authors: Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; Simoniello, R. Bibcode: 2012MNRAS.420.1405B Altcode: 2011MNRAS.tmp.2018B; 2011arXiv1111.2492B We investigate the spherical harmonic degree (l) dependence of the 'seismic' quasi-biennial oscillation (QBO) observed in low-degree solar p-mode frequencies, using Sun-as-a-star Birmingham Solar Oscillations Network data. The amplitude of the seismic QBO is modulated by the 11-yr solar cycle, with the amplitude of the signal being largest at solar maximum. The amplitude of the signal is noticeably larger for the l= 2 and 3 modes than for the l= 0 and 1 modes. The seismic QBO shows some frequency dependence but this dependence is not as strong as observed in the 11-yr solar cycle. These results are consistent with the seismic QBO having its origins in shallow layers of the interior (one possibility being the bottom of the shear layer extending 5 per cent below the solar surface). Under this scenario the magnetic flux responsible for the seismic QBO is brought to the surface (where its influence on the p modes is stronger) by buoyant flux from the 11-yr cycle, the strong component of which is observed at predominantly low latitudes. As the l= 2 and 3 modes are much more sensitive to equatorial latitudes than the l= 0 and 1 modes the influence of the 11-yr cycle on the seismic QBO is more visible in l= 2 and 3 mode frequencies. Our results imply that close to solar maximum the main influence of the seismic QBO occurs at low latitudes (<45°), which is where the strong component of the 11-yr solar cycle resides. To isolate the latitudinal dependence of the seismic QBO from the 11-yr solar cycle we must consider epochs when the 11-yr solar cycle is weak. However, away from solar maximum, the amplitude of the seismic QBO is weak making the latitudinal dependence hard to constrain. Title: Asteroseismology of old open clusters with Kepler: direct estimate of the integrated red giant branch mass-loss in NGC 6791 and 6819 Authors: Miglio, A.; Brogaard, K.; Stello, D.; Chaplin, W. J.; D'Antona, F.; Montalbán, J.; Basu, S.; Bressan, A.; Grundahl, F.; Pinsonneault, M.; Serenelli, A. M.; Elsworth, Y.; Hekker, S.; Kallinger, T.; Mosser, B.; Ventura, P.; Bonanno, A.; Noels, A.; Silva Aguirre, V.; Szabo, R.; Li, J.; McCauliff, S.; Middour, C. K.; Kjeldsen, H. Bibcode: 2012MNRAS.419.2077M Altcode: 2011arXiv1109.4376M; 2011MNRAS.tmp.1877M Mass-loss of red giant branch (RGB) stars is still poorly determined, despite its crucial role in the chemical enrichment of galaxies. Thanks to the recent detection of solar-like oscillations in G-K giants in open clusters with Kepler, we can now directly determine stellar masses for a statistically significant sample of stars in the old open clusters NGC 6791 and 6819. The aim of this work is to constrain the integrated RGB mass-loss by comparing the average mass of stars in the red clump (RC) with that of stars in the low-luminosity portion of the RGB [i.e. stars with L≲L(RC)]. Stellar masses were determined by combining the available seismic parameters νmax and Δν with additional photometric constraints and with independent distance estimates. We measured the masses of 40 stars on the RGB and 19 in the RC of the old metal-rich cluster NGC 6791. We find that the difference between the average mass of RGB and RC stars is small, but significant [? (random) ±0.04 (systematic) M⊙]. Interestingly, such a small ? does not support scenarios of an extreme mass-loss for this metal-rich cluster. If we describe the mass-loss rate with Reimers prescription, a first comparison with isochrones suggests that the observed ? is compatible with a mass-loss efficiency parameter in the range 0.1 ≲η≲ 0.3. Less stringent constraints on the RGB mass-loss rate are set by the analysis of the ∼2 Gyr old NGC 6819, largely due to the lower mass-loss expected for this cluster, and to the lack of an independent and accurate distance determination. In the near future, additional constraints from frequencies of individual pulsation modes and spectroscopic effective temperatures will allow further stringent tests of the Δν and νmax scaling relations, which provide a novel, and potentially very accurate, means of determining stellar radii and masses. Title: Fundamental properties of five Kepler stars using global asteroseismic quantities and ground-based observations Authors: Creevey, O. L.; Doǧan, G.; Frasca, A.; Thygesen, A. O.; Basu, S.; Bhattacharya, J.; Biazzo, K.; Brandão, I. M.; Bruntt, H.; Mazumdar, A.; Niemczura, E.; Shrotriya, T.; Sousa, S. G.; Stello, D.; Subramaniam, A.; Campante, T. L.; Handberg, R.; Mathur, S.; Bedding, T. R.; García, R. A.; Régulo, C.; Salabert, D.; Molenda-Żakowicz, J.; Quirion, P. -O.; White, T. R.; Bonanno, A.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Christiansen, J. L.; Elsworth, Y.; Fanelli, M. N.; Karoff, C.; Kinemuchi, K.; Kjeldsen, H.; Gai, N.; Monteiro, M. J. P. F. G.; Suárez, J. C. Bibcode: 2012A&A...537A.111C Altcode: 2011arXiv1111.4615C We present an asteroseismic study of the solar-like stars KIC 11395018, KIC 10273246, KIC 10920273, KIC 10339342, and KIC 11234888 using short-cadence time series of more than eight months from the Kepler satellite. For four of these stars, we derive atmospheric parameters from spectra acquired with the Nordic Optical Telescope. The global seismic quantities (average largefrequency separation and frequency of maximum power), combined with the atmospheric parameters, yield the mean density and surface gravity with precisions of 2% and ~0.03 dex, respectively. We also determine the radius, mass, and age with precisions of 2-5%, 7-11%, and ~35%, respectively, using grid-based analyses. Coupling the stellar parameters with photometric data yields an asteroseismic distance with a precision better than 10%. A vsini measurement provides a rotational period-inclination correlation, and using the rotational periods from the recent literature, we constrain the stellar inclination for three of the stars. An Li abundance analysis yields an independent estimate of the age, but this is inconsistent with the asteroseismically determined age for one of the stars. We assess the performance of five grid-based analysis methods and find them all to provide consistent values of the surface gravity to ~0.03 dex when both atmospheric and seismic constraints are at hand. The different grid-based analyses all yield fitted values of radius and mass to within 2.4σ, and taking the mean of these results reduces it to 1.5σ. The absence of a metallicity constraint when the average large frequency separation is measured with a precision of 1% biases the fitted radius and mass for the stars with non-solar metallicity (metal-rich KIC 11395018 and metal-poor KIC 10273246), while including a metallicity constraint reduces the uncertainties in both of these parameters by almost a factor of two. We found that including the average small frequency separation improves the determination of the age only for KIC 11395018 and KIC 11234888, and for the latter this improvement was due to the lack of strong atmospheric constraints. Title: Characterization of the power excess of solar-like oscillations in red giants with Kepler Authors: Mosser, B.; Elsworth, Y.; Hekker, S.; Huber, D.; Kallinger, T.; Mathur, S.; Belkacem, K.; Goupil, M. J.; Samadi, R.; Barban, C.; Bedding, T. R.; Chaplin, W. J.; García, R. A.; Stello, D.; De Ridder, J.; Middour, C. K.; Morris, R. L.; Quintana, E. V. Bibcode: 2012A&A...537A..30M Altcode: 2011arXiv1110.0980M Context. The space mission Kepler provides us with long and uninterrupted photometric time series of red giants. This allows us to examine their seismic global properties and to compare these with theoretical predictions.
Aims: We aim to describe the oscillation power excess observed in red giant oscillation spectra with global seismic parameters, and to investigate empirical scaling relations governing these parameters. From these scalings relations, we derive new physical properties of red giant oscillations.
Methods: Various different methods were compared in order to validate the processes and to derive reliable output values. For consistency, a single method was then used to determine scaling relations for the relevant global asteroseismic parameters: mean mode height, mean height of the background signal superimposed on the oscillation power excess, width of the power excess, bolometric amplitude of the radial modes and visibility of non-radial modes. A method for deriving oscillation amplitudes is proposed, which relies on the complete identification of the red giant oscillation spectrum.
Results: The comparison of the different methods has shown the important role of the way the background is modelled. The convergence reached by the collaborative work enables us to derive significant results concerning the oscillation power excess. We obtain several scaling relations, and identify the influence of the stellar mass and the evolutionary status. The effect of helium burning on the red giant interior structure is confirmed: it yields a strong mass-radius relation for clump stars. We find that none of the amplitude scaling relations motivated by physical considerations predict the observed mode amplitudes of red giant stars. In parallel, the degree-dependent mode visibility exhibits important variations. Both effects seem related to the significant influence of the high mode mass of non-radial mixed modes. A family of red giants with very weak dipole modes is identified, and its properties are analyzed.
Conclusions: The clear correlation between the power densities of the background signal and of the stellar oscillation induces important consequences to be considered for deriving a reliable theoretical relation of the mode amplitude. As a by-product of this work, we have verified that red giant asteroseismology delivers new insights for stellar and Galactic physics, given the evidence for mass loss at the tip of the red giant branch.

Appendices are available in electronic form at http://www.aanda.org Title: Oscillation mode linewidths of main-sequence and subgiant stars observed by Kepler Authors: Appourchaux, T.; Benomar, O.; Gruberbauer, M.; Chaplin, W. J.; García, R. A.; Handberg, R.; Verner, G. A.; Antia, H. M.; Campante, T. L.; Davies, G. R.; Deheuvels, S.; Hekker, S.; Howe, R.; Salabert, D.; Bedding, T. R.; White, T. R.; Houdek, G.; Silva Aguirre, V.; Elsworth, Y. P.; van Cleve, J.; Clarke, B. D.; Hall, J. R.; Kjeldsen, H. Bibcode: 2012A&A...537A.134A Altcode: 2011arXiv1112.3295A Context. Solar-like oscillations have been observed by Kepler and CoRoT in several solar-type stars.
Aims: We study the variations in the stellar p-mode linewidth as a function of effective temperature.
Methods: We study a time series of nine months of Kepler data. We analyse the power spectra of 42 cool main-sequence stars and subgiants using both maximum likelihood estimators and Bayesian estimators to recover individual mode characteristics such as frequencies, linewidths, and mode heights.
Results: We report on the mode linewidth at both maximum power and maximum mode height for these 42 stars as a function of effective temperature.
Conclusions: We show that the mode linewidth at either maximum mode height or maximum amplitude follows a scaling relation with effective temperature, which is a combination of a power law and a lower bound. The typical power-law index is about 13 for the linewidth derived from the maximum mode height, and about 16 for the linewidth derived from the maximum amplitude, while the lower bound is about 0.3 μHz and 0.7 μHz, respectively. We stress that this scaling relation is only valid for cool main-sequence stars and subgiants, and does not have any predictive power outside the temperature range of these stars. Title: Testing Scaling Relations for Solar-like Oscillations from the Main Sequence to Red Giants Using Kepler Data Authors: Huber, D.; Bedding, T. R.; Stello, D.; Hekker, S.; Mathur, S.; Mosser, B.; Verner, G. A.; Bonanno, A.; Buzasi, D. L.; Campante, T. L.; Elsworth, Y. P.; Hale, S. J.; Kallinger, T.; Silva Aguirre, V.; Chaplin, W. J.; De Ridder, J.; García, R. A.; Appourchaux, T.; Frandsen, S.; Houdek, G.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Broomhall, A. M.; Corsaro, E.; Salabert, D.; Sanderfer, D. T.; Seader, S. E.; Smith, J. C. Bibcode: 2011ApJ...743..143H Altcode: 2011arXiv1109.3460H We have analyzed solar-like oscillations in ~1700 stars observed by the Kepler Mission, spanning from the main sequence to the red clump. Using evolutionary models, we test asteroseismic scaling relations for the frequency of maximum power (νmax), the large frequency separation (Δν), and oscillation amplitudes. We show that the difference of the Δν-νmax relation for unevolved and evolved stars can be explained by different distributions in effective temperature and stellar mass, in agreement with what is expected from scaling relations. For oscillation amplitudes, we show that neither (L/M) s scaling nor the revised scaling relation by Kjeldsen & Bedding is accurate for red-giant stars, and demonstrate that a revised scaling relation with a separate luminosity-mass dependence can be used to calculate amplitudes from the main sequence to red giants to a precision of ~25%. The residuals show an offset particularly for unevolved stars, suggesting that an additional physical dependency is necessary to fully reproduce the observed amplitudes. We investigate correlations between amplitudes and stellar activity, and find evidence that the effect of amplitude suppression is most pronounced for subgiant stars. Finally, we test the location of the cool edge of the instability strip in the Hertzsprung-Russell diagram using solar-like oscillations and find the detections in the hottest stars compatible with a domain of hybrid stochastically excited and opacity driven pulsation. Title: Frequency dependence of the large frequency separation of solar-like oscillators: influence of the helium second-ionization zone Authors: Hekker, S.; Basu, Sarbani; Elsworth, Y.; Chaplin, W. J. Bibcode: 2011MNRAS.418L.119H Altcode: 2011arXiv1109.2595H The large frequency separation (Δν) between modes of the same degree and consecutive orders in a star is approximately proportional to the square root of its mean density. To determine Δν as accurately as possible, a mean large frequency separation (<Δν>) computed over several orders is often used. It is, however, known that Δν varies with frequency in a second-order effect. From observations, it has been shown that this frequency dependence is more important for main-sequence stars than it is for red giant stars. Here we use YREC models to verify and explain this observational result. We find that for stars with R ≳ 8 R⊙, the effect of the helium second-ionization zone (He II zone) is relatively small. For these stars, the deep location of the He II zone induces a frequency modulation covering only a few Δν, while the amplitude of the modulation is low due to the relatively weak and extended He II layer, causing a shallow wide depression in the first adiabatic exponent (Γ1). For less evolved stars, the He II zone is located closer to the surface, and it is more confined, i.e. a deep narrow depression in Γ1. This causes frequency modulations with relatively high amplitudes covering up to about 20Δν, inducing a relatively large frequency modulation. Additionally, we find that for less evolved stars, the He II zone is stronger and more localized for more massive stars and for stars with low metallicities further increasing the amplitude of the frequency modulation. Title: Granulation in Red Giants: Observations by the Kepler Mission and Three-dimensional Convection Simulations Authors: Mathur, S.; Hekker, S.; Trampedach, R.; Ballot, J.; Kallinger, T.; Buzasi, D.; García, R. A.; Huber, D.; Jiménez, A.; Mosser, B.; Bedding, T. R.; Elsworth, Y.; Régulo, C.; Stello, D.; Chaplin, W. J.; De Ridder, J.; Hale, S. J.; Kinemuchi, K.; Kjeldsen, H.; Mullally, F.; Thompson, S. E. Bibcode: 2011ApJ...741..119M Altcode: 2011arXiv1109.1194M The granulation pattern that we observe on the surface of the Sun is due to hot plasma rising to the photosphere where it cools down and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones than the Sun, we cannot a priori assume that their granulation is a scaled version of solar granulation. Until now, neither observations nor one-dimensional analytical convection models could put constraints on granulation in red giants. With asteroseismology, this study can now be performed. We analyze ~1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (timescale τgran and power P gran). We search for a correlation between these parameters and the global acoustic-mode parameter (the position of maximum power, νmax) as well as with stellar parameters (mass, radius, surface gravity (log g), and effective temperature (T eff)). We show that τeffvpropν-0.89 max and P granvpropν-1.90 max, which is consistent with the theoretical predictions. We find that the granulation timescales of stars that belong to the red clump have similar values while the timescales of stars in the red giant branch are spread in a wider range. Finally, we show that realistic three-dimensional simulations of the surface convection in stars, spanning the (T eff, log g) range of our sample of red giants, match the Kepler observations well in terms of trends. Title: Asteroseismic Diagrams from a Survey of Solar-like Oscillations with Kepler Authors: White, Timothy R.; Bedding, Timothy R.; Stello, Dennis; Appourchaux, Thierry; Ballot, Jérôme; Benomar, Othman; Bonanno, Alfio; Broomhall, Anne-Marie; Campante, Tiago L.; Chaplin, William J.; Christensen-Dalsgaard, Jørgen; Corsaro, Enrico; Doǧan, Gülnur; Elsworth, Yvonne P.; Fletcher, Stephen T.; García, Rafael A.; Gaulme, Patrick; Handberg, Rasmus; Hekker, Saskia; Huber, Daniel; Karoff, Christoffer; Kjeldsen, Hans; Mathur, Savita; Mosser, Benoit; Monteiro, Mario J. P. F. G.; Régulo, Clara; Salabert, David; Silva Aguirre, Victor; Thompson, Michael J.; Verner, Graham; Morris, Robert L.; Sanderfer, Dwight T.; Seader, Shawn E. Bibcode: 2011ApJ...742L...3W Altcode: 2011arXiv1110.1375W Photometric observations made by the NASA Kepler Mission have led to a dramatic increase in the number of main-sequence and subgiant stars with detected solar-like oscillations. We present an ensemble asteroseismic analysis of 76 solar-type stars. Using frequencies determined from the Kepler time-series photometry, we have measured three asteroseismic parameters that characterize the oscillations: the large frequency separation (Δν), the small frequency separation between modes of l = 0 and l = 2 (δν02), and the dimensionless offset (epsilon). These measurements allow us to construct asteroseismic diagrams, namely the so-called Christensen-Dalsgaard diagram of δν02 versus Δν, and the recently re-introduced epsilon diagram. We compare the Kepler results with previously observed solar-type stars and with theoretical models. The positions of stars in these diagrams places constraints on their masses and ages. Additionally, we confirm the observational relationship between epsilon and T eff that allows for the unambiguous determination of radial order and should help resolve the problem of mode identification in F stars. Title: Kepler Mission Stellar and Instrument Noise Properties Authors: Gilliland, Ronald L.; Chaplin, William J.; Dunham, Edward W.; Argabright, Vic S.; Borucki, William J.; Basri, Gibor; Bryson, Stephen T.; Buzasi, Derek L.; Caldwell, Douglas A.; Elsworth, Yvonne P.; Jenkins, Jon M.; Koch, David G.; Kolodziejczak, Jeffrey; Miglio, Andrea; van Cleve, Jeffrey; Walkowicz, Lucianne M.; Welsh, William F. Bibcode: 2011ApJS..197....6G Altcode: 2011arXiv1107.5207G Kepler mission results are rapidly contributing to fundamentally new discoveries in both the exoplanet and asteroseismology fields. The data returned from Kepler are unique in terms of the number of stars observed, precision of photometry for time series observations, and the temporal extent of high duty cycle observations. As the first mission to provide extensive time series measurements on thousands of stars over months to years at a level hitherto possible only for the Sun, the results from Kepler will vastly increase our knowledge of stellar variability for quiet solar-type stars. Here, we report on the stellar noise inferred on the timescale of a few hours of most interest for detection of exoplanets via transits. By design the data from moderately bright Kepler stars are expected to have roughly comparable levels of noise intrinsic to the stars and arising from a combination of fundamental limitations such as Poisson statistics and any instrument noise. The noise levels attained by Kepler on-orbit exceed by some 50% the target levels for solar-type, quiet stars. We provide a decomposition of observed noise for an ensemble of 12th magnitude stars arising from fundamental terms (Poisson and readout noise), added noise due to the instrument and that intrinsic to the stars. The largest factor in the modestly higher than anticipated noise follows from intrinsic stellar noise. We show that using stellar parameters from galactic stellar synthesis models, and projections to stellar rotation, activity, and hence noise levels reproduce the primary intrinsic stellar noise features. Title: Constructing a One-solar-mass Evolutionary Sequence Using Asteroseismic Data from Kepler Authors: Silva Aguirre, V.; Chaplin, W. J.; Ballot, J.; Basu, S.; Bedding, T. R.; Serenelli, A. M.; Verner, G. A.; Miglio, A.; Monteiro, M. J. P. F. G.; Weiss, A.; Appourchaux, T.; Bonanno, A.; Broomhall, A. M.; Bruntt, H.; Campante, T. L.; Casagrande, L.; Corsaro, E.; Elsworth, Y.; García, R. A.; Gaulme, P.; Handberg, R.; Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Mosser, B.; Salabert, D.; Schönrich, R.; Sousa, S. G.; Stello, D.; White, T. R.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Houdek, G.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Thompson, M. J.; Caldwell, D. A.; Christiansen, J. L.; Wohler, B. Bibcode: 2011ApJ...740L...2S Altcode: 2011arXiv1108.2031S Asteroseismology of solar-type stars has entered a new era of large surveys with the success of the NASA Kepler mission, which is providing exquisite data on oscillations of stars across the Hertzsprung-Russell diagram. From the time-series photometry, the two seismic parameters that can be most readily extracted are the large frequency separation (Δν) and the frequency of maximum oscillation power (νmax). After the survey phase, these quantities are available for hundreds of solar-type stars. By scaling from solar values, we use these two asteroseismic observables to identify for the first time an evolutionary sequence of 1 M sun field stars, without the need for further information from stellar models. Comparison of our determinations with the few available spectroscopic results shows an excellent level of agreement. We discuss the potential of the method for differential analysis throughout the main-sequence evolution and the possibility of detecting twins of very well-known stars. Title: Asteroseismology from multi-month Kepler photometry: the evolved Sun-like stars KIC 10273246 and KIC 10920273 Authors: Campante, T. L.; Handberg, R.; Mathur, S.; Appourchaux, T.; Bedding, T. R.; Chaplin, W. J.; García, R. A.; Mosser, B.; Benomar, O.; Bonanno, A.; Corsaro, E.; Fletcher, S. T.; Gaulme, P.; Hekker, S.; Karoff, C.; Régulo, C.; Salabert, D.; Verner, G. A.; White, T. R.; Houdek, G.; Brandão, I. M.; Creevey, O. L.; Doǧan, G.; Bazot, M.; Christensen-Dalsgaard, J.; Cunha, M. S.; Elsworth, Y.; Huber, D.; Kjeldsen, H.; Lundkvist, M.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Stello, D.; Clarke, B. D.; Girouard, F. R.; Hall, J. R. Bibcode: 2011A&A...534A...6C Altcode: 2011arXiv1108.3807C Context. The evolved main-sequence Sun-like stars KIC 10273246 (F-type) and KIC 10920273 (G-type) were observed with the NASA Kepler satellite for approximately ten months with a duty cycle in excess of 90%. Such continuous and long observations are unprecedented for solar-type stars other than the Sun.
Aims: We aimed mainly at extracting estimates of p-mode frequencies - as well as of other individual mode parameters - from the power spectra of the light curves of both stars, thus providing scope for a full seismic characterization.
Methods: The light curves were corrected for instrumental effects in a manner independent of the Kepler science pipeline. Estimation of individual mode parameters was based both on the maximization of the likelihood of a model describing the power spectrum and on a classic prewhitening method. Finally, we employed a procedure for selecting frequency lists to be used in stellar modeling.
Results: A total of 30 and 21 modes of degree l = 0,1,2 - spanning at least eight radial orders - have been identified for KIC 10273246 and KIC 10920273, respectively. Two avoided crossings (l = 1 ridge) have been identified for KIC 10273246, whereas one avoided crossing plus another likely one have been identified for KIC 10920273. Good agreement is found between observed and predicted mode amplitudes for the F-type star KIC 10273246, based on a revised scaling relation. Estimates are given of the rotational periods, the parameters describing stellar granulation and the global asteroseismic parameters Δν and νmax. Title: Observational Constraints, Stellar Models, and Kepler Data for theta Cyg, the Brightest Star Observable by Kepler Authors: Guzik, J. A.; Houdek, G.; Chaplin, W. J.; Kurtz, D.; Gilliland, R. L.; Mullally, F.; Rowe, J. F.; Haas, M. R.; Bryson, S. T.; Still, M. D.; Boyajian, T. Bibcode: 2011arXiv1110.2120G Altcode: The V=4.48 F4 main-sequence star theta Cyg is the brightest star observable in the Kepler spacecraft field-of-view. Short-cadence (58.8 s) photometric data were obtained by Kepler during 2010 June-September. Preliminary analysis shows solar-like oscillations in the frequency range 1200- 2500 microHz. To interpret these data and to motivate further observations, we use observational constraints from the literature to construct stellar evolution and pulsation models for this star. We compare the observed large frequency separation of the solar-like oscillations with the model predictions, and discuss the prospects for gamma Doradus-like g-mode pulsations, given the observational constraints. We discuss the value of angular diameter measurements from optical interferometry for constraining stellar properties and the implications for asteroseismology. Title: An Asteroseismic Membership Study of the Red Giants in Three Open Clusters Observed by Kepler: NGC 6791, NGC 6819, and NGC 6811 Authors: Stello, Dennis; Meibom, Søren; Gilliland, Ronald L.; Grundahl, Frank; Hekker, Saskia; Mosser, Benoît; Kallinger, Thomas; Mathur, Savita; García, Rafael A.; Huber, Daniel; Basu, Sarbani; Bedding, Timothy R.; Brogaard, Karsten; Chaplin, William J.; Elsworth, Yvonne P.; Molenda-Żakowicz, Joanna; Szabó, Robert; Still, Martin; Jenkins, Jon M.; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Serenelli, Aldo M.; Wohler, Bill Bibcode: 2011ApJ...739...13S Altcode: 2011arXiv1107.1234S Studying star clusters offers significant advances in stellar astrophysics due to the combined power of having many stars with essentially the same distance, age, and initial composition. This makes clusters excellent test benches for verification of stellar evolution theory. To fully exploit this potential, it is vital that the star sample is uncontaminated by stars that are not members of the cluster. Techniques for determining cluster membership therefore play a key role in the investigation of clusters. We present results on three clusters in the Kepler field of view based on a newly established technique that uses asteroseismology to identify fore- or background stars in the field, which demonstrates advantages over classical methods such as kinematic and photometry measurements. Four previously identified seismic non-members in NGC 6819 are confirmed in this study, and three additional non-members are found—two in NGC 6819 and one in NGC 6791. We further highlight which stars are, or might be, affected by blending, which needs to be taken into account when analyzing these Kepler data. Title: Assessing the Nature and Impact of Observed Stellar Variability on Kepler’s Ability to Detect Earth-Size Planets Authors: Jenkins, Jon Michael; Dunham, E. W.; Argabright, V. S.; Borucki, W. J.; Caldwell, D. A.; Chaplin, W. J.; Christiansen, J. L.; Gautier, T. N.; Gilliland, R. L.; Kolodziejczak, J.; Machalek, P.; Van Cleve, J.; Basri, G.; Buzasi, D. L.; Haas, M. R.; Howell, S. B.; Tenenbaum, P.; Walkowicz, L. M.; Welsh, W. F. Bibcode: 2011ESS.....2.1914J Altcode: The Kepler spacecraft was launched on March 6 2009 on a 3.5-year mission to determine the frequency of Earth-size and larger planets in or near the habitable zones of their stars. Kepler has been observing 160,000 stars to detect transiting planets for over two years and has discovered more than 16 confirmed or validated planets and has identified over 1200 candidate planets. There is sufficient data and experience with the photometer to characterize Kepler’s ability to detect weak signatures of small, terrestrial planets. The photometer’s sensitivity depends on the total combined differential photometric precision (CDPP) and on the mission lifetime. These driving requirements for Kepler called for a total CDPP of 20 ppm for 12th magnitude G2 dwarf stars in 6.5 hours, and a mission lifetime of 3.5 years. The noise budget includes 14 ppm for shot noise, 10 ppm for instrument noise and 10 ppm adopted for intrinsic stellar variability. The CDPP requirement was necessarily set without knowledge of actual typical levels of stellar variability. We find that Kepler’s noise metrics for 12th magnitude dwarf stars are dominated by stellar variability and the overall combined noise is ∼50% higher than the required value. While this does reduce Kepler’s ability to achieve its scientific objectives, Kepler’s originally envisioned capability to detect terrestrial planets can be recovered by extending the duration of the flight mission to 8 years. Title: Verification of the Kepler Input Catalog from Asteroseismology of Solar-type Stars Authors: Verner, G. A.; Chaplin, W. J.; Basu, S.; Brown, T. M.; Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Metcalfe, T. S.; Mosser, B.; Quirion, P. -O.; Appourchaux, T.; Bedding, T. R.; Bruntt, H.; Campante, T. L.; Elsworth, Y.; García, R. A.; Handberg, R.; Régulo, C.; Roxburgh, I. W.; Stello, D.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Allen, C.; Clarke, B. D.; Girouard, F. R. Bibcode: 2011ApJ...738L..28V Altcode: 2011arXiv1109.0869V We calculate precise stellar radii and surface gravities from the asteroseismic analysis of over 500 solar-type pulsating stars observed by the Kepler space telescope. These physical stellar properties are compared with those given in the Kepler Input Catalog (KIC), determined from ground-based multi-color photometry. For the stars in our sample, we find general agreement but we detect an average overestimation bias of 0.23 dex in the KIC determination of log (g) for stars with log (g)KIC > 4.0 dex, and a resultant underestimation bias of up to 50% in the KIC radii estimates for stars with R KIC < 2 R sun. Part of the difference may arise from selection bias in the asteroseismic sample; nevertheless, this result implies there may be fewer stars characterized in the KIC with R ~ 1 R sun than is suggested by the physical properties in the KIC. Furthermore, if the radius estimates are taken from the KIC for these affected stars and then used to calculate the size of transiting planets, a similar underestimation bias may be applied to the planetary radii. Title: Amplitudes of Solar-like Oscillations: Constraints from Red Giants in Open Clusters Observed by Kepler Authors: Stello, Dennis; Huber, Daniel; Kallinger, Thomas; Basu, Sarbani; Mosser, Benoît; Hekker, Saskia; Mathur, Savita; García, Rafael A.; Bedding, Timothy R.; Kjeldsen, Hans; Gilliland, Ronald L.; Verner, Graham A.; Chaplin, William J.; Benomar, Othman; Meibom, Søren; Grundahl, Frank; Elsworth, Yvonne P.; Molenda-Żakowicz, Joanna; Szabó, Robert; Christensen-Dalsgaard, Jørgen; Tenenbaum, Peter; Twicken, Joseph D.; Uddin, Kamal Bibcode: 2011ApJ...737L..10S Altcode: 2011arXiv1107.0490S Scaling relations that link asteroseismic quantities to global stellar properties are important for gaining understanding of the intricate physics that underpins stellar pulsations. The common notion that all stars in an open cluster have essentially the same distance, age, and initial composition implies that the stellar parameters can be measured to much higher precision than what is usually achievable for single stars. This makes clusters ideal for exploring the relation between the mode amplitude of solar-like oscillations and the global stellar properties. We have analyzed data obtained with NASA's Kepler space telescope to study solar-like oscillations in 100 red giant stars located in either of the three open clusters, NGC 6791, NGC 6819, and NGC 6811. By fitting the measured amplitudes to predictions from simple scaling relations that depend on luminosity, mass, and effective temperature, we find that the data cannot be described by any power of the luminosity-to-mass ratio as previously assumed. As a result we provide a new improved empirical relation which treats luminosity and mass separately. This relation turns out to also work remarkably well for main-sequence and subgiant stars. In addition, the measured amplitudes reveal the potential presence of a number of previously unknown unresolved binaries in the red clump in NGC 6791 and NGC 6819, pointing to an interesting new application for asteroseismology as a probe into the formation history of open clusters. Title: Global asteroseismic properties of solar-like oscillations observed by Kepler: a comparison of complementary analysis methods Authors: Verner, G. A.; Elsworth, Y.; Chaplin, W. J.; Campante, T. L.; Corsaro, E.; Gaulme, P.; Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Mosser, B.; Appourchaux, T.; Ballot, J.; Bedding, T. R.; Bonanno, A.; Broomhall, A. -M.; García, R. A.; Handberg, R.; New, R.; Stello, D.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; White, T. R.; Caldwell, D. A.; Christiansen, J. L.; Fanelli, M. N. Bibcode: 2011MNRAS.415.3539V Altcode: 2011MNRAS.tmp..892V; 2011arXiv1105.0571V We present the asteroseismic analysis of 1948 F-, G- and K-type main-sequence and subgiant stars observed by the National Aeronautics and Space Administration Kepler mission. We detect and characterize solar-like oscillations in 642 of these stars. This represents the largest cohort of main-sequence and subgiant solar-like oscillators observed to date. The photometric observations are analysed using the methods developed by nine independent research teams. The results are combined to validate the determined global asteroseismic parameters and calculate the relative precision by which the parameters can be obtained. We correlate the relative number of detected solar-like oscillators with stellar parameters from the Kepler Input Catalogue and find a deficiency for stars with effective temperatures in the range 5300 ≲Teff≲ 5700 K and a drop-off in detected oscillations in stars approaching the red edge of the classical instability strip. We compare the power-law relationships between the frequency of peak power, νmax, the mean large frequency separation, Δν, and the maximum mode amplitude, Amax, and show that there are significant method-dependent differences in the results obtained. This illustrates the need for multiple complementary analysis methods to be used to assess the robustness and reproducibility of results derived from global asteroseismic parameters. Title: A new efficient method for determining weighted power spectra: detection of low-frequency solar p-modes by analysis of BiSON data Authors: Fletcher, S. T.; Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; New, R. Bibcode: 2011MNRAS.415.1310F Altcode: 2011arXiv1104.5355F; 2011MNRAS.tmp..724F We present a new and highly efficient algorithm for computing a power spectrum made from evenly spaced data which combines the noise-reducing advantages of the weighted fit with the computational advantages of the fast Fourier transform. We apply this method to a 10-yr data set of the solar p-mode oscillations obtained by the Birmingham Solar Oscillations Network (BiSON) and thereby uncover three new low-frequency modes. These are the ℓ= 2, n= 5 and n= 7 modes and the ℓ= 3, n=7 mode. In the case of the ℓ= 2, n= 5 mode, this is believed to be the first such identification of this mode in the literature. The statistical weights needed for the method are derived from a combination of the real data and a sophisticated simulation of the instrument performance. Variations in the weights are due mainly to the differences in the noise characteristics of the various BiSON instruments, the change in those characteristics over time and the changing line-of-sight velocity between the stations and the Sun. It should be noted that a weighted data set will have a more time-dependent signal than an unweighted set and that, consequently, its frequency spectrum will be more susceptible to aliasing. Title: Characterization of red giant stars in the public Kepler data Authors: Hekker, S.; Gilliland, R. L.; Elsworth, Y.; Chaplin, W. J.; De Ridder, J.; Stello, D.; Kallinger, T.; Ibrahim, K. A.; Klaus, T. C.; Li, J. Bibcode: 2011MNRAS.414.2594H Altcode: 2011MNRAS.tmp..559H; 2011arXiv1103.0141H The first public release of long-cadence stellar photometric data collected by the NASA Kepler mission has now been made available. In this paper, we characterize the red giant (G-K) stars in this large sample in terms of their solar-like oscillations. We use published methods and well-known scaling relations in the analysis. Just over 70 per cent of the red giants in the sample show detectable solar-like oscillations, and from these oscillations we are able to estimate the fundamental properties of the stars. This asteroseismic analysis reveals different populations: low-luminosity H-shell burning red giant branch stars, cool high-luminosity red giants on the red giant branch and He-core burning clump and secondary-clump giants. Title: Solar-like Oscillations in KIC 11395018 and KIC 11234888 from 8 Months of Kepler Data Authors: Mathur, S.; Handberg, R.; Campante, T. L.; García, R. A.; Appourchaux, T.; Bedding, T. R.; Mosser, B.; Chaplin, W. J.; Ballot, J.; Benomar, O.; Bonanno, A.; Corsaro, E.; Gaulme, P.; Hekker, S.; Régulo, C.; Salabert, D.; Verner, G.; White, T. R.; Brandão, I. M.; Creevey, O. L.; Doǧan, G.; Elsworth, Y.; Huber, D.; Hale, S. J.; Houdek, G.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Quintana, E. V.; Sanderfer, D. T.; Seader, S. E. Bibcode: 2011ApJ...733...95M Altcode: 2011arXiv1103.4085M We analyze the photometric short-cadence data obtained with the Kepler mission during the first 8 months of observations of two solar-type stars of spectral types G and F: KIC 11395018 and KIC 11234888, respectively, the latter having a lower signal-to-noise ratio (S/N) compared with the former. We estimate global parameters of the acoustic (p) modes such as the average large and small frequency separations, the frequency of the maximum of the p-mode envelope, and the average line width of the acoustic modes. We were able to identify and to measure 22 p-mode frequencies for the first star and 16 for the second one even though the S/N of these stars are rather low. We also derive some information about the stellar rotation periods from the analyses of the low-frequency parts of the power spectral densities. A model-independent estimation of the mean density, mass, and radius is obtained using the scaling laws. We emphasize the importance of continued observations for the stars with low S/N for an improved characterization of the oscillation modes. Our results offer a preview of what will be possible for many stars with the long data sets obtained during the remainder of the mission. Title: Preparation of Kepler light curves for asteroseismic analyses Authors: García, R. A.; Hekker, S.; Stello, D.; Gutiérrez-Soto, J.; Handberg, R.; Huber, D.; Karoff, C.; Uytterhoeven, K.; Appourchaux, T.; Chaplin, W. J.; Elsworth, Y.; Mathur, S.; Ballot, J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Houdek, G.; Jenkins, J. M.; Kjeldsen, H.; McCauliff, S.; Metcalfe, T.; Middour, C. K.; Molenda-Zakowicz, J.; Monteiro, M. J. P. F. G.; Smith, J. C.; Thompson, M. J. Bibcode: 2011MNRAS.414L...6G Altcode: 2011arXiv1103.0382G The Kepler mission is providing photometric data of exquisite quality for the asteroseismic study of different classes of pulsating stars. These analyses place particular demands on the pre-processing of the data, over a range of time-scales from minutes to months. Here, we describe processing procedures developed by the Kepler Asteroseismic Science Consortium to prepare light curves that are optimized for the asteroseismic study of solar-like oscillating stars in which outliers, jumps and drifts are corrected. Title: Asteroseismic inferences on red giants in open clusters NGC 6791, NGC 6819, and NGC 6811 using Kepler Authors: Hekker, S.; Basu, S.; Stello, D.; Kallinger, T.; Grundahl, F.; Mathur, S.; García, R. A.; Mosser, B.; Huber, D.; Bedding, T. R.; Szabó, R.; De Ridder, J.; Chaplin, W. J.; Elsworth, Y.; Hale, S. J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Still, M.; McCauliff, S.; Quintana, E. V. Bibcode: 2011A&A...530A.100H Altcode: 2011arXiv1104.4393H Context. Four open clusters are present in the Kepler field of view and timeseries of nearly a year in length are now available. These timeseries allow us to derive asteroseismic global oscillation parameters of red-giant stars in the three open clusters NGC 6791, NGC 6819 and NGC 6811. From these parameters and effective temperatures, we derive masses, radii and luminosities for the clusters as well as field red giants.
Aims: We study the influence of evolution and metallicity on the observed red-giant populations.
Methods: The global oscillation parameters are derived using different published methods and the effective temperatures are derived from 2MASS colours. The observational results are compared with BaSTI evolution models.
Results: We find that the mass has significant influence on the asteroseismic quantities Δν vs. νmax relation, while the influence of metallicity is negligible, under the assumption that the metallicity does not affect the excitation/damping of the oscillations. The positions of the stars in the H-R diagram depend on both mass and metallicity. Furthermore, the stellar masses derived for the field stars are bracketed by those of the cluster stars.
Conclusions: Both the mass and metallicity contribute to the observed difference in locations in the H-R diagram of the old metal-rich cluster NGC 6791 and the middle-aged solar-metallicity cluster NGC 6819. For the young cluster NGC 6811, the explanation of the position of the stars in the H-R diagram challenges the assumption of solar metallicity, and this open cluster might have significantly lower metallicity [Fe/H] in the range - 0.3 to - 0.7 dex. Also, nearly all the observed field stars seem to be older than NGC 6811 and younger than NGC 6791. Title: Accurate p-mode measurements of the G0V metal-rich CoRoT target HD 52265 Authors: Ballot, J.; Gizon, L.; Samadi, R.; Vauclair, G.; Benomar, O.; Bruntt, H.; Mosser, B.; Stahn, T.; Verner, G. A.; Campante, T. L.; García, R. A.; Mathur, S.; Salabert, D.; Gaulme, P.; Régulo, C.; Roxburgh, I. W.; Appourchaux, T.; Baudin, F.; Catala, C.; Chaplin, W. J.; Deheuvels, S.; Michel, E.; Bazot, M.; Creevey, O.; Dolez, N.; Elsworth, Y.; Sato, K. H.; Vauclair, S.; Auvergne, M.; Baglin, A. Bibcode: 2011A&A...530A..97B Altcode: 2011arXiv1105.3551B Context. The star HD 52265 is a G0V metal-rich exoplanet-host star observed in the seismology field of the CoRoT space telescope from November 2008 to March 2009. The satellite collected 117 days of high-precision photometric data on this star, showing that it presents solar-like oscillations. HD 52265 was also observed in spectroscopy with the Narval spectrograph at the same epoch.
Aims: We characterise HD 52265 using both spectroscopic and seismic data.
Methods: The fundamental stellar parameters of HD 52265 were derived with the semi-automatic software VWA, and the projected rotational velocity was estimated by fitting synthetic profiles to isolated lines in the observed spectrum. The parameters of the observed p modes were determined with a maximum-likelihood estimation. We performed a global fit of the oscillation spectrum, over about ten radial orders, for degrees l = 0 to 2. We also derived the properties of the granulation, and analysed a signature of the rotation induced by the photospheric magnetic activity.
Results: Precise determinations of fundamental parameters have been obtained: Teff = 6100 ± 60 K, log g = 4.35 ± 0.09, [M/H] = 0.19 ± 0.05, as well as vsini=3.6+0.3-1.0kms. We have measured a mean rotation period Prot = 12.3 ± 0.15 days, and find a signature of differential rotation. The frequencies of 31 modes are reported in the range 1500-2550 μHz. The large separation exhibits a clear modulation around the mean value Dnu=98.3 ± 0.1 μHz. Mode widths vary with frequency along an S-shape with a clear local maximum around 1800 μHz. We deduce lifetimes ranging between 0.5 and 3 days for these modes. Finally, we find a maximal bolometric amplitude of about 3.96 ± 0.24 ppm for radial modes.

The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain. Title: Solar-cycle variations of large frequency separations of acoustic modes: implications for asteroseismology Authors: Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; New, R. Bibcode: 2011MNRAS.413.2978B Altcode: 2011MNRAS.tmp..428B; 2011arXiv1102.0906B We have studied solar-cycle changes in the large frequency separations that can be observed in Birmingham Solar Oscillations Network (BiSON) data. The large frequency separation is often one of the first outputs from asteroseismic studies because it can help constrain stellar properties like mass and radius. We have used three methods for estimating the large separations: use of individual p-mode frequencies, computation of the autocorrelation of frequency-power spectra, and computation of the power spectrum of the power spectrum. The values of the large separations obtained by the different methods are offset from each other and have differing sensitivities to the realization noise. A simple model was used to predict solar-cycle variations in the large separations, indicating that the variations are due to the well-known solar-cycle changes to mode frequency. However, this model is only valid over a restricted frequency range. We discuss the implications of these results for asteroseismology. Title: VizieR Online Data Catalog: Solar-like oscillations in Kepler red giants (Hekker+, 2011) Authors: Hekker, S.; Elsworth, Y.; De Ridder, J.; Mosser, B.; Garcia, R. A.; Kallinger, T.; Mathur, S.; Huber, D.; Buzasi, D. L.; Preston, H. L.; Hale, S. J.; Ballot, J.; Chaplin, W. J.; Regulo, C.; Bedding, T. R.; Stello, D.; Borucki, W. J.; Koch, D. G.; Jenkins, J.; Allen, C.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J. Bibcode: 2011yCat..35250131H Altcode: 2011yCat..35259131H For this investigation we use Kepler data obtained during the first four months of operation. These data have been analysed by different groups using already published methods and the results are compared. We also performed simulations to investigate the uncertainty on the resulting parameters due to different realizations of the stochastic signal.

(1 data file). Title: The OCTAVE automated pipeline for extracting individual mode parameters of solar-like oscillations in main-sequence stars Authors: Fletcher, S. T.; Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; Hekker, S.; New, R. Bibcode: 2011MNRAS.413..359F Altcode: 2011MNRAS.tmp..197F With the launch of the NASA Kepler spacecraft, the number of solar-like stars for which there are high-precision photometric observations available has increased considerably. In order to analyse the data from a large number of stars in a reasonable amount of time, automated pipelines are desirable. Here we present an extension of the OCTAVE (Birmingham-Sheffield Hallam) pipeline, which has been developed as part of the AsteroFLAG collaboration. While the first parts of the pipeline extracted overall oscillation parameters of the stars, here we present a significant extension to that pipeline designed in order to extract individual mode frequencies and amplitudes. The pipeline also attempts to label the detected modes by straightening and then identifying the ridges within the echelle diagrams in an automated manner. Tests have been performed on artificial stars and the pipeline is shown to return estimates of the mode frequencies that are in line with the input parameters. There does appear to be some positive bias in the returned value of the mode amplitudes which must be accounted for when employing the pipeline for real data. Title: Helioseismic Studies With Multi-wavelength Data From HMI And AIA Onboard SDO Authors: Hill, Frank; Jain, K.; Tripathy, S.; Kholikov, S.; Gonzalez Hernandez, I.; Leibacher, J.; Howe, R.; Baudin, F.; Carlsson, M.; Chaplin, W.; Tarbell, T. Bibcode: 2011SPD....42.2111H Altcode: 2011BAAS..43S.2111H The successful launch of the Solar Dynamics Observatory (SDO) in February 2010 opens important, new possibilities for helioseismic exploration of the solar interior and atmosphere using multi-wavelength observations from multiple instruments. In order to better understand the solar interior and atmosphere, as well as the physics of the helioseismic modes and waves themselves, we exploit the potential of the Atmospheric Imaging Assembly (AIA) 1600 and 1700 Angstrom continuum measurements and the contemporaneous Helioseismic and Magnetic Imager (HMI) Fe I 6173.3 Angstrom velocity and intensity observations. Standard techniques of helioseismology e.g Sun-as-a-star, spherical harmonic analysis, ring diagrams, and time- distance analysis are applied to obtain acoustic mode parameters and other characteristics. Here we present our preliminary results, and interpret these in the context of the differences in the heights of formation of the lines. Title: Predicting the Detectability of Oscillations in Solar-type Stars Observed by Kepler Authors: Chaplin, W. J.; Kjeldsen, H.; Bedding, T. R.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Appourchaux, T.; Elsworth, Y.; García, R. A.; Houdek, G.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Verner, G. A.; Batalha, N.; Borucki, W. J.; Brown, T. M.; Bryson, S. T.; Christiansen, J. L.; Clarke, B. D.; Jenkins, J. M.; Klaus, T. C.; Koch, D.; An, D.; Ballot, J.; Basu, S.; Benomar, O.; Bonanno, A.; Broomhall, A. -M.; Campante, T. L.; Corsaro, E.; Creevey, O. L.; Esch, L.; Gai, N.; Gaulme, P.; Hale, S. J.; Handberg, R.; Hekker, S.; Huber, D.; Mathur, S.; Mosser, B.; New, R.; Pinsonneault, M. H.; Pricopi, D.; Quirion, P. -O.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; Stello, D.; Suran, M. D. Bibcode: 2011ApJ...732...54C Altcode: 2011arXiv1103.0702C Asteroseismology of solar-type stars has an important part to play in the exoplanet program of the NASA Kepler Mission. Precise and accurate inferences on the stellar properties that are made possible by the seismic data allow very tight constraints to be placed on the exoplanetary systems. Here, we outline how to make an estimate of the detectability of solar-like oscillations in any given Kepler target, using rough estimates of the temperature and radius, and the Kepler apparent magnitude. Title: Evidence for the Impact of Stellar Activity on the Detectability of Solar-like Oscillations Observed by Kepler Authors: Chaplin, W. J.; Bedding, T. R.; Bonanno, A.; Broomhall, A. -M.; García, R. A.; Hekker, S.; Huber, D.; Verner, G. A.; Basu, S.; Elsworth, Y.; Houdek, G.; Mathur, S.; Mosser, B.; New, R.; Stevens, I. R.; Appourchaux, T.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kawaler, S. D.; Kjeldsen, H.; Ballot, J.; Benomar, O.; Corsaro, E.; Campante, T. L.; Gaulme, P.; Hale, S. J.; Handberg, R.; Jarvis, E.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; Stello, D.; Mullally, F.; Li, J.; Wohler, W. Bibcode: 2011ApJ...732L...5C Altcode: 2011arXiv1103.5570C We use photometric observations of solar-type stars, made by the NASA Kepler Mission, to conduct a statistical study of the impact of stellar surface activity on the detectability of solar-like oscillations. We find that the number of stars with detected oscillations falls significantly with increasing levels of activity. The results present strong evidence for the impact of magnetic activity on the properties of near-surface convection in the stars, which appears to inhibit the amplitudes of the stochastically excited, intrinsically damped solar-like oscillations. Title: Ensemble Asteroseismology of Solar-Type Stars with the NASA Kepler Mission Authors: Chaplin, W. J.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Basu, S.; Miglio, A.; Appourchaux, T.; Bedding, T. R.; Elsworth, Y.; García, R. A.; Gilliland, R. L.; Girardi, L.; Houdek, G.; Karoff, C.; Kawaler, S. D.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Verner, G. A.; Ballot, J.; Bonanno, A.; Brandão, I. M.; Broomhall, A. -M.; Bruntt, H.; Campante, T. L.; Corsaro, E.; Creevey, O. L.; Doğan, G.; Esch, L.; Gai, N.; Gaulme, P.; Hale, S. J.; Handberg, R.; Hekker, S.; Huber, D.; Jiménez, A.; Mathur, S.; Mazumdar, A.; Mosser, B.; New, R.; Pinsonneault, M. H.; Pricopi, D.; Quirion, P. -O.; Régulo, C.; Salabert, D.; Serenelli, A. M.; Silva Aguirre, V.; Sousa, S. G.; Stello, D.; Stevens, I. R.; Suran, M. D.; Uytterhoeven, K.; White, T. R.; Borucki, W. J.; Brown, T. M.; Jenkins, J. M.; Kinemuchi, K.; Van Cleve, J.; Klaus, T. C. Bibcode: 2011Sci...332..213C Altcode: 2011arXiv1109.4723C In addition to its search for extrasolar planets, the NASA Kepler mission provides exquisite data on stellar oscillations. We report the detections of oscillations in 500 solar-type stars in the Kepler field of view, an ensemble that is large enough to allow statistical studies of intrinsic stellar properties (such as mass, radius, and age) and to test theories of stellar evolution. We find that the distribution of observed masses of these stars shows intriguing differences to predictions from models of synthetic stellar populations in the Galaxy. Title: An In-depth Study of Grid-based Asteroseismic Analysis Authors: Gai, Ning; Basu, Sarbani; Chaplin, William J.; Elsworth, Yvonne Bibcode: 2011ApJ...730...63G Altcode: 2010arXiv1009.3018G NASA's Kepler mission is providing basic asteroseismic data for hundreds of stars. One of the more common ways of determining stellar characteristics from these data is by the so-called grid-based modeling. We have made a detailed study of grid-based analysis techniques to study the errors (and error correlations) involved. As had been reported earlier, we find that it is relatively easy to get very precise values of stellar radii using grid-based techniques. However, we find that there are small, but significant, biases that can result because of the grid of models used. The biases can be minimized if metallicity is known. Masses cannot be determined as precisely as the radii and suffer from larger systematic effects. We also find that the errors in mass and radius are correlated. A positive consequence of this correlation is that log g can be determined both precisely and accurately with almost no systematic biases. Radii and log g can be determined with almost no model dependence to within 5% for realistic estimates of errors in asteroseismic and conventional observations. Errors in mass can be somewhat higher unless accurate metallicity estimates are available. Age estimates of individual stars are the most model dependent. The errors are larger, too. However, we find that for star clusters, it is possible to get a relatively precise age if one assumes that all stars in a given cluster have the same age. Title: Kepler Detected Gravity-Mode Period Spacings in a Red Giant Star Authors: Beck, P. G.; Bedding, T. R.; Mosser, B.; Stello, D.; Garcia, R. A.; Kallinger, T.; Hekker, S.; Elsworth, Y.; Frandsen, S.; Carrier, F.; De Ridder, J.; Aerts, C.; White, T. R.; Huber, D.; Dupret, M. -A.; Montalbán, J.; Miglio, A.; Noels, A.; Chaplin, W. J.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Brown, T. M.; Kawaler, S. D.; Mathur, S.; Jenkins, J. M. Bibcode: 2011Sci...332..205B Altcode: Stellar interiors are inaccessible through direct observations. For this reason, helioseismologists made use of the Sun’s acoustic oscillation modes to tune models of its structure. The quest to detect modes that probe the solar core has been ongoing for decades. We report the detection of mixed modes penetrating all the way to the core of an evolved star from 320 days of observations with the Kepler satellite. The period spacings of these mixed modes are directly dependent on the density gradient between the core region and the convective envelope. Title: Sounding Open Clusters: Asteroseismic Constraints from Kepler on the Properties of NGC 6791 and NGC 6819 Authors: Basu, Sarbani; Grundahl, Frank; Stello, Dennis; Kallinger, Thomas; Hekker, Saskia; Mosser, Benoit; García, Rafael A.; Mathur, Savita; Brogaard, Karsten; Bruntt, Hans; Chaplin, William J.; Gai, Ning; Elsworth, Yvonne; Esch, Lisa; Ballot, Jerome; Bedding, Timothy R.; Gruberbauer, Michael; Huber, Daniel; Miglio, Andrea; Yildiz, Mutlu; Kjeldsen, Hans; Christensen-Dalsgaard, Jørgen; Gilliland, Ronald L.; Fanelli, Michael M.; Ibrahim, Khadeejah A.; Smith, Jeffrey C. Bibcode: 2011ApJ...729L..10B Altcode: 2011arXiv1102.2231B We present initial results on some of the properties of open clusters NGC 6791 and NGC 6819 derived from asteroseismic data obtained by NASA's Kepler mission. In addition to estimating the mass, radius, and log g of stars on the red giant branch (RGB) of these clusters, we estimate the distance to the clusters and their ages. Our model-independent estimate of the distance modulus of NGC 6791 is (m - M)0 = 13.11 ± 0.06. We find (m - M)0 = 11.85 ± 0.05 for NGC 6819. The average mass of stars on the RGB of NGC 6791 is 1.20 ± 0.01 M sun, while that of NGC 6819 is 1.68 ± 0.03 M sun. It should be noted that we do not have data that cover the entire RGB and the actual mass will be somewhat lower. We have determined model-dependent estimates of ages of these clusters. We find ages between 6.8 and 8.6 Gyr for NGC 6791, however, most sets of models give ages around 7 Gyr. We obtain ages between 2 and 2.4 Gyr for NGC 6819. Title: Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars Authors: Bedding, Timothy R.; Mosser, Benoit; Huber, Daniel; Montalbán, Josefina; Beck, Paul; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne P.; García, Rafael A.; Miglio, Andrea; Stello, Dennis; White, Timothy R.; De Ridder, Joris; Hekker, Saskia; Aerts, Conny; Barban, Caroline; Belkacem, Kevin; Broomhall, Anne-Marie; Brown, Timothy M.; Buzasi, Derek L.; Carrier, Fabien; Chaplin, William J.; di Mauro, Maria Pia; Dupret, Marc-Antoine; Frandsen, Søren; Gilliland, Ronald L.; Goupil, Marie-Jo; Jenkins, Jon M.; Kallinger, Thomas; Kawaler, Steven; Kjeldsen, Hans; Mathur, Savita; Noels, Arlette; Silva Aguirre, Victor; Ventura, Paolo Bibcode: 2011Natur.471..608B Altcode: 2011arXiv1103.5805B Red giants are evolved stars that have exhausted the supply of hydrogen in their cores and instead burn hydrogen in a surrounding shell. Once a red giant is sufficiently evolved, the helium in the core also undergoes fusion. Outstanding issues in our understanding of red giants include uncertainties in the amount of mass lost at the surface before helium ignition and the amount of internal mixing from rotation and other processes. Progress is hampered by our inability to distinguish between red giants burning helium in the core and those still only burning hydrogen in a shell. Asteroseismology offers a way forward, being a powerful tool for probing the internal structures of stars using their natural oscillation frequencies. Here we report observations of gravity-mode period spacings in red giants that permit a distinction between evolutionary stages to be made. We use high-precision photometry obtained by the Kepler spacecraft over more than a year to measure oscillations in several hundred red giants. We find many stars whose dipole modes show sequences with approximately regular period spacings. These stars fall into two clear groups, allowing us to distinguish unambiguously between hydrogen-shell-burning stars (period spacing mostly ~50seconds) and those that are also burning helium (period spacing ~100 to 300 seconds). Title: Variations of the amplitudes of oscillation of the Be star Achernar Authors: Goss, K. J. F.; Karoff, C.; Chaplin, W. J.; Elsworth, Y.; Stevens, I. R. Bibcode: 2011MNRAS.411..162G Altcode: 2010arXiv1010.0834G; 2010MNRAS.tmp.1668G We report on finding variations in amplitude of the two main oscillation frequencies found in the Be star Achernar, over a period of 5 yr. They were uncovered by analysing photometric data of the star from the Solar Mass Ejection Imager (SMEI) instrument. The two frequencies observed, 0.775 and 0.725 d-1, were analysed in detail and their amplitudes were found to increase and decrease significantly over the 5-yr period, with the amplitude of the 0.725 d-1 frequency changing by up to a factor of 8. The nature of this event has yet to be properly understood, but the possibility of it being due to the effects of a stellar outburst or a stellar cycle are discussed. Title: The radius and mass of the close solar twin 18 Scorpii derived from asteroseismology and interferometry Authors: Bazot, M.; Ireland, M. J.; Huber, D.; Bedding, T. R.; Broomhall, A. -M.; Campante, T. L.; Carfantan, H.; Chaplin, W. J.; Elsworth, Y.; Meléndez, J.; Petit, P.; Théado, S.; Van Grootel, V.; Arentoft, T.; Asplund, M.; Castro, M.; Christensen-Dalsgaard, J.; Do Nascimento, J. D.; Dintrans, B.; Dumusque, X.; Kjeldsen, H.; McAlister, H. A.; Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Santos, N. C.; Sousa, S.; Sturmann, J.; Sturmann, L.; ten Brummelaar, T. A.; Turner, N.; Vauclair, S. Bibcode: 2011A&A...526L...4B Altcode: 2012arXiv1209.0217B The growing interest in solar twins is motivated by the possibility of comparing them directly to the Sun. To carry on this kind of analysis, we need to know their physical characteristics with precision. Our first objective is to use asteroseismology and interferometry on the brightest of them: 18 Sco. We observed the star during 12 nights with HARPS for seismology and used the PAVO beam-combiner at CHARA for interferometry. An average large frequency separation 134.4 ± 0.3 μHz and angular and linear radiuses of 0.6759 ± 0.0062 mas and 1.010 ± 0.009 R⊙ were estimated. We used these values to derive the mass of the star, 1.02 ± 0.03 M⊙.

Based on observations collected at the European Southern Observatory (ID 183.D-0729(A)) and at the CHARA Array, operated by Georgia State University. Title: Are short-term variations in solar oscillation frequencies the signature of a second solar dynamo? Authors: Broomhall, Anne-Marie; Fletcher, Stephen T.; Salabert, David; Basu, Sarbani; Chaplin, William J.; Elsworth, Yvonne; García, Rafael A.; Jiménez, Antonio; New, Roger Bibcode: 2011JPhCS.271a2025B Altcode: 2010arXiv1012.4933B In addition to the well-known 11-year solar cycle, the Sun's magnetic activity also shows significant variation on shorter time scales, e.g. between one and two years. We observe a quasi-biennial (2-year) signal in the solar p-mode oscillation frequencies, which are sensitive probes of the solar interior. The signal is visible in Sun-as-a-star data observed by different instruments and here we describe the results obtained using BiSON, GOLF, and VIRGO data. Our results imply that the 2-year signal is susceptible to the influence of the main 11-year solar cycle. However, the source of the signal appears to be separate from that of the 11-year cycle. We speculate as to whether it might be the signature of a second dynamo, located in the region of near-surface rotational shear. Title: Solar-like oscillations in red giants observed with Kepler: comparison of global oscillation parameters from different methods Authors: Hekker, S.; Elsworth, Y.; De Ridder, J.; Mosser, B.; García, R. A.; Kallinger, T.; Mathur, S.; Huber, D.; Buzasi, D. L.; Preston, H. L.; Hale, S. J.; Ballot, J.; Chaplin, W. J.; Régulo, C.; Bedding, T. R.; Stello, D.; Borucki, W. J.; Koch, D. G.; Jenkins, J.; Allen, C.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J. Bibcode: 2011A&A...525A.131H Altcode: 2010arXiv1008.2959H Context. The large number of stars for which uninterrupted high-precision photometric timeseries data are being collected with Kepler and CoRoT initiated the development of automated methods to analyse the stochastically excited oscillations in main-sequence, subgiant and red-giant stars.
Aims: We investigate the differences in results for global oscillation parameters of G and K red-giant stars due to different methods and definitions. We also investigate uncertainties originating from the stochastic nature of the oscillations.
Methods: For this investigation we use Kepler data obtained during the first four months of operation. These data have been analysed by different groups using already published methods and the results are compared. We also performed simulations to investigate the uncertainty on the resulting parameters due to different realizations of the stochastic signal.
Results: We obtain results for the frequency of maximum oscillation power (ν_max) and the mean large separation (<Δν>) from different methods for over one thousand red-giant stars. The results for these parameters agree within a few percent and seem therefore robust to the different analysis methods and definitions used here. The uncertainties for ν_max and <Δν> due to differences in realization noise are not negligible and should be taken into account when using these results for stellar modelling.

Table 7 is only available in electronic form at http://www.aanda.org Title: Low-degree helioseismology with AIA Authors: Howe, R.; Hill, F.; Komm, R.; Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2011JPhCS.271a2058H Altcode: We form unresolved-sun time series from the 1600 and 1700 Angstrom images produced by the Atmospheric Imaging Assembly, and find a clean low-degree p-mode spectrum at each wavelength. The time series and spectra are compared with Doppler velocity and continuum intensity time series from the Helioseismic and Magnetic Imager and velocity series from the Birmingham Solar Oscillation Network. The UV data have a slight phase shift with respect to the velocity, and show more sensitivity to high-frequency and less to low-frequency modes. Unlike the HMI (visible) continuum observations, the UV spectra show little or no granulation noise at low frequencies and thus potentially allow more low-frequency modes to be recovered. These results suggest that asteroseismology at near-UV wavelengths should be very feasible and even an improvement on visible-wavelength intensity measurements, at least in low-activity stars. Title: Asteroseismology of solar-type stars with Kepler I: Data analysis Authors: Karoff, C.; Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; Garcia, R. A.; Houdek, G.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Basu, S.; Bedding, T. R.; Campante, T. L.; Eggenberger, P.; Fletcher, S. T.; Gaulme, P.; Handberg, R.; Hekker, S.; Martic, M.; Mathur, S.; Mosser, B.; Regulo, C.; Roxburgh, I. W.; Salabert, D.; Stello, D.; Verner, G. A.; Belkacem, K.; Biazzo, K.; Cunha, M. S.; Gruberbauer, M.; Guzik, J. A.; Kupka, F.; Leroy, B.; Ludwig, H. -G.; Mathis, S.; Noels, A.; Noyes, R. W.; Roca Cortes, T.; Roth, M.; Sato, K. H.; Schmitt, J.; Suran, M. D.; Trampedach, R.; Uytterhoeven, K.; Ventura, R. Bibcode: 2010AN....331..972K Altcode: 2010arXiv1005.0507K We report on the first asteroseismic analysis of solar-type stars observed by Kepler. Observations of three G-type stars, made at one-minute cadence during the first 33.5 days of science operations, reveal high signal-to-noise solar-like oscillation spectra in all three stars: About 20 modes of oscillation can clearly be distinguished in each star. We discuss the appearance of the oscillation spectra, including the presence of a possible signature of faculae, and the presence of mixed modes in one of the three stars. Title: Asteroseismology of solar-type stars with Kepler: II. Stellar modeling Authors: Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Chaplin, W. J.; Basu, S.; Bonanno, A.; Di Mauro, M. P.; Doğan, G.; Eggenberger, P.; Karoff, C.; Stello, D.; WG1, KASC Bibcode: 2010AN....331..977M Altcode: 2010arXiv1006.5695M Observations from the Kepler satellite were recently published for three bright G-type stars, which were monitored during the first 33.5 days of science operations. One of these stars, KIC 11026764, exhibits a characteristic pattern of oscillation frequencies suggesting that the star has evolved significantly. We have derived initial estimates of the properties of KIC 11026764 from the oscillation frequencies observed by Kepler, combined with ground-based spectroscopic data. We present preliminary results from detailed modeling of this star, employing a variety of independent codes and analyses that attempt to match the asteroseismic and spectroscopic constraints simultaneously. Title: Challenges and opportunities for helio- and asteroseismology Authors: Chaplin, W. J. Bibcode: 2010AN....331.1090C Altcode: 2010arXiv1006.5320C I consider some of the challenges and opportunities facing helio- and asteroseismology, which reflect major themes of presentation and discussion from the HELAS IV international conference ``Seismological Challenges for Stellar Structure''. I concentrate in particular on the exciting prospects for asteroseismology, now that the field is being provided with data of unprecedented quality and in unprecedented volumes. Title: Solar-like oscillations in cluster stars Authors: Stello, D.; Basu, S.; Bedding, T. R.; Brogaard, K.; Bruntt, H.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Demarque, P.; Elsworth, Y. P.; García, R. A.; Gilliland, R. L.; Hekker, S.; Huber, D.; Karoff, C.; Kjeldsen, H.; Lebreton, Y.; Mathur, S.; Meibom, S.; Molenda-Żakowicz, J.; Noels, A.; Roxburgh, I. W.; Silva Aguirre, V.; Sterken, C.; Szabó, R. Bibcode: 2010AN....331..985S Altcode: 2010arXiv1007.0009S This article summaries a talk given at the HELAS IV international meeting We present a brief overview of the history of attempts to obtain a clear detection of solar-like oscillations in cluster stars, and discuss the results on the first clear detection, which was made by the Kepler Asteroseismic Science Consortium (KASC) Working Group 2.

Data from Kepler. Title: Asteroseismology of Red Giants from the First Four Months of Kepler Data: Global Oscillation Parameters for 800 Stars Authors: Huber, D.; Bedding, T. R.; Stello, D.; Mosser, B.; Mathur, S.; Kallinger, T.; Hekker, S.; Elsworth, Y. P.; Buzasi, D. L.; De Ridder, J.; Gilliland, R. L.; Kjeldsen, H.; Chaplin, W. J.; García, R. A.; Hale, S. J.; Preston, H. L.; White, T. R.; Borucki, W. J.; Christensen-Dalsgaard, J.; Clarke, B. D.; Jenkins, J. M.; Koch, D. Bibcode: 2010ApJ...723.1607H Altcode: 2010arXiv1010.4566H We have studied solar-like oscillations in ~800 red giant stars using Kepler long-cadence photometry. The sample includes stars ranging in evolution from the lower part of the red giant branch to the helium main sequence. We investigate the relation between the large frequency separation (Δν) and the frequency of maximum power (νmax) and show that it is different for red giants than for main-sequence stars, which is consistent with evolutionary models and scaling relations. The distributions of νmax and Δν are in qualitative agreement with a simple stellar population model of the Kepler field, including the first evidence for a secondary clump population characterized by M >~ 2 M sun and νmax ~= 40-110 μHz. We measured the small frequency separations δν02 and δν01 in over 400 stars and δν03 in over 40. We present C-D diagrams for l = 1, 2, and 3 and show that the frequency separation ratios δν02/Δν and δν01/Δν have opposite trends as a function of Δν. The data show a narrowing of the l = 1 ridge toward lower νmax, in agreement with models predicting more efficient mode trapping in stars with higher luminosity. We investigate the offset epsilon in the asymptotic relation and find a clear correlation with Δν, demonstrating that it is related to fundamental stellar parameters. Finally, we present the first amplitude-νmax relation for Kepler red giants. We observe a lack of low-amplitude stars for νmax >~ 110 μHz and find that, for a given νmax between 40 and 110 μHz, stars with lower Δν (and consequently higher mass) tend to show lower amplitudes than stars with higher Δν. Title: A Precise Asteroseismic Age and Radius for the Evolved Sun-like Star KIC 11026764 Authors: Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Molenda-Żakowicz, J.; Appourchaux, T.; Chaplin, W. J.; Doǧan, G.; Eggenberger, P.; Bedding, T. R.; Bruntt, H.; Creevey, O. L.; Quirion, P. -O.; Stello, D.; Bonanno, A.; Silva Aguirre, V.; Basu, S.; Esch, L.; Gai, N.; Di Mauro, M. P.; Kosovichev, A. G.; Kitiashvili, I. N.; Suárez, J. C.; Moya, A.; Piau, L.; García, R. A.; Marques, J. P.; Frasca, A.; Biazzo, K.; Sousa, S. G.; Dreizler, S.; Bazot, M.; Karoff, C.; Frandsen, S.; Wilson, P. A.; Brown, T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Campante, T. L.; Fletcher, S. T.; Handberg, R.; Régulo, C.; Salabert, D.; Schou, J.; Verner, G. A.; Ballot, J.; Broomhall, A. -M.; Elsworth, Y.; Hekker, S.; Huber, D.; Mathur, S.; New, R.; Roxburgh, I. W.; Sato, K. H.; White, T. R.; Borucki, W. J.; Koch, D. G.; Jenkins, J. M. Bibcode: 2010ApJ...723.1583M Altcode: 2010arXiv1010.4329M The primary science goal of the Kepler Mission is to provide a census of exoplanets in the solar neighborhood, including the identification and characterization of habitable Earth-like planets. The asteroseismic capabilities of the mission are being used to determine precise radii and ages for the target stars from their solar-like oscillations. Chaplin et al. published observations of three bright G-type stars, which were monitored during the first 33.5 days of science operations. One of these stars, the subgiant KIC 11026764, exhibits a characteristic pattern of oscillation frequencies suggesting that it has evolved significantly. We have derived asteroseismic estimates of the properties of KIC 11026764 from Kepler photometry combined with ground-based spectroscopic data. We present the results of detailed modeling for this star, employing a variety of independent codes and analyses that attempt to match the asteroseismic and spectroscopic constraints simultaneously. We determine both the radius and the age of KIC 11026764 with a precision near 1%, and an accuracy near 2% for the radius and 15% for the age. Continued observations of this star promise to reveal additional oscillation frequencies that will further improve the determination of its fundamental properties. Title: Asteroseismology of red giants from the first four months of Kepler data: Fundamental stellar parameters Authors: Kallinger, T.; Mosser, B.; Hekker, S.; Huber, D.; Stello, D.; Mathur, S.; Basu, S.; Bedding, T. R.; Chaplin, W. J.; De Ridder, J.; Elsworth, Y. P.; Frandsen, S.; García, R. A.; Gruberbauer, M.; Matthews, J. M.; Borucki, W. J.; Bruntt, H.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Koch, D. G. Bibcode: 2010A&A...522A...1K Altcode: 2010arXiv1010.4589K Context. Clear power excess in a frequency range typical for solar-type oscillations in red giants has been detected in more than 1000 stars, which have been observed during the first 138 days of the science operation of the NASA Kepler satellite. This sample includes stars in a wide mass and radius range with spectral types G and K, extending in luminosity from the bottom of the giant branch up to high-luminous red giants, including the red bump and clump. The high-precision asteroseismic observations with Kepler provide a perfect source for testing stellar structure and evolutionary models, as well as investigating the stellar population in our Galaxy.
Aims: We aim to extract accurate seismic parameters from the Kepler time series and use them to infer asteroseismic fundamental parameters from scaling relations and a comparison with red-giant models.
Methods: We fit a global model to the observed power density spectra, which allows us to accurately estimate the granulation background signal and the global oscillation parameters, such as the frequency of maximum oscillation power. We find regular patterns of radial and non-radial oscillation modes and use a new technique to automatically identify the mode degree and the characteristic frequency separations between consecutive modes of the same spherical degree. In most cases, we can also measure the small separation between l = 0, 1, and 2 modes. Subsequently, the seismic parameters are used to estimate stellar masses and radii and to place the stars in an H-R diagram by using an extensive grid of stellar models that covers a wide parameter range. Using Bayesian techniques throughout our entire analysis allows us to determine reliable uncertainties for all parameters.
Results: We provide accurate seismic parameters and their uncertainties for a large sample of red giants and determine their asteroseismic fundamental parameters. We investigate the influence of the stars' metallicities on their positions in the H-R diagram. Finally, we study the red-giant populations in the red clump and bump and compare them to a synthetic population. We find a mass and metallicity gradient in the red clump and clear evidence of a secondary-clump population. Title: Modelling the autocovariance of the power spectrum of a solar-type oscillator Authors: Campante, T. L.; Karoff, C.; Chaplin, W. J.; Elsworth, Y. P.; Handberg, R.; Hekker, S. Bibcode: 2010MNRAS.408..542C Altcode: 2010arXiv1006.0925C; 2010MNRAS.tmp.1125C Asteroseismology is able to conduct studies on the interiors of solar-type stars from the analysis of stellar acoustic spectra. However, such an analysis process often has to rely upon subjective choices made throughout. A recurring problem is to determine whether a signal in the acoustic spectrum originates from a radial or a dipolar oscillation mode. In order to overcome this problem, we present a procedure for modelling and fitting the autocovariance of the power spectrum which can be used to obtain global seismic parameters of solar-type stars, doing so in an automated fashion without the need to make subjective choices. From the set of retrievable global seismic parameters we emphasize the mean small frequency separation and, depending on the intrinsic characteristics of the power spectrum, the mean rotational frequency splitting. Since this procedure is automated, it can serve as a useful tool in the analysis of the more than 1000 solar-type stars expected to be observed as part of the Kepler Asteroseismic Investigation (KAI). We apply the aforementioned procedure to simulations of the Sun. Assuming different apparent magnitudes, we address the issues of how accurately and how precisely we can retrieve the several global seismic parameters were the Sun to be observed as part of the KAI. Title: Oscillation mode lifetimes of red giants observed during the initial and first anticentre long run of CoRoT Authors: Hekker, S.; Barban, C.; Baudin, F.; De Ridder, J.; Kallinger, T.; Morel, T.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2010A&A...520A..60H Altcode: 2010arXiv1006.4284H Context. Long timeseries of data increase the frequency resolution in the power spectrum. This allows for resolving stochastically excited modes with long mode lifetimes, as well as features that are close together in frequency. The CoRoT fields observed during the initial run and second long run partly overlap, and stars in this overlapping field observed in both runs are used to create timeseries with a longer timespan than available from the individual runs.
Aims: We aim to measure the mode lifetimes of red giants and compare them with theoretical predictions. We also investigate the dependence of the mode lifetimes on frequency and the degree of the oscillation modes.
Methods: We perform simulations to investigate the influence of the gap in the data between the initial and second long run, the total length of the run and the signal-to-noise ratio on the measured mode lifetime. This provides us with a correction factor to apply to the mode lifetimes measured from a maximum likelihood fit to the oscillation frequencies.
Results: We find that the length of the timeseries, the signal-to-noise ratio and possible gaps do have a non-negligible effect on the measurements of the mode lifetime of stochastically excited oscillation modes, but we can correct for it. For the four stars for which we can perform a fit of the oscillation frequencies, we find that the mode lifetimes depend on frequency and on degree of the mode, which quantitatively agrees with theoretical predictions.

The CoRoT space mission which was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain. Light curves can be retrieved from the CoRoT archive: http://idoc-corot.ias.u-psud.fr. Title: A comparison of frequentist and Bayesian inference: searching for low-frequency p modes and g modes in Sun-as-a-star data Authors: Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; Appourchaux, T.; New, R. Bibcode: 2010MNRAS.406..767B Altcode: 2010MNRAS.tmp..680B; 2010arXiv1004.4505B We describe and use two different statistical approaches to try and detect low-frequency solar oscillations in Sun-as-a-star data: a frequentist approach and a Bayesian approach. We have used frequentist statistics to search contemporaneous Sun-as-a-star data for coincident, statistically prominent features. However, we find that this approach leads to numerous false detections. We have also used Bayesian statistics to search for evidence of low-frequency p modes and g modes in Sun-as-a-star data. We describe how Bayesian statistics can be used to search near-contemporaneous data for coincident prominent features. Near-contemporaneous data were used to circumvent the difficulties in deriving probabilities that occur when common noise is present in the data. We find that the Bayesian approach, which is reliant on the assumptions made when determining the posterior probability, leads to significantly fewer false detections and those that are observed can be discredited using a priori knowledge. Therefore, we have more confidence in the mode candidates found with Bayesian statistics. Title: A Seismic Signature of a Second Dynamo? Authors: Fletcher, Stephen T.; Broomhall, Anne-Marie; Salabert, David; Basu, Sarbani; Chaplin, William J.; Elsworth, Yvonne; Garcia, Rafael A.; New, Roger Bibcode: 2010ApJ...718L..19F Altcode: 2010arXiv1006.4305F The Sun is a variable star whose magnetic activity varies most perceptibly on a timescale of approximately 11 years. However, significant variation is also observed on much shorter timescales. We observe a quasi-biennial (2 year) signal in the natural oscillation frequencies of the Sun. The oscillation frequencies are sensitive probes of the solar interior and so by studying them we can gain information about conditions beneath the solar surface. Our results strongly point to the 2 year signal being distinct and separate from, but nevertheless susceptible to the influence of, the main 11 year solar cycle. Title: Determining stellar radii using large separations: an error analysis Authors: Basu, Sarbani; Chaplin, William J.; Elsworth, Yvonne Bibcode: 2010Ap&SS.328...79B Altcode: 2009Ap&SS.tmp..185B The Kepler mission will provide large separations for many stars. One of the tasks of Kepler Asteroseismic Consortium is to determine radii of the observed stars from the large separations and other catalogued “classical” data such as effective temperature, metallicities, brightness, distance etc. We present the results of a detailed analysis of errors in the radius estimates caused by errors in the input parameters. This exercise enables us to determine which parameters will benefit from follow-up observations of the interesting cases. Title: The solar-like CoRoT target HD 170987: spectroscopic and seismic observations Authors: Mathur, S.; García, R. A.; Catala, C.; Bruntt, H.; Mosser, B.; Appourchaux, T.; Ballot, J.; Creevey, O. L.; Gaulme, P.; Hekker, S.; Huber, D.; Karoff, C.; Piau, L.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; Verner, G. A.; Auvergne, M.; Baglin, A.; Chaplin, W. J.; Elsworth, Y.; Michel, E.; Samadi, R.; Sato, K.; Stello, D. Bibcode: 2010A&A...518A..53M Altcode: 2010arXiv1004.4891M Context. The CoRoT mission is in its third year of observation and the data from the second long run in the galactic centre direction are being analysed. The solar-like oscillating stars that have been observed up to now have given some interesting results, specially concerning the amplitudes that are lower than predicted. We present here the results from the analysis of the star HD 170987.
Aims: The goal of this research work is to characterise the global parameters of HD 170987. We look for global seismic parameters such as the mean large separation, maximum amplitude of the modes, and surface rotation because the signal-to-noise ratio in the observations does not allow us to measure individual modes. We also aim to retrieve the parameters of the star and its chemical composition.
Methods: We studied the chemical composition of the star through ground-based observations performed with the NARVAL spectrograph. We used several methods to calculate the global parameters from the acoustic oscillations based on CoRoT data. The light curve of the star has been interpolated with inpainting algorithms to reduce the effect of data gaps.
Results: We found the power excess related to p modes in the range [400-1200] μHz with a mean large separation of 55.2 ± 0.8 μHz with a probability above 95 % that increases to 55.9 ± 0.2 μHz in a higher frequency range [500-1250] μHz and a rejection level of 1%. A hint of the variation of this quantity with frequency was also found. The rotation period of the star is estimated to be around 4.3 days with an inclination axis of i = 50° +20-13. We measured a bolometric amplitude per radial mode in a range [2.4-2.9] ppm around 1000 μHz. Finally we estimate the stellar mass with a grid of models, M = 1.43 ± 0.05 M_⊙, the radius, R = 1.96 ± 0.046 R_⊙, and the age ~2.4 Gyr.

The CoRoT space mission, launched on 2006 December 27, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain. Title: Differences Between the Current Solar Minimum and Earlier Minima Authors: Basu, S.; Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; Fletcher, S.; New, R. Bibcode: 2010ASPC..428...37B Altcode: 2010arXiv1003.4262B The Birmingham Solar-Oscillations Network (BiSON) has collected helioseismic data over three solar cycles. We use these data to determine how the internal properties of the Sun during this minimum differ from the previous two minima. The Cycle 24 data show oscillatory differences with respect to the other two sets, indicating relatively localized changes in the solar interior. Analysis of MDI data from Cycle 23 and Cycle 24 also show significant signs of differences. Title: The New Solar Minimum: How Deep does the Problem Go? Authors: Fletcher, S.; New, R.; Broomhall, A. -M.; Chaplin, W.; Elsworth, Y. Bibcode: 2010ASPC..428...43F Altcode: 2010arXiv1003.4228F Although there are now some tentative signs that the start of cycle 24 has begun there is still considerable interest in the somewhat unusual behavior of the current solar minimum and the apparent delay in the true start of the next cycle. While this behavior is easily tracked by observing the change in surface activity, a question can also be asked about what is happening beneath the surface where the magnetic activity ultimately originates. In order to try to answer this question we can look at the behavior of the frequencies of the Sun's natural seismic modes of oscillation—the p modes. These seismic frequencies also respond to changes in activity and are probes of conditions in the solar interior.
The Birmingham Solar Oscillations Network (BiSON) has made measurements of low-degree (low-l) p mode frequencies over the last three solar cycles, and so is in a unique position to explore the current unusual and extended solar minimum. We compare the frequency shifts in the low-l p-modes obtained from the BiSON data with the change in surface activity as measured by different proxies and show there are significant differences especially during the declining phase of solar cycle 23 and into the current minimum. We also observe quasi-biennial periodic behavior in the p mode frequencies over the last two cycles that, unlike in the surface measurements, seems to be present at mid- and low-activity levels. Additionally we look at the frequency shifts of individual l modes. Title: Detection of Solar-like Oscillations from Kepler Photometry of the Open Cluster NGC 6819 Authors: Stello, Dennis; Basu, Sarbani; Bruntt, Hans; Mosser, Benoît; Stevens, Ian R.; Brown, Timothy M.; Christensen-Dalsgaard, Jørgen; Gilliland, Ronald L.; Kjeldsen, Hans; Arentoft, Torben; Ballot, Jérôme; Barban, Caroline; Bedding, Timothy R.; Chaplin, William J.; Elsworth, Yvonne P.; García, Rafael A.; Goupil, Marie-Jo; Hekker, Saskia; Huber, Daniel; Mathur, Savita; Meibom, Søren; Sangaralingam, Vinothini; Baldner, Charles S.; Belkacem, Kevin; Biazzo, Katia; Brogaard, Karsten; Suárez, Juan Carlos; D'Antona, Francesca; Demarque, Pierre; Esch, Lisa; Gai, Ning; Grundahl, Frank; Lebreton, Yveline; Jiang, Biwei; Jevtic, Nada; Karoff, Christoffer; Miglio, Andrea; Molenda-Żakowicz, Joanna; Montalbán, Josefina; Noels, Arlette; Roca Cortés, Teodoro; Roxburgh, Ian W.; Serenelli, Aldo M.; Silva Aguirre, Victor; Sterken, Christiaan; Stine, Peter; Szabó, Robert; Weiss, Achim; Borucki, William J.; Koch, David; Jenkins, Jon M. Bibcode: 2010ApJ...713L.182S Altcode: 2010arXiv1001.0026S Asteroseismology of stars in clusters has been a long-sought goal because the assumption of a common age, distance, and initial chemical composition allows strong tests of the theory of stellar evolution. We report results from the first 34 days of science data from the Kepler Mission for the open cluster NGC 6819—one of the four clusters in the field of view. We obtain the first clear detections of solar-like oscillations in the cluster red giants and are able to measure the large frequency separation, Δν, and the frequency of maximum oscillation power, νmax. We find that the asteroseismic parameters allow us to test cluster membership of the stars, and even with the limited seismic data in hand, we can already identify four possible non-members despite their having a better than 80% membership probability from radial velocity measurements. We are also able to determine the oscillation amplitudes for stars that span about 2 orders of magnitude in luminosity and find good agreement with the prediction that oscillation amplitudes scale as the luminosity to the power of 0.7. These early results demonstrate the unique potential of asteroseismology of the stellar clusters observed by Kepler. Title: Solar-like Oscillations in Low-luminosity Red Giants: First Results from Kepler Authors: Bedding, T. R.; Huber, D.; Stello, D.; Elsworth, Y. P.; Hekker, S.; Kallinger, T.; Mathur, S.; Mosser, B.; Preston, H. L.; Ballot, J.; Barban, C.; Broomhall, A. M.; Buzasi, D. L.; Chaplin, W. J.; García, R. A.; Gruberbauer, M.; Hale, S. J.; De Ridder, J.; Frandsen, S.; Borucki, W. J.; Brown, T.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Jenkins, J. M.; Kjeldsen, H.; Koch, D.; Belkacem, K.; Bildsten, L.; Bruntt, H.; Campante, T. L.; Deheuvels, S.; Derekas, A.; Dupret, M. -A.; Goupil, M. -J.; Hatzes, A.; Houdek, G.; Ireland, M. J.; Jiang, C.; Karoff, C.; Kiss, L. L.; Lebreton, Y.; Miglio, A.; Montalbán, J.; Noels, A.; Roxburgh, I. W.; Sangaralingam, V.; Stevens, I. R.; Suran, M. D.; Tarrant, N. J.; Weiss, A. Bibcode: 2010ApJ...713L.176B Altcode: 2010arXiv1001.0229B We have measured solar-like oscillations in red giants using time-series photometry from the first 34 days of science operations of the Kepler Mission. The light curves, obtained with 30 minute sampling, reveal clear oscillations in a large sample of G and K giants, extending in luminosity from the red clump down to the bottom of the giant branch. We confirm a strong correlation between the large separation of the oscillations (Δν) and the frequency of maximum power (νmax). We focus on a sample of 50 low-luminosity stars (νmax > 100 μHz, L <~ 30 L sun) having high signal-to-noise ratios and showing the unambiguous signature of solar-like oscillations. These are H-shell-burning stars, whose oscillations should be valuable for testing models of stellar evolution and for constraining the star formation rate in the local disk. We use a new technique to compare stars on a single échelle diagram by scaling their frequencies and find well-defined ridges corresponding to radial and non-radial oscillations, including clear evidence for modes with angular degree l = 3. Measuring the small separation between l = 0 and l = 2 allows us to plot the so-called C-D diagram of δν02 versus Δν. The small separation δν01 of l = 1 from the midpoint of adjacent l = 0 modes is negative, contrary to the Sun and solar-type stars. The ridge for l = 1 is notably broadened, which we attribute to mixed modes, confirming theoretical predictions for low-luminosity giants. Overall, the results demonstrate the tremendous potential of Kepler data for asteroseismology of red giants. Title: A Multi-Site Campaign to Measure Solar-Like Oscillations in Procyon. II. Mode Frequencies Authors: Bedding, Timothy R.; Kjeldsen, Hans; Campante, Tiago L.; Appourchaux, Thierry; Bonanno, Alfio; Chaplin, William J.; Garcia, Rafael A.; Martić, Milena; Mosser, Benoit; Butler, R. Paul; Bruntt, Hans; Kiss, László L.; O'Toole, Simon J.; Kambe, Eiji; Ando, Hiroyasu; Izumiura, Hideyuki; Sato, Bun'ei; Hartmann, Michael; Hatzes, Artie; Barban, Caroline; Berthomieu, Gabrielle; Michel, Eric; Provost, Janine; Turck-Chièze, Sylvaine; Lebrun, Jean-Claude; Schmitt, Jerome; Bertaux, Jean-Loup; Benatti, Serena; Claudi, Riccardo U.; Cosentino, Rosario; Leccia, Silvio; Frandsen, Søren; Brogaard, Karsten; Glowienka, Lars; Grundahl, Frank; Stempels, Eric; Arentoft, Torben; Bazot, Michaël; Christensen-Dalsgaard, Jørgen; Dall, Thomas H.; Karoff, Christoffer; Lundgreen-Nielsen, Jens; Carrier, Fabien; Eggenberger, Patrick; Sosnowska, Danuta; Wittenmyer, Robert A.; Endl, Michael; Metcalfe, Travis S.; Hekker, Saskia; Reffert, Sabine Bibcode: 2010ApJ...713..935B Altcode: 2010arXiv1003.0052B We have analyzed data from a multi-site campaign to observe oscillations in the F5 star Procyon. The data consist of high-precision velocities that we obtained over more than three weeks with 11 telescopes. A new method for adjusting the data weights allows us to suppress the sidelobes in the power spectrum. Stacking the power spectrum in a so-called échelle diagram reveals two clear ridges, which we identify with even and odd values of the angular degree (l = 0 and 2, and l = 1 and 3, respectively). We interpret a strong, narrow peak at 446 μHz that lies close to the l = 1 ridge as a mode with mixed character. We show that the frequencies of the ridge centroids and their separations are useful diagnostics for asteroseismology. In particular, variations in the large separation appear to indicate a glitch in the sound-speed profile at an acoustic depth of ~1000 s. We list frequencies for 55 modes extracted from the data spanning 20 radial orders, a range comparable to the best solar data, which will provide valuable constraints for theoretical models. A preliminary comparison with published models shows that the offset between observed and calculated frequencies for the radial modes is very different for Procyon than for the Sun and other cool stars. We find the mean lifetime of the modes in Procyon to be 1.29+0.55 -0.49 days, which is significantly shorter than the 2-4 days seen in the Sun. Title: The Asteroseismic Potential of Kepler: First Results for Solar-Type Stars Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; García, R. A.; Houdek, G.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Brown, T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D.; Jenkins, J. M.; Ballot, J.; Basu, S.; Bazot, M.; Bedding, T. R.; Benomar, O.; Bonanno, A.; Brandão, I. M.; Bruntt, H.; Campante, T. L.; Creevey, O. L.; Di Mauro, M. P.; Doǧan, G.; Dreizler, S.; Eggenberger, P.; Esch, L.; Fletcher, S. T.; Frandsen, S.; Gai, N.; Gaulme, P.; Handberg, R.; Hekker, S.; Howe, R.; Huber, D.; Korzennik, S. G.; Lebrun, J. C.; Leccia, S.; Martic, M.; Mathur, S.; Mosser, B.; New, R.; Quirion, P. -O.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; Schou, J.; Sousa, S. G.; Stello, D.; Verner, G. A.; Arentoft, T.; Barban, C.; Belkacem, K.; Benatti, S.; Biazzo, K.; Boumier, P.; Bradley, P. A.; Broomhall, A. -M.; Buzasi, D. L.; Claudi, R. U.; Cunha, M. S.; D'Antona, F.; Deheuvels, S.; Derekas, A.; García Hernández, A.; Giampapa, M. S.; Goupil, M. J.; Gruberbauer, M.; Guzik, J. A.; Hale, S. J.; Ireland, M. J.; Kiss, L. L.; Kitiashvili, I. N.; Kolenberg, K.; Korhonen, H.; Kosovichev, A. G.; Kupka, F.; Lebreton, Y.; Leroy, B.; Ludwig, H. -G.; Mathis, S.; Michel, E.; Miglio, A.; Montalbán, J.; Moya, A.; Noels, A.; Noyes, R. W.; Pallé, P. L.; Piau, L.; Preston, H. L.; Roca Cortés, T.; Roth, M.; Sato, K. H.; Schmitt, J.; Serenelli, A. M.; Silva Aguirre, V.; Stevens, I. R.; Suárez, J. C.; Suran, M. D.; Trampedach, R.; Turck-Chièze, S.; Uytterhoeven, K.; Ventura, R.; Wilson, P. A. Bibcode: 2010ApJ...713L.169C Altcode: 2010arXiv1001.0506C We present preliminary asteroseismic results from Kepler on three G-type stars. The observations, made at one-minute cadence during the first 33.5 days of science operations, reveal high signal-to-noise solar-like oscillation spectra in all three stars: about 20 modes of oscillation may be clearly distinguished in each star. We discuss the appearance of the oscillation spectra, use the frequencies and frequency separations to provide first results on the radii, masses, and ages of the stars, and comment in the light of these results on prospects for inference on other solar-type stars that Kepler will observe. Title: Discovery of a Red Giant with Solar-like Oscillations in an Eclipsing Binary System from Kepler Space-based Photometry Authors: Hekker, S.; Debosscher, J.; Huber, D.; Hidas, M. G.; De Ridder, J.; Aerts, C.; Stello, D.; Bedding, T. R.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Brown, T. M.; Kjeldsen, H.; Borucki, W. J.; Koch, D.; Jenkins, J. M.; Van Winckel, H.; Beck, P. G.; Blomme, J.; Southworth, J.; Pigulski, A.; Chaplin, W. J.; Elsworth, Y. P.; Stevens, I. R.; Dreizler, S.; Kurtz, D. W.; Maceroni, C.; Cardini, D.; Derekas, A.; Suran, M. D. Bibcode: 2010ApJ...713L.187H Altcode: 2010arXiv1001.0399H Oscillating stars in binary systems are among the most interesting stellar laboratories, as these can provide information on the stellar parameters and stellar internal structures. Here we present a red giant with solar-like oscillations in an eclipsing binary observed with the NASA Kepler satellite. We compute stellar parameters of the red giant from spectra and the asteroseismic mass and radius from the oscillations. Although only one eclipse has been observed so far, we can already determine that the secondary is a main-sequence F star in an eccentric orbit with a semi-major axis larger than 0.5 AU and orbital period longer than 75 days. Title: The Octave (Birmingham-Sheffield Hallam) automated pipeline for extracting oscillation parameters of solar-like main-sequence stars Authors: Hekker, S.; Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y. P.; Fletcher, S. T.; New, R.; Arentoft, T.; Quirion, P. -O.; Kjeldsen, H. Bibcode: 2010MNRAS.402.2049H Altcode: 2009MNRAS.tmp.1945H; 2009arXiv0911.2612H The number of main-sequence stars for which we can observe solar-like oscillations is expected to increase considerably with the short-cadence high-precision photometric observations from the NASA Kepler satellite. Because of this increase in the number of stars, automated tools are needed to analyse these data in a reasonable amount of time. In the framework of the asteroFLAG consortium, we present an automated pipeline which extracts frequencies and other parameters of solar-like oscillations in main-sequence and subgiant stars. The pipeline uses only the time series data as input and does not require any other input information. Tests on 353 artificial stars reveal that we can obtain accurate frequencies and oscillation parameters for about three quarters of the stars. We conclude that our methods are well suited for the analysis of main-sequence stars, which show mainly p-mode oscillations. Title: Automated Asteroseismic Analysis of Solar-type Stars Authors: Karoff, C.; Campante, T. L.; Chaplin, W. J. Bibcode: 2010arXiv1003.4167K Altcode: The rapidly increasing volume of asteroseismic observations on solar-type stars has revealed a need for automated analysis tools. The reason for this is not only that individual analyses of single stars are rather time consuming, but more importantly that these large volumes of observations open the possibility to do population studies on large samples of stars and such population studies demand a consistent analysis. By consistent analysis we understand an analysis that can be performed without the need to make any subjective choices on e.g. mode identification and an analysis where the uncertainties are calculated in a consistent way. Here we present a set of automated asterosesimic analysis tools. The main engine of these set of tools is an algorithm for modelling the autocovariance spectra of the stellar acoustic spectra allowing us to measure not only the frequency of maximum power and the large frequency separation, but also the small frequency separation and potentially the mean rotational rate and the inclination. The measured large and small frequency separations and the frequency of maximum power are used as input to an algorithm that estimates fundamental stellar parameters such as mass, radius, luminosity, effective temperature, surface gravity and age based on grid modeling. All the tools take into account the window function of the observations which means that they work equally well for space-based photometry observations from e.g. the NASA Kepler satellite and ground-based velocity observations from e.g. the ESO HARPS spectrograph. Title: Kepler Asteroseismology Program: Introduction and First Results Authors: Gilliland, Ronald L.; Brown, Timothy M.; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Aerts, Conny; Appourchaux, Thierry; Basu, Sarbani; Bedding, Timothy R.; Chaplin, William J.; Cunha, Margarida S.; De Cat, Peter; De Ridder, Joris; Guzik, Joyce A.; Handler, Gerald; Kawaler, Steven; Kiss, László; Kolenberg, Katrien; Kurtz, Donald W.; Metcalfe, Travis S.; Monteiro, Mario J. P. F. G.; Szabó, Robert; Arentoft, Torben; Balona, Luis; Debosscher, Jonas; Elsworth, Yvonne P.; Quirion, Pierre-Olivier; Stello, Dennis; Suárez, Juan Carlos; Borucki, William J.; Jenkins, Jon M.; Koch, David; Kondo, Yoji; Latham, David W.; Rowe, Jason F.; Steffen, Jason H. Bibcode: 2010PASP..122..131G Altcode: 2010arXiv1001.0139G Asteroseismology involves probing the interiors of stars and quantifying their global properties, such as radius and age, through observations of normal modes of oscillation. The technical requirements for conducting asteroseismology include ultrahigh precision measured in photometry in parts per million, as well as nearly continuous time series over weeks to years, and cadences rapid enough to sample oscillations with periods as short as a few minutes. We report on results from the first 43 days of observations, in which the unique capabilities of Kepler in providing a revolutionary advance in asteroseismology are already well in evidence. The Kepler asteroseismology program holds intrinsic importance in supporting the core planetary search program through greatly enhanced knowledge of host star properties, and extends well beyond this to rich applications in stellar astrophysics. Title: Sounding stellar cycles with Kepler - preliminary results from ground-based chromospheric activity measurements† Authors: Karoff, C.; Metcalfe, T. S.; Chaplin, W. J.; Frandsen, S.; Grundahl, F.; Kjeldsen, H.; Buzasi, D.; Arentoft, T.; Christensen-Dalsgaard, J. Bibcode: 2010IAUS..264...57K Altcode: 2009arXiv0910.1436K Due to its unique long-term coverage and high photometric precision, observations from the Kepler asteroseismic investigation will provide us with the possibility to sound stellar cycles in a number of solar-type stars with asteroseismology. By comparing these measurements with conventional ground-based chromospheric activity measurements we might be able to increase our understanding of the relation between the chromospheric changes and the changes in the eigenmodes.

In parallel with the Kepler observations we have therefore started a programme at the Nordic Optical Telescope to observe and monitor chromospheric activity in the stars that are most likely to be selected for observations for the whole satellite mission. The ground-based observations presented here can be used both to guide the selection of the special Kepler targets and as the first step in a monitoring programme for stellar cycles. Also, the chromospheric activity measurements obtained from the ground-based observations can be compared with stellar parameters such as ages and rotation in order to improve stellar evolution models. Title: Determining global parameters of the oscillations of solar-like stars Authors: Mathur, S.; García, R. A.; Régulo, C.; Creevey, O. L.; Ballot, J.; Salabert, D.; Arentoft, T.; Quirion, P. -O.; Chaplin, W. J.; Kjeldsen, H. Bibcode: 2010A&A...511A..46M Altcode: 2009arXiv0912.3367M Context. Helioseismology has enabled us to better understand the solar interior, while also allowing us to better constrain solar models. But now is a tremendous epoch for asteroseismology as space missions dedicated to studying stellar oscillations have been launched within the last years (MOST and CoRoT). CoRoT has already proved valuable results for many types of stars, while Kepler, which was launched in March 2009, will provide us with a huge number of seismic data very soon. This is an opportunity to better constrain stellar models and to finally understand stellar structure and evolution.
Aims: The goal of this research work is to estimate the global parameters of any solar-like oscillating target in an automatic manner. We want to determine the global parameters of the acoustic modes (large separation, range of excited pressure modes, maximum amplitude, and its corresponding frequency), retrieve the surface rotation period of the star and use these results to estimate the global parameters of the star (radius and mass).
Methods: To prepare for the arrival and the analysis of hundreds of solar-like oscillating stars, we have developed a robust and automatic pipeline, which was partially adapted from helioseismic methods. The pipeline consists of data analysis techniques, such as Fast Fourier Transform, wavelets, autocorrelation, as well as the application of minimisation algorithms for stellar-modelling.
Results: We apply our pipeline to some simulated lightcurves from the asteroFLAG team and the Aarhus-asteroFLAG simulator, and obtain results that are consistent with the input data to the simulations. Our strategy gives correct results for stars with magnitudes below 11 with only a few 10% of bad determinations among the reliable results. We then apply the pipeline to the Sun and three CoRoT targets. In particular we determine the large separation and radius of the Sun, HD49933, HD181906, and HD181420. Title: Determination of Stellar Radii from Asteroseismic Data Authors: Basu, Sarbani; Chaplin, William J.; Elsworth, Yvonne Bibcode: 2010ApJ...710.1596B Altcode: 2009arXiv0909.0506B The NASA Kepler mission is designed to find planets through transits. Accurate and precise radii of the detected planets depend on knowing the radius of the host star accurately, which is difficult unless the temperature and luminosity of the star are known precisely. Kepler, however, has an asteroseismology program that will provide seismic variables that can characterize stellar radii easily, accurately, and extremely precisely. In this paper, we describe the Yale-Birmingham (YB) method to determine stellar radii using a combination of seismic and conventional variables and analyze the effect of these variables on the result. We find that for main-sequence stars, a knowledge of the parallax is not important to get accurate radii using the YB method: we can get results to an accuracy and precision of better than a few percent if we know the effective temperature and the seismic parameters for these stars. Metallicity does not make much difference either. However, good estimates of the effective temperature and metallicity, along with those of the seismic parameters, are essential to determine radii of subgiants properly. On the other hand, for red giants we find that determining radii properly is not possible without a good estimate of the parallax. We find that the so-called "surface term" in the seismic data has minimal effect on the inferred radii. Uncertainties in the convective mixing length can matter under some circumstances and can cause a systematic shift in the inferred radii. Blind tests with data simulated to match those expected from the asteroseismic survey phase of Kepler show that it will be possible to infer stellar radii successfully using our method. Title: The quest for the solar g modes Authors: Appourchaux, T.; Belkacem, K.; Broomhall, A. -M.; Chaplin, W. J.; Gough, D. O.; Houdek, G.; Provost, J.; Baudin, F.; Boumier, P.; Elsworth, Y.; García, R. A.; Andersen, B. N.; Finsterle, W.; Fröhlich, C.; Gabriel, A.; Grec, G.; Jiménez, A.; Kosovichev, A.; Sekii, T.; Toutain, T.; Turck-Chièze, S. Bibcode: 2010A&ARv..18..197A Altcode: 2010A&ARv.tmp....1A; 2009arXiv0910.0848A Solar gravity modes (or g modes)—oscillations of the solar interior on which buoyancy acts as the restoring force—have the potential to provide unprecedented inference on the structure and dynamics of the solar core, inference that is not possible with the well-observed acoustic modes (or p modes). The relative high amplitude of the g-mode eigenfunctions in the core and the evanesence of the modes in the convection zone make the modes particularly sensitive to the physical and dynamical conditions in the core. Owing to the existence of the convection zone, the g modes have very low amplitudes at photospheric levels, which makes the modes extremely hard to detect. In this article, we review the current state of play regarding attempts to detect g modes. We review the theory of g modes, including theoretical estimation of the g-mode frequencies, amplitudes and damping rates. Then we go on to discuss the techniques that have been used to try to detect g modes. We review results in the literature, and finish by looking to the future, and the potential advances that can be made—from both data and data-analysis perspectives—to give unambiguous detections of individual g modes. The review ends by concluding that, at the time of writing, there is indeed a consensus amongst the authors that there is currently no undisputed detection of solar g modes. Title: The Inhomogeneous Response Across the Solar Disc of Unresolved Doppler Velocity Observations Authors: Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; New, R. Bibcode: 2009ASPC..416..245B Altcode: 2008arXiv0810.3856B Unresolved Doppler velocity measurements are not homogeneous across the solar disc (Brookes et al. 1978). We consider one cause of the inhomogeneity that originates from the BiSON instrumentation itself: the intensity of light observed from a region on the solar disc is dependent on the distance between that region on the image of the solar disc formed in the instrument and the detector. The non-uniform weighting affects the realization of the solar noise and the amplitudes of the solar oscillations observed by a detector. An "offset velocity", which varies with time, is observed in BiSON data and has consequences for the long-term stability of observations. We have attempted to model, in terms of the inhomogeneous weighting, the average observed offset velocity. Title: Are Low-Degree p-Mode Frequencies Predictable from One Cycle to the Next? Authors: Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; New, R.; Verner, G. A. Bibcode: 2009ASPC..416..183B Altcode: 2008arXiv0810.3591B The Birmingham Solar-Oscillations Network (BiSON) has been collecting data for over 30 yrs and so observations span nearly three eleven yr solar activity cycles. This allows us to address important questions concerning the solar cycle and its effect on solar oscillations, such as: how consistent is the acoustic behavior from one cycle to the next? We have used the p-mode frequencies observed in BiSON data from one solar activity cycle (cycle 22) to predict the mode frequencies that were observed in the next activity cycle (cycle 23). Some bias in the predicted frequencies was observed when short 108 days time series were used to make the predictions. We also found that the accuracy of the predictions was dependent on which activity proxy was used to make the predictions and on the length of the relevant time series. Title: Pseudo-Global Fitting of Gapped Helioseismic Data Authors: Fletcher, S.; New, R.; Chaplin, W.; Elsworth, Y. Bibcode: 2009ASPC..416..519F Altcode: 2009arXiv0904.4126F Mode fitting or "peak-bagging" is an important procedure in helioseismology allowing one to determine the various mode parameters of solar oscillations. We have recently developed a new "pseudo-global" fitting algorithm as a way of reducing the systematic bias in the fits of certain mode parameters that are seen when using "local" fitting techniques to analyze "Sun-as-a-star" p-mode data. This new algorithm has been designed specifically to gain the advantages of fitting the entire power spectrum, while retaining the efficiency of local fitting techniques.

Using simulated data with a full fill we have previously shown that the pseudo-global routine reduces the bias in estimates of the frequencies and asymmetries and in the estimates of the solar background when compared with a traditional fitting technique. Here we present results that show that the pseudo-global routine is also effective in reducing bias in the parameter estimates when the time-series has significant gaps. As such we are now able to employ the routine in order to fit ground-based helioseismic data such as that collected by the Birmingham Solar Oscillations Network (BiSON). Title: Analysis of GOLF Power Spectra Weighted to Account for Noise Variations Through the Data Set Authors: New, R.; Fletcher, S.; Chaplin, W.; Elsworth, Y.; García, R. A. Bibcode: 2009ASPC..416..325N Altcode: It has been established that the noise in Doppler velocity measurements obtained by resonant scattering spectrometers varies with season of the year and, of course, with instrument conditions. For example, recent analysis has characterized the noise in data taken by the Global Oscillations at Low Frequencies (GOLF) instrument on the ESA/NASA satellite SoHO, which shows seasonal variation and a secular increase associated with the degradation of GOLF's photomultiplier tubes. Using the noise characteristics it is possible to generate power spectra using the weighted sine-wave fit technique often employed in asteroseismic work. This paper presents the first analyses of such weighted power spectra, which have been generated from several years of GOLF data, and compares the results generated by more commonly employed unweighted transform techniques. Title: BiSON Update Authors: Allison, J.; Barnes, I.; Broomhall, A. -M.; Chaplin, W.; Davies, G.; Elsworth, Y.; Hale, S.; Jackson, B.; Miller, B.; New, R.; Fletcher, S. Bibcode: 2009ASPC..416..227A Altcode: We present an update on the operation of the Birmingham Solar Oscillations Network (BiSON) network including our various running statistics such as duty cycle. We also give an update regarding our status and briefly outline the foreseeable future of the network. Title: The Simulation of Realistic BiSON-like Helioseismic Data Authors: Fletcher, S.; New, R.; Broomhall, A. -M.; Chaplin, W.; Elsworth, Y. Bibcode: 2009ASPC..416..337F Altcode: 2009arXiv0903.3486F When simulating full-disc helioseismic data, instrumental noise has traditionally been treated as time-independent. However, in reality, instrumental noise will often vary to some degree over time due to line-of-sight velocity variations and possibly degrading hardware.

Here we present a new technique for simulating Birmingham Solar Oscillations Network (BiSON) helioseismic data with a more realistic analogue for instrumental noise. This is achieved by simulating the potassium solar Fraunhofer line as observed by the BiSON instruments. Intensity measurements in the red and blue wing of the line can then be simulated and appropriate time-dependent instrumental noise can be added. The simulated time-series can then be formed in the same way as with real data. Here we present the simulation method and the first generation of a BiSON-like instrumental-noise time series. Title: The relation between Δν and νmax for solar-like oscillations Authors: Stello, D.; Chaplin, W. J.; Basu, S.; Elsworth, Y.; Bedding, T. R. Bibcode: 2009MNRAS.400L..80S Altcode: 2009MNRAS.tmpL.341S; 2009arXiv0909.5193S; 2009MNRAS.tmpL.349S Establishing relations between global stellar parameters and asteroseismic quantities can help improve our understanding of stellar astrophysics and facilitate the interpretation of observations. We present an observed relation between the large frequency separation, Δν, and the frequency of maximum power, νmax. We find that Δν ~ ν0.77max, allowing prediction of Δν to about 15 per cent given νmax. Our result is further supported by established scaling relations for Δν and νmax and by extended stellar model calculations, which confirm that Δν can be estimated using this relation for basically any star showing solar-like oscillations in the investigated range (0.5 < M/M solar < 4.0). Title: A fresh look at the seismic spectrum of HD49933: analysis of 180 days of CoRoT photometry Authors: Benomar, O.; Baudin, F.; Campante, T. L.; Chaplin, W. J.; García, R. A.; Gaulme, P.; Toutain, T.; Verner, G. A.; Appourchaux, T.; Ballot, J.; Barban, C.; Elsworth, Y.; Mathur, S.; Mosser, B.; Régulo, C.; Roxburgh, I. W.; Auvergne, M.; Baglin, A.; Catala, C.; Michel, E.; Samadi, R. Bibcode: 2009A&A...507L..13B Altcode: 2009arXiv0910.3060B Context: Solar-like oscillations have now been observed in several stars, thanks to ground-based spectroscopic observations and space-borne photometry. CoRoT, which has been in orbit since December 2006, has observed the star HD49933 twice. The oscillation spectrum of this star has proven difficult to interpret.
Aims: Thanks to a new timeseries provided by CoRoT, we aim to provide a robust description of the oscillations in HD49933, i.e., to identify the degrees of the observed modes, and to measure mode frequencies, widths, amplitudes and the average rotational splitting.
Methods: Several methods were used to model the Fourier spectrum: Maximum Likelihood Estimators and Bayesian analysis using Markov Chain Monte-Carlo techniques.
Results: The different methods yield consistent result, and allow us to make a robust identification of the modes and to extract precise mode parameters. Only the rotational splitting remains difficult to estimate precisely, but is clearly relatively large (several μHz in size).

The CoRoT space mission, launched on 2006 December 27, was developed and is operated by the CNES, with participation of the Science Programs of ESA, ESA's RSSD, Austria, Belgium, Brazil, Germany and Spain.

Figures 5-9 and Table 2 are only available in electronic form at http://www.aanda.org Title: Automated extraction of oscillation parameters for Kepler observations of solar-type stars Authors: Huber, D.; Stello, D.; Bedding, T. R.; Chaplin, W. J.; Arentoft, T.; Quirion, P. -O.; Kjeldsen, H. Bibcode: 2009CoAst.160...74H Altcode: 2009arXiv0910.2764H The recent launch of the Kepler space telescope brings the opportunity to study oscillations systematically in large numbers of solar-like stars. In the framework of the asteroFLAG project, we have developed an automated pipeline to estimate global oscillation parameters, such as the frequency of maximum power (νmax ) and the large frequency spacing (Δν), for a large number of time series. We present an effective method based on the autocorrelation function to find excess power and use a scaling relation to estimate granulation timescales as initial conditions for background modelling. We derive reliable uncertainties for νmax and Δν through extensive simulations. We have tested the pipeline on about 2000 simulated Kepler stars with magnitudes of V ∼ 7-12 and were able to correctly determine νmax and Δν for about half of the sample. For about 20%, the returned large frequency spacing is accurate enough to determine stellar radii to a 1% precision. We conclude that the methods presented here are a promising approach to process the large amount of data expected from Kepler. Title: Solar-like oscillations in HD 181420: data analysis of 156 days of CoRoT data Authors: Barban, C.; Deheuvels, S.; Baudin, F.; Appourchaux, T.; Auvergne, M.; Ballot, J.; Boumier, P.; Chaplin, W. J.; García, R. A.; Gaulme, P.; Michel, E.; Mosser, B.; Régulo, C.; Roxburgh, I. W.; Verner, G.; Baglin, A.; Catala, C.; Samadi, R.; Bruntt, H.; Elsworth, Y.; Mathur, S. Bibcode: 2009A&A...506...51B Altcode: Context: The estimate of solar-like oscillation properties, such as their frequencies, amplitudes and lifetimes, is challenging because of their low amplitudes and will benefit from long and uninterrupted observing runs. The space telescope CoRoT allows us to obtain high-performance photometric data over a long and quasi continuous period. Among its main targets are stars for which we expect solar-like oscillations.
Aims: HD 181420, an F2 main sequence star, has been observed by CoRoT during its first long run covering about 156 days. With this unprecedently high-quality set of data, our aim is to derive the p-mode parameters that can be used to probe the stellar interior.
Methods: The CoRoT data obtained on HD 181420 is analysed using a classical Fourier approach for the search for the p mode signature. The p-mode parameters are then derived using global fitting of the power spectrum by a Lorentzian model, as used widely in the solar case.
Results: From the p-mode frequencies, the mean value of the large spacing is estimated to be 75 {μ Hz}. The p-mode amplitudes are slightly less than 4 ppm with a line width of about 8 {μ Hz} at the maximum of the p modes. The inclination angle is estimated to be around 45 °. The large mode line-width combined with the observed mode spacing make it difficult to identify the ℓ=2 modes and to estimate the rotational splitting. We explore two scenarios for the identification of the modes.

The CoRoT space mission, launched on 2006 December 27, was delopped and is operated by the CNES with participation of the Science Programs of ESA; ESA's RSSD, Austria, Belgium, Brazil, Germany and Spain. Title: Solar-like oscillations with low amplitude in the CoRoT target HD 181906 Authors: García, R. A.; Régulo, C.; Samadi, R.; Ballot, J.; Barban, C.; Benomar, O.; Chaplin, W. J.; Gaulme, P.; Appourchaux, T.; Mathur, S.; Mosser, B.; Toutain, T.; Verner, G. A.; Auvergne, M.; Baglin, A.; Baudin, F.; Boumier, P.; Bruntt, H.; Catala, C.; Deheuvels, S.; Elsworth, Y.; Jiménez-Reyes, S. J.; Michel, E.; Pérez Hernández, F.; Roxburgh, I. W.; Salabert, D. Bibcode: 2009A&A...506...41G Altcode: 2009arXiv0907.0608G Context: The F8 star HD 181906 (effective temperature ∼6300 K) was observed for 156 days by the CoRoT satellite during the first long run in the direction of the galactic centre. Analysis of the data reveals a spectrum of solar-like acoustic oscillations. However, the faintness of the target (mv = 7.65) means the signal-to-noise (S/N) in the acoustic modes is quite low, and this low S/N leads to complications in the analysis.
Aims: We extract global variables of the star, as well as key parameters of the p modes observed in the power spectrum of the lightcurve.
Methods: The power spectrum of the lightcurve, a wavelet transform and spot fitting were used to obtain the average rotation rate of the star and its inclination angle. Then, the autocorrelation of the power spectrum and the power spectrum of the power spectrum were used to properly determine the large separation. Finally, estimations of the mode parameters were done by maximizing the likelihood of a global fit, where several modes were fit simultaneously.
Results: We have been able to infer the mean surface rotation rate of the star (~4 μHz) with indications of the presence of surface differential rotation, the large separation of the p modes (~87 μHz), hence also the “ridges” corresponding to overtones of the acoustic modes.

CoRoT (Convection, Rotation and planetary Transits) is a minisatellite developed by the French Space agency CNES in collaboration with the Science Programmes of ESA, Austria, Belgium, Brazil, Germany and Spain. Title: Sounding stellar cycles with Kepler - I. Strategy for selecting targets Authors: Karoff, C.; Metcalfe, T. S.; Chaplin, W. J.; Elsworth, Y.; Kjeldsen, H.; Arentoft, T.; Buzasi, D. Bibcode: 2009MNRAS.399..914K Altcode: 2009arXiv0906.5441K; 2009MNRAS.tmp.1226K The long-term monitoring and high photometric precision of the Kepler satellite will provide a unique opportunity to sound the stellar cycles of many solar-type stars using asteroseismology. This can be achieved by studying periodic changes in the amplitudes and frequencies of the oscillation modes observed in these stars. By comparing these measurements with conventional ground-based chromospheric activity indices, we can improve our understanding of the relationship between chromospheric changes and those taking place deep in the interior throughout the stellar activity cycle. In addition, asteroseismic measurements of the convection zone depth and differential rotation may help us determine whether stellar cycles are driven at the top or at the base of the convection zone. In this paper, we analyse the precision that will be possible using Kepler to measure stellar cycles, convection zone depths and differential rotation. Based on this analysis, we describe a strategy for selecting specific targets to be observed by the Kepler Asteroseismic Investigation for the full length of the mission, to optimize their suitability for probing stellar cycles in a wide variety of solar-type stars. Title: Analysing Solar-like Oscillations with an Automatic Pipeline Authors: Mathur, S.; García, R. A.; Régulo, C.; Ballot, J.; Salabert, D.; Chaplin, W. J. Bibcode: 2009AIPC.1170..540M Altcode: 2009arXiv0907.1139M The Kepler mission will provide a huge amount of asteroseismic data during the next few years, among which hundreds of solar-like stars will be targeted. The amount of stars and their observation length represent a step forward in the comprehension of the stellar evolution that has already been initiated by CoRoT and MOST missions. Up to now, the slow cadence of observed targets allowed an individual and personalized analysis of each star. During the survey phase of Kepler, this will be impossible. This is the reason why, within the AsteroFLAG team, we have been developing automatic pipelines for the Kepler solar-like oscillation stars. Our code starts by finding the frequency-range where p-mode power is present and, after fitting the background, it looks for the mode amplitudes as well as the central frequency of the p-mode hump. A good estimation of the large separation can thus be inferred in this region. If the signal to noise is high enough, the code obtains the characteristics of the p modes by doing a global fitting on the power spectrum. Here, we will first describe a few features of this pipeline and its application to AsteroFLAG synthetic data to check the validity of the code. Title: Corrections of Sun-as-a-star p-mode frequencies for effects of the solar cycle Authors: Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; Fletcher, S. T.; New, R. Bibcode: 2009A&A...503..241B Altcode: 2009arXiv0907.2855B Solar p-mode frequencies vary with solar activity. It is important to take this into account when comparing the frequencies observed from epochs that span different regions of the solar cycle. We present details of how to correct observed p-mode frequencies for the effects of the solar cycle. We describe three types of correction. The first allows mode frequencies to be corrected to a nominal activity level, such as the canonical quiet-Sun level. The second accounts for the effect on the observed mode frequencies, powers, and damping rates of the continually varying solar cycle and is pertinent to frequencies obtained from very long data sets. The third corrects for Sun-as-a-star observations not seeing all components of the modes. Suitable combinations of the three correction procedures allow the frequencies obtained from different sets of data to be compared and enable activity-independent inversions of the solar interior. As an example of how to apply the corrections we describe those used to produce a set of definitive Sun-as-a-star frequencies. Title: Is the Current Lack of Solar Activity Only Skin Deep? Authors: Broomhall, A. -M.; Chaplin, W. J.; Elsworth, Y.; Fletcher, S. T.; New, R. Bibcode: 2009ApJ...700L.162B Altcode: 2009arXiv0907.3417B The Sun is a variable star whose magnetic activity and total irradiance vary on a timescale of approximately 11 years. The current activity minimum has attracted considerable interest because of its unusual duration and depth. This raises the question: what might be happening beneath the surface where the magnetic activity ultimately originates? The surface activity can be linked to the conditions in the solar interior by the observation and analysis of the frequencies of the Sun's natural seismic modes of oscillation—the p modes. These seismic frequencies respond to changes in activity and are probes of conditions within the Sun. The Birmingham Solar-Oscillations Network (BiSON) has made measurements of p-mode frequencies over the last three solar activity cycles, and so is in a unique position to explore the current unusual and extended solar minimum. We show that the BiSON data reveal significant variations of the p-mode frequencies during the current minimum. This is in marked contrast to the surface activity observations, which show little variation over the same period. The level of the minimum is significantly deeper in the p-mode frequencies than in the surface observations. We observe a quasi-biennial signal in the p-mode frequencies, which has not previously been observed at mid- and low-activity levels. The stark differences in the behavior of the frequencies and the surface activity measures point to activity-related processes occurring in the solar interior, which are yet to reach the surface, where they may be attenuated. Title: Radius Determination of Solar-type Stars Using Asteroseismology: What to Expect from the Kepler Mission Authors: Stello, Dennis; Chaplin, William J.; Bruntt, Hans; Creevey, Orlagh L.; García-Hernández, Antonio; Monteiro, Mario J. P. F. G.; Moya, Andrés; Quirion, Pierre-Olivier; Sousa, Sergio G.; Suárez, Juan-Carlos; Appourchaux, Thierry; Arentoft, Torben; Ballot, Jerome; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen; Elsworth, Yvonne; Fletcher, Stephen T.; García, Rafael A.; Houdek, Günter; Jiménez-Reyes, Sebastian J.; Kjeldsen, Hans; New, Roger; Régulo, Clara; Salabert, David; Toutain, Thierry Bibcode: 2009ApJ...700.1589S Altcode: 2009arXiv0906.0766S For distant stars, as observed by the NASA Kepler satellite, parallax information is currently of fairly low quality and is not complete. This limits the precision with which the absolute sizes of the stars and their potential transiting planets can be determined by traditional methods. Asteroseismology will be used to aid the radius determination of stars observed during NASA's Kepler mission. We report on the recent asteroFLAG hare-and-hounds Exercise#2, where a group of "hares" simulated data of F-K main-sequence stars that a group of "hounds" sought to analyze, aimed at determining the stellar radii. We investigated stars in the range 9 < V < 15, both with and without parallaxes. We further test different uncertainties in T eff, and compare results with and without using asteroseismic constraints. Based on the asteroseismic large frequency spacing, obtained from simulations of 4 yr time series data from the Kepler mission, we demonstrate that the stellar radii can be correctly and precisely determined, when combined with traditional stellar parameters from the Kepler Input Catalogue. The radii found by the various methods used by each independent hound generally agree with the true values of the artificial stars to within 3%, when the large frequency spacing is used. This is 5-10 times better than the results where seismology is not applied. These results give strong confidence that radius estimation can be performed to better than 3% for solar-like stars using automatic pipeline reduction. Even when the stellar distance and luminosity are unknown we can obtain the same level of agreement. Given the uncertainties used for this exercise we find that the input log g and parallax do not help to constrain the radius, and that T eff and metallicity are the only parameters we need in addition to the large frequency spacing. It is the uncertainty in the metallicity that dominates the uncertainty in the radius. Title: New aspects of Doppler imaging in Sun-as-a-star observations Authors: Broomhall, A. M.; Chaplin, W. J.; Elsworth, Y.; New, R. Bibcode: 2009MNRAS.397..793B Altcode: 2009MNRAS.tmp..780B; 2009arXiv0904.4122B; 2009MNRAS.tmp..750B Birmingham Solar Oscillations Network (BiSON) instruments use resonant scattering spectrometers to make unresolved Doppler velocity observations of the Sun. Unresolved measurements are not homogenous across the solar disc and so the observed data do not represent a uniform average over the entire surface. The influence on the inhomogeneity of the solar rotation and limb darkening has been considered previously and is well understood. Here, we consider a further effect that originates from the instrumentation itself. The intensity of light observed from a particular region on the solar disc is dependent on the distance between that region on the image of the solar disc formed in the instrument and the detector. The majority of BiSON instruments have two detectors positioned on opposite sides of the image of the solar disc and the observations made by each detector are weighted towards differing regions of the disc. Therefore, the visibility and amplitudes of the solar oscillations and the realization of the solar noise observed by each detector will differ. We find that the modelled bias is sensitive to many different parameters such as the width of solar absorption lines, the strength of the magnetic field in the resonant scattering spectrometer, the orientation of the Sun's rotation axis, the size of the image observed by the instrument and the optical depth in the vapour cell. We find that the modelled results best match the observations when the optical depth at the centre of the vapour cell is 0.55. The inhomogeneous weighting means that a `velocity offset' is introduced into unresolved Doppler velocity observations of the Sun, which varies with time, and so has an impact on the long-term stability of the observations. Title: Fresh Insights on the Structure of the Solar Core Authors: Basu, Sarbani; Chaplin, William J.; Elsworth, Yvonne; New, Roger; Serenelli, Aldo M. Bibcode: 2009ApJ...699.1403B Altcode: 2009arXiv0905.0651B We present new results on the structure of the solar core, obtained with new sets of frequencies of solar low-degree p modes obtained from the BiSON network. We find that different methods used in extracting the different sets of frequencies cause shifts in frequencies, but the shifts are not large enough to affect solar structure results. We find that the BiSON frequencies show that the solar sound speed in the core is slightly larger than that inferred from data from Michelson Doppler Imager low-degree modes, and the uncertainties on the inversion results are smaller. Density results also change by a larger amount, and we find that solar models now tend to show smaller differences in density compared to the Sun. The result is seen at all radii, a result of the fact that conservation of mass implies that density differences in one region have to cancel out density differences in others, since our models are constructed to have the same mass as the Sun. The uncertainties on the density results are much smaller too. We attribute the change in results to having more, and lower frequency, low-degree mode frequencies available. These modes provide greater sensitivity to conditions in the core. Title: Definitive Sun-as-a-star p-mode frequencies: 23 years of BiSON observations Authors: Broomhall, A. -M.; Chaplin, W. J.; Davies, G. R.; Elsworth, Y.; Fletcher, S. T.; Hale, S. J.; Miller, B.; New, R. Bibcode: 2009MNRAS.396L.100B Altcode: 2009MNRAS.tmpL.242B; 2009arXiv0903.5219B We present a list of `best possible' estimates of low-degree p-mode frequencies from 8640 days of observations made by the Birmingham Solar-Oscillations Network (BiSON). This is the longest stretch of helioseismic data ever used for this purpose, giving exquisite precision in the estimated frequencies. Every effort has been made in the analysis to ensure that the frequency estimates are also accurate. In addition to presenting the raw best-fitting frequencies from our `peak-bagging' analysis, we also provide tables of corrected frequencies pertinent to the quiet-Sun and an intermediate level of solar activity. Title: Mode lifetimes of stellar oscillations. Implications for asteroseismology Authors: Chaplin, W. J.; Houdek, G.; Karoff, C.; Elsworth, Y.; New, R. Bibcode: 2009A&A...500L..21C Altcode: 2009arXiv0905.1722C Context: Successful inference from asteroseismology relies on at least two factors: that the oscillations in the stars have amplitudes large enough to be clearly observable, and that the oscillations themselves be stable enough to enable precise measurements of mode frequencies and other parameters. Solar-like p modes are damped by convection, and hence the stability of the modes depends on the lifetime.
Aims: We seek a simple scaling relation between the mean lifetime of the most prominent solar-like p modes in stars, and the fundamental stellar parameters.
Methods: We base our search for a relation on the use of stellar equilibrium and pulsation computations of a grid of stellar models, and the first asteroseismic results on lifetimes of main-sequence, sub-giant and red-giant stars.
Results: We find that the mean lifetimes of all three classes of solar-like stars scale like T_eff-4 (where T_eff is the effective temperature). When this relation is combined with the well-known scaling relation of Kjeldsen & Bedding for mode amplitudes observed in narrow-band intensity observations, we obtain the unexpected result that the height (the maximum power spectral density) of mode peaks in the frequency power spectrum scales as g-2 (where g is the surface gravity). As it is the mode height (and not the amplitude) that fixes the S/N at which the modes can be measured, and as g changes only slowly along the main sequence, this suggests that stars cooler than the Sun might be as good targets for asteroseismology as their hotter counterparts. When observations are instead made in Doppler velocity, our results imply that mode height does increase with increasing effective temperature. Title: Efficient Pseudo-Global Fitting for Helioseismic Data Authors: Fletcher, S. T.; Chaplin, W. J.; Elsworth, Y.; New, Roger Bibcode: 2009ApJ...694..144F Altcode: 2009arXiv0902.4427F Mode fitting or "peak bagging" is an important procedure in helioseismology allowing one to determine the various mode parameters of solar oscillations. Here we describe a way of reducing the systematic bias in the fits of certain mode parameters that are seen when using "local" fitting techniques to analyze the Sun-as-a-star p-mode power spectrum. To do this we have developed a new "pseudo-global" fitting algorithm designed to gain the advantages of fitting the entire power spectrum, but without the problems involved in fitting a model incorporating many hundreds of parameters. We have performed a comparative analysis between the local and pseudo-global peak-bagging techniques by fitting the "limit" profiles of simulated helioseismic data. Results show that for asymmetric modes the traditional fitting technique returns systematically biased estimates of the central frequency parameter. This bias is significantly reduced when employing the pseudo-global routine. Similarly, we show that estimates of the background returned from the pseudo-global routine match the input values much more closely than the estimates from the local fitting method. We have also used the two fitting techniques to analyze a set of real solar data collected by the Global Oscillations at Low Frequencies instrument on board the ESA/NASA Solar and Heliospheric Observatory spacecraft. Similar differences between the estimated frequencies returned by the two techniques are seen when fitting both the real and simulated data. We show that the background fits returned by the pseudo-global routine more closely match the estimate of the background one can infer from interpolating between fits to the high and low frequency ends of the p-mode power spectrum. Title: Excitation and Damping of p-Mode Oscillations of α Cen B Authors: Chaplin, W. J.; Houdek, G.; Elsworth, Y.; New, R.; Bedding, T. R.; Kjeldsen, H. Bibcode: 2009ApJ...692..531C Altcode: 2008arXiv0810.5022C This paper presents an analysis of observational data on the p-mode spectrum of the star α Cen B, and a comparison with theoretical computations of the stochastic excitation and damping of the modes. We find that at frequencies gsim4500 μHz, the model damping rates appear to be too weak to explain the observed shape of the power spectral density of α Cen B. The conclusion rests on the assumption that most of the disagreement is due to problems modeling the damping rates, not the excitation rates, of the modes. This assumption is supported by a parallel analysis of BiSON Sun-as-a-star data, for which it is possible to use analysis of very long timeseries to place tight constraints on the assumption. The BiSON analysis shows that there is a similar high-frequency disagreement between theory and observation in the Sun. We demonstrate that by using suitable comparisons of theory and observation it is possible to make inference on the dependence of the p-mode linewidths on frequency, without directly measuring those linewidths, even though the α Cen B dataset is only a few nights long. Use of independent measures from a previous study of the α Cen B linewidths in two parts of its spectrum also allows us to calibrate our linewidth estimates for the star. The resulting calibrated linewidth curve looks similar to a frequency-scaled version of its solar cousin, with the scaling factor equal to the ratio of the respective acoustic cut-off frequencies of the two stars. The ratio of the frequencies at which the onset of high-frequency problems is seen in both stars is also given approximately by the same scaling factor. Title: SMEI observations of previously unseen pulsation frequencies in γ Doradus Authors: Tarrant, N. J.; Chaplin, W. J.; Elsworth, Y. P.; Spreckley, S. A.; Stevens, I. R. Bibcode: 2008A&A...492..167T Altcode: 2008arXiv0810.0612T Aims: As g-mode pulsators, gamma-Doradus-class stars may naïvely be expected to show a large number of modes. Taking advantage of the long photometric time-series generated by the solar mass ejection imager (SMEI) instrument, we have studied the star gamma Doradus to determine whether any other modes than the three already known are present at observable amplitude.
Methods: High-precision photometric data from SMEI taken between April 2003 and March 2006 were subjected to periodogram analysis with the PERIOD04 package.
Results: We confidently determine three additional frequencies at 1.39, 1.87, and 2.743 d-1. These are above and beyond the known frequencies of 1.320, 1.364, and 1.47 d-1.
Conclusions: Two of the new frequencies, at 1.39 and 1.87 d-1, are speculated to be additional modes of oscillation, with the third frequency at 2.743-1 a possible combination frequency. Title: Asteroseismology of Red Giant stars Authors: Tarrant, N. J.; Chaplin, W. J.; Elsworth, Y. P.; Spreckley, S. A.; Stevens, I. R. Bibcode: 2008CoAst.157...92T Altcode: 2008arXiv0810.3839T Sun-like oscillations, that is p-modes excited stochastically by convective noise, have now been observed in a number of Red Giant stars. Compared to those seen in the Sun, these modes are of large amplitude and long period, making the oscillations attractive prospects for observation. However, the low Q-factor of these modes, and issues relating to the rising background at low frequencies, present some interesting challenges for identifying modes and determining the related asteroseismic parameters. We report on the analysis procedure adopted for peak-bagging by our group at Birming- ham, and the techniques used to robustly ensure these are not a product of noise. I also show results from a number of giants extracted from multi-year observations with the SMEI instrument Title: Reliability of P mode event classification using contemporaneous BiSON and GOLF observations Authors: Simoniello, R.; Chaplin, W. J.; Elsworth, Y. P.; García, R. A. Bibcode: 2008JPhCS.118a2088S Altcode: 2008arXiv0808.1668S We carried out a comparison of the signals seen in contemporaneous BiSON and GOLF data sets. Both instruments perform Doppler shift velocity measurements in integrated sunlight, although BiSON perform measurements from the two wings of potassium absorption line and GOLF from one wing of the NaD1 line. Discrepancies between the two datasets have been observed. We show,in fact, that the relative power depends on the wing in which GOLF data observes. During the blue wing period, the relative power is mugh higher than in BiSON datasets, while a good agreement has been observed during the red period. Title: solarFLAG hare and hounds: estimation of p-mode frequencies from Sun-as-star helioseismology data Authors: Jiménez-Reyes, S. J.; Chaplin, W. J.; García, R. A.; Appourchaux, T.; Baudin, F.; Boumier, P.; Elsworth, Y.; Fletcher, S. T.; Lazrek, M.; Leibacher, J. W.; Lochard, J.; New, R.; Régulo, C.; Salabert, D.; Toutain, T.; Verner, G. A.; Wachter, R. Bibcode: 2008MNRAS.389.1780J Altcode: 2008arXiv0807.0989J; 2008MNRAS.tmp..954J; 2008MNRAS.tmp.1026J We report on the results of the latest solarFLAG hare-and-hounds exercise, which was concerned with testing methods for extraction of frequencies of low-degree solar p modes from data collected by Sun-as-a-star observations. We have used the new solarFLAG simulator, which includes the effects of correlated mode excitation and correlations with background noise, to make artificial time-series data that mimic Doppler velocity observations of the Sun-as-a-star. The correlations give rise to asymmetry of mode peaks in the frequency power spectrum. 10 members of the group (the hounds) applied their `peak-bagging' codes to a 3456-d data set, and the estimated mode frequencies were returned to the hare (who was WJC) for comparison. Analysis of the results reveals a systematic bias in the estimated frequencies of modes above ~1.8mHz. The bias is negative, meaning the estimated frequencies systematically underestimate the input frequencies.

We identify two sources that are the dominant contributions to the frequency bias. Both sources involve failure to model accurately subtle aspects of the observed power spectral density in the part (window) of the frequency power spectrum that is being fitted. One source of bias arises from a failure to account for the power spectral density coming from all those modes whose frequencies lie outside the fitting windows. The other source arises from a failure to account for the power spectral density of the weak l = 4 and 5 modes, which are often ignored in Sun-as-a-star analysis. The Sun-as-a-star peak-bagging codes need to allow for both sources, otherwise the frequencies are likely to be biased. Title: AsteroFLAG — from the Sun to the stars Authors: Chaplin, W. J.; Appourchaux, T.; Arentoft, T.; Ballot, J.; Baudin, F.; Bazot, M.; Bedding, T. R.; Christensen-Dalsgaard, J.; Creevey, O. L.; Duez, V.; Elsworth, Y.; Fletcher, S. T.; García, R. A.; Gough, D. O.; Jiménez, A.; Jiménez-Reyes, S. J.; Houdek, G.; Kjeldsen, H.; Lazrek, M.; Leibacher, J. W.; Monteiro, M. J. P. F. G.; Neiner, C.; New, R.; Régulo, C.; Salabert, D.; Samadi, R.; Sekii, T.; Sousa, S. G.; Toutain, T.; Turck-Chièze, S. Bibcode: 2008JPhCS.118a2048C Altcode: We stand on the threshold of a critical expansion of asteroseismology of Sun-like stars, the study of stellar interiors by observation and analysis of their global acoustic modes of oscillation. The Sun-like oscillations give a very rich spectrum allowing the internal structure and dynamics to be probed down into the stellar cores to very high precision. Asteroseismic observations of many stars will allow multiple-point tests of crucial aspects of stellar evolution and dynamo theory. The aims of the asteroFLAG collaboration are to help the community to refine existing, and to develop new, methods for analysis of the asteroseismic data on the Sun-like oscillators. Title: Perspectives in Global Helioseismology and the Road Ahead Authors: Chaplin, William J.; Basu, Sarbani Bibcode: 2008SoPh..251...53C Altcode: 2008arXiv0801.4213C; 2008SoPh..tmp...36C We review the impact of global helioseismology on key questions concerning the internal structure and dynamics of the Sun and consider the exciting challenges the field faces as it enters a fourth decade of science exploitation. We do so with an eye on the past, looking at the perspectives global helioseismology offered in its earlier phases, in particular the mid-to-late 1970s and the 1980s. We look at how modern, higher quality, longer datasets coupled with new developments in analysis have altered, refined, and changed some of those perspectives and opened others that were not previously available for study. We finish by discussing outstanding challenges and questions for the field. Title: CoRoT sounds the stars: p-mode parameters of Sun-like oscillations on HD 49933 Authors: Appourchaux, T.; Michel, E.; Auvergne, M.; Baglin, A.; Toutain, T.; Baudin, F.; Benomar, O.; Chaplin, W. J.; Deheuvels, S.; Samadi, R.; Verner, G. A.; Boumier, P.; García, R. A.; Mosser, B.; Hulot, J. -C.; Ballot, J.; Barban, C.; Elsworth, Y.; Jiménez-Reyes, S. J.; Kjeldsen, H.; Régulo, C.; Roxburgh, I. W. Bibcode: 2008A&A...488..705A Altcode: Context: The first asteroseismology results from CoRoT are presented, on a star showing Sun-like oscillations. We have analyzed a 60 day lightcurve of high-quality photometric data collected by CoRoT on the F5 V star HD 49933. The data reveal a rich spectrum of overtones of low-degree p modes.
Aims: Our aim was to extract robust estimates of the key parameters of the p modes observed in the power spectrum of the lightcurve.
Methods: Estimation of the mode parameters was performed using maximum likelihood estimation of the power spectrum. A global fitting strategy was adopted whereby 15 mode orders of the mode spectrum (45 modes) were fitted simultaneously.
Results: The parameter estimates that we list include mode frequencies, peak linewidths, mode amplitudes, and a mean rotational frequency splitting. We find that the average large frequency (overtone) spacing derived from the fitted mode frequencies is 85.9 ± 0.15 μHz. The frequency of maximum amplitude of the radial modes is at 1760 μHz, where the observed rms mode amplitude is 3.75 ± 0.23 ppm. The mean rotational splitting of the non-radial modes appears to be in the range ≈2.7 μHz to ≈3.4 μHz. The angle of inclination offered by the star, as determined by fits to the amplitude ratios of the modes, appears to be in the range ≈50 degrees to ≈62 degrees.

The CoRoT space mission, launched on

2006 December 27, was developed and is operated by the CNES, with

participation of the Science Programs of ESA, ESA's RSSD, Austria,

Belgium, Brazil, Germany and Spain. Title: Uncovering the Bias in Low-Degree p-Mode Linewidth Fitting Authors: Chaplin, W. J.; Elsworth, Y.; Miller, B. A.; New, R.; Verner, G. A. Bibcode: 2008SoPh..251..189C Altcode: 2008SoPh..tmp..115C Obtaining reliable estimates of linewidths in the power spectra of low-degree p modes is problematic at low frequency. In this regime, the mode coherence time increases with decreasing frequency, often causing the modes to be unresolved in relatively long duration spectra. The signal-to-noise ratio is also less favourable at low frequency, resulting in fits to power spectra underestimating the true linewidth of the p modes owing to the tails of the Lorentzian peaks becoming dominated by the background noise. We use a numerical simulation approach to assess the effect of this bias on the fitted widths of p-mode peaks and calculate observational duration limits required to obtain an unbiased estimate of the p-mode linewidth as a function of frequency. This is done in four different cases, where the precision of the artificial data is set at 0.25, 0.50, 0.75, and 1.00 m s−1 by adding random scatter to increase the sample standard deviation per 40-second measurement. In all cases, the observational duration required to accurately obtain width estimates increases beyond that required for sufficient spectral resolution below a certain threshold frequency. For modes at ≈ 1500 μHz, with an amplitude of approximately ten times the background, observations of up to 972 days are required to obtain an unbiased estimate of the linewidth. This is equivalent to ≈ 18 times the coherence time of the corresponding p modes. Title: The Amplitude of Solar Oscillations Using Stellar Techniques Authors: Kjeldsen, Hans; Bedding, Timothy R.; Arentoft, Torben; Butler, R. Paul; Dall, Thomas H.; Karoff, Christoffer; Kiss, László L.; Tinney, C. G.; Chaplin, William J. Bibcode: 2008ApJ...682.1370K Altcode: 2008arXiv0804.1182K The amplitudes of solar-like oscillations depend on the excitation and damping, both of which are controlled by convection. Comparing observations with theory should therefore improve our understanding of the underlying physics. However, theoretical models invariably compute oscillation amplitudes relative to the Sun, and it is therefore vital to have a good calibration of the solar amplitude using stellar techniques. We have used daytime spectra of the Sun, obtained with HARPS and UCLES, to measure the solar oscillations and made a detailed comparison with observations using the BiSON helioseismology instrument. We find that the mean solar amplitude measured using stellar techniques, averaged over one full solar cycle, is 18.7 +/- 0.7 cm s-1 for the strongest radial modes (l = 0) and 25.2 +/- 0.9 cm s-1 for l = 1. In addition, we use simulations to establish an equation that estimates the uncertainty of amplitude measurements that are made of other stars, given that the mode lifetime is known. Finally, we also give amplitudes of solar-like oscillations for three stars that we measured from a series of short observations with HARPS (γ Ser, β Aql, and α For), together with revised amplitudes for five other stars for which we have previously published results (α Cen A, α Cen B, β Hyi, ν Ind, and δ Pav). Title: Challenges for asteroseismic analysis of Sun-like stars Authors: Chaplin, W. J.; Houdek, G.; Appourchaux, T.; Elsworth, Y.; New, R.; Toutain, T. Bibcode: 2008A&A...485..813C Altcode: 2008arXiv0804.4371C Context: Asteroseismology of Sun-like stars is undergoing rapid expansion with, for example, new data from the CoRoT mission and continuation of ground-based campaigns. There is also the exciting upcoming prospect of NASA's Kepler mission, which will allow the asteroseismic study of several hundred Sun-like targets, in some cases for periods lasting up to a few years.
Aims: The seismic mode parameters are the input data needed for making inference on stars and their internal structures. In this paper we discuss the ease with which it will be possible to extract estimates of individual mode parameters, dependent on the mass, age, and visual brightness of the star. Our results are generally applicable; however, we look at mode detectability in the context of the upcoming Kepler observations.
Methods: To inform our discussions we make predictions of various seismic parameters. To do this we use simple empirical scaling relations and detailed pulsation computations of the stochastic excitation and damping characteristics of the Sun-like p modes.
Results: The issues related to parameter extraction on individual p modes discussed here are mode detectability, the detectability and impact of stellar activity cycles, and the ability to measure properties of rotationally split components, which is dependent on the relative importance of the rotational characteristics of the star and the damping of the stochastically excited p modes. Title: Oscillations in β Ursae Minoris. Observations with SMEI Authors: Tarrant, N. J.; Chaplin, W. J.; Elsworth, Y.; Spreckley, S. A.; Stevens, I. R. Bibcode: 2008A&A...483L..43T Altcode: 2008arXiv0804.3253T Aims: From observations of the K4III star β UMi we attempt to determine whether oscillations or any other form of variability is present.
Methods: A high-quality photometric time series of ≈1000 days in length obtained from the SMEI instrument on the Coriolis satellite is analysed. Various statistical tests were performed to determine the significance of features seen in the power density spectrum of the light curve.
Results: Two oscillations with frequencies 2.44 and 2.92 μHz have been identified. We interpret these oscillations as consecutive overtones of an acoustic spectrum, implying a large frequency spacing of 0.48 μHz. Using derived asteroseismic parameters in combination with known astrophysical parameters, we estimate the mass of β UMi to be 1.3 ± 0.3 {M}⊙. Peaks of the oscillations in the power density spectrum show width, implying that modes are stochastically excited and damped by convection. The mode lifetime is estimated at 18±9 days. Title: A modified peak-bagging technique for fitting low-ℓ solar p-modes Authors: Fletcher, S. T.; Chaplin, W. J.; Elsworth, Y.; New, R. Bibcode: 2008AN....329..447F Altcode: 2008arXiv0803.3033F We introduce a modified version of a standard power spectrum `peak-bagging' technique which is designed to gain some of the advantages that fitting the entire low-degree p-mode power spectrum simultaneously would bring, but without the problems involved in fitting a model incorporating many hundreds of parameters. Employing Monte-Carlo simulations we show that by using this modified fitting code it is possible to determine the true background level in the vicinity of the p-mode peaks. In addition to this we show how small biases in other mode parameters, which are related to inaccurate estimates of the true background, are also consequently removed. Title: A framework for describing correlated excitation of solar p-modes Authors: Chaplin, W. J.; Elsworth, Y.; Toutain, T. Bibcode: 2008AN....329..440C Altcode: 2008arXiv0804.3338C In a previous paper we suggested that, for a given p mode, the excitation function is the same as the component of the solar background noise that has an identical surface spherical harmonic projection (over the corresponding range of temporal frequency). An important consequence of this surmise is that the excitation of overtones of a given angular degree and azimuthal order will be correlated in time. In this note, we introduce the basic principles and a mathematical description of correlated mode excitation. We use simple, illustrative examples, involving two modes. Our treatment suggests that in the real observations, any signatures of the correlation would not appear as a correlation of the output amplitudes of overtones, but rather as subtle modifications to the power spectral density at frequencies between the central frequencies of the overtones. These modifications give a contribution to the observed peak asymmetries. Title: AsteroFLAG: First results from hare-and-hounds Exercise #1 Authors: Chaplin, W. J.; Appourchaux, T.; Arentoft, T.; Ballot, J.; Christensen-Dalsgaard, J.; Creevey, O. L.; Elsworth, Y.; Fletcher, S. T.; García, R. A.; Houdek, G.; Jiménez-Reyes, S. J.; Kjeldsen, H.; New, R.; Régulo, C.; Salabert, D.; Sekii, T.; Sousa, S. G.; Toutain, T.; rest of asteroFLAG Group Bibcode: 2008AN....329..549C Altcode: 2008arXiv0803.4143C We report on initial results from the first phase of Exercise #1 of the asteroFLAG hare and hounds. The asteroFLAG group is helping to prepare for the asteroseismology component of NASA's Kepler mission, and the first phase of Exercise #1 is concerned with testing extraction of estimates of the large and small frequency spacings of the low-degree p modes from Kepler-like artificial data. These seismic frequency spacings will provide key input for complementing the exoplanet search data. Title: The visibility of low-frequency solar acoustic modes Authors: Broomhall, A. M.; Chaplin, W. J.; Elsworth, Y.; Fletcher, S. T. Bibcode: 2008AN....329..461B Altcode: 2008arXiv0802.1418B We make predictions of the detectability of low-frequency p modes. Estimates of the powers and damping times of these low-frequency modes are found by extrapolating the observed powers and widths of higher-frequency modes with large observed signal-to-noise ratios. The extrapolations predict that the low-frequency modes will have small signal-to-noise ratios and narrow widths in a frequency-power spectrum. Monte Carlo simulations were then performed where timeseries containing mode signals and normally distributed Gaussian noise were produced. The mode signals were simulated to have the powers and damping times predicted by the extrapolations. Various statistical tests were then performed on the frequency-amplitude spectra formed from these timeseries to investigate the fraction of spectra in which the modes could be detected. The results of these simulations were then compared to the number of p-modes candidates observed in real Sun-as-a-star data at low frequencies. The fraction of simulated spectra in which modes were detected decreases rapidly as the frequency of modes decreases and so the fraction of simulations in which the low-frequency modes were detected was very small. However, increasing the signal-to-noise (S/N) ratio of the low-frequency modes by a factor of 2 above the extrapolated values led to significantly more detections. Therefore efforts should continue to further improve the quality of solar data that is currently available. Title: A devil in the detail: parameter cross-talk from the solar cycle and estimation of solar p-mode frequencies Authors: Chaplin, W. J.; Jiménez-Reyes, S. J.; Eff-Darwich, A.; Elsworth, Y.; New, R. Bibcode: 2008MNRAS.385.1605C Altcode: 2008MNRAS.tmp..261C; 2008arXiv0801.1431C Frequencies, powers and damping rates of the solar p modes are all observed to vary over the 11-yr solar activity cycle. Here, we show that simultaneous variations in these parameters give rise to a subtle cross-talk effect, which we call the `devil in the detail', that biases p-mode frequencies estimated from analysis of long power frequency spectra. We also show that the resonant peaks observed in the power frequency spectra show small distortions due to the effect. Most of our paper is devoted to a study of the effect for Sun-as-a-star observations of the low-l p modes. We show that for these data the significance of the effect is marginal. We also touch briefly on the likely l dependence of the effect, and discuss the implications of these results for solar structure inversions. Title: Distortion of the p-mode peak profiles by the solar-cycle frequency shifts: do we need to worry? Authors: Chaplin, W. J.; Elsworth, Y.; New, R.; Toutain, T. Bibcode: 2008MNRAS.384.1668C Altcode: 2007arXiv0712.2931C; 2008MNRAS.tmp..140C We seek to address whether solar-cycle frequency shifts of the Sun's low-l p modes `distort' the underlying shapes of the mode peaks, when those peaks are observed in power frequency spectra made from data spanning large fractions, or more, of the cycle period. We present analytical descriptions of the expected profiles, and validate the predictions through use of artificial seismic time-series data, in which temporal variations of the oscillator frequencies are introduced. Our main finding is that for the Sun-like frequency shifts the distortion of the asymmetrical Lorentzian-like profiles is very small, but also just detectible. Our analysis indicates that by fitting modes to the usual Lorentzian-like models - which do not allow for the distortion - rather than new models we derive, there is a bias in the mode height and linewidth parameters that is comparable in size to the observational uncertainties given by multi-year data sets. Bias in the frequency parameter gives much less cause for worry, being over an order of magnitude smaller than the corresponding frequency uncertainties. The distortion discussed in this paper may need to be considered when multiyear Sun-like asteroseismic data sets are analysed on stars showing strong activity cycles. Title: Asteroseismology of red giants: photometric observations of Arcturus by SMEI Authors: Tarrant, N. J.; Chaplin, W. J.; Elsworth, Y.; Spreckley, S. A.; Stevens, I. R. Bibcode: 2007MNRAS.382L..48T Altcode: 2007MNRAS.tmpL.110T; 2007arXiv0706.3346T We present new results on oscillations of the K1.5III giant Arcturus (α Boo), from analysis of just over 2.5 yr of precise photometric observations made by the Solar Mass Ejection Imager on board the Coriolis satellite. A strong mode of oscillation is uncovered by the analysis, having frequency 3.51 +/- 0.03μHz. By fitting its mode peak, we are able to offer a highly constrained direct estimate of the damping time (τ = 24 +/- 1d). The data also hint at the possible presence of several radial-mode overtones, and maybe some non-radial modes. We are also able to measure the properties of the granulation on the star, with the characteristic time-scale for the granulation estimated to be ~0.50 +/- 0.05 d. Title: Solar Heavy-Element Abundance: Constraints from Frequency Separation Ratios of Low-Degree p-Modes Authors: Chaplin, William J.; Serenelli, Aldo M.; Basu, Sarbani; Elsworth, Yvonne; New, Roger; Verner, Graham A. Bibcode: 2007ApJ...670..872C Altcode: 2007arXiv0705.3154C We use very precise frequencies of low-degree solar-oscillation modes measured from 4752 days of data collected by the Birmingham Solar-Oscillations Network to derive seismic information on the solar core. We compare these observations to results from a large Monte Carlo simulation of standard solar models, and use the results to constrain the mean molecular weight of the solar core and the metallicity of the solar convection zone. We find that only a high value of solar metallicity is consistent with the seismic observations. We can determine the mean molecular weight of the solar core to a very high precision, and, depending on the sequence of Monte Carlo models used, we find that the average mean molecular weight in the inner 20% by radius of the Sun ranges from 0.7209 to 0.7231, with uncertainties of less than 0.5% on each value. Our lowest seismic estimate of solar metallicity is Z=0.0187, and our highest is Z=0.0239, with uncertainties in the range of 12%-19%. Our results indicate that the discrepancies between solar models constructed with low metallicity and the helioseismic observations extend to the solar core, and thus cannot be attributed to deficiencies in the modeling of the solar convection zone. Title: Needles in haystacks: how to use contemporaneous data in the search for low-frequency modes of oscillation of the Sun Authors: Broomhall, A. M.; Chaplin, W. J.; Elsworth, Y.; Appourchaux, T. Bibcode: 2007MNRAS.379....2B Altcode: 2007MNRAS.tmp..525B We show how to take advantage of contemporaneous data from two different instruments in the search for low-frequency modes of oscillation of the Sun. Contemporaneous data allow searches to be made for prominent, sharp concentrations of power which are coincident in frequency. Crucial to determining objective measures of the joint probability of the random occurrence of such features, which are potential candidates for modes, is a good understanding of the characteristics of the background noise. In this paper we show how to make proper allowance, in the calculation of the probability, for noise that is common to data from different instruments. This common noise is solar in origin, and comes from the solar granulation. Its presence makes calculation of the probability a non-trivial problem. We demonstrate application of the technique in searches for low-frequency p modes. The data we searched comprised 3071 d of contemporaneous Sun-as-a-star Doppler velocity observations made by the ground-based Birmingham Solar-Oscillations Network (BiSON), and the GOLF instrument onboard the ESA/NASA SOHO spacecraft. Title: On understanding the meaning of l = 2 and 3 p-mode frequencies as measured by various helioseismic instruments Authors: Appourchaux, T.; Chaplin, W. J. Bibcode: 2007A&A...469.1151A Altcode: Aims:Frequencies of the low-degree p-mode oscillations of the Sun may be extracted either from data collected by instruments that make full-disc observations of the Sun as a star, or from data collected by instruments that resolve, or image, the Sun's surface onto many detector elements. The two methods can show marked differences in their sensitivity to modes having certain combinations of degree and azimuthal order. These different sensitivities lead to differences in measurements of the central frequencies of the modes, which must be properly accounted for if data from two different instruments are to be compared, or combined.
Methods: We perform an analytical derivation of the p-mode frequency offsets expected between contemporaneous Sun-as-a-star and resolved-Sun data.
Results: Here, we demonstrate that the empirical factors derived by Chaplin et al. (2004, A&A, 424, 713) are reproduced by our analysis, but with a more marked dependence upon the mode linewidth. Title: On prospects for sounding activity cycles of Sun-like stars with acoustic modes Authors: Chaplin, W. J.; Elsworth, Y.; Houdek, G.; New, R. Bibcode: 2007MNRAS.377...17C Altcode: 2007MNRAS.tmp..170C Data are now available on the Sun-like, p-mode oscillations of a growing number of late-type stars. With extension of these observations to dedicated, long-term campaigns, it will soon become possible to probe acoustically magnetic activity, and stellar cycles, by observation of systematic shifts in the mode frequencies giving additional information to the stellar dynamo theorists. Here, we use model computations of the damping rates of stochastically excited radial p modes to make predictions of the precision with which it will be possible to measure stellar-cycle frequency shifts of Sun-like stars along the lower main sequence. We assume the first analyses will average shifts across the most prominent modes to reduce uncertainties. We also make some predictions of the expected frequency shifts, based on existing stellar CaII H& K data. Our main conclusion is that the basic properties of the acoustic signatures of the cycles should be measurable to reasonably high precision given only a few multimonth segments of data. It should also be possible to make inference on the surface distribution of the activity, through measurement of shifts of modes of different degree. Our computations also reveal an interesting feature in the predicted appearance of the acoustic mode spectra of stars cooler than about 5400K: the modelled power spectral density of the modes shows two maxima, at different frequencies. By computing average shifts of modes across the two maxima, where the signal-to-noise ratio is highest, it should be possible to get the first measures of the frequency dependence of the p-mode shifts. This dependence provides information on the mechanism responsible for driving these shifts. Title: Solar p-Mode Frequencies over Three Solar Cycles Authors: Chaplin, W. J.; Elsworth, Y.; Miller, B. A.; Verner, G. A.; New, R. Bibcode: 2007ApJ...659.1749C Altcode: We analyze thirty years of solar oscillations data collected by the Birmingham Solar Oscillations Network (BiSON). Estimates of the mean frequency shifts of low-degree p-modes have been extracted over a period spanning solar cycles 21-23. Two methods of analysis are used to extract the frequency shifts: one method uses results on fitted frequencies of individual modes, which are then averaged to give mean frequency shifts; the other method uses cross-correlations of power frequency spectra made from subsets of the data shifted in time. The frequency shifts are correlated against six proxies of solar activity, which are sensitive to magnetic and irradiance variability at a range of locations from the photosphere to the corona. We find proxies that have good sensitivity to the effects of weak-component magnetic flux-which is more widely distributed in latitude than the strong flux in the active regions-are those that follow the frequency shifts most consistently over the three cycles. This list includes the Mg II H and K core-to-wing data, the 10.7 cm radio flux, and the He I equivalent width data. While the two methods of analysis give consistent results, use of the cross-correlation function to measure mean frequency shifts returns less precise values in cases in which the duty cycle is greater than 30%. Estimation of uncertainties from the cross-correlation method also requires that proper allowance be made for strong correlations in the data. Title: Sun-as-a-star observations: evidence for degree dependence of changes in damping of low-ℓ p modes along the solar cycle Authors: Salabert, D.; Chaplin, W. J.; Elsworth, Y.; New, R.; Verner, G. A. Bibcode: 2007A&A...463.1181S Altcode: 2006astro.ph..9156S Aims:We use 9.5-yr of BiSON Sun-as-a-star data to search for dependence of solar-cycle parameter changes on the angular degree, ℓ, of the data. The nature of the Sun-as-a-star observations is such that for changes measured at fixed frequency, or for changes averaged across the same range in frequency, any ℓ dependence present carries information on the latitudinal distribution of the agent (i.e., the activity) responsible for those changes.
Methods: We split the 9.5-yr timeseries into contiguous 108-d pieces, and determine mean changes in the damping of, power in, and energy supplied to the modes through the solar cycle. We also apply a careful correction to account for the deleterious effects of the ground-based BiSON window function on the results.
Results: From our full analysis we obtain a marginally significant result for the damping parameter, where the mean change is found to be weakest at ℓ=0. The other parameters show hints of some dependence in ℓ.
Conclusions: .Our main conclusion is that the mean fractional solar-cycle change in the ℓ=0 damping rates is approximately 50% smaller than was previously assumed. It had been common practice to use an average over all low-ℓ modes; our downward revision of the radial-mode value has implications for comparisons with models of the global solar cycle changes, which are usually based on a spherically symmetric geometry. Title: Solar Abundances and Helioseismology: Fine-Structure Spacings and Separation Ratios of Low-Degree p-Modes Authors: Basu, Sarbani; Chaplin, William J.; Elsworth, Yvonne; New, Roger; Serenelli, Aldo M.; Verner, Graham A. Bibcode: 2007ApJ...655..660B Altcode: 2006astro.ph.10052B We have used 4752 days of data collected by the Birmingham Solar Oscillations Network (BiSON) to determine very precise oscillation frequencies of acoustic low-degree modes that probe the solar core. We compare the fine (small frequency) spacings and frequency separation ratios formed from these data with those of different solar models. We find that models constructed with low metallicity are incompatible with the observations. The results provide strong support for lowering the theoretical uncertainties on the neutrino fluxes. These uncertainties were recently raised due to the controversy over solar abundances. Title: On the Variation of the Peak Asymmetry of Low-l Solar p Modes Authors: Jiménez-Reyes, S. J.; Chaplin, W. J.; Elsworth, Y.; García, R. A.; Howe, R.; Socas-Navarro, H.; Toutain, T. Bibcode: 2007ApJ...654.1135J Altcode: The resonant peaks of solar p modes show small amounts of asymmetry in frequency. Here, we use five independent sets of contemporaneous data, collected over a ~=8 yr period, to investigate whether peak asymmetry in low angular degree p modes changes over the solar activity cycle. Three of the data sets are from instruments on board the ESA/NASA SOHO spacecraft (GOLF, MDI, and VIRGO/SPM); and two are from ground-based networks (BiSON and GONG). Evidence for variation in asymmetry, well correlated with the activity cycle, is uncovered in the GOLF and BiSON Doppler velocity data. Suggestions of a similar trend are present in the GONG Doppler velocity data. Apparent changes in the MDI Doppler velocity data are somewhat less significant. Meanwhile, analysis of the SPM intensity data failed to uncover any evidence for significant change of the asymmetry parameter. Title: BiSON update Authors: Allison, J.; Barnes, I.; Chaplin, W. J.; Elsworth, Y. P.; Hale, S. J.; Jackson, B.; Miller, B. A.; Verner, G. A.; New, R. Bibcode: 2006ESASP.624E..99A Altcode: 2006soho...18E..99A No abstract at ADS Title: Analysis of velocity-noise variations arising from photon-noise in data from the GOLF instrument Authors: New, R.; Chaplin, W. J.; Elsworth, Y. P.; García, R. A.; Jiménez-Reyes, S. J. Bibcode: 2006ESASP.624E.100N Altcode: 2006soho...18E.100N No abstract at ADS Title: The seismic Sun over three activity cycles Authors: Chaplin, W. J.; Elsworth, Y.; Hale, S. J.; Miller, B. A.; Verner, G. A.; New, R. Bibcode: 2006ESASP.624E...8C Altcode: 2006soho...18E...8C No abstract at ADS Title: Helioseismology with low-degree observations: where we stand, and what the future holds Authors: Chaplin, W. J. Bibcode: 2006ESASP.624E..21C Altcode: 2006soho...18E..21C No abstract at ADS Title: A study of the role of phase evolution in the amplitudes of low-degree solar p-modes Authors: Simoniello, R.; Chaplin, W. J.; Elsworth, Y.; New, R. Bibcode: 2006ESASP.624E.106S Altcode: 2006soho...18E.106S No abstract at ADS Title: Are the shapes of the p-mode peaks `distorted' by the solar cycle when they are observed in long, multi-year power frequency spectra? Authors: Chaplin, W. J.; Elsworth, Y.; New, R.; Toutain, T. Bibcode: 2006ESASP.624E..91C Altcode: 2006soho...18E..91C No abstract at ADS Title: Frequency, splitting, linewidth and amplitude estimates of low-l p modes of alpha Cen A: analysis of WIRE photometry Authors: Fletcher, S. T.; Chaplin, W. J.; Elsworth, Y.; Schou, J.; Buzasi, D. Bibcode: 2006ESASP.624E..27F Altcode: 2006soho...18E..27F No abstract at ADS Title: The internal structure of the Sun inferred from g modes and low-frequency p modes Authors: Elsworth, Y. P.; Baudin, F.; Chaplin, W; Andersen, B; Appourchaux, T.; Boumier, P.; Broomhall, A. -M.; Corbard, T.; Finsterle, W.; Fröhlich, C.; Gabriel, A.; García, R. A.; Gough, D. O.; Grec, G.; Jiménez, A.; Kosovichev, A.; Provost, J.; Sekii, T.; Toutain, T.; Turck-Chièze, S. Bibcode: 2006ESASP.624E..22E Altcode: 2006soho...18E..22E The Phoebus group is an international collaboration of helioseismologists, its aim being to detect low-frequency solar g modes. Here, we report on recent work, including the development and application of new techniques based on the detection of coincidences in contemporaneous datasets and the asymptotic properties of the g-mode frequencies. The length of the time series available to the community is now more than ten years, and this has reduced significantly the upper detection limits on the g-mode amplitudes. Furthermore, low-degree p modes can now be detected clearly at frequencies below 1000 μHz. Title: Peak asymmetry of solar p modes: a framework to explain the effects of the correlated noise from the acoustic source Authors: Toutain, T.; Elsworth, Y.; Chaplin, W. J. Bibcode: 2006MNRAS.371.1731T Altcode: 2006MNRAS.tmp..904T It is well known that in the power spectrum solar p modes have asymmetric profiles, which depart from a Lorentzian shape. We present a framework to explain the contribution of correlated background noise, from the acoustic source, to this asymmetry. An important prediction is that observed peak asymmetry may differ depending on the way the p-mode observations are made, and on how the data are prepared. Furthermore, if valid, the proposed framework may provide the basis for separating the contribution of the correlated noise from that of the source location and properties. Title: On the prospects for sounding activity cycles on Sun-like stars Authors: Chaplin, W. J.; Elsworth, Y.; Houdek, G.; New, R. Bibcode: 2006ESASP.624E.112C Altcode: 2006soho...18E.112C No abstract at ADS Title: Rotation inversions of artificial solarFLAG Sun-as-a-star data Authors: Chaplin, W. J.; Sekii, T.; Appourchaux, T.; Baudin, F.; Boumier, P.; Corbard, T.; Elsworth, Y.; Fletcher, S. T.; Garcia, R. A.; Jiménez-Reyes, S. J.; Lazrek, M.; New, R.; Salabert, D.; Toutain, T.; Wachter, R. Bibcode: 2006ESASP.624E..82C Altcode: 2006soho...18E..82C No abstract at ADS Title: Reliable analysis of power and phase features as seen from BiSON and GOLF observations Authors: Simoniello, R.; Elsworth, Y. P.; Chaplin, W. J.; García, R. Bibcode: 2006ESASP.624E.101S Altcode: 2006soho...18E.101S No abstract at ADS Title: Evidence for degree dependence of changes in p-mode damping along the solar cycle in Sun-as-a-star data Authors: Salabert, D.; Chaplin, W. J.; Elsworth, Y.; New, R.; Verner, G. A. Bibcode: 2006ESASP.624E.113S Altcode: 2006soho...18E.113S No abstract at ADS Title: Needles in haystacks: how to use contemporaneous data in the search for g-modes Authors: Broomhall, A. M.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2006ESASP.624E..96B Altcode: 2006soho...18E..96B No abstract at ADS Title: Frequency, splitting, linewidth and amplitude estimates of low-ℓ p modes of α Cen A: analysis of Wide-Field Infrared Explorer photometry Authors: Fletcher, S. T.; Chaplin, W. J.; Elsworth, Y.; Schou, J.; Buzasi, D. Bibcode: 2006MNRAS.371..935F Altcode: 2006astro.ph..7172F; 2006MNRAS.tmp..824F We present results of fitting the 50-d time series of photometry of α Cen A taken by the Wide-Field Infrared Explorer (WIRE) satellite in 1999. Both power spectrum and autocovariance function (ACF) fitting techniques were used in an attempt to determine mode frequencies, rotational splittings, lifetimes and amplitudes of low-l p modes. In all, using both techniques, we managed to fit 18 modes (seven l = 0, eight l = 1 and three l = 2) with frequencies determined to within 1-2 μHz. These estimates are shown to be 0.6 +/- 0.3 μHz lower, on average, than the frequencies determined from two other more recent studies, which used data gathered about 19 months after the WIRE observations. This could be indicative of an activity cycle, although due to the large uncertainty, more data would be needed to confirm this.

Over a range of 1700-2650 μHz, we were also able to use the ACF fitting to determine an average lifetime of 3.9 +/- 1.4 d, and an average rotational splitting of 0.54 +/- 0.22 μHz, which is the first ever reliable estimate of this parameter. In contrast to the ACF, the power spectrum fitting was shown to return significantly biased results for these parameters. Title: Recent Progresses on g-Mode Search Authors: Appourchaux, T.; Andersen, B.; Baudin, F.; Boumier, P.; Broomhall, A. -M.; Chaplin, W.; Corbard, T.; Elsworth, Y.; Finsterle, W.; Fröhlich, C.; Gabriel, A.; Garcia, R.; Gough, D. O.; Grec, G.; Jiménez, A.; Kosovichev, A.; Provost, J.; Sekii, T.; Toutain, T.; Turck-Chièze, S. Bibcode: 2006ESASP.617E...2A Altcode: 2006soho...17E...2A No abstract at ADS Title: Anomalous variations in low-degree helioseismic mode frequencies Authors: Howe, R.; Chaplin, W. J.; Elsworth, Y.; Hill, F.; Komm, R. W.; Isaak, G. R.; New, R. Bibcode: 2006MNRAS.369..933H Altcode: 2006MNRAS.tmp..504H We compare changes in the frequencies of solar acoustic modes with degree between 0 and 2, as derived from Global Oscillation Network Group (GONG), Birmingham Solar Oscillations Network (BiSON) and Michelson Doppler Imager (MDI) spectra obtained between 1995 and 2003. We find that, after the solar-activity dependence has been removed from the frequencies, there remain variations that appear to be significant, and are often well correlated between the different data sets. We consider possible explanations for these fluctuations, and conclude that they are likely to be related to the stochastic excitation of the modes. The existence of such fluctuations has possible relevance to the analysis of other low-degree acoustic mode spectra such as those from solar-type stars. Title: Solar FLAG hare and hounds: on the extraction of rotational p-mode splittings from seismic, Sun-as-a-star data Authors: Chaplin, W. J.; Appourchaux, T.; Baudin, F.; Boumier, P.; Elsworth, Y.; Fletcher, S. T.; Fossat, E.; García, R. A.; Isaak, G. R.; Jiménez, A.; Jiménez-Reyes, S. J.; Lazrek, M.; Leibacher, J. W.; Lochard, J.; New, R.; Pallé, P.; Régulo, C.; Salabert, D.; Seghouani, N.; Toutain, T.; Wachter, R. Bibcode: 2006MNRAS.369..985C Altcode: 2006MNRAS.tmp..515C; 2006astro.ph..6748C We report on results from the first solar Fitting at Low-Angular degree Group (solar FLAG) hare-and-hounds exercise. The group is concerned with the development of methods for extracting the parameters of low-l solar p-mode data (`peak bagging'), collected by Sun-as-a-star observations. Accurate and precise estimation of the fundamental parameters of the p modes is a vital pre-requisite of all subsequent studies. Nine members of the FLAG (the `hounds') fitted an artificial 3456-d data set. The data set was made by the `hare' (WJC) to simulate full-disc Doppler velocity observations of the Sun. The rotational frequency splittings of the l = 1, 2 and 3 modes were the first parameter estimates chosen for scrutiny. Significant differences were uncovered at l = 2 and 3 between the fitted splittings of the hounds. Evidence is presented that suggests this unwanted bias had its origins in several effects. The most important came from the different way in which the hounds modelled the visibility ratio of the different rotationally split components. Our results suggest that accurate modelling of the ratios is vital to avoid the introduction of significant bias in the estimated splittings. This is of importance not only for studies of the Sun, but also of the solar analogues that will be targets for asteroseismic campaigns.

Solar FLAG URL: http://bison.ph.bham.ac.uk/~wjc/Research/FLAG.html

E-mail: wjc@bison.ph.bham.ac.uk ‡

George Isaak passed away in 2005 June 5, prior to the completion of this work. He is greatly missed by us all. Title: BiSON Data Show Change in Solar Structure with Magnetic Activity Authors: Verner, G. A.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2006ApJ...640L..95V Altcode: We find evidence for an activity-dependent change in solar structure at the second helium ionization zone (~0.98 Rsolar). We use low-degree p-mode frequencies obtained from 13 years of observations by the Birmingham Solar Oscillations Network (BiSON) to track changes in the amplitude of the rapid-variation signature imposed by the bump in the adiabatic exponent, Γ1, at the He II ionization zone. This is the first indication of structural change detected using only low-degree data and confirms the recent results of high-degree and local helioseismic studies. Title: The Detectability of Signatures of Rapid Variation in Low-Degree Stellar p-Mode Oscillation Frequencies Authors: Verner, G. A.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2006ApJ...638..440V Altcode: Regions of rapid variation in stellar interiors introduce characteristic periodic signatures into the frequencies of their p-mode oscillations. These signatures have previously been isolated in solar data and have been used to estimate the level of convective overshoot and the envelope helium abundance in the Sun. Precise asteroseismic data are now becoming available for a number of distant Sun-like stars, and the techniques developed for low-degree solar data can be used in the stellar case. In this paper, we address the observational duration required to isolate and examine these rapid-variation signatures through the use of low-degree solar data as a Sun-like stellar analog. We also outline the difficulties involved and bias introduced when using a limited number of poorly constrained mode frequencies. The signature resulting from the region of the second ionization of helium is found to be detectable in spectra of shorter duration than those required to isolate the smaller amplitude signature arising from the base of the convective envelope. Observations of just 84 days may be sufficient to extract reliable information on the acoustic depth and extent of the He II ionization zone, although longer observations are required to obtain sufficient precision to estimate the envelope helium abundance. The acoustic radius of the base of the convective envelope and the amplitude of the signature are reliably isolated in spectra of at least 182 days. Title: Impact of the Solar Activity Cycle on Frequency Separation Ratios in Helioseismology Authors: Chaplin, W. J.; Elsworth, Y.; Miller, B. A.; New, R.; Verner, G. A. Bibcode: 2005ApJ...635L.105C Altcode: Roxburgh & Vorontsov have recently proposed the use of ratios of small to large frequency separations of low angular degree p-modes as a means of eliminating from asteroseismic data the unwanted influence of the structure of the near-surface layers of stars. Here we have studied the impact of the solar activity cycle on the magnitude of these so-called frequency separation ratios using data collected by Sun-as-a-star observations. The ratios are observed to change with the shifting level of global solar activity. The effect, which we detect in BiSON Doppler velocity data at a marginal level of significance, is shown to be a consequence of the influence of acoustic asphericity from the surface activity on the azimuthally dependent Sun-as-a-star frequencies. The results suggest that any analysis that makes use of ratios formed from long helioseismic data sets may therefore show effects of bias. While the effect is less significant in shorter data sets, of length similar to what will soon be available from asteroseismic campaigns, an approximate doubling of the effects from the solar asphericity may be sufficient to cause complications for stellar analyses. Title: Chaplin, Ballai: Helioseismology: The sound of the Sun Authors: Chaplin, W. J.; Ballai, I. Bibcode: 2005A&G....46d..27C Altcode: Observations of resonant phenomena on the Sun are now being made that have their origins not only in the interior, but also in structures in the tenuous solar atmosphere. The challenge for solar researchers is to reconcile the flood of observations and theory from these varied scales and locations to further improve our understanding of the Sun. Here, we look at some of the exciting challenges facing researchers delving into the seismology of the Sun. Title: Seismology of the Sun: from the inner core to the corona Authors: Ballai, I.; Chaplin, W. Bibcode: 2005Obs...125..224B Altcode: No abstract at ADS Title: On model predictions of the power spectral density of radial solar p modes Authors: Chaplin, W. J.; Houdek, G.; Elsworth, Y.; Gough, D. O.; Isaak, G. R.; New, R. Bibcode: 2005MNRAS.360..859C Altcode: 2005MNRAS.tmp..510C We investigate the frequency dependence of the power spectral density of low-degree solar p modes by comparing measurements with the results of a stochastic-excitation model. In the past it was common practice to use the total power in such investigations. Using the maximum of the power spectral density instead provides a direct comparison with the measured mode heights in the observed power spectrum. This method permits a more careful calibration of the adjustable parameters in the excitation model, a model which we present here, for the first time, in a format that precisely and unambiguously relates the amplitudes of the modes of oscillation to the Reynolds stress in the equilibrium model. We find that errors in the theory of the linear mode damping rates, particularly at low frequency, have a dramatic impact on the predictions of the mode heights in the spectral density, whereas parameter changes in the stochastic excitation model, within a plausible domain of parameter space, have a comparatively small effect. Title: Towards the future - Birmingham UKSP 2005 Authors: Chaplin, W. J.; Erdélyi, R. Bibcode: 2005A&G....46c..15C Altcode: This year's annual UK Solar Physics Meeting was held in parallel with the National Astronomy Meeting in Birmingham, from 4-8 April 2005. Bill Chaplin and Robert Erdélyi report on proceedings. Title: Noise characteristics of full-disc helioseismic observations made by resonant scattering spectrometers Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R.; Pintér, B. Bibcode: 2005MNRAS.359..607C Altcode: 2005MNRAS.tmp..294C Resonant scattering spectrometers (RSSs) have been used to make high-precision full-disc helioseismic observations since the 1970s. They are capable of very high-precision determinations of line-shift, meaning that they are used to obtain precise velocity measurements, and, for suitably configured RSSs, the disc-averaged longitudinal magnetic field (SMMF). In order to exploit fully the very extensive high-precision data sets, it is essential to understand the noise characteristics of the instruments. This paper re-examines the consequences for velocity and SMMF determinations of there being noise on the scattered light signals measured by an RSS. It presents a theoretical description, and analysis of simulations, which match well the noise variations found recently in both BiSON velocity and SMMF observations. It also outlines a method for using the differences between the power spectra of redundant channels to analyse instrumental noise characteristics. Title: Monte Carlo simulation of solar p-mode profiles revisited: Bias and uncertainty estimation from one, not many, fits Authors: Toutain, T.; Elsworth, Y.; Chaplin, W. J. Bibcode: 2005A&A...433..713T Altcode: It is quite common in helioseismology to use extensive Monte Carlo simulations to investigate the bias and associated uncertainties in fitted p-mode parameters. This can, however, be very time-intensive if the fitting problem is complicated or large datasets (in time or resolution) are involved. Here, we show that it is often possible to reduce significantly the task by taking advantage of the statistical properties of the p-mode profiles. Title: Inferred acoustic rates of solar p modes from several helioseismic instruments Authors: Baudin, F.; Samadi, R.; Goupil, M. -J.; Appourchaux, T.; Barban, C.; Boumier, P.; Chaplin, W. J.; Gouttebroze, P. Bibcode: 2005A&A...433..349B Altcode: Acoustic rates of excitation of solar p modes can be estimated from observations in order to place constraints on the modelling of the excitation process and the layers where it occurs in the star. For several reasons (including a poor signal to noise ratio and mode overlap), this estimation is difficult. In this work, we use three completely independent datasets to obtain robust estimates in the solar case for ℓ=1 modes. We also show that the height in the solar atmosphere where the modes are observed must be taken into account. Our three sets of results are shown to be consistent, particularly in the lower part of the p-mode spectrum (from 1.8 mHz to 2.8 mHz). At higher frequencies, the agreement is not as good, because of a larger dispersion of the measurements and also because of some systematic differences which might be due to observation height estimation or to a systematic influence of the noise. Title: The Search for Correlation between BiSON SMMF Data and CME Events Authors: Chaplin, William J.; Dumbill, Andrew M.; Elsworth, Yvonne P.; Isaak, George R.; McLeod, Clive P.; Miller, Brek A.; New, Roger; Pintér, Balázs Bibcode: 2005HiA....13..141C Altcode: The Birmingham Solar Oscillation Network (BiSON) has acquired high precision solar mean magnetic field (SMMF) data on a 40-second cadence for a decade. We present first attempts to compare such data from recent years with the occurence of CME's as recorded by LASCO using correlation techniques applied to measurements from different BiSON instruments to maximise the sensitivity to CME related SMMF responses. SMMF measurements were recorded at the time of occurence of several hundreds CME's. Title: On the detectability of a rotation-rate gradient in the solar core Authors: Chaplin, W. J.; Sekii, T.; Elsworth, Y.; Gough, D. O. Bibcode: 2004MNRAS.355..535C Altcode: 2004MNRAS.tmp..451C We consider the problem of uncovering a possible gradient of rotation in the solar core using seismic frequency splittings of low-degree p-modes. The data are presumed to come from full-disc observations of the Sun. In particular, we formulate an approach for determining the diagnostic potential of a low-l splitting set to uncover, by inversion, a difference in rotation between two target radii: one deep in the core, the other in the mid-regions of the radiative zone. Our formulation assumes the underlying rotation rate to be flat in the outer part of the zone, but to vary linearly in the core (with the breakpoint in behaviour located between the two target radii). Artificial data are used to test the formulation, and to investigate the relative importance at low l of deeply penetrating, high-order modes and relatively shallow, low-order modes. Our results suggest that in order to detect a significant difference between the rotation at r= 0.1R and 0.35R- with the input splitting data coming from a 10-yr set of high-quality observations - that difference would need to be a significant fraction of the rotation rate itself. Title: Phase Variation as a New Tool in the Investigation of the Excitation and Damping of Solar p-modes Authors: Simoniello, R.; Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; New, R. Bibcode: 2004ApJ...616..594S Altcode: We report on a novel way of using the phase evolution in solar oscillation data as a tool in the study of p-mode excitation and damping. A mathematical formalism is presented, backed by extensive simulations, that enables the determination of the line width of modes close to the peak of the solar oscillation spectrum. The method potentially avoids the usual problem of strong correlation between the width and the height of the modes. We also identify further possible uses of the technique. Title: Flag Hare-And Exercise: on the Extraction of Sectoral Mode Splittings from Full-Disc Sun-As Data Authors: Chaplin, W. J.; Appourchaux, T.; Baudin, F.; Boumier, P.; Elsworth, Y.; Fletcher, S. T.; Fossat, E.; García, R. A.; Isaak, G. R.; Jiménez, A.; Jiménez-Reyes, S. J.; Lazrek, M.; Lochard, J.; New, R.; Pallé, P.; Régulo, C.; Salabert, D.; Toutain, T. Bibcode: 2004ESASP.559..356C Altcode: 2004soho...14..356C No abstract at ADS Title: Impact of Observational Duty Cycle on P-Mode Eigenfrequencies Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R.; Salabert, D. Bibcode: 2004ESASP.559..364C Altcode: 2004soho...14..364C No abstract at ADS Title: Twenty-Eight Years of BISON Data Authors: Miller, B. A.; Hale, S. J.; Elsworth, Y.; Chaplin, W. J.; Isaak, G. R.; New, R. Bibcode: 2004ESASP.559..571M Altcode: 2004soho...14..571M No abstract at ADS Title: The Phase of Global Solar Oscillations Authors: Simoniello, R.; Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R. Bibcode: 2004ESASP.559..251S Altcode: 2004soho...14..251S No abstract at ADS Title: Exploring P-Modes Big Excitations Using 10 Years of BISON Data Authors: Simoniello, R.; Chaplin, W. J.; Elsworth, Y. P. Bibcode: 2004ESASP.559..631S Altcode: 2004soho...14..631S No abstract at ADS Title: Novel Techniques for the Identification of Noise Contributions to Full-Disc Helioseismic Power Spectra Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R.; Pintér, B. Bibcode: 2004ESASP.559..360C Altcode: 2004soho...14..360C No abstract at ADS Title: Low-Degree Helioseismology: the State of Play on its Silver Anniversary. Analysis and Measurement of LOW-l Solar P-Mode Parameters in the Authors: Chaplin, W. J. Bibcode: 2004ESASP.559...34C Altcode: 2004soho...14...34C No abstract at ADS Title: Time-Domain Authors: Fletcher, S. T.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2004ESASP.559...44F Altcode: 2004soho...14...44F No abstract at ADS Title: On comparing estimates of low-l solar p-mode frequencies from Sun-as-a-star and resolved observations Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R. Bibcode: 2004A&A...424..713C Altcode: Low-angular-degree (low-l) solar p modes provide a sensitive probe of the radiative interior and core of the Sun. Estimates of their centroid frequencies can be used to constrain the spherically symmetric structure of these deep-lying layers. The required data can be extracted from two types of observation: one where the modes are detected in integrated sunlight, i.e., a Sun-as-a-star view; and a second where the visible disc is imaged onto many pixels, and the collected images then decomposed into their constituent spherical harmonics. While the imaging strategy provides access to all of the individual components of a multiplet, the Sun-as-a-star technique is sensitive to only about two thirds of these (average over l=0 to 3) with those modes that are detected having different levels of visibility. Because the various components can have contrasting spatial structure over the solar surface, they can respond very differently to changes in activity along the solar cycle. Since the Sun-as-a-star and resolved analyses take as input a different ``subset'' of modes, the extracted frequency estimates are expected to differ depending upon the phase of the cycle. Differences also arise from the types of models used to fit the modes. Here, we present expressions that allow the sizes of these differences to be predicted. Title: Impact of observational duty cycle on the measurement of low-ℓ solar p-mode frequencies Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R.; Salabert, D. Bibcode: 2004A&A...424..301C Altcode: We investigate the impact of a multi-site, ground-based observational window function on the extraction of estimates of the frequencies of low-angular-degree (low-ℓ) solar p modes from decade-long datasets. To effect this study we have made use of some ≈10 yr of full-disc, ``Sun-as-a-star'' Doppler velocity data collected by the Birmingham-Solar Oscillations Network (BiSON). A coherent combination of observations made by all six BiSON sites provided the principal time series of data. This set was then modulated by a whole series of different window functions and the resulting sets analyzed. The windows were made from different combinations and numbers of BiSON stations. We find that for the majority of low-ℓ modes the bias in the frequencies given by the effects of the window function is not significant. However, for modes above ≈3300 μ Hz, and some ℓ=2 modes near ≈2500 μ Hz, the bias is important when the frequencies are extracted from long datasets.

Appendix A is only available in electronic form at http://www.edpsciences.org Title: The solar cycle as seen by low-l p-mode frequencies: comparison with global and decomposed activity proxies Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R. Bibcode: 2004MNRAS.352.1102C Altcode: 2004MNRAS.tmp..158C We present a detailed study of variations observed in low-angular degree solar p-mode frequencies during solar cycles 22 and 23, and their relation to global and spatially decomposed proxies of the surface activity. To do so, we have analysed 11yr of unresolved (Sun-as-a-star) Doppler velocity observations of the solar disc made by the Birmingham Solar-Oscillations Network (BiSON). The sensitivity of these observations to different azimuthal orders, m, is such that for the degree range studied (0 <=l<= 2) extracted frequencies can be regarded as providing a measure of the response of the sectoral modes (with |m| =l).

After allowing for the dependence of the frequency shifts on mode frequency and inertia, we find the average l= 0 shift is significantly weaker than that at l= 2; the magnitude of the average l= 1 shift lies in between the two. The comparative sizes of the shifts are observed to match those of the corresponding spherical harmonic (Legendre) components of both the Kitt Peak magnetogram (KPMI) and HeI equivalent width activity indices, and reflect, therefore, the sensitivity of the observed mode components to the distribution of activity over the solar surface (i.e. a `spatial' contribution to the shifts). When the falling and rising parts of the cycles are analysed independently, we uncover a significant difference in behaviour at l= 1. Possible reasons for this are discussed. Title: On the Spatial Dependence of Low-Degree Solar p-Mode Frequency Shifts from Full-Disk and Resolved-Sun Observations Authors: Jiménez-Reyes, S. J.; García, R. A.; Chaplin, W. J.; Korzennik, S. G. Bibcode: 2004ApJ...610L..65J Altcode: We have analyzed low angular degree (low-l) solar p-mode frequency shifts extracted from two types of observations, both made by instruments on board the ESA/NASA Solar and Heliospheric Observatory satellite during a period that covers the rising phase of activity, cycle 23 (1995-2002). The first are full-disk (Sun-as-a-star) averages made in Doppler velocity by the Global Oscillations at Low Frequency spectrophotometer; the second are Doppler velocity observations made with high spatial resolution by the Michelson Doppler Imager. We compare the eigenfrequency shifts from both sets of data and find that they are consistent at the level of precision of the observations. Furthermore, the sizes of the shifts uncovered for different mode components are found to scale in proportion to the corresponding spherical harmonic components of the observed line-of-sight surface magnetic field, with the sectoral mode components showing (as expected) the largest shifts. Title: Search for solar cycle changes in the signature of rapid variation in BiSON data Authors: Verner, G. A.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2004MNRAS.351..311V Altcode: The second helium ionization zone and the base of the convective envelope are regions of rapid variation of solar structure which introduce characteristic signatures into the frequencies of p-mode oscillations. These signals provide a direct seismological method to probe the acoustic properties of these regions. In this work we isolate these signatures in over 9 yr of low-degree BiSON data and extract information on the acoustic depth and local properties from each signal. Any temporal variations are investigated by fitting the signals extracted from 432, 864 and 1728-d spectra. The extracted parameters are found to be in agreement over the different length spectra and within one formal standard deviation of the values obtained for model `S'. There is no evidence found for any systematic variation in the acoustic depth, width or magnitude of the second helium ionization zone, which suggests any activity-dependent disturbance to the near surface layers does not propagate down to this layer. The convection zone signal does show some temporal variation that may be correlated with solar activity, although further analysis with current data is required. The isolation of these signatures in low-degree data confirms that this method can be used to provide structural information on Sun-like stars once similar asteroseismic data become available. Title: Extended search for correlation between solar mean magnetic field BiSON data and coronal mass ejections Authors: Chaplin, William J.; Dumbill, Andrew M.; Elsworth, Yvonne P.; Isaak, George R.; McLeod, Clive P.; Miller, Brek A.; New, Roger; Pintér, Balázs Bibcode: 2004SoPh..220..307C Altcode: The Birmingham Solar-Oscillations Network (BiSON) has acquired high-precision solar mean magnetic field (SMMF) data on a 40-s cadence for a decade. We present attempts to compare such data from recent years with the occurrence of coronal mass ejections (CMEs) as recorded by LASCO, using correlation techniques applied to measurements from different BiSON instruments to maximise the sensitivity to CME-related SMMF responses. SMMF measurements were recorded at the time of occurrence of several hundred CMEs. No CME event shows a convincing response in our SMMF data at short periods setting a threshold amplitude of 12 mG. By averaging data sets we are able to set lower thresholds, which depend somewhat on the distribution of response strengths. A brief summary of the very first results of this study is also given in Chaplin et al. Title: A comparison of the use of genetic and hill-climbing algorithms to fit low-l solar p-mode spectra Authors: Fletcher, S. T.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2004SoPh..220..361F Altcode: We present a comparative study of low-l solar p-mode parameters extracted by genetic-algorithm and `standard' hill-climbing minimisation routines. To effect this we make use of observations made in integrated sunlight by the Birmingham Solar-Oscillations Network (BiSON) and the GOLF instrument on board the ESA/NASA SOHO satellite, in addition to artificial data. We find that over the central part of the p-mode range the two fitting routines return similar results. However, at low frequencies — where the S/N in the modes is low and their resonant peaks narrow — we find that the genetic routine appears to offer more robust estimates of the underlying parameters. Title: About the rotation of the solar radiative interior Authors: García, R. A.; Corbard, T.; Chaplin, W. J.; Couvidat, S.; Eff-Darwich, A.; Jiménez-Reyes, S. J.; Korzennik, S. G.; Ballot, J.; Boumier, P.; Fossat, E.; Henney, C. J.; Howe, R.; Lazrek, M.; Lochard, J.; Pallé, P. L.; Turck-Chièze, S. Bibcode: 2004SoPh..220..269G Altcode: In the modern era of helioseismology we have a wealth of high-quality data available, e.g., more than 6 years of data collected by the various instruments on board the SOHO mission, and an even more extensive ground-based set of observations covering a full solar cycle. Thanks to this effort a detailed picture of the internal rotation of the Sun has been constructed. In this paper we present some of the actions that should be done to improve our knowledge of the inner rotation profile discussed during the workshop organized at Saclay on June 2003 on this topic. In particular we will concentrate on the extraction of the rotational frequency splittings of low- and medium-degree modes and their influence on the rotation of deeper layers. Furthermore, for the first time a full set of individual |m|-component rotational splittings is computed for modes ℓ≤4 and 1<ν<2 mHz, opening new studies on the latitudinal dependence of the rotation rate in the radiative interior. It will also be shown that these splittings have the footprints of the differential rotation of the convective zone which can be extremely useful to study the differential rotation of other stars where only these low-degree modes will be available. Title: Tracing the ``Acoustic'' Solar Cycle: A Direct Comparison of BiSON and GOLF Low-l p-Mode Variations Authors: Jiménez-Reyes, S. J.; Chaplin, W. J.; Elsworth, Y.; García, R. A. Bibcode: 2004ApJ...604..969J Altcode: We present a detailed, comparative study of low angular degree solar p-mode variations extracted by analyses of two sets of observational data. These were collected by the ground-based Birmingham Solar-Oscillations Network (BiSON) and the Global Oscillations at Low Frequency (GOLF) instrument on board the ESA/NASA SOHO satellite. The ~5.5 yr period analyzed covers the complete rising phase of solar activity cycle 23 (1996-2002). We find an excellent level of agreement in the uncovered variations, indicating that the two data sets are highly correlated and dominated by the same mode realization noise (the signature of the stochastic forcing of the resonances). The results lend further support to the surmise that changes in damping alone may account for observed variations in mode power and damping. While significant variations in peak asymmetry are uncovered in the near-continuous GOLF set, a similar analysis of the BiSON database yields a null result. This reflects the deleterious impact of its ground-based window function on the precision with which the asymmetry can be determined. As such we are unable to rule out the possibility that variations of magnitude similar to those in GOLF may be present in the BiSON observations. Title: Solar p-mode frequencies at ℓ=2: What do analyses of unresolved observations actually measure? Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R.; Toutain, T. Bibcode: 2004A&A...416..341C Altcode: We have studied in detail the extraction of estimates of ℓ=2 p-mode frequencies from unresolved observations of the visible disc of the Sun. Examples of data of this type include ground-based observations made by the Birmingham Solar-Oscillations Network (BiSON), and space-borne observations made by the GOLF and VIRGO/SPM instruments on board the ESA/NASA SOHO satellite. The fitting of the modes is complicated in practice by the asymmetric arrangement in frequency of the three components (m=-2, 0 and 2) that are prominent in such data. In order to investigate the effect of this we used a series of 10-yr artificial datasets into which varying degrees of asymmetry were introduced. The sets were designed to mimic the characteristics of the BiSON and GOLF data, and were analyzed both with and without the BiSON window function from the period 1992 through 2001. Since reliable estimates of the asymmetry have only recently been extracted from unresolved observations (Chaplin et al. \cite{Chaplin03}a) it has for a long time been standard practice to fit the ℓ=2 modes to a model that assumes a symmetrically arranged multiplet. We have tested the impact of this on the accuracy of the extracted frequencies. Furthermore, we demonstrate that asymmetric models can be successfully applied, provided the data are of sufficient length and quality. We also discuss the implications of our simulations for analyses of real solar data. Title: Use of genetic algorithms to determine low-l rotational p-mode splittings at high frequencies Authors: Fletcher, S. T.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2003MNRAS.346..825F Altcode: We present a comparative study of genetic and standard fitting routines applied to the task of extracting reliable estimates of the rotational splitting of full-disc, low-angular-degree (low-l) solar p-mode data at high frequencies. 100 artificial proxies of a 10-yr data base of observations made by the Birmingham Solar-Oscillations Network (BiSON) were used to test the two approaches. All sets were analysed over the frequency range from 3000 to 4000 μHz.

Previous work, based on non-linear `hill-climbing' fitting techniques, has demonstrated the unfortunate tendency for full-disc estimates of the splitting to overestimate the true, underlying values at high frequencies. Here, we show that the resulting bias is less severe when a genetic-fitting approach is adopted. This is largely the result of the number of erroneous `null-valued' estimates of the splitting being considerably reduced: these estimates are, in effect, re-introduced into the expected normal distribution of fitted splittings. We also illustrate the diverse control one has when using a genetic algorithm as a fitting routine; this diversity is shown to allow further refinement in the estimate of the rotational splitting.

Finally, we address the issue of the reliability of the formal splitting uncertainties returned by the mode fitting, and find that complications arising from the strong anticorrelation between the splittings and their error estimates are not alleviated by the use of the genetic technique. Title: Excitation and Damping of Low-Degree Solar p-Modes during Activity Cycle 23: Analysis of GOLF and VIRGO Sun Photometer Data Authors: Jiménez-Reyes, S. J.; García, R. A.; Jiménez, A.; Chaplin, W. J. Bibcode: 2003ApJ...595..446J Altcode: We have used observations made by the Global Oscillations at Low Frequency (GOLF) and the Variability of Irradiance and Gravity Oscillations Sun Photometer (VIRGO/SPM) instruments on board the ESA/NASA Solar and Heliospheric Observatory satellite to study variations in the excitation and damping of low angular degree (low-l) solar p-modes on the rising phase of activity cycle 23. Our analysis includes a correction procedure that for the first time allows GOLF data to be ``treated'' as a single homogeneous set, thereby compensating for the change of operational configuration partway through the mission. Over the range 2.5<=ν<=3.5mHz, we uncover an increase in damping and decrease in mode power that is consistent with previous findings. Furthermore, an excellent level of agreement is found between the variations extracted from the GOLF and VIRGO/SPM data. We find no net long-term changes to the modal energy supply rate. However, an analysis of the residuals uncovers the presence of a quasi-periodic signature of period ~1.5 yr (most pronounced for SPM). While it is true that several workers claim to have uncovered similar periodicities in other phenomena related to the near-surface layers of the Sun here, we are at present more inclined to attribute our finding to an artifact of the mode-fitting procedure. We also uncover a significant change in the asymmetry of mode peaks in the GOLF data, as found in previous studies of much longer data sets. These assumed that the dominant contribution to this arose from the switch in operating configuration partway through the mission (which altered the depth in the solar atmosphere sampled by the instrument). However, our preliminary analysis of data collected over the 100 day period beginning 2002 November 19-when the instrument switched back to its original configuration-suggests that this change may have a solar cycle component. Title: Studies of the solar mean magnetic field with the Birmingham Solar-Oscillations Network (BiSON) Authors: Chaplin, W. J.; Dumbill, A. M.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R.; Pintér, B. Bibcode: 2003MNRAS.343..813C Altcode: The first analysis of 10 yr of solar mean magnetic field data from the Birmingham Solar-Oscillations Network (BiSON) instrument at Sutherland, SA is presented. Long-period (>1 d) variations correlate well with those observed by the Stanford group, but our daily mean values have a statistical precision over 10 times better than previous work. Differences between the absolute values determined from Sutherland and Stanford are discussed, as are systematic annual variations of the order of 15 per cent. At high frequencies (>0.5 mHz), the mean noise spectral density for our decade of observations is 0.53 G2 Hz-1, setting a lower limit to the noise level than that obtained from brief observations by GOLF on board the ESA/NASA satellite SOHO in 1996. The high-frequency mean noise spectral density is different in different years. The lowest annual value, obtained for 1997, is 0.22 G2 Hz-1, whilst the highest, for 1995, is 1.46 G2 Hz-1. It is not yet clear whether these variations are related to solar activity. Title: Observation of, and temporal variations in, solar p-mode multiplet frequency asymmetries at l= 2 Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R.; Thiery, S.; Boumier, P.; Gabriel, A. H. Bibcode: 2003MNRAS.343..343C Altcode: The predominant contribution to the frequency splitting of low-l solar p modes arises from the rotation of the solar interior and this lifts the frequency degeneracy in l to give a symmetric pattern where the observed (synodic) separation between adjacent m (i.e. for |Δm|= 1) is ~400 nHz. Magnetic fields can also contribute to the splitting, but they do so in such a way as to introduce asymmetries in the arrangement of the components within each multiplet. In disc-integrated data this effect may become apparent when l>= 2. Here, we attempt to extract estimates of the frequency asymmetries at l= 2 from the analysis of disc-integrated data collected by the ground-based Birmingham Solar Oscillations Network (BiSON) and the GOLF instrument on board the ESA/NASA SOHO satellite. Our analyses demonstrate that we have evidence for there being non-zero asymmetries present (significance ~3-4σ) during an epoch coincident with high levels of surface activity close to the maximum of solar cycle 23. The asymmetries are indistinguishable from zero at minimum levels of activity near the cycle 22/23 boundary.

We also compare the observed asymmetries with those calculated from a model that is based upon the recent predictions of Moreno-Insertis & Solanki. While the level of agreement between the two is found to be reasonable, the observations suggest (though with poor constraints placed upon this) that the influence on the mode frequencies of high-latitude activity may not be as strong as in the model. Title: A Comparison of Low-Degree Solar p-Mode Parameters from BiSON and GONG: Underlying Values and Temporal Variations Authors: Howe, R.; Chaplin, W. J.; Elsworth, Y. P.; Hill, F.; Komm, R.; Isaak, G. R.; New, R. Bibcode: 2003ApJ...588.1204H Altcode: Approximately 5 years of the l=0 time series from the GONG project have been analyzed using the algorithm developed for the BiSON zero-dimensional data. The data cover the period 1995-2000. The results are compared with those from a parallel analysis of contemporaneous BiSON data and also with the results of the traditional GONG analysis of the low-degree time series. The spectra analyzed were prepared using the multitaper spectral analysis technique used in the recent reanalysis of the GONG data. We consider both solar cycle trends and temporally averaged values for mode frequencies, line widths, amplitudes, and asymmetry parameters. Title: Using the BiSON signal to probe the photosphere Authors: McCarty, B.; Chaplin, W. J.; Elsworth, Y. Bibcode: 2003ESASP.517..349M Altcode: 2003soho...12..349M Red and blue-wing velocity residuals have been generated from each side of the 770-nm potassium line profile as observed by BiSON. Analysis of these single-sided residuals allows an estimate of the velocity scale height, H, to be made. An initial investigation using data from one BiSON station gives a value of H ~ 530±45 km. Title: Degree dependence of mode parameters with solar activity in BiSON data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; New, R. Bibcode: 2003ESASP.517..119C Altcode: 2003soho...12..119C The line-width, velocity power and rate of supply of energy to the low-degree p modes of the Sun are investigated over falling phase of cycle 22 and the rising phase of cycle 23 by fitting in the Fourier transform domain. We see that for the first time for low-degree modes we are able to parameterise the solar activity dependence as a function of the angular degree of the mode. Title: Probing the solar core with BiSON: the challenge at low l and low frequency Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R.; Pintér, B. Bibcode: 2003ESASP.517..183C Altcode: 2003soho...12..183C In this contribution we touch upon a few issues of relevance to the current status of low-angular-degree (low-l) p-mode Helioseismology. In particular: the precision in frequency, both historic and current, achievable at low l; the quest to extend the low-frequency detection threshold nearer to the p-mode fundamental; and the level of agreement between frequencies extracted from different data using various analysis techniques. Title: Amplitude modulation of low degree p-modes - comparison of BISON and VIRGO Authors: Andersen, Bo; Leifsen, Torben; Chaplin, William J.; Elsworth, Yvonne Bibcode: 2003ESASP.517..151A Altcode: 2003soho...12..151A Using both VIRGO and MDI data we have previously studied the amplitude variation of the l=0 p-modes for radial orders 12 to 32. In this study we extend the investigation backward in time to 1992 by including data from the BISON network. For the large amplitude modes there is a strong correlation between the space based radiance measurements from VIRGO and the ground based Doppler shift measurements from BISON. The extreme rotational modulation of l=0, n=22 is confirmed to be a phenomenon confined to the period of minimum solar activity. Also with neighbouring l=1, n=21 a clear modulation is seen at slightly lower frequency. Some persistent frequencies occur in other l=0,1 modes, but not to the same level in time and amplitude. Title: Comparing results from the GONG l = 0 and BiSON time series Authors: Howe, R.; Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Komm, R. W.; New, R. Bibcode: 2003ESASP.517..303H Altcode: 2003soho...12..303H Approximately 5 years of the l = 0 time series from the GONG project have been analysed using the algorithm developed for the BiSON 0-dimensional data. The data cover the period 1995-2000. The results are compared with those from a parallel analysis of contemporaneous BiSON data, and also with the results of the traditional GONG analysis of the low-degree time series. The spectra analysed were prepared using the multitaper spectral analysis technique used in the recent re-analysis of the GONG data. We consider both solar-cycle trends and temporally averaged values for mode frequencies, linewidths, amplitudes and asymmetry parameters. Title: High-frequency interference peaks in BiSON data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Marchenkov, K. I.; Miller, B. A.; New, R. Bibcode: 2003ESASP.517..247C Altcode: 2003soho...12..247C We have analyzed 9 yr of non-imaged Doppler velocity observations of the visible disc of the Sun in an effort to search for pseudo-mode-like structure in the data above the acoustic cut-off frequency of the solar atmosphere (≍5400 μHz). These data were collected by the ground-based Birmingham Solar-Oscillations Network (BiSON) over the period 1992 January through 2000 December. Our analysis uncovers the presence of a pseudo-mode-like structure above the acoustic cut-off frequency that persists up to ≍8500 μHz, with a spacing between adjacent peaks (or troughs) of ~68 μHz. The signature - which disappears at higher frequencies - has a slightly different repeat period (i.e., frequency separation between successive peaks or troughs) to that found by Garcia et al. (1998) in full-disc GOLF data. Title: The Search for Correlation Between BISON Smmf Data and Cme's Authors: Chaplin, William J.; Dumbill, Andy M.; Elsworth, Yvonne; Isaak, George R.; McLeod, Clive P.; Miller, Brek A.; New, Roger; Pinter, Balazs Bibcode: 2003IAUJD...3E..30C Altcode: The Birmingham Solar Oscillation Network (BiSON) has acquired high precision solar mean magnetic field (SMMF) data on a 40-second cadence for a decade. We present first attempts to compare such data from recent years with the occurence of CME's as recorded by LASCO using correlation techniques applied to measurements from different BiSON instruments to maximise the sensitivity to CME related SMMF responses. SMMF measurements were recorded at the time of occurence of several hundreds CME's. Title: Time Variation of the Low Degree P-Mode Parameters Authors: Jimenez-Reyes, Sebastian J.; Garcia, Rafael A.; Jimenez, Antonio; Chaplin, W. J. Bibcode: 2003IAUJD..12E..20J Altcode: High quality data collected from GOLF VIRGO and MDI from the SoHO satellite and from the BiSON ground based network have been used to analyze the low degree (<= 3) p-mode parameters during the increasing phase of solar cycle 23. The variations of amplitudes frequencies linewidth asymmetries velocity power and energy supply rate will be showed and discussed. Special attention will be given to two of these parameters: the asymmetries and the energy supply rate.

The average of velocity line profile asymmetries of p-modes between 2.5 and 3.5 mHz appears very well correlated with the solar activity cycle while no clear correlation in average appears in intensity measurements. An individual analysis of the different degrees will be also shown and possible consequences on the location of the excitation source will be discussed.

It is well known that the energy supply rate is roughly constant in average during the solar cycle. Our results agree with this conclusion but a clear 1.5 years modulation appears and with slightly larger amplitude for the intensity observation. Title: On the measurement bias of low-l solar p-mode excitation parameters: The impact of a ground-based window function Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R.; Pintér, B.; Thiery, S. Bibcode: 2003A&A...398..305C Altcode: We present a study of the impact of a ground-based, multi-station window function on estimates of the power and damping of low-l solar p modes extracted from fits to resonant structure in the frequency domain. The window functions come from six-site observations made by the Birmingham Solar-Oscillations Network (BiSON) over the 10-yr period beginning 1991 January. Two strategies were adopted. In the first, we used an 800-d time series of continuous observations made by the GOLF instrument on board the ESA/NASA SOHO satellite. These data were modulated by a variety of BiSON window functions, with fractional duty cycles ranging from ~ 0.4 to ~ 0.8, and the resulting series analyzed. In the second we generated artificial 10-yr time series and studied the effect on these of the complete BiSON window. Title: Does the Energy Supplied to Low-l Solar p-Modes Vary over the Activity Cycle? Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R.; Toutain, T. Bibcode: 2003ApJ...582L.115C Altcode: We report on the average behavior of the excitation and damping of low angular degree (low l) solar p-mode oscillations over the decade from 1991 to 2000 using both long and short time duration Fourier transforms. The data in question were collected by the ground-based Birmingham Solar Oscillations Network. Throughout most of the period under study, the energy supply rate to the modes remains roughly constant-implying a near-constant level of forcing-while the damping and velocity power show a fairly smooth increase and decrease, respectively, in response to increasing levels of solar activity (in line with previous findings). However, here we uncover evidence of there being a sharp increase in the mode velocity power over a brief period of approximately 100 days centered on 1998 late March. The magnitude and sign of this are contrary to the expectation based on the long-timescale, solar-cycle trend; such unusual behavior is absent in the damping. This implies that the forcing of, or rate of energy supplied to, the modes increased in magnitude over this period. Title: Peak finding at low signal-to-noise ratio: low-ℓ solar acoustic eigenmodes at n≤9 from the analysis of BiSON data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Marchenkov, K. I.; Miller, B. A.; New, R.; Pinter, B.; Appourchaux, T. Bibcode: 2002MNRAS.336..979C Altcode: We make use of 9 yr of full-disc helioseismic data - as collected by the ground-based Birmingham Solar-Oscillations Network (BiSON) - to search for low-frequency, low-angular-degree (low-l) acoustic modes. A range of tests are applied to the power spectrum of the observations that search for prominent mode-like structure: strong spikes, structure spanning several bins signifying the presence of width (from damping), and the occurrence of prominent multiplet structure at l>= 1 arising principally from the solar rotation and made from several spikes separated suitably in frequency. For each test we present analytical expressions that allow the probability that the uncovered structure is part of the broad-band noise background to be assessed. These make use of the cumulative binomial (Bernoulli) distribution and serve to provide an objective measure of the significance of the detections. This work has to date uncovered nine significant detections of non-broad-band origin that we have identified as low-l modes with radial overtone numbers n<= 9. Title: Observation of, and variations in, multiplet frequency asymmetries at low l Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Marchenkov, K. I.; Miller, B. A.; New, R.; Pinter, B.; Thiery, S. Bibcode: 2002ESASP.508...71C Altcode: 2002soho...11...71C The predominant contribution to the frequency splitting of low-l solar p modes arises from the rotation of the solar interior and this lifts the frequency degeneracy in l to give a symmetric pattern where the observed (synodic) separation between adjacent m (i.e., for |Δm| = 1) is ~400nHz. Magnetic fields can also contribute to the splitting, but they do so in such a way as to introduce asymmetries in the arrangement of the components within each multiplet. In full-disc data this effect may become apparent when l >= 2. Here, we extract estimates of the frequency asymmetry for l = 2, investigate variations over the activity cycle and compare the results with the near-surface predictions of Dziembowski et al. (2000) which are based upon observations from higher l. Title: Does the energy supply rate to the p modes vary over the solar cycle? Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; New, R. Bibcode: 2002ESASP.508...33C Altcode: 2002soho...11...33C The rate of supply of energy to the low-degree p modes of the Sun is investigated using both long and short time-duration Fourier transforms. We see that, although on average the energy supply rate to the modes is independent of solar activity, there is a period of high solar activity where the energy-supply rate is increased. Furthermore we see that the correlations between the mode line width and the power in the modes are different on the falling phase of cycle 22 and the rising phase of cycle 23 with a strong correlation between the energy supply rate and the mode power on the rising phase of cycle 23. Title: On the measurement precision of solar p-mode eigenfrequencies Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R. Bibcode: 2002MNRAS.330..731C Altcode: We make use of 3456d of observations of the low-l p-mode oscillations of the Sun in order to study the evolution over time of the measurement precision of the radial eigenfrequencies. These data were collected by the ground-based Birmingham Solar-Oscillations Network (BiSON) between 1991 January and 2000 June. When the power spectrum of the complete time series is fitted, the analysis yields frequency uncertainties that are close to those expected from the returned coherence times of the modes. The slightly elevated levels compared with the prediction appear to be consistent with a degradation of the signal-to-noise ratio in the spectrum that is the result of the influence of the window function of the observations (duty cycle 71 per cent). The fractional frequency precision reaches levels of a several parts in 106 for many of the modes. The corresponding errors reported from observations made by the GOLF instrument on board the ESA/NASA SOHO satellite, when extrapolated to the length of the BiSON data set, are shown to be (on average) about ~25 per cent smaller than their BiSON counterparts owing to the uninterrupted nature of the data from which they were derived.

An analysis of the BiSON data in contiguous segments of different lengths, T, demonstrates that the frequency uncertainties scale as T-1/2. This is to be expected in the regime where the coherence (life) times of the modes, τnl, are smaller than the observing time T (the `oversampled' regime). We show that mode detections are only now beginning to encroach on the `undersampled' regime (where T<τnl). Title: Variation of acoustic mode centroid frequencies over the solar cycle Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; Isaak, G. R.; New, R. Bibcode: 2002AdSpR..29.1881C Altcode: Together with a brief historical overview, we use high-quality helioseismic data collected by three different observational programmes during the declining phase of activity cycle 22, and a substantial portion of the rising phase of the current cycle (23), to study the phenomenological nature of the cycle-induced (centroid) eigenfrequencies. Our analyses (for 1600 ≤ ν ≤ 4000 μHz) make use of observations made by the ground-based GONG over the angular degree range 4 ≤ l ≤ 150; the ground-based BiSON over 0 ≤ l ≤ 2; and the VIRGO/LOI instrument on board the ESA/NASA SOHO satellite over 0 ≤ l ≤ 8. We show that GONG shifts averaged over different ranges in l, together with the BiSON and LOI data averaged over their full quoted ranges, all scale at a given frequency with the normalized mode inertia ratio Qnl (Christensen-Dalsgaard & Berthomieu 1991). This is to be expected if the time-dependent perturbation affecting the modes is confined in the surface layers; the excellent agreement also reflects favourably on the external consistency of the different observations. We have also analyzed the frequency dependence of the shifts by fitting a power-law of the form δν nl ∝ (ν nl/ Enl to the data (where the Enl are the mode inertias, and α is the power-law index to be extracted). Previous studies have suggested that a relation with α = 0 provides an adequate description of the shifts up to ν ≈ 3500 μHz. However, here we show that while nevertheless describing the shifts well up to ∼ 2500 μHz, the linear scaling breaks down conspicuously at higher frequencies. Above this threshold, the shifts follow a power-law dependence with α ∼ 2. Title: Rigid rotation of the solar core? On the reliable extraction of low-l rotational p-mode splittings from full-disc observations of the Sun Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Marchenkov, K. I.; Miller, B. A.; New, R. Bibcode: 2001MNRAS.327.1127C Altcode: We present low-l rotational p-mode splittings from the analysis of 8yr of observations made by the Birmingham Solar-Oscillations Network (BiSON) of the full solar disc. These data are presented in the light of a thorough investigation of the fitting techniques used to extract them. Particular attention is paid to both the origin and magnitude of bias present in these estimates. An extensive Monte Carlo strategy has been adopted to facilitate this study - in all, several thousand complete, artificial proxies of the 96-month data set have been generated to test the analysis of real `full-disc' data. These simulations allow for an assessment of any complications in the analysis which might arise from variations in the properties of the p modes over the 11-yr solar activity cycle. The use of such an extended data set affords greater precision in the splittings, and by implication the rotation rate inferred from these data, and reduces bias inherent in the analysis, thereby giving a more accurate determination of the rotation. The grand, weighted sidereal average of the BiSON set is 434+/-2nHz, a value consistent with that expected were the deep radiative interior (r/R<0.5) to rotate at the same frequency, and in the same `rigid' manner, as the more precisely and accurately studied outer part of the radiative zone. Title: Changes in convective properties over the solar cycle: effect on p-mode damping rates Authors: Houdek, G.; Chaplin, W. J.; Appourchaux, T.; Christensen-Dalsgaard, J.; Däppen, W.; Elsworth, Y.; Gough, D. O.; Isaak, G. R.; New, R.; Rabello-Soares, M. C. Bibcode: 2001MNRAS.327..483H Altcode: Measurements of both solar irradiance and p-mode oscillation frequencies indicate that the structure of the Sun changes with the solar cycle. Balmforth, Gough & Merryfield investigated the effect of symmetrical thermal disturbances on the solar structure and the resulting pulsation frequency changes. They concluded that thermal perturbations alone cannot account for the variations in both irradiance and p-mode frequencies, and that the presence of a magnetic field affecting acoustical propagation is the most likely explanation of the frequency change, in the manner suggested earlier by Gough & Thompson and by Goldreich et al. Numerical simulations of Boussinesq convection in a magnetic field have shown that at high Rayleigh number the magnetic field can modify the preferred horizontal length scale of the convective flow. Here, we investigate the effect of changing the horizontal length scale of convective eddies on the linewidths of the acoustic resonant mode peaks observed in helioseismic power spectra. The turbulent fluxes in these model computations are obtained from a time-dependent, non-local generalization of the mixing-length formalism. The modelled variations are compared with p-mode linewidth changes revealed by the analysis of helioseismic data collected by the Birmingham Solar-Oscillations Network (BiSON); these low-degree (low-l) observations cover the complete falling phase of solar activity cycle 22. The results are also discussed in the light of observations of solar-cycle variations of the horizontal size of granules and with results from 2D simulations by Steffen of convective granules. Title: The phenomenology of solar-cycle-induced acoustic eigenfrequency variations: a comparative and complementary analysis of GONG, BiSON and VIRGO/LOI data Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; Isaak, G. R.; New, R. Bibcode: 2001MNRAS.324..910C Altcode: We use high-quality helioseismic data collected by three different observational programmes during the declining phase of activity cycle 22,Q7 and a substantial portion of the rising phase of the current cycle (23), to study the phenomenological nature of the cycle-induced (centroid) eigenfrequency variations. We have analysed the frequency dependence of the shifts by fitting a power law of the form δνnl~(νnl)α/Enl to the data (where the Enl are the mode inertias, and α is the power-law index to be extracted). Previous studies have suggested that a relation with α=0 provides an adequate description of the shifts up to ν~3500μHz. However, here we show that while nevertheless describing the shifts well up to ~2500μHz, the linear scaling breaks down conspicuously at higher frequencies. Above this threshold, the shifts follow a power-law dependence with α~2. Our analyses (for 1600<=ν<=4000μHz) make use of observations made by the ground-based GONG over the angular degree range 4<=l<=150 the ground-based BiSON over 0<=l<=2 and the VIRGO/LOI instrument on board the ESA/NASA SOHO satellite over 0<=l<=8. We show that GONG shifts averaged over different ranges in l, together with the BiSON and LOI data averaged over their full quoted ranges, all scale at fixed frequency with the normalized mode inertia ratio QnlQ1. This is to be expected if the solar-cycle perturbation affecting the modes is confined in the surface layers; the excellent agreement also reflects favourably on the external consistency of the different observations. Title: Changes to low-ll solar p-mode frequencies over the solar cycle: correlations on different time-scales Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Marchenkov, K. I.; Miller, B. A.; New, R. Bibcode: 2001MNRAS.322...22C Altcode: We have studied variations in the frequencies of low-l solar p modes through the analysis of nine years of helioseismic data collected by the Birmingham Solar Oscillations Network (BiSON)†. This is the first time that such a long data set has been explored with the extra accuracy afforded by fitting the modes to asymmetric profiles. The epoch covered (1991-99) spans the declining activity phase of solar cycle 22, and a substantial portion of the initial activity increase during cycle 23. The complete time series has been split into contiguous segments of length 27, 54, 108 and 216d in order to facilitate the study of changes occurring on different time-scales. Further, we have characterized the observed shifts as a function of six well-known indicators of solar activity. These indices reflect changes taking place in the photosphere, chromosphere and corona, but only over the visible hemisphere of the Sun. Since the low-l eigenfrequencies respond to global variations in activity, we discuss the implications of this mismatch for the analyses performed. We demonstrate that, as expected, the low-l modes adjust to changes in the activity measures on time-scales as short as a few months. Our analysis indicates that all six proxies correlate equally well (at the level of precision of the data) with the measured shifts. Further, the sensitivity of the shifts to changes in five of the activity indices is the same, to within ~15per cent (1σ) or so, on the falling and rising phases considered. There is, however, a slight suggestion that the sensitivity to changes in the disc-averaged line-of-sight magnetic field component (as determined from daily Kitt Peak magnetograms) may be higher on the rising phase of the cycle. Title: Non linear inversion for the sound speed in the solar interior using BiSON and SOI/MDI p-mode frequencies Authors: Marchenkov, K. I.; Roxburgh, I. W.; Vorontsov, S. V.; Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; New, R. Bibcode: 2001ESASP.464..531M Altcode: 2001soho...10..531M The results of the global sound-speed inversion obtained with solar p-mode frequencies provided by the recent high-quality observational data (BiSON, SOI/MDI) are presented and discussed. The iterative nonlinear inversion technique used here is a generalization (for the case of exact solution of the adiabatic oscillation equations) of the Born quasiasymptotic approximate inversion developed by Marchenkov et al. (2000). Title: BiSON Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Marchenkov, K.; Miller, B. A.; New, R.; Pinter, B. Bibcode: 2001ESASP.464..313C Altcode: 2001soho...10..313C The current status of the Birmingham Solar Oscillation Network (BiSON) is discussed. Title: Helioseismic signatures of localized structural discontinuities in BiSON and GONG data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; New, R. Bibcode: 2001ESASP.464...79C Altcode: 2001soho...10...79C We use high-quality helioseismic data collected by BiSON and GONG in an attempt to search for variations over time of the influence on the acoustic mode frequencies of localized structural perturbations located beneath the solar surface. Our analysis of the BiSON data is aimed at a study of the effects of the He II ionization zone. We use GONG data (4 <= l <= 140) to extract estimates of the solar-cycle-induced eigenfrequency shifts over the range 1600 <= ν <= 4000 μHz. A careful analysis of these data may have uncovered tentative evidence for an oscillatory behaviour that would be the signature of a time-dependent solar cycle perturbation located approximately ~20 Mm beneath the photosphere. Title: A long-term look at acoustic modes with a nine-year BiSON spectrum Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Marchenkov, K.; Miller, B. A.; New, R.; Pinter, B. Bibcode: 2001ESASP.464...51C Altcode: 2001soho...10...51C We present data taken from BiSON to illuminate solar-activity related changes in the oscillation parameters. We also use the full dataset to hunt for low order p-modes. Title: Does the excitation and damping of the acoustic eigenmodes vary over the solar cycle? An insight from LOI observations Authors: Chaplin, W. J.; Appourchaux, T. Bibcode: 2001ESASP.464..601C Altcode: 2001soho...10..601C We have used observations made by the LOI instrument on board the ESA/NASA SOHO satellite in order to try and uncover variations in the excitation and damping of the low-angular-degree solar acoustic eigenmodes over the solar cycle. These data were collected on the rising phase of activity cycle 23. We have divided the dataset into independent 136-d and 1-yr time series and fitted the modes in the complex Fourier (frequency) domain to yield estimates of the line widths and amplitudes of the modes. The extracted parameters have then been analyzed in order to search for solar-cycle-induced variations. Over the range 2600 <= ν <= 3600μHz, we uncover a mean implied activity minimum-to-maximum increase in the frequency-domain line widths of 21+/-3 per cent; a mean decrease of 37+/-3 per cent decrease in the mode heights; and a mean decrease of 18+/-4 per cent in the mode powers. Our analysis indicates that - at the level of precision of the available data - the rate at which energy is supplied to the modes remains constant (uncovered variation 3+/-5 per cent). These results are in reasonable agreement with recent claims by Chaplin et al. (2000) and Komm, Howe and Hill (2000) from analyses of BiSON and GONG data respectively. Furthermore, the signs and relative magnitudes of the extracted changes are consistent with the speculation made by Chaplin et al. that it is alterations in the damping, and not the forcing, of the modes that gives rise to the variations observed over the solar activity cycle. Title: Characteristics of full-disc BiSON power spectra above the acoustic cut-off frequency of the solar atmosphere Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Marchenkov, K. I.; Miller, B. A.; New, R. Bibcode: 2001ESASP.464..191C Altcode: 2001soho...10..191C We have analyzed 60 months of non-imaged Doppler velocity observations of the visible disc of the Sun in an effort to search for pseudo-mode-like structure in the data above the acoustic cut-off frequency of the solar atmosphere (≍5400 μHz). These data were collected by the ground-based Birmingham Solar-Oscillations Network (BiSON). Our analysis uncovers marginally significant evidence for the presence of a pseudo-mode-like structure in the range 5900 <= ν <= 6600 μHz, with a spacing between adjacent peaks (or troughs) of ~70 μHz. The signature - which, owing to the low signal to noise, disappears at higher frequencies - has a similar repeat period and phase to that found by Garcia et al. (1998) in full-disc GOLF data. However, the zero-to-peak power is a factor of ~10 weaker in strength. Title: Probing the solar cycle: a comparative and complementary analysis of GONG BiSON and VIRGO/LOI eigenfrequency shifts Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; New, R.; Appourchaux, T. Bibcode: 2001ESASP.464...83C Altcode: 2001soho...10...83C We use high-quality helioseismic data collected by GONG (over 4 <= l <= 140), BiSON (0 <= l <= 2) and VIRGO/LOI (0 <= l <= 8) to study the phenomenological nature of the cycle-induced (centroid) eigenfrequency variations. We have analyzed the frequency dependence of the shifts by fitting a power-law of the form δνnl ~ (νnl)α/Enl to the data (where the Enl are the mode inertias, and α is the power-law index to be extracted). Previous studies have suggested that a relation with α = 0 provides an adequate description of the shifts up to ν ≍ 3500 μHz. However, here we show that while nevertheless describing the shifts well up to ~2500 μHz, the linear scaling breaks down conspicuously at higher frequencies. Above this threshold, the shifts follow a power-law dependence with α ~ 2. We also ahow that GONG shifts, averaged over different ranges in l together with the BiSON and LOI data averaged over their full quoted ranges, all scale at fixed frequency with the normalized mode inertia ratio Qnl (Christensen-Dalsgaard & Berthomieu 1991). This is to be expected if the solar-cycle perturbation affecting the modes is confined in the surface layers; the excellent agreement also reflects favourably on the external consistency of the different observations. Title: g-mode detection: Where do we stand? Authors: Appourchaux, T.; Andersen, B.; Berthomieu, G.; Chaplin, W.; Elsworth, Y.; Finsterle, W.; Frölich, C.; Gough, D. O.; Hoeksema, T.; Isaak, G.; Kosovichev, A.; Provost, J.; Scherrer, P.; Sekii, T.; Toutain, T. Bibcode: 2001ESASP.464..467A Altcode: 2001soho...10..467A We review the recent developments in determining the upper limits to g-mode amplitudes obtained by SOHO instruments, GONG and BiSON. We address how this limit can be improved by way of new helioseismic instruments and/or new collaborations, hopefully providing in the not too distant future unambiguous g-mode detection. Title: Observational Upper Limits to Low-Degree Solar g-Modes Authors: Appourchaux, T.; Fröhlich, C.; Andersen, B.; Berthomieu, G.; Chaplin, W. J.; Elsworth, Y.; Finsterle, W.; Gough, D. O.; Hoeksema, J. T.; Isaak, G. R.; Kosovichev, A. G.; Provost, J.; Scherrer, P. H.; Sekii, T.; Toutain, T. Bibcode: 2000ApJ...538..401A Altcode: Observations made by the Michelson Doppler Imager (MDI) and Variability of solar IRradiance and Gravity Oscillations (VIRGO) on the Solar and Heliospheric Observatory (SOHO) and by the ground-based Birmingham Solar Oscillations Network (BiSON) and Global Oscillations Network Group (GONG) have been used in a concerted effort to search for solar gravity oscillations. All spectra are dominated by solar noise in the frequency region from 100 to 1000 μHz, where g-modes are expected to be found. Several methods have been used in an effort to extract any g-mode signal present. These include (1) the correlation of data-both full-disk and imaged (with different spatial-mask properties)-collected over different time intervals from the same instrument, (2) the correlation of near-contemporaneous data from different instruments, and (3) the extraction-through the application of complex filtering techniques-of the coherent part of data collected at different heights in the solar atmosphere. The detection limit is set by the loss of coherence caused by the temporal evolution and the motion (e.g., rotation) of superficial structures. Although we cannot identify any g-mode signature, we have nevertheless set a firm upper limit to the amplitudes of the modes: at 200 μHz, they are below 10 mm s-1 in velocity, and below 0.5 parts per million in intensity. The velocity limit corresponds very approximately to a peak-to-peak vertical displacement of δR/Rsolar=2.3×10-8 at the solar surface. These levels which are much lower than prior claims, are consistent with theoretical predictions. Title: Source of excitation of low-l solar p modes: characteristics and solar-cycle variations Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R. Bibcode: 2000MNRAS.314...75C Altcode: We investigate various properties of the excitation source that is responsible for driving the acoustic p-mode oscillations of the Sun. Current prejudice places this in the superadiabatic layer of the convection zone. We consider in detail how the precise nature of the resonant mode spectrum is modified: (i) as a result of the impact of different source-multipole mixtures; and (ii) as a function of the radial extent of the source. To do this, we model the observed resonant spectra with the solutions to a simple, one-dimensional wave equation which is intended to describe the essential elements of the solar resonant acoustic cavity. Further, we also fit these models to the low-l peaks in a high-resolution power spectrum generated from data collected by the Birmingham Solar-Oscillations Network (BiSON). We also use the extensive BiSON data set to search for variations in the source characteristics over the solar cycle. Title: Variations in the excitation and damping of low-l solar p modes over the solar activity cycle* Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R. Bibcode: 2000MNRAS.313...32C Altcode: We have searched helioseismic data collected by the Birmingham Solar Oscillations Network (BiSON) for solar-cycle changes to those low-l p-mode parameters that relate to the excitation and damping of the resonances. These data - collected between 1991 and 1997 - cover the complete declining phase of solar activity cycle 22 (up to and including the cycle 22/23 boundary). Over the range 2600<=ν<=3600μHz, we uncover a mean 24+/-3per cent increase in the frequency-domain linewidths; a mean decrease of 46+/-5per cent decrease in the mode heights, and a mean decrease of 22+/-3per cent in the modal velocity powers. The rate at which energy is supplied to the modes remains constant, at the level of precision of the observations (measured change 0+/-4per cent). We use expressions derived from the equation of a damped harmonic oscillator to illustrate the diagnostic properties of the observables: these indicate that both the signs and relative sizes of the extracted variations can arise from changes solely to the net damping; the net forcing of the modes need not change. The results possibly hint at the changes being maximal at frequencies near ~3100μHz. They might therefore suggest an origin for the observed variations that is peaked in the superadiabatic layer of the convection zone, which couples most strongly to the eigenfunctions of modes at the centre of the p-mode spectrum. Title: Depth of excitation and reversal of asymmetry of low-l solar P modes: a complementary analysis of BiSON* and VIRGO/SPM† data Authors: Chaplin, W. J.; Appourchaux, T. Bibcode: 1999MNRAS.309..761C Altcode: We use the solutions to a simple, one-dimensional wave equation - which is intended to describe the essential elements of the solar resonant acoustic cavity - as formalistic models to which to fit low-l modes in observational helioseismic power spectra. We have analysed data collected in velocity, by the ground-based Birmingham Solar-Oscillations Network (BiSON), and in intensity, by the full-disc VIRGO Sun photometers (SPM) on board the ESA/NASA SOHO satellite. Our analysis extracts, as a function of the modal radial overtone number n, direct estimates of: the location of the excitation source of the acoustic resonances; and the size of the component of the convective granulation that is correlated to the observations of the resonances, and is responsible for the reversal of asymmetry of the mode profiles when different observation techniques are applied (i.e. intensity or Doppler velocity measurements). This information is coded in the complicated forms of the observed, resonant profiles. Title: Skew-symmetric solar P modes in low-l BiSON ^* data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R. Bibcode: 1999MNRAS.308..424C Altcode: The p-mode oscillations of the Sun are manifestations of resonantly trapped acoustic waves propagating within its interior. The effective size of the resulting resonant cavity changes with the properties of the modes - the interaction of this phenomenon with a highly localized excitation source in the upper layers of the convection zone gives rise to skew-symmetric resonant profiles whose degree of asymmetry changes with frequency. Here, we have fitted low-angular-degree (low-l) resonant p-mode peaks - in a power spectrum generated from 32 months of BiSON Doppler velocity observations of the visible solar disc - to a skew-symmetric formalism to account for this effect. We present the fitted frequencies, fine-structure spacings [d_0(n) and d_1(n)] and mode-skewness estimates; and discuss the quantitative impact of fitting a skew, rather than symmetric, limit model. We also consider the reliability of the extracted parameters through the application of a useful statistical test, and extensive Monte Carlo fits to artificial data. Title: Rotation of the solar core from BiSON and LOWL frequency observations Authors: Chaplin, W. J.; Christensen-Dalsgaard, J.; Elsworth, Y.; Howe, R.; Isaak, G. R.; Larsen, R. M.; New, R.; Schou, J.; Thompson, M. J.; Tomczyk, S. Bibcode: 1999MNRAS.308..405C Altcode: Determination of the rotation of the solar core requires very accurate data on splittings for the low-degree modes which penetrate to the core, as well as for modes of higher degree to suppress the contributions from the rest of the Sun to the splittings of the low-degree modes. Here we combine low-degree data based on 32 months of observations with the BiSON network and data from the LOWL instrument. The data are analysed with a technique that specifically aims at obtaining an inference of rotation that is localized to the core. Our analysis provides what we believe is the most stringent constraint to date on the rotation of the deep solar interior. Title: An analysis of solar p-mode frequencies extracted from BiSON data: 1991-1996 Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Lines, R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1998MNRAS.300.1077C Altcode: We present a comprehensive frequency analysis of Doppler velocity observations of the visible solar disc made by the Birmingham Solar Oscillations Network (BiSON) from 1990-1996, i.e. covering the falling phase of activity cycle 22, up to and including the cycle 22/23 boundary. We have fitted low-degree (low-l) solar p modes in a variety of power spectra of differing lengths generated from these data. The analysis of the extracted frequencies reveals the expected clear solar-cycle dependence; in addition, there is now sufficient accuracy in the data to show that the low-l modal eigenfrequencies are less affected by the solar cycle than their higher l counterparts. The observed low-degree frequency shifts up to ~3900muHz are consistent - at the level of precision of the data - with an inverse mode-mass scaling. At frequencies above this, the blending of modes adjacent in frequency space makes it increasingly difficult to extract reliable frequency estimates. However, our data show indications of a turnover and possibly also an eventual sign change in the solar cycle shifts at frequencies above ~4000muHz, as seen in higher l data. We have parametrized the observed shifts as a function of the 10.7-cm radio flux, and produced an activity-corrected, average frequency table which incorporates eigenfrequencies from 18 4-month and 9 8-month spectra. We also present the fitted frequencies from a 32-month power spectrum, generated from data collected at or close to solar minimum. In addition, we also searched for frequency asymmetries in the l=2 mode multiplets. These could result from strong near-surface magnetic activity, or a buried magnetic field. Our fits merely place an upper limit to any mean asymmetry - over the range 10<=n<=21 - of between ~-80 and ~170nHz (3sigma). Title: Solar p-mode excitation: further insight from recent low-l BiSON helioseismological data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Lines, R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1998MNRAS.298L...7C Altcode: We present measurements of low-degree solar p-mode velocity powers, energies and energy supply rates between ~1600muHz and ~4700muHz, as derived from the analysis of several years of high-quality helioseismological data collected by the Birmingham Solar-Oscillations Network (BiSON). For the radial (l=0) modes, we find that the total energy E per mode (kinetic plus potential) peaks at ~3200muHz, reaching ~10^28erg. The rate at which energy is supplied to the modes E=2piDeltanu.E, where Deltanu is the FWHM modal line width, is observed to plateau between ~3000 and ~4000muHz, reaching a maximum of ~10^23ergs^-1. At frequencies below the plateau, the supply rate follows a simple power law with a dependence of E~nu^7.0+/-0.4 and at very-high frequencies the data follow E~nu^-4.5+/-1.1. These assume modal inertias normalized at T=T_eff with the mode-mass calculation normalized at the optical depth of the BiSON observations, the fitted power laws in E are approximately ~nu^6.5+/-1.1 and ~nu^-6.2+/-1.1 respectively. Title: Solar p-mode Excitation: Further Insights from Recent Low-l BiSON Helioseismological Data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Lines, R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1998ESASP.418..879C Altcode: 1998soho....6..879C We present measurements of low-degree solar p-mode velocity powers, energies and energy supply rates between ~1600 μ Hz and ~4700 μ Hz, as derived from the analysis of several years of high-quality helioseismological data collected by the Birmingham Solar-Oscillations Network (BiSON). For the radial (ell = 0) modes, we find that the total energy E per mode (kinetic plus potential) peaks at ~3200 μ Hz, reaching ~1028 ergs. The rate at which energy is supplied to the modes dot{E} = 2pi Δ ν cdot E, where Δ ν is the fwhm modal line width, is observed to plateau between ~3000 μ Hz and ~4000 μ Hz, reaching a maximum of ~1023 ergs s-1. At frequencies below the plateau, the supply rate follows a simple power law with a dependence of dot{E} propto nu7.0 plus or minus 0.4; and at very-high frequencies the data follow dot{E} propto nu-4.5 plus or minus 1.1. Title: Low Degree p-mode solar cycle trends from BISON data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1998IAUS..185..171C Altcode: The resonant p-mode oscillations of the Sun are manifestations of trapped, standing sound waves in the solar interior. The frequencies of the discrete spectrum of sustained modes are consequently modified by the mechanical properties of the layers through which the waves traverse. Quasi-periodic changes to the solar structure -- on an 11 (22)-year timescale -- result in certain measurable mode properties being affected. Here, we have used high-quality Doppler velocity data, collected in integrated sunlight by the Birmingham Solar-Oscillations Network (BiSON), in order to assess the resulting impact on the low-degree modes of oscillation over the falling phase of solar cycle 22, and the beginning of cycle 23. Title: Further inside into p-mode excitation and damping from recent BiSON data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1998IAUS..185..221C Altcode: The resonant p-mode oscillations of the Sun are believed to be excited stochastically in its outer layers. Here, we seek to gain additional insight into the p-mode excitation and damping problem by following the power evolution, with time, of individual low-degree (low-ell) multiplets. Sine-wave fits have been performed -- at the appropriate frequencies -- on short stretches of high-quality Doppler velocity data, collected in integrated sunlight by the Birmingham Solar-Oscillations Network (BiSON). The results of these analyses will be presented and discussed. Title: Observational Upper Limits for Low-Degree Solar g-modes Authors: Fröhlich, C.; Finsterle, W.; Andersen, B.; Appourchaux, T.; Chaplin, W. J.; Elsworth, Y.; D. O. Gough; Hoeksema, J. T.; Isaak, G. R.; Kosovichev, A. G.; Provost, J.; Scherrer, P. H.; Sekii, T.; Toutain, T. Bibcode: 1998ESASP.418...67F Altcode: 1998soho....6...67F No abstract at ADS Title: Touching on the effects of an imperfect Window Function Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1998IAUS..185...47C Altcode: No abstract at ADS Title: A comparison of low-degree solar p-mode frquencies from BISON and LOI Authors: Appourchaux, T.; Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1998IAUS..185...45A Altcode: Here, we compare the low-degree solar p-mode frequencies returned from the analysis of two, contemporaneous, independent helioseismological data sets collected during 1996. The first comprises Doppler velocity observations of the 770-nm line of potassium, made in integrated sunlight by the six-station, terrestrial Birmingham Solar-Oscillations Network (BiSON). The second consists of irradiance distribution measurements of the solar disc, made at 500rm nm, by the Luminosity Oscillations Imager (LOI), which is part of the VIRGO experiment on the ESA/NASA SOHO satellite. Title: Comparative Studies of Low-Order and Low-Degree Solar p Modes Authors: Appourchaux, T.; Andersen, B.; Chaplin, W.; Elsworth, Y.; Finsterle, W.; Frohlich, C.; Gough, D.; Hoeksema, J. T.; Isaak, G.; Kosovichev, A.; Provost, J.; Scherrer, P.; Sekii, T.; Toutain, T. Bibcode: 1998ESASP.418...95A Altcode: 1998soho....6...95A The amplitudes of solar p-modes decrease steeply with decreasing radial order below about 17. The background solar signal (solar noise) in general increases steadily with decreasing frequency. For the irradiance and radiance measurements with VIRGO or SOI/MDI on SOHO this combination makes it difficult to detect low degree modes below about 1.8 mHz. The solar noise as observed in velocity with SOI/MDI or the ground based BISON network is significantly lower in this region than in intensity measurements. This allows low degree modes to be observed close to 1 mHz. We present results of detection and charaterization of the lowest order observable p-modes both in velocity and intensity measurements. Where applicable the properties of the modes observed with the two methods are compared. Title: The Extraction of Rotational Splittings from Monte Carlo Simulations of Unresolved Low-l Data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Miller, B. A.; New, R. Bibcode: 1998ESASP.418..135C Altcode: 1998soho....6..135C The rotation of the Sun lifts the frequency degeneracy in ell of the acoustic eigenmode spectrum. The extraction of reliable estimates of these splittings is a particularly challenging task. Here, we address the problem in the context of the analysis of full-disc helioseismological data. In essence, a set of ``zero-dimensional'' data are collected. Consequently: (i) a power spectrum of the data will consist of many closely spaced resonant peaks, with the most prominent aspect being an alternating quadrupole-monopole and octupole-dipole mode-pair structure; (ii) the data cannot be spatially filtered to extract ``single-mode'' power spectra -- however, this does mean that they are unaffected by spatial sideband leakage (which presents its own set of problems for resolved data); and (iii) the composition of the power spectrum may be further complicated by the introduction of temporal sidebands and other window-function-aliased power as a result of an imperfect observational duty cycle. At low frequencies, the modes are very weak -- however, their long coherence times give sharp, well defined resonant peaks in the frequency domain, enabling the m-dependent structure of the mode to be well resolved (given a sufficiently long integration time). At higher frequencies, despite increased signal-to-noise, the increasing mode line widths lead to a substantial blending of adjacent features in the frequency domain -- as the frequency-domain line widths increase still further, so the problems associated with extracting reliable estimates of the mode splittings become ever more severe. Here, we have used artificial p-mode data -- generated by a model which is based upon a randomly forced, damped harmonic oscillator -- to assess the veracity of maximum-likelihood fitting approaches for different parts of the low-ell spectrum. Among other points of interest, the results of these simulations reveal a clear tendency for the formal uncertainty of the fitted splitting to be anti-correlated with the magnitude of the splitting for modes at higher n. Title: A search l=2 asymmetries in BISON data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1998IAUS..185..169C Altcode: The rotation of the Sun lifts the frequency degeneracy in the angular degree ell of the resonant p-mode oscillations of the solar cavity, giving rise to a multiplet structure, each resulting component being identified by an azimuthal order m. A buried magnetic field will perturb these frequencies still further via the Lorentz force. Here, we have used low-degree solar p-mode data, collected by the Birmingham Solar-Oscillations Network (BiSON) in integrated sunlight, in an effort to search for such an effect in modes of degree ell=2. The Lorentz perturbation will shift the outer, sectoral (m=pm 2) components in the same sense, while the m=0 component remains unaffected, giving the integrated-sunlight-observed ell=2 multiplet an asymmetric frequency structure. The degree of asymmetry is expected to change with the solar cycle. Results obtained by attempting to fit explicitly the asymmetric structure, and by overlaying many independent mode realizations, will be presented and discussed. Title: Solar internal sound speed as inferred from combined BiSON and LOWL oscillation frequencies Authors: Basu, Sarbani; Christensen-Dalsgaard, J.; Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; New, R.; Schou, J.; Thompson, M. J.; Tomczyk, S. Bibcode: 1997MNRAS.292..243B Altcode: 1997astro.ph..2105B Observations of the Sun with the LOWL instrument provide a homogeneous set of solar p-mode frequencies from low to intermediate degree that allow one to determine the structure of much of the solar interior avoiding systematic errors that are introduced when different data sets are combined, i.e., principally the effects of solar cycle changes on the frequencies. Unfortunately, the LOWL data set contains very few of the lowest-degree modes, which are essential for determining reliably the structure of the solar core - in addition, these lowest-degree data have fairly large associated uncertainties. However, observations made by the Birmingham Solar-Oscillations Network (BiSON) in integrated sunlight provide high-accuracy measurements of a large number of low-degree modes. In this paper we demonstrate that the low-degree mode set of the LOWL data can be successfully combined with the more accurate BiSON data, provided the observations are contemporaneous for those frequencies where the solar cycle induced effects are important. We show that this leads to a factor of 2 decrease in the error on the inferred sound speed in the solar core. We find that the solar sound speed is higher than in solar models for r<0.2Rsolar. The density of the solar core is, however, lower than that in solar models. Title: Techniques used in the analysis of data collected by the Birmingham Solar-Oscillations Network (BiSON). II. Frequency domain analysis & data merging Authors: Chaplin, W. J.; Elsworth, Y.; Howe, R.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1997A&AS..125..195C Altcode: The Birmingham Solar-Oscillations Network (BiSON) consists of 6 solar observatories dedicated to the collection of full-disc solar Doppler velocity data -- these data are sensitive to the lowest spatial degrees of oscillation (0 <= l <= 4). In Paper I of this series, we described the calibration of raw data from the BiSON instruments to produce solar velocity residuals representing the oscillations of the Sun's surface. In this paper, we discuss the combination of velocity residuals into time series -- including a thorough discussion of the treatment of data overlaps between sites -- and the analysis of the power spectra computed from such time series to derive the characteristics of the acoustic modes. Title: A Key to Understanding the Sun and Stars: The Birmingham Solar-Oscillations Network (BiSON) Authors: Chaplin, W. J. Bibcode: 1997IrAJ...24..103C Altcode: The Birmingham Solar-Oscillations Network (BiSON) consists of six semi- and fully-automatic observatories, dedicated to the continuous observation of the low-degree, globally coherent, p-mode oscillations of the Sun. These resonant modes are manifestations of trapped, standing sound waves that penetrate into the core of the Sun and which consequently provide a sensitive probe of its deep radiative interior. Here, we discuss briefly the nature of the oscillations, introduce BiSON, and touch upon some of the important science extracted by the network which has, among other topics, impacted upon: solar and stellar physics; stellar evolutionary theory; the solar neutrino problem; and cosmology. Title: Solar p-mode linewidths from recent BiSON helioseismological data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1997MNRAS.288..623C Altcode: We present low-degree solar p-mode linewidths from the analysis of several high-resolution frequency spectra generated from high-quality Doppler velocity data collected - in integrated sunlight - by the Birmingham Solar-Oscillations Network (BiSON) between 1991 July and 1995 July. We have used linewidths, Deltanu, measured in a 32-month frequency spectrum, to test the power-law dependence of the widths at low frequencies. Over the range 1473<=nu<=1822Hz, we find Deltanu~nu^7.0+/-1.5. If an effort is made to correct for finite observing time systematics, the fitted index increases to 7.3 (and even higher, to 7.8, if a naive, single-bin-width correction is applied). This is somewhat steeper than reported in previous observations of intermediate-degree modes, and is more in line with theoretical calculations which predict Deltanu~nu^8 over this frequency range. If one assumes that the steep dependence reported here persists down to lower frequencies, low-degree-mode coherence (e-folding) times at 800Hz of >14yr, and at 300 muHz (i.e. near the frequency expected for the fundamental) of >13000yr are implied. Title: The observation and simulation of stochastically excited solar p modes Authors: Chaplin, W. J.; Elsworth, Y.; Howe, R.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1997MNRAS.287...51C Altcode: We use low-degree p-mode data, collected in integrated sunlight by the Birmingham Solar-Oscillations Network (BiSON), to derive the distribution of the observed strengths of the solar oscillations. We demonstrate that certain features of the observations cannot be explained by a model of the oscillations that is based upon a stochastically forced, damped harmonic oscillator. The solution of the equation of motion of the oscillator, as derived by the use of the Laplace transform, is presented, and its application to the simulation of real p-mode data, in the form of a coded algorithm, is discussed. A variety of tests are applied - both in the time and in the frequency domains - to artificially generated time series. These confirm that the model serves both as a useful diagnostic tool and for providing additional insight into the p-mode excitation and damping problem. Title: The Solar Core: New Low-l p-Mode Fine-Spacing Results from BiSON Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1997ApJ...480L..75C Altcode: 1997astro.ph..2141C The fine-structure spacing dl(n) = νl,n - νl+2,n-1 for low-degree solar p modes of angular degree l and radial order n is sensitive to conditions in the deep radiative interior of the Sun. Here we present fine-structure spacings derived from the analysis of nearly 5 years of helioseismological data collected between 1991 July and 1996 February by the Birmingham Solar Oscillations Network (BiSON). These data cover 9 <= n <= 28 for d0(n), and 11 <= n <= 27 for d1(n). The measured spacings are much more precise and cover a greater range than earlier measurements from BiSON data (Elsworth et al. 1990a). The predicted fine-structure spacings for a ``standard'' solar model are clearly excluded by the BiSON data (at ~10 σ) models that include helium and heavy-element settling provide a much better match to the observed spacings (see also Elsworth et al. 1995). Since the inclusion of core settling in solar models will tend to increase slightly the predicted neutrino flux, the BiSON fine-structure data appear to reinforce previous conclusions, i.e., an astrophysical solution to the solar neutrino problem seems unlikely.

Birmingham Solar Oscillations Network; http://bison.ph.bham.ac.uk. Title: Solar core rotation from low-degree BiSON p-mode splittings: 1981-95 Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1996MNRAS.283L..31C Altcode: In this paper, we present an analysis of the rotational splittings of low-degree solar p modes, as measured in full-disc helioseismological data collected by the Birmingham Solar-Oscillations Network (BiSON) between 1981 and 1995. These data provide coverage over solar activity cycles 21 and 22. Rotationally split multiplets were fitted in two 4-month and seven 8-month frequency spectra with a technique that minimizes a maximum-likelihood function consistent with chi^2 2-d.o.f. statistics. The fitted modes used in the analysis map the range 1<=l<=3 and 2.0<=nu<=3.1mHz. The lower limit to the analysed frequency range was determined by the poorer quality of the pre-1990 data; the upper, very conservative, cut-off was imposed in order to avoid using data where the linewidths of the modes begin to increase substantially above 1muHz. Global splitting averages (for 1<=l<=3) were computed over the quoted mode-frequency range by: (i) weighting each datum according to the scatter observed in the sectoral splittings as a function of l and (ii) weighting each datum according to its formal uncertainty, as computed by the mode-fitting procedure. The l-weighted averages show a slight decline over the period 1981-95: however, the gradient is only significant at the ~2sigma level (-3.8+/-1.8nHz yr^-1). If one were to interpret any trends in the low-degree splittings as being indicative of a modification of the rotational behaviour of the solar core (for r/R_solar<=0.25), we would estimate that a ~60 per cent change in the core rotation rate is excluded at the 3sigma level by the l-weighted data. The `formally' weighted averages imply a very significant change with epoch. However, an analysis of the data appears to show that the formal uncertainties may somewhat underestimate the actual errors on the measured splittings, leading to an overestimation of the significance of any inferred change with epoch. Title: Low-frequency, low-degree solar p-mode measurements from recent BiSON* data Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; Lines, R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1996MNRAS.282L..15C Altcode: We present high-quality measurements of the frequencies of some acoustic modes of oscillation of the Sun, as determined from recent full-disc BiSON data. These cover the range 0<=<~<=3 and 7<=<e1>n<=</e1>14. Several of the mode frequencies have been measured to accuracies as high as 5 parts in 10^6, as determined by the formal mode-fitting uncertainties. When compared with the model frequencies of the AARHUS group (model OPAL1 from Basu et al.) in which the Livermore equation of state, the Livermore opacities and both helium and heavy element diffusion and settling have been incorporated, the frequency differences (in the sense BiSON minus OPAL1) are typically of the order of only ~-0.1 muHz over this frequency region. Title: BiSON Performance Authors: Chaplin, William J.; Elsworth, Yvonne; Howe, Rachel; Isaak, George R.; McLeod, Clive P.; Miller, Brek A.; van der Raay, H. B.; Wheeler, Sarah J.; New, Roger Bibcode: 1996SoPh..168....1C Altcode: Since 1981 we have been operating the Birmingham Solar-Oscillations Network (BiSON), a global network of resonant-scattering spectrometers, observing the low-l solar p modes. Here we discuss historical developments, culminating in the establishment of a 6-station network in 1992 September, and the subsequent performance of that network. The data record of each station from 1992 to 1994 has been analysed in terms of weather and equipment breakdowns. Our early experience suggests that the best long-term coverage possible with a 6-station network is limited in practice to about 80%, which falls short of previous predictions. Title: Low-degree, L=4 modes in full-disc BiSON* helioseismological data Authors: Chaplin, W. J.; Elsworth, Y.; Howe, R.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1996MNRAS.280.1162C Altcode: We demonstrate that some L=4 acoustic eigenmodes of the Sun are clearly distinguishable in long power spectra generated from Doppler velocity residuals collected in unimaged sunlight by the six-station Birmingham Solar Oscillations Network (BiSON). Modes covering the range n=17 to 21 have been measured in 16-month-long power spectra. They have typical amplitudes -when measured in full-disc Doppler velocity data - of less than ~1 cm s^-1 per root bin, and their frequencies have been determined to fractional accuracies of the order of 3 parts in 10^5. The sensitivity of the whole-disc observations to these modes - as implied by the data - appears to be approximately a factor of 2 greater than the theoretical predictions of Christensen-Dalsgaard. Title: Solar core rotation: low-degree solar p-mode rotational splitting results from BiSON* Authors: Chaplin, W. J.; Elsworth, Y.; Howe, R.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1996MNRAS.280..849C Altcode: In a recent paper (Elsworth et al.), we presented rotational splitting measurements of low-degree, low-frequency solar p modes, which, for the first time, show visually well-separated components at frequencies as low as ~1.5 mHz. At the present time, these data appear to rule out a rapidly rotating solar core. Here, we expand our analysis of these data to a full discussion of the statistical properties of the measured splittings. We have considered two fully independent Fourier spectra, generated from Doppler velocity residuals collected by the six-station Birmingham Solar-Oscillations Network (BiSON) between 1992 January 1 and 1994 August 23 (Fourier spectra 16A and 16C from Elsworth et al.). We present formal uncertainties from maximum-likelihood fits to the mode multiplets, analyse and compare the statistical properties of the sets, and search for possible trends in the splitting measures with n. Title: Recent results from the Birmingham Solar-Oscillations Network (BiSON). Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1996BAAS...28..936C Altcode: No abstract at ADS Title: Recent Results from the Birmingham Solar-Oscillations Network (BiSON) Authors: Chaplin, W. J.; Elsworth, Y.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1996AAS...188.6904C Altcode: 1996BAAS...28R.936C The Birmingham Solar-Oscillations Network (BiSON) consists of 6 semi and fully automatic observatories, dedicated to the collection of low-degree solar oscillations data in integrated sunlight. The network was established in 1981 with two permanent stations; the addition of several more sites culminated with the addition of a sixth in 1992. Here, we give an update on the current status of the network. In addition, we discuss recent important scientific results from analysed data, including: low-degree rotational splitting results covering the period 1981 to 1995; and the measurement of low-frequency modes, down to ~ 1.2mHz, in a power spectrum generated from 32 months of recent BiSON data. Title: The Recent Performance of the 6-STATION BISON Network Authors: Chaplin, W. J.; Elsworth, Y.; Howe, R.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; van der Raay, H. B. Bibcode: 1995ESASP.376b.391C Altcode: 1995help.confP.391C; 1995soho....2..391C No abstract at ADS Title: Some Notes on the Calibration of Doppler Velocity Residuals Collected by a Resonant Scattering Spectrometer Authors: Chaplin, W. J.; Elsworth, Y.; Howe, R.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1995ESASP.376b.163C Altcode: 1995soho....2..163C; 1995help.confP.163C Discusses three alternative calibration techniques for Doppler velocity data collected by a resonant-scattering spectrometer viewing the unimaged solar disc, that allow long-term, low-frequency information to be preserved. In the first, the effects of curvature in the solar reference line are removed by normalizing the observed ratio, R(v) - the difference between the resonantly-scattered intensities in the blue and red wings of the source line, normalized by the scattered sum - by a function that reflects the variation of the total intensity over the instrument bandwidth. In the second method, a linearized function is formed from a power series of R(v). A straight forward example of this technique appears to be subject to systematic, low-frequency errors of the order of ≡1 to 2 m s-1. And in the third method, Doppler velocity data collected over a full observing season could, in principle, form an internal reference - a look-up curve. Title: The Measurement of L = 4 Modes in Full-Disc BISON Data Authors: Chaplin, W. J.; Elsworth, Y.; Howe, R.; Isaak, G. R.; McLeod, C. P.; Miller, B. A. Bibcode: 1995ESASP.376b.387C Altcode: 1995help.confP.387C; 1995soho....2..387C No abstract at ADS Title: An Investigation of the Correlation Between Unusually Large Amplitude P-Modes and Solar Activity Authors: Chaplin, W. J.; Elsworth, Y.; Howe, R.; Isaak, G. R.; McLeod, C. P.; Miller, B. A.; New, R. Bibcode: 1995ESASP.376b.335C Altcode: 1995help.confP.335C; 1995soho....2..335C No abstract at ADS Title: A search for small-amplitude, acoustic, p-mode oscillations on alpha CMi Authors: Bedford, D. K.; Chaplin, W. J.; Coates, D. W.; Davies, A. R.; Innis, J. L.; Isaak, G. R.; Speake, C. C. Bibcode: 1995MNRAS.273..367B Altcode: We have searched for small-amplitude, acoustic, p-mode oscillations on the F5 IV-V subgiant alpha CMi (HR 2943) in high-quality Doppler velocity measurements made in 1991, 1992 and 1993 with a magneto-optical-filter spectrometer. An internal precision of 0.13 m^-2 s^-2 muHz^-1 (1 sigma) has been achieved in one of the 1993 data sets. Conclusive evidence for the presence of a p-mode spectrum may be established by extracting the mean first-order-half spacing 1/2Deltav. Fourier analysis of the 1991 and 1992 data appears to indicate the presence of a strong concentration of periodic power. However, the analysis of substantially higher quality 1993 data fails to reveal a strong peak; we are therefore forced to conclude tentatively that we have, at present, failed to find conclusive evidence for an acoustic oscillation spectrum on alpha CMi. Title: High-precision, longitudinal, disc-averaged magnetic field measurements of α Canis Minoris and β Leporis. Authors: Bedford, D. K.; Chaplin, W. J.; Davies, A. R.; Innis, J. L.; Isaak, G. R.; Speake, C. C. Bibcode: 1995A&A...293..377B Altcode: High-precision longitudinal, disc-averaged magnetic field measurements have been made on two late-type stars, α CMi (HR 2943) and β Lep (HR 1829). A magneto-optical filter has been used to measure the degree of circular polarization in the wings of a line of neutral potassium (7699 A) formed in the atmosphere of the target star. From 10 nights of data taken on α CMi on the 1.9-m reflector at the South African Astronomical Observatory (SAAO) in 1993 January, an upper limit to any net longitudinal field component present - assuming the field to be constant over the period of observation - of -0.40+/-0.26G was established. Similarly, upper limits for β Lep of -4.3+/-6.4G and -0.7+/-1.6G were established, from 4 and 10 nights of data taken in 1992 and 1993 January respectively. No significant, periodic, day-to-day variations were seen in the three time series of data. Title: High-precision velocity observations of Procyon A - II. Measurement of the orbital motion of Procyon A during 1986-90. Authors: Innis, J. L.; Isaak, G. R.; Speake, C. C.; Chaplin, W. J.; Brazier, R. I.; Jones, A. R. Bibcode: 1994MNRAS.271..573I Altcode: Radial velocity observations of high internal precision have been obtained, with the Birmingham stellar spectrometer, of the F5 IV-V star Procyon A. The velocities have been derived using a `null technique' by determining the time when the topocentric velocity of Procyon A passes through zero (which occurs in January each year). At this time, the barycentric velocity of the star is equal to the barycentric velocity of the instrument, which can be calculated to a high accuracy. Seven such velocities have been determined from five observing runs during the years 1986 to 1990 inclusive. The internal precision and external errors (e.g. our zero-point) cannot be uniquely determined from so few points but the former appears to be in the range 10 to 40 m s- . We have compared our data with the orbit of Procyon recently derived by Irwin et al. The mean annual acceleration of Procyon A over the two years 1988 to 1990, according to the orbit of Irwin et al., is 133 m s- yr . Our measured value is 122 m s1 yr , with an error of the order oft 10 m s- , in reasonable agreement with the value obtained by Irwin et al. A detailed comparison will be possible when several more years of data have been obtained. Key words: techniques: radial velocities - binaries: spectroscopic - stars: individual: Procyon. Title: The longitudinal magnetic field of Procyon. Authors: Bedford, D. K.; Chaplin, W. J.; Innis, J. L.; Isaak, G. R.; McLeod, C. P.; Speake, C. C. Bibcode: 1994MNRAS.269..639B Altcode: An upper limit of 4.3 G (3 u) on the longitudinal magnetic field, and its variation, of the bright star Procyon is placed by the extended measurement of the circular polarization in the blue and red wings of the 770-nm absorption line of neutral potassium. Key words: line: profiles - polarization - stars: individual: Procyon - stars: magnetic fields. Title: A high-precision determination of the radial velocity of the G5 II giant beta Lep. Authors: Bedford, D. K.; Chaplin, W. J.; Davies, A. R.; Innis, J. L.; Isaak, G. R.; Speake, C. C. Bibcode: 1994MNRAS.269..435B Altcode: We apply a null technique to measure to a high accuracy the barycentric radial velocity of the G5 II giant P Lep (HR 1829). We use a magneto-optical filter as a spectroscopic bridge to determine the time at which the geocentric velocity of the star passes through zero. From data taken on the 1.9-m reflector at the South African Astronomical Observatory (SAAO) in 1992 and 1993 January, the barycentric radial velocity of P Lep is calculated to be -13.6+0.2 and -13.576+0.040 km s ' respectively. Key words: techniques: radial velocities - stars: individual: P Lep - stars: oscillations. Title: High-precision velocity and magnetic measurements of bright stars with a magneto-optical filter Authors: Chaplin, William James Bill Bibcode: 1994PhDT.......304C Altcode: No abstract at ADS Title: Metal epoxy-coated mirrors for stellar seismology Authors: Bedford, David K.; Chaplin, W. J.; Isaak, G. R. Bibcode: 1993SPIE.1931...96B Altcode: A 0.9 m diameter f/1.8 paraboloidal mirror of moderate quality (approximately 2 arcmin) has been produced by spinning an epoxy- coated spherical substrate. This mirror has been used to build a prototype flux collector for stellar seismology. The objective is to produce 2 m mirrors for this application. Title: High Precision Velocity Measurements of the Star Procyon - a Possible Stellar Signal Authors: Bedford, D. K.; Chaplin, W. J.; Davies, A. R.; Innis, J. L.; Isaak, G. R.; Speake, C. C. Bibcode: 1993ASPC...42..383B Altcode: 1993gong.conf..383B No abstract at ADS