Author name code: brooks ADS astronomy entries on 2022-09-14 author:"Brooks, David H." AND (aff:"Fairfax" OR aff:"Kyoto" OR aff:"Glasgow") ------------------------------------------------------------------------ Title: Parallel Plasma Loops and the Energization of the Solar Corona Authors: Peter, Hardi; Chitta, Lakshmi Pradeep; Chen, Feng; Pontin, David I.; Winebarger, Amy R.; Golub, Leon; Savage, Sabrina L.; Rachmeler, Laurel A.; Kobayashi, Ken; Brooks, David H.; Cirtain, Jonathan W.; De Pontieu, Bart; McKenzie, David E.; Morton, Richard J.; Testa, Paola; Tiwari, Sanjiv K.; Walsh, Robert W.; Warren, Harry P. Bibcode: 2022ApJ...933..153P Altcode: 2022arXiv220515919P The outer atmosphere of the Sun is composed of plasma heated to temperatures well in excess of the visible surface. We investigate short cool and warm (<1 MK) loops seen in the core of an active region to address the role of field-line braiding in energizing these structures. We report observations from the High-resolution Coronal imager (Hi-C) that have been acquired in a coordinated campaign with the Interface Region Imaging Spectrograph (IRIS). In the core of the active region, the 172 Å band of Hi-C and the 1400 Å channel of IRIS show plasma loops at different temperatures that run in parallel. There is a small but detectable spatial offset of less than 1″ between the loops seen in the two bands. Most importantly, we do not see observational signatures that these loops might be twisted around each other. Considering the scenario of magnetic braiding, our observations of parallel loops imply that the stresses put into the magnetic field have to relax while the braiding is applied: the magnetic field never reaches a highly braided state on these length scales comparable to the separation of the loops. This supports recent numerical 3D models of loop braiding in which the effective dissipation is sufficiently large that it keeps the magnetic field from getting highly twisted within a loop. Title: Constraining Global Coronal Models with Multiple Independent Observables Authors: Badman, Samuel T.; Brooks, David H.; Poirier, Nicolas; Warren, Harry P.; Petrie, Gordon; Rouillard, Alexis P.; Nick Arge, C.; Bale, Stuart D.; de Pablos Agüero, Diego; Harra, Louise; Jones, Shaela I.; Kouloumvakos, Athanasios; Riley, Pete; Panasenco, Olga; Velli, Marco; Wallace, Samantha Bibcode: 2022ApJ...932..135B Altcode: 2022arXiv220111818B Global coronal models seek to produce an accurate physical representation of the Sun's atmosphere that can be used, for example, to drive space-weather models. Assessing their accuracy is a complex task, and there are multiple observational pathways to provide constraints and tune model parameters. Here, we combine several such independent constraints, defining a model-agnostic framework for standardized comparison. We require models to predict the distribution of coronal holes at the photosphere, and neutral line topology at the model's outer boundary. We compare these predictions to extreme-ultraviolet (EUV) observations of coronal hole locations, white-light Carrington maps of the streamer belt, and the magnetic sector structure measured in situ by Parker Solar Probe and 1 au spacecraft. We study these metrics for potential field source surface (PFSS) models as a function of source surface height and magnetogram choice, as well as comparing to the more physical Wang-Sheeley-Arge (WSA) and the Magnetohydrodynamic Algorithm outside a Sphere (MAS) models. We find that simultaneous optimization of PFSS models to all three metrics is not currently possible, implying a trade-off between the quality of representation of coronal holes and streamer belt topology. WSA and MAS results show the additional physics that they include address this by flattening the streamer belt while maintaining coronal hole sizes, with MAS also improving coronal hole representation relative to WSA. We conclude that this framework is highly useful for inter- and intra-model comparisons. Integral to the framework is the standardization of observables required of each model, evaluating different model aspects. Title: Detection of Stellar-like Abundance Anomalies in the Slow Solar Wind Authors: Brooks, David H.; Baker, Deborah; van Driel-Gesztelyi, Lidia; Warren, Harry P.; Yardley, Stephanie L. Bibcode: 2022ApJ...930L..10B Altcode: 2022arXiv220409332B The elemental composition of the Sun's hot atmosphere, the corona, shows a distinctive pattern that is different from the underlying surface or photosphere. Elements that are easy to ionize in the chromosphere are enhanced in abundance in the corona compared to their photospheric values. A similar pattern of behavior is often observed in the slow-speed (<500 km s-1) solar wind and in solar-like stellar coronae, while a reversed effect is seen in M dwarfs. Studies of the inverse effect have been hampered in the past because only unresolved (point-source) spectroscopic data were available for these stellar targets. Here we report the discovery of several inverse events observed in situ in the slow solar wind using particle-counting techniques. These very rare events all occur during periods of high solar activity that mimic conditions more widespread on M dwarfs. The detections allow a new way of connecting the slow wind to its solar source and are broadly consistent with theoretical models of abundance variations due to chromospheric fast-mode waves with amplitudes of 8-10 km s-1, sufficient to accelerate the solar wind. The results imply that M-dwarf winds are dominated by plasma depleted in easily ionized elements and lend credence to previous spectroscopic measurements. Title: Multiwavelength optical and NIR variability analysis of the Blazar PKS 0027-426 Authors: Guise, E.; Hönig, S. F.; Almeyda, T.; Horne, K.; Kishimoto, M.; Aguena, M.; Allam, S.; Andrade-Oliveira, F.; Asorey, J.; Banerji, M.; Bertin, E.; Boulderstone, B.; Brooks, D.; Burke, D. L.; Carnero Rosell, A.; Carollo, D.; Carrasco Kind, M.; Carretero, J.; Costanzi, M.; da Costa, L. N.; Davis, T. M.; De Vicente, J.; Doel, P.; Everett, S.; Ferrero, I.; Flaugher, B.; Frieman, J.; Gandhi, P.; Goad, M.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Hinton, S. R.; Hollowood, D. L.; Honscheid, K.; James, D. J.; Johnson, M. A. C.; Kuehn, K.; Lewis, G. F.; Lidman, C.; Lima, M.; Maia, M. A. G.; Malik, U.; Menanteau, F.; Miquel, R.; Morgan, R.; Ogando, R. L. C.; Palmese, A.; Paz-Chinchón, F.; Pereira, M. E. S.; Pieres, A.; Plazas Malagón, A. A.; Sanchez, E.; Scarpine, V.; Serrano, S.; Sevilla-Noarbe, I.; Seymour, N.; Smith, M.; Soares-Santos, M.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; To, C.; Tucker, B. E. Bibcode: 2022MNRAS.510.3145G Altcode: 2021arXiv210813386G; 2021MNRAS.tmp.3142G We present multiwavelength spectral and temporal variability analysis of PKS 0027-426 using optical griz observations from Dark Energy Survey between 2013 and 2018 and VEILS Optical Light curves of Extragalactic TransienT Events (VOILETTE) between 2018 and 2019 and near-infrared (NIR) JKs observations from Visible and Infrared Survey Telescope for Astronomy Extragalactic Infrared Legacy Survey (VEILS) between 2017 and 2019. Multiple methods of cross-correlation of each combination of light curve provides measurements of possible lags between optical-optical, optical-NIR, and NIR-NIR emission, for each observation season and for the entire observational period. Inter-band time lag measurements consistently suggest either simultaneous emission or delays between emission regions on time-scales smaller than the cadences of observations. The colour-magnitude relation between each combination of filters was also studied to determine the spectral behaviour of PKS 0027-426. Our results demonstrate complex colour behaviour that changes between bluer when brighter, stable when brighter, and redder when brighter trends over different time-scales and using different combinations of optical filters. Additional analysis of the optical spectra is performed to provide further understanding of this complex spectral behaviour. Title: Evolution of Plasma Composition in an Eruptive Flux Rope Authors: Baker, D.; Green, L. M.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, L.; Mihailescu, T.; To, A. S. H.; Long, D. M.; Yardley, S. L.; Janvier, M.; Valori, G. Bibcode: 2022ApJ...924...17B Altcode: 2021arXiv211011714B Magnetic flux ropes are bundles of twisted magnetic field enveloping a central axis. They harbor free magnetic energy and can be progenitors of coronal mass ejections (CMEs). However, identifying flux ropes on the Sun can be challenging. One of the key coronal observables that has been shown to indicate the presence of a flux rope is a peculiar bright coronal structure called a sigmoid. In this work, we show Hinode EUV Imaging Spectrometer observations of sigmoidal active region (AR) 10977. We analyze the coronal plasma composition in the AR and its evolution as a sigmoid (flux rope) forms and erupts as a CME. Plasma with photospheric composition was observed in coronal loops close to the main polarity inversion line during episodes of significant flux cancellation, suggestive of the injection of photospheric plasma into these loops driven by photospheric flux cancellation. Concurrently, the increasingly sheared core field contained plasma with coronal composition. As flux cancellation decreased and a sigmoid/flux rope formed, the plasma evolved to an intermediate composition in between photospheric and typical AR coronal compositions. Finally, the flux rope contained predominantly photospheric plasma during and after a failed eruption preceding the CME. Hence, plasma composition observations of AR 10977 strongly support models of flux rope formation by photospheric flux cancellation forcing magnetic reconnection first at the photospheric level then at the coronal level. Title: Investigating the origin of magnetic perturbations associated with the FIP Effect Authors: Murabito, M.; Stangalini, M.; Baker, D.; Valori, G.; Jess, D. B.; Jafarzadeh, S.; Brooks, D. H.; Ermolli, I.; Giorgi, F.; Grant, S. D. T.; Long, D. M.; van Driel-Gesztelyi, L. Bibcode: 2021A&A...656A..87M Altcode: 2021arXiv210811164M Recently, magnetic oscillations were detected in the chromosphere of a large sunspot and found to be linked to the coronal locations where a first ionization potential (FIP) effect was observed. In an attempt to shed light on the possible excitation mechanisms of these localized waves, we further investigate the same data by focusing on the relation between the spatial distribution of the magnetic wave power and the overall field geometry and plasma parameters obtained from multi-height spectropolarimetric non-local thermodynamic equilibrium (NLTE) inversions of IBIS data. We find, in correspondence with the locations where the magnetic wave energy is observed at chromospheric heights, that the magnetic fields have smaller scale heights, meaning faster expansions of the field lines, which ultimately results in stronger vertical density stratification and wave steepening. In addition, the acoustic spectrum of the oscillations at the locations where magnetic perturbations are observed is broader than that observed at other locations, which suggests an additional forcing driver to the p-modes. Analysis of the photospheric oscillations in the sunspot surroundings also reveals a broader spectrum between the two opposite polarities of the active region (the leading spot and the trailing opposite polarity plage), and on the same side where magnetic perturbations are observed in the umbra. We suggest that strong photospheric perturbations between the two polarities are responsible for this broader spectrum of oscillations, with respect to the p-mode spectrum, resulting in locally excited acoustic waves that, after crossing the equipartition layer, located close to the umbra-penumbra boundary at photopheric heights, are converted into magnetic waves and steepen due to the strong density gradient.

Movie associated to Fig. 1 is available at https://www.aanda.org Title: Signature and escape of highly fractionated plasma in an active region Authors: Brooks, David H.; Yardley, Stephanie L. Bibcode: 2021MNRAS.508.1831B Altcode: 2021MNRAS.tmp.2443B; 2021arXiv210911157B Accurate forecasting of space weather requires knowledge of the source regions where solar energetic particles (SEP) and eruptive events originate. Recent work has linked several major SEP events in 2014, January, to specific features in the host active region (AR 11944). In particular, plasma composition measurements in and around the footpoints of hot, coronal loops in the core of the active region were able to explain the values later measured in situ by the Wind spacecraft. Due to important differences in elemental composition between SEPs and the solar wind, the magnitude of the Si/S elemental abundance ratio emerged as a key diagnostic of SEP seed population and solar wind source locations. We seek to understand if the results are typical of other active regions, even if they are not solar wind sources or SEP productive. In this paper, we use a novel composition analysis technique, together with an evolutionary magnetic field model, in a new approach to investigate a typical solar active region (AR 11150), and identify the locations of highly fractionated (high Si/S abundance ratio) plasma. Material confined near the footpoints of coronal loops, as in AR 11944, that in this case have expanded to the AR periphery, show the signature, and can be released from magnetic field opened by reconnection at the AR boundary. Since the fundamental characteristics of closed field loops being opened at the AR boundary is typical of active regions, this process is likely to be general. Title: The Formation and Lifetime of Outflows in a Solar Active Region Authors: Brooks, David H.; Harra, Louise; Bale, Stuart D.; Barczynski, Krzysztof; Mandrini, Cristina; Polito, Vanessa; Warren, Harry P. Bibcode: 2021ApJ...917...25B Altcode: 2021arXiv210603318B Active regions are thought to be one contributor to the slow solar wind. Upflows in EUV coronal spectral lines are routinely observed at their boundaries, and provide the most direct way for upflowing material to escape into the heliosphere. The mechanisms that form and drive these upflows, however, remain to be fully characterized. It is unclear how quickly they form, or how long they exist during their lifetimes. They could be initiated low in the atmosphere during magnetic flux emergence, or as a response to processes occurring high in the corona when the active region is fully developed. On 2019 March 31 a simple bipolar active region (AR 12737) emerged and upflows developed on each side. We used observations from Hinode, SDO, IRIS, and Parker Solar Probe (PSP) to investigate the formation and development of the upflows from the eastern side. We used the spectroscopic data to detect the upflow, and then used the imaging data to try to trace its signature back to earlier in the active region emergence phase. We find that the upflow forms quickly, low down in the atmosphere, and that its initiation appears associated with a small field-opening eruption and the onset of a radio noise storm detected by PSP. We also confirmed that the upflows existed for the vast majority of the time the active region was observed. These results suggest that the contribution to the solar wind occurs even when the region is small, and continues for most of its lifetime. Title: Measurements of Coronal Magnetic Field Strengths in Solar Active Region Loops Authors: Brooks, David H.; Warren, Harry P.; Landi, Enrico Bibcode: 2021ApJ...915L..24B Altcode: 2021arXiv210610884B The characteristic electron densities, temperatures, and thermal distributions of 1 MK active region loops are now fairly well established, but their coronal magnetic field strengths remain undetermined. Here we present measurements from a sample of coronal loops observed by the Extreme-ultraviolet Imaging Spectrometer on Hinode. We use a recently developed diagnostic technique that involves atomic radiation modeling of the contribution of a magnetically induced transition to the Fe X 257.262 Å spectral line intensity. We find coronal magnetic field strengths in the range of 60-150 G. We discuss some aspects of these new results in the context of previous measurements using different spectropolarimetric techniques, and their influence on the derived Alfvén speeds and plasma β in coronal loops. Title: Comparison of active region upflow and core properties using simultaneous spectroscopic observations from IRIS and Hinode Authors: Barczynski, Krzysztof; Harra, Louise; Kleint, Lucia; Panos, Brandon; Brooks, David H. Bibcode: 2021A&A...651A.112B Altcode: 2021arXiv210410234B Context. The origin of the slow solar wind is still an open issue. It has been suggested that upflows at the edge of active regions are a possible source of the plasma outflow and therefore contribute to the slow solar wind.
Aims: We investigate the origin and morphology of the upflow regions and compare the upflow region and the active region core properties.
Methods: We studied how the plasma properties of flux, Doppler velocity, and non-thermal velocity change throughout the solar atmosphere, from the chromosphere via the transition region to the corona in the upflow region and the core of an active region. We studied limb-to-limb observations of the active region (NOAA 12687) obtained from 14 to 25 November 2017. We analysed spectroscopic data simultaneously obtained from IRIS and Hinode/EIS in the six emission lines Mg II 2796.4Å, C II 1335.71Å, Si IV 1393.76Å, Fe XII 195.12Å, Fe XIII 202.04Å, and Fe XIV 270.52Å and 274.20Å. We studied the mutual relationships between the plasma properties for each emission line, and we compared the plasma properties between the neighbouring formation temperature lines. To find the most characteristic spectra, we classified the spectra in each wavelength using the machine learning technique k-means.
Results: We find that in the upflow region the Doppler velocities of the coronal lines are strongly correlated, but the transition region and coronal lines show no correlation. However, their fluxes are strongly correlated. The upflow region has a lower density and lower temperature than the active region core. In the upflow region, the Doppler velocity and non-thermal velocity show a strong correlation in the coronal lines, but the correlation is not seen in the active region core. At the boundary between the upflow region and the active region core, the upflow region shows an increase in the coronal non-thermal velocity, the emission obtained from the DEM, and the domination of the redshifted regions in the chromosphere.
Conclusions: The obtained results suggest that at least three parallel mechanisms generate the plasma upflow: (1) The reconnection between closed loops and open magnetic field lines in the lower corona or upper chromosphere; (2) the reconnection between the chromospheric small-scale loops and open magnetic field; and (3) the expansion of the magnetic field lines that allows the chromospheric plasma to escape to the solar corona. Title: Widespread occurrence of high-velocity upflows in solar active regions Authors: Yardley, S. L.; Brooks, D. H.; Baker, D. Bibcode: 2021A&A...650L..10Y Altcode: 2021arXiv210601396Y
Aims: We performed a systematic study of 12 active regions (ARs) with a broad range of areas, magnetic fluxes, and associated solar activity in order to determine whether there are upflows present at the AR boundaries and, if these upflows exist, whether there is a high-speed asymmetric blue wing component present in them.
Methods: To identify the presence and locations of the AR upflows, we derive relative Doppler velocity maps by fitting a Gaussian function to Hinode/EIS Fe XII 192.394 Å line profiles. To determine whether there is a high-speed asymmetric component present in the AR upflows, we fit a double Gaussian function to the Fe XII 192.394 Å mean spectrum that is computed in a region of interest situated in the AR upflows.
Results: Upflows are observed at both the eastern and western boundaries of all ARs in our sample, with average upflow velocities ranging between −5 and −26 km s−1. A blue wing asymmetry is present in every line profile. The intensity ratio between the minor high-speed asymmetric Gaussian component compared to the main component is relatively small for the majority of regions; however, in a minority of cases (8/30) the ratios are large and range between 20 and 56 %.
Conclusions: These results suggest that upflows and the high-speed asymmetric blue wing component are a common feature of all ARs. Title: The active region source of a type III radio storm observed by Parker Solar Probe during encounter 2 Authors: Harra, L.; Brooks, D. H.; Bale, S. D.; Mandrini, C. H.; Barczynski, K.; Sharma, R.; Badman, S. T.; Vargas Domínguez, S.; Pulupa, M. Bibcode: 2021A&A...650A...7H Altcode: 2021arXiv210204964H Context. We investigated the source of a type III radio burst storm during encounter 2 of NASA's Parker Solar Probe (PSP) mission.
Aims: It was observed that in encounter 2 of NASA's PSP mission there was a large amount of radio activity and, in particular, a noise storm of frequent, small type III bursts from 31 March to 6 April 2019. Our aim is to investigate the source of these small and frequent bursts.
Methods: In order to do this, we analysed data from the Hinode EUV Imaging Spectrometer, PSP FIELDS, and the Solar Dynamics Observatory Atmospheric Imaging Assembly. We studied the behaviour of active region 12737, whose emergence and evolution coincides with the timing of the radio noise storm and determined the possible origins of the electron beams within the active region. To do this, we probed the dynamics, Doppler velocity, non-thermal velocity, FIP bias, and densities, and carried out magnetic modelling.
Results: We demonstrate that although the active region on the disc produces no significant flares, its evolution indicates it is a source of the electron beams causing the radio storm. They most likely originate from the area at the edge of the active region that shows strong blue-shifted plasma. We demonstrate that as the active region grows and expands, the area of the blue-shifted region at the edge increases, which is also consistent with the increasing area where large-scale or expanding magnetic field lines from our modelling are anchored. This expansion is most significant between 1 and 4 April 2019, coinciding with the onset of the type III storm and the decrease of the individual burst's peak frequency, indicating that the height at which the peak radiation is emitted increases as the active region evolves. Title: Plasma Upflows Induced by Magnetic Reconnection Above an Eruptive Flux Rope Authors: Baker, Deborah; Mihailescu, Teodora; Démoulin, Pascal; Green, Lucie M.; van Driel-Gesztelyi, Lidia; Valori, Gherardo; Brooks, David H.; Long, David M.; Janvier, Miho Bibcode: 2021SoPh..296..103B Altcode: 2021arXiv210616137B One of the major discoveries of Hinode's Extreme-ultraviolet Imaging Spectrometer (EIS) is the presence of upflows at the edges of active regions. As active regions are magnetically connected to the large-scale field of the corona, these upflows are a likely contributor to the global mass cycle in the corona. Here we examine the driving mechanism(s) of the very strong upflows with velocities in excess of 70 km s−1, known as blue-wing asymmetries, observed during the eruption of a flux rope in AR 10977 (eruptive flare SOL2007-12-07T04:50). We use Hinode/EIS spectroscopic observations combined with magnetic-field modeling to investigate the possible link between the magnetic topology of the active region and the strong upflows. A Potential Field Source Surface (PFSS) extrapolation of the large-scale field shows a quadrupolar configuration with a separator lying above the flux rope. Field lines formed by induced reconnection along the separator before and during the flux-rope eruption are spatially linked to the strongest blue-wing asymmetries in the upflow regions. The flows are driven by the pressure gradient created when the dense and hot arcade loops of the active region reconnect with the extended and tenuous loops overlying it. In view of the fact that separator reconnection is a specific form of the more general quasi-separatrix (QSL) reconnection, we conclude that the mechanism driving the strongest upflows is, in fact, the same as the one driving the persistent upflows of ≈10 - 20 km s−1 observed in all active regions. Title: The Evolution of Plasma Composition during a Solar Flare Authors: To, Andy S. H.; Long, David M.; Baker, Deborah; Brooks, David H.; van Driel-Gesztelyi, Lidia; Laming, J. Martin; Valori, Gherardo Bibcode: 2021ApJ...911...86T Altcode: 2021arXiv210209985T We analyze the coronal elemental abundances during a small flare using Hinode/EIS observations. Compared to the preflare elemental abundances, we observed a strong increase in coronal abundance of Ca XIV 193.84 Å, an emission line with low first ionization potential (FIP < 10 eV), as quantified by the ratio Ca/Ar during the flare. This is in contrast to the unchanged abundance ratio observed using Si X 258.38 Å/S X 264.23 Å. We propose two different mechanisms to explain the different composition results. First, the small flare-induced heating could have ionized S, but not the noble gas Ar, so that the flare-driven Alfvén waves brought up Si, S, and Ca in tandem via the ponderomotive force which acts on ions. Second, the location of the flare in strong magnetic fields between two sunspots may suggest fractionation occurred in the low chromosphere, where the background gas is neutral H. In this region, high-FIP S could behave more like a low-FIP than a high-FIP element. The physical interpretations proposed generate new insights into the evolution of plasma abundances in the solar atmosphere during flaring, and suggests that current models must be updated to reflect dynamic rather than just static scenarios. Title: Upflows in the Upper Solar Atmosphere Authors: Tian, Hui; Harra, Louise; Baker, Deborah; Brooks, David H.; Xia, Lidong Bibcode: 2021SoPh..296...47T Altcode: 2021arXiv210202429T Spectroscopic observations at extreme- and far-ultraviolet wavelengths have revealed systematic upflows in the solar transition region and corona. These upflows are best seen in the network structures of the quiet Sun and coronal holes, boundaries of active regions, and dimming regions associated with coronal mass ejections. They have been intensively studied in the past two decades because they are likely to be closely related to the formation of the solar wind and heating of the upper solar atmosphere. We present an overview of the characteristics of these upflows, introduce their possible formation mechanisms, and discuss their potential roles in the mass and energy transport in the solar atmosphere. Although past investigations have greatly improved our understanding of these upflows, they have left us with several outstanding questions and unresolved issues that should be addressed in the future. New observations from the Solar Orbiter mission, the Daniel K. Inouye Solar Telescope, and the Parker Solar Probe will likely provide critical information to advance our understanding of the generation, propagation, and energization of these upflows. Title: Spectropolarimetric fluctuations in a sunspot chromosphere Authors: Stangalini, M.; Baker, D.; Valori, G.; Jess, D. B.; Jafarzadeh, S.; Murabito, M.; To, A. S. H.; Brooks, D. H.; Ermolli, I.; Giorgi, F.; MacBride, C. D. Bibcode: 2021RSPTA.37900216S Altcode: 2020arXiv200905302S The instrumental advances made in this new era of 4 m class solar telescopes with unmatched spectropolarimetric accuracy and sensitivity will enable the study of chromospheric magnetic fields and their dynamics with unprecedented detail. In this regard, spectropolarimetric diagnostics can provide invaluable insight into magneto-hydrodynamic (MHD) wave processes. MHD waves and, in particular, Alfvénic fluctuations associated with particular wave modes were recently recognized as important mechanisms not only for the heating of the outer layers of the Sun's atmosphere and the acceleration of the solar wind, but also for the elemental abundance anomaly observed in the corona of the Sun and other Sun-like stars (also known as first ionization potential) effect. Here, we take advantage of state-of-the-art and unique spectropolarimetric Interferometric BIdimensional Spectrometer observations to investigate the relation between intensity and circular polarization (CP) fluctuations in a sunspot chromosphere. Our results show a clear link between the intensity and CP fluctuations in a patch which corresponds to a narrow range of magnetic field inclinations. This suggests the presence of Alfvénic perturbations in the sunspot.

This article is part of the Theo Murphy meeting issue `High-resolution wave dynamics in the lower solar atmosphere'. Title: Alfvénic Perturbations in a Sunspot Chromosphere Linked to Fractionated Plasma in the Corona Authors: Baker, Deborah; Stangalini, Marco; Valori, Gherardo; Brooks, David H.; To, Andy S. H.; van Driel-Gesztelyi, Lidia; Démoulin, Pascal; Stansby, David; Jess, David B.; Jafarzadeh, Shahin Bibcode: 2021ApJ...907...16B Altcode: 2020arXiv201204308B In this study, we investigate the spatial distribution of highly varying plasma composition around one of the largest sunspots of solar cycle 24. Observations of the photosphere, chromosphere, and corona are brought together with magnetic field modeling of the sunspot in order to probe the conditions that regulate the degree of plasma fractionation within loop populations of differing connectivities. We find that, in the coronal magnetic field above the sunspot umbra, the plasma has photospheric composition. Coronal loops rooted in the penumbra contain fractionated plasma, with the highest levels observed in the loops that connect within the active region. Tracing field lines from regions of fractionated plasma in the corona to locations of Alfvénic fluctuations detected in the chromosphere shows that they are magnetically linked. These results indicate a connection between sunspot chromospheric activity and observable changes in coronal plasma composition. Title: Investigating the Chromospheric Footpoints of the Solar Wind Authors: Bryans, Paul; McIntosh, Scott W.; Brooks, David H.; De Pontieu, Bart Bibcode: 2020ApJ...905L..33B Altcode: Coronal holes present the source of the fast solar wind. However, the fast solar wind is not unimodal—there are discrete, but subtle, compositional, velocity, and density structures that differentiate different coronal holes as well as wind streams that originate within one coronal hole. In this Letter we exploit full-disk observational "mosaics" performed by the Interface Region Imaging Spectrograph (IRIS) spacecraft to demonstrate that significant spectral variation exists within the chromospheric plasma of coronal holes. The spectral differences outline the boundaries of some—but not all—coronal holes. In particular, we show that the "peak separation" of the Mg II h line at 2803 Å illustrates changes in what appear to be open magnetic features within a coronal hole. These observations point to a chromospheric source for the inhomogeneities found in the fast solar wind. These chromospheric signatures can provide additional constraints on magnetic field extrapolations close to the source, potentially on spatial scales smaller than from traditional coronal hole detection methods based on intensity thresholding in the corona. This is of increased importance with the advent of Parker Solar Probe and Solar Orbiter and the ability to accurately establish the connectivity between their in situ measurements and remote sensing observations of the solar atmosphere. Title: IRIS Observations of the Low-atmosphere Counterparts of Active Region Outflows Authors: Polito, Vanessa; De Pontieu, Bart; Testa, Paola; Brooks, David H.; Hansteen, Viggo Bibcode: 2020ApJ...903...68P Altcode: 2020arXiv201015945P Active region (AR) outflows have been studied in detail since the launch of Hinode/EIS and are believed to provide a possible source of mass and energy to the slow solar wind. In this work, we investigate the lower atmospheric counterpart of AR outflows using observations from the Interface Region Imaging Spectrograph (IRIS). We find that the IRIS Si IV, C II> and Mg II transition region (TR) and chromospheric lines exhibit different spectral features in the outflows as compared to neighboring regions at the footpoints ("moss") of hot AR loops. The average redshift of Si IV in the outflow region (≍5.5 km s-1) is smaller than typical moss (≍12-13 km s-1) and quiet Sun (≍7.5 km s-1) values, while the C II line is blueshifted (≍-1.1-1.5 km s-1), in contrast to the moss where it is observed to be redshifted by about ≍2.5 km s-1. Further, we observe that the low atmosphere underneath the coronal outflows is highly structured, with the presence of blueshifts in Si IV and positive Mg II k2 asymmetries (which can be interpreted as signatures of chromospheric upflows) which are mostly not observed in the moss. These observations show a clear correlation between the coronal outflows and the chromosphere and TR underneath, which has not been shown before. Our work strongly suggests that these regions are not separate environments and should be treated together, and that current leading theories of AR outflows, such as the interchange reconnection model, need to take into account the dynamics of the low atmosphere. Title: Directly comparing coronal and solar wind elemental fractionation Authors: Stansby, D.; Baker, D.; Brooks, D. H.; Owen, C. J. Bibcode: 2020A&A...640A..28S Altcode: 2020arXiv200500371S Context. As the solar wind propagates through the heliosphere, dynamical processes irreversibly erase the signatures of the near-Sun heating and acceleration processes. The elemental fractionation of the solar wind should not change during transit, however, making it an ideal tracer of these processes.
Aims: We aim to verify directly if the solar wind elemental fractionation is reflective of the coronal source region fractionation, both within and across different solar wind source regions.
Methods: A backmapping scheme was used to predict where solar wind measured by the Advanced Composition Explorer (ACE) originated in the corona. The coronal composition measured by the Hinode Extreme ultraviolet Imaging Spectrometer (EIS) at the source regions was then compared with the in situ solar wind composition.
Results: On hourly timescales, there is no apparent correlation between coronal and solar wind composition. In contrast, the distribution of fractionation values within individual source regions is similar in both the corona and solar wind, but distributions between different sources have a significant overlap.
Conclusions: The matching distributions directly verify that elemental composition is conserved as the plasma travels from the corona to the solar wind, further validating it as a tracer of heating and acceleration processes. The overlap of fractionation values between sources means it is not possible to identify solar wind source regions solely by comparing solar wind and coronal composition measurements, but a comparison can be used to verify consistency with predicted spacecraft-corona connections. Title: Directly Comparing Coronal and Solar Wind Elemental Fractionation Authors: Stansby, D.; Baker, D.; Owen, C.; Brooks, D. Bibcode: 2020SPD....5120801S Altcode: The elemental fractionation of the quasi-collisionless solar wind should not change during transit, making it an ideal tracer of coronal heating and acceleration processes. We aimed to verify directly if the solar wind elemental fractionation is reflective of the coronal source region fractionation, both within and across different solar wind source regions. A backmapping scheme was used to predict where solar wind measured by the Advanced Composition Explorer (ACE) across 15 days originated in the corona. The coronal composition measured by Hinode Extreme ultraviolet Imaging Spectrometer (EIS) at the source regions was then compared with the in-situ solar wind composition. On hourly timescales there was no apparent correlation between coronal and solar wind composition. In contrast, the distribution of fractionation values within individual source regions was similar in both the corona and solar wind, but distributions between different sources had significant overlap. The overlap of fractionation values between sources means it is not possible to identify solar wind source regions solely by comparing solar wind and coronal composition measurements, but a comparison can be used to verify consistency with predicted spacecraft-corona connections. Title: Observation and Modeling of High-temperature Solar Active Region Emission during the High-resolution Coronal Imager Flight of 2018 May 29 Authors: Warren, Harry P.; Reep, Jeffrey W.; Crump, Nicholas A.; Ugarte-Urra, Ignacio; Brooks, David H.; Winebarger, Amy R.; Savage, Sabrina; De Pontieu, Bart; Peter, Hardi; Cirtain, Jonathan W.; Golub, Leon; Kobayashi, Ken; McKenzie, David; Morton, Richard; Rachmeler, Laurel; Testa, Paola; Tiwari, Sanjiv; Walsh, Robert Bibcode: 2020ApJ...896...51W Altcode: Excellent coordinated observations of NOAA active region 12712 were obtained during the flight of the High-resolution Coronal Imager (Hi-C) sounding rocket on 2018 May 29. This region displayed a typical active region core structure with relatively short, high-temperature loops crossing the polarity inversion line and bright "moss" located at the footpoints of these loops. The differential emission measure (DEM) in the active region core is very sharply peaked at about 4 MK. Further, there is little evidence for impulsive heating events in the moss, even at the high spatial resolution and cadence of Hi-C. This suggests that active region core heating is occurring at a high frequency and keeping the loops close to equilibrium. To create a time-dependent simulation of the active region core, we combine nonlinear force-free extrapolations of the measured magnetic field with a heating rate that is dependent on the field strength and loop length and has a Poisson waiting time distribution. We use the approximate solutions to the hydrodynamic loop equations to simulate the full ensemble of active region core loops for a range of heating parameters. In all cases, we find that high-frequency heating provides the best match to the observed DEM. For selected field lines, we solve the full hydrodynamic loop equations, including radiative transfer in the chromosphere, to simulate transition region and chromospheric emission. We find that for heating scenarios consistent with the DEM, classical signatures of energy release, such as transition region brightenings and chromospheric evaporation, are weak, suggesting that they would be difficult to detect. Title: The Drivers of Active Region Outflows into the Slow Solar Wind Authors: Brooks, David H.; Winebarger, Amy R.; Savage, Sabrina; Warren, Harry P.; De Pontieu, Bart; Peter, Hardi; Cirtain, Jonathan W.; Golub, Leon; Kobayashi, Ken; McIntosh, Scott W.; McKenzie, David; Morton, Richard; Rachmeler, Laurel; Testa, Paola; Tiwari, Sanjiv; Walsh, Robert Bibcode: 2020ApJ...894..144B Altcode: 2020arXiv200407461B Plasma outflows from the edges of active regions have been suggested as a possible source of the slow solar wind. Spectroscopic measurements show that these outflows have an enhanced elemental composition, which is a distinct signature of the slow wind. Current spectroscopic observations, however, do not have sufficient spatial resolution to distinguish what structures are being measured or determine the driver of the outflows. The High-resolution Coronal Imager (Hi-C) flew on a sounding rocket in 2018 May and observed areas of active region outflow at the highest spatial resolution ever achieved (250 km). Here we use the Hi-C data to disentangle the outflow composition signatures observed with the Hinode satellite during the flight. We show that there are two components to the outflow emission: a substantial contribution from expanded plasma that appears to have been expelled from closed loops in the active region core and a second contribution from dynamic activity in active region plage, with a composition signature that reflects solar photospheric abundances. The two competing drivers of the outflows may explain the variable composition of the slow solar wind. Title: Can Subphotospheric Magnetic Reconnection Change the Elemental Composition in the Solar Corona? Authors: Baker, Deborah; van Driel-Gesztelyi, Lidia; Brooks, David H.; Démoulin, Pascal; Valori, Gherardo; Long, David M.; Laming, J. Martin; To, Andy S. H.; James, Alexander W. Bibcode: 2020ApJ...894...35B Altcode: 2020arXiv200303325B Within the coronae of stars, abundances of those elements with low first ionization potential (FIP) often differ from their photospheric values. The coronae of the Sun and solar-type stars mostly show enhancements of low-FIP elements (the FIP effect) while more active stars such as M dwarfs have coronae generally characterized by the inverse-FIP effect (I-FIP). Here we observe patches of I-FIP effect solar plasma in AR 12673, a highly complex βγδ active region. We argue that the umbrae of coalescing sunspots, and more specifically strong light bridges within the umbrae, are preferential locations for observing I-FIP effect plasma. Furthermore, the magnetic complexity of the active region and major episodes of fast flux emergence also lead to repetitive and intense flares. The induced evaporation of the chromospheric plasma in flare ribbons crossing umbrae enables the observation of four localized patches of I-FIP effect plasma in the corona of AR 12673. These observations can be interpreted in the context of the ponderomotive force fractionation model which predicts that plasma with I-FIP effect composition is created by the refraction of waves coming from below the chromosphere. We propose that the waves generating the I-FIP effect plasma in solar active regions are generated by subphotospheric reconnection of coalescing flux systems. Although we only glimpse signatures of I-FIP effect fractionation produced by this interaction in patches on the Sun, on highly active M stars it may be the dominant process. Title: A Solar Magnetic-fan Flaring Arch Heated by Nonthermal Particles and Hot Plasma from an X-Ray Jet Eruption Authors: Lee, Kyoung-Sun; Hara, Hirohisa; Watanabe, Kyoko; Joshi, Anand D.; Brooks, David H.; Imada, Shinsuke; Prasad, Avijeet; Dang, Phillip; Shimizu, Toshifumi; Savage, Sabrina L.; Moore, Ronald; Panesar, Navdeep K.; Reep, Jeffrey W. Bibcode: 2020ApJ...895...42L Altcode: 2020arXiv200509875L We have investigated an M1.3 limb flare, which develops as a magnetic loop/arch that fans out from an X-ray jet. Using Hinode/EIS, we found that the temperature increases with height to a value of over 107 K at the loop top during the flare. The measured Doppler velocity (redshifts of 100-500 km s-1) and the nonthermal velocity (≥100 km s-1) from Fe XXIV also increase with loop height. The electron density increases from 0.3 × 109 cm-3 early in the flare rise to 1.3 × 109 cm-3 after the flare peak. The 3D structure of the loop derived with Solar TErrestrial RElations Observatory/EUV Imager indicates that the strong redshift in the loop-top region is due to upflowing plasma originating from the jet. Both hard X-ray and soft X-ray emission from the Reuven Ramaty High Energy Solar Spectroscopic Imager were only seen as footpoint brightenings during the impulsive phase of the flare, then, soft X-ray emission moved to the loop top in the decay phase. Based on the temperature and density measurements and theoretical cooling models, the temperature evolution of the flare arch is consistent with impulsive heating during the jet eruption followed by conductive cooling via evaporation and minor prolonged heating in the top of the fan loop. Investigating the magnetic field topology and squashing factor map from Solar Dynamics Observatory/HMI, we conclude that the observed magnetic-fan flaring arch is mostly heated from low atmospheric reconnection accompanying the jet ejection, instead of from reconnection above the arch as expected in the standard flare model. Title: Is the High-Resolution Coronal Imager Resolving Coronal Strands? Results from AR 12712 Authors: Williams, Thomas; Walsh, Robert W.; Winebarger, Amy R.; Brooks, David H.; Cirtain, Jonathan W.; De Pontieu, Bart; Golub, Leon; Kobayashi, Ken; McKenzie, David E.; Morton, Richard J.; Peter, Hardi; Rachmeler, Laurel A.; Savage, Sabrina L.; Testa, Paola; Tiwari, Sanjiv K.; Warren, Harry P.; Watkinson, Benjamin J. Bibcode: 2020ApJ...892..134W Altcode: 2020arXiv200111254W Following the success of the first mission, the High-Resolution Coronal Imager (Hi-C) was launched for a third time (Hi-C 2.1) on 2018 May 29 from the White Sands Missile Range, NM, USA. On this occasion, 329 s of 17.2 nm data of target active region AR 12712 were captured with a cadence of ≈4 s, and a plate scale of 0.129 arcsec pixel-1. Using data captured by Hi-C 2.1 and co-aligned observations from SDO/AIA 17.1 nm, we investigate the widths of 49 coronal strands. We search for evidence of substructure within the strands that is not detected by AIA, and further consider whether these strands are fully resolved by Hi-C 2.1. With the aid of multi-scale Gaussian normalization, strands from a region of low emission that can only be visualized against the contrast of the darker, underlying moss are studied. A comparison is made between these low-emission strands and those from regions of higher emission within the target active region. It is found that Hi-C 2.1 can resolve individual strands as small as ≈202 km, though the more typical strand widths seen are ≈513 km. For coronal strands within the region of low emission, the most likely width is significantly narrower than the high-emission strands at ≈388 km. This places the low-emission coronal strands beneath the resolving capabilities of SDO/AIA, highlighting the need for a permanent solar observatory with the resolving power of Hi-C. Title: Hi-C 2.1 Observations of Jetlet-like Events at Edges of Solar Magnetic Network Lanes Authors: Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.; Winebarger, Amy R.; Tiwari, Sanjiv K.; Savage, Sabrina L.; Golub, Leon E.; Rachmeler, Laurel A.; Kobayashi, Ken; Brooks, David H.; Cirtain, Jonathan W.; De Pontieu, Bart; McKenzie, David E.; Morton, Richard J.; Peter, Hardi; Testa, Paola; Walsh, Robert W.; Warren, Harry P. Bibcode: 2019ApJ...887L...8P Altcode: 2019arXiv191102331P We present high-resolution, high-cadence observations of six, fine-scale, on-disk jet-like events observed by the High-resolution Coronal Imager 2.1 (Hi-C 2.1) during its sounding-rocket flight. We combine the Hi-C 2.1 images with images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and the Interface Region Imaging Spectrograph (IRIS), and investigate each event’s magnetic setting with co-aligned line-of-sight magnetograms from the SDO/Helioseismic and Magnetic Imager (HMI). We find that (i) all six events are jetlet-like (having apparent properties of jetlets), (ii) all six are rooted at edges of magnetic network lanes, (iii) four of the jetlet-like events stem from sites of flux cancelation between majority-polarity network flux and merging minority-polarity flux, and (iv) four of the jetlet-like events show brightenings at their bases reminiscent of the base brightenings in coronal jets. The average spire length of the six jetlet-like events (9000 ± 3000 km) is three times shorter than that for IRIS jetlets (27,000 ± 8000 km). While not ruling out other generation mechanisms, the observations suggest that at least four of these events may be miniature versions of both larger-scale coronal jets that are driven by minifilament eruptions and still-larger-scale solar eruptions that are driven by filament eruptions. Therefore, we propose that our Hi-C events are driven by the eruption of a tiny sheared-field flux rope, and that the flux rope field is built and triggered to erupt by flux cancelation. Title: Fine-scale Explosive Energy Release at Sites of Prospective Magnetic Flux Cancellation in the Core of the Solar Active Region Observed by Hi-C 2.1, IRIS, and SDO Authors: Tiwari, Sanjiv K.; Panesar, Navdeep K.; Moore, Ronald L.; De Pontieu, Bart; Winebarger, Amy R.; Golub, Leon; Savage, Sabrina L.; Rachmeler, Laurel A.; Kobayashi, Ken; Testa, Paola; Warren, Harry P.; Brooks, David H.; Cirtain, Jonathan W.; McKenzie, David E.; Morton, Richard J.; Peter, Hardi; Walsh, Robert W. Bibcode: 2019ApJ...887...56T Altcode: 2019arXiv191101424T The second Hi-C flight (Hi-C 2.1) provided unprecedentedly high spatial and temporal resolution (∼250 km, 4.4 s) coronal EUV images of Fe IX/X emission at 172 Å of AR 12712 on 2018 May 29, during 18:56:21-19:01:56 UT. Three morphologically different types (I: dot-like; II: loop-like; III: surge/jet-like) of fine-scale sudden-brightening events (tiny microflares) are seen within and at the ends of an arch filament system in the core of the AR. Although type Is (not reported before) resemble IRIS bombs (in size, and brightness with respect to surroundings), our dot-like events are apparently much hotter and shorter in span (70 s). We complement the 5 minute duration Hi-C 2.1 data with SDO/HMI magnetograms, SDO/AIA EUV images, and IRIS UV spectra and slit-jaw images to examine, at the sites of these events, brightenings and flows in the transition region and corona and evolution of magnetic flux in the photosphere. Most, if not all, of the events are seated at sites of opposite-polarity magnetic flux convergence (sometimes driven by adjacent flux emergence), implying likely flux cancellation at the microflare’s polarity inversion line. In the IRIS spectra and images, we find confirming evidence of field-aligned outflow from brightenings at the ends of loops of the arch filament system. In types I and II the explosion is confined, while in type III the explosion is ejective and drives jet-like outflow. The light curves from Hi-C, AIA, and IRIS peak nearly simultaneously for many of these events, and none of the events display a systematic cooling sequence as seen in typical coronal flares, suggesting that these tiny brightening events have chromospheric/transition region origin. Title: The High-Resolution Coronal Imager, Flight 2.1 Authors: Rachmeler, Laurel A.; Winebarger, Amy R.; Savage, Sabrina L.; Golub, Leon; Kobayashi, Ken; Vigil, Genevieve D.; Brooks, David H.; Cirtain, Jonathan W.; De Pontieu, Bart; McKenzie, David E.; Morton, Richard J.; Peter, Hardi; Testa, Paola; Tiwari, Sanjiv K.; Walsh, Robert W.; Warren, Harry P.; Alexander, Caroline; Ansell, Darren; Beabout, Brent L.; Beabout, Dyana L.; Bethge, Christian W.; Champey, Patrick R.; Cheimets, Peter N.; Cooper, Mark A.; Creel, Helen K.; Gates, Richard; Gomez, Carlos; Guillory, Anthony; Haight, Harlan; Hogue, William D.; Holloway, Todd; Hyde, David W.; Kenyon, Richard; Marshall, Joseph N.; McCracken, Jeff E.; McCracken, Kenneth; Mitchell, Karen O.; Ordway, Mark; Owen, Tim; Ranganathan, Jagan; Robertson, Bryan A.; Payne, M. Janie; Podgorski, William; Pryor, Jonathan; Samra, Jenna; Sloan, Mark D.; Soohoo, Howard A.; Steele, D. Brandon; Thompson, Furman V.; Thornton, Gary S.; Watkinson, Benjamin; Windt, David Bibcode: 2019SoPh..294..174R Altcode: 2019arXiv190905942R The third flight of the High-Resolution Coronal Imager (Hi-C 2.1) occurred on May 29, 2018; the Sounding Rocket was launched from White Sands Missile Range in New Mexico. The instrument has been modified from its original configuration (Hi-C 1) to observe the solar corona in a passband that peaks near 172 Å, and uses a new, custom-built low-noise camera. The instrument targeted Active Region 12712, and captured 78 images at a cadence of 4.4 s (18:56:22 - 19:01:57 UT; 5 min and 35 s observing time). The image spatial resolution varies due to quasi-periodic motion blur from the rocket; sharp images contain resolved features of at least 0.47 arcsec. There are coordinated observations from multiple ground- and space-based telescopes providing an unprecedented opportunity to observe the mass and energy coupling between the chromosphere and the corona. Details of the instrument and the data set are presented in this paper. Title: Active Region Modulation of Coronal Hole Solar Wind Authors: Macneil, Allan R.; Owen, Christopher J.; Baker, Deborah; Brooks, David H.; Harra, Louise K.; Long, David M.; Wicks, Robert T. Bibcode: 2019ApJ...887..146M Altcode: Active regions (ARs) are a candidate source of the slow solar wind (SW), the origins of which are a topic of ongoing research. We present a case study that examines the processes by which SW is modulated in the presence of an AR in the vicinity of the SW source. We compare properties of SW associated with a coronal hole (CH)-quiet Sun boundary to SW associated with the same CH but one Carrington rotation later, when this region bordered the newly emerged NOAA AR 12532. Differences found in a range of in situ parameters are compared between these rotations in the context of source region mapping and remote sensing observations. Marked changes exist in the structure and composition of the SW, which we attribute to the influence of the AR on SW production from the CH boundary. These unique observations suggest that the features that emerge in the AR-associated wind are consistent with an increased occurrence of interchange reconnection during SW production, compared with the initial quiet Sun case. Title: Achievements of Hinode in the first eleven years Authors: Hinode Review Team; Al-Janabi, Khalid; Antolin, Patrick; Baker, Deborah; Bellot Rubio, Luis R.; Bradley, Louisa; Brooks, David H.; Centeno, Rebecca; Culhane, J. Leonard; Del Zanna, Giulio; Doschek, George A.; Fletcher, Lyndsay; Hara, Hirohisa; Harra, Louise K.; Hillier, Andrew S.; Imada, Shinsuke; Klimchuk, James A.; Mariska, John T.; Pereira, Tiago M. D.; Reeves, Katharine K.; Sakao, Taro; Sakurai, Takashi; Shimizu, Toshifumi; Shimojo, Masumi; Shiota, Daikou; Solanki, Sami K.; Sterling, Alphonse C.; Su, Yingna; Suematsu, Yoshinori; Tarbell, Theodore D.; Tiwari, Sanjiv K.; Toriumi, Shin; Ugarte-Urra, Ignacio; Warren, Harry P.; Watanabe, Tetsuya; Young, Peter R. Bibcode: 2019PASJ...71R...1H Altcode: Hinode is Japan's third solar mission following Hinotori (1981-1982) and Yohkoh (1991-2001): it was launched on 2006 September 22 and is in operation currently. Hinode carries three instruments: the Solar Optical Telescope, the X-Ray Telescope, and the EUV Imaging Spectrometer. These instruments were built under international collaboration with the National Aeronautics and Space Administration and the UK Science and Technology Facilities Council, and its operation has been contributed to by the European Space Agency and the Norwegian Space Center. After describing the satellite operations and giving a performance evaluation of the three instruments, reviews are presented on major scientific discoveries by Hinode in the first eleven years (one solar cycle long) of its operation. This review article concludes with future prospects for solar physics research based on the achievements of Hinode. Title: Structure and dynamics of the hot flaring loop-top source observed by Hinode, SDO, RHESSI, and STEREO Authors: Lee, Kyoung-Sun; Hara, Hirohisa; Watanabe, Kyoko; Joshi, Anand D.; Imada, Shinsuke; Brooks, David H.; Dang, Phillip; Shimizu, Toshifumi; Savage, Sabrina Bibcode: 2019AAS...23421605L Altcode: We have investigated an M1.3 flare on 2014 January 13 around 21:48 UT observed at the west limb using the Hinode, SDO, RHESSI, and STEREO. Especially, the Hinode/EIS scanned the flaring loop covering the loop-top region over the limb, which is a good target to investigate the dynamics of the flaring loop with their height. Using the multi-wavelength observations from the Hinode/EIS and SDO/AIA, we found a very hot emission above the loop-top observed in Fe XXIV and 131Å channel. Measuring the intensity, Doppler velocity and line width for the flaring loop, we found that hot emission observed at the cusp-like shape of the loop-top region which shows strong redshift about 500 km s-1 in Doppler velocity and strong enhancement of the non-thermal velocity (line width enhancement) larger than 100 km s-1. Combining with the STEREO observation, we have examined the 3D structure with loop tilt angle and have investigated the velocity distribution of the loop-top region. With the loop tilt angle, we could identify the strong redshift at the loop-top region may indicate an up-flow along the loop-top region. From RHESSI hard X-ray (HXR), and soft X-ray (SXR) emission, we found that the footpoint brightening region at the beginning of the flare has a both HXR (25-50 keV) and SXR (12-25 keV) emission in which imply that the region has non-thermal emission or accelerated particles. Then, within 10 minutes the soft X-ray (SXR) emission observed near the cusp shape region at loop top. The temporal variation of the HXR and SXR emissions and the Doppler velocity variation of the hot plasma component at the loop-top imply that the strong flow in a hot component near loop-top could be the evaporation flows which detected at the corona along the tilted loop. Moreover, The temporal evolution of the temperature observed by SDO/AIA and Hinode/EIS also shows the cooling process of the flare plasma which is consistent with the impulsively heated flare model. Title: Comprehensive Determination of the Hinode/EIS Roll Angle Authors: Pelouze, Gabriel; Auchère, Frédéric; Bocchialini, Karine; Harra, Louise; Baker, Deborah; Warren, Harry P.; Brooks, David H.; Mariska, John T. Bibcode: 2019SoPh..294...59P Altcode: 2019arXiv190311923P We present a new coalignment method for the EUV Imaging Spectrometer (EIS) on board the Hinode spacecraft. In addition to the pointing offset and spacecraft jitter, this method determines the roll angle of the instrument, which has never been systematically measured, and which is therefore usually not corrected. The optimal pointing for EIS is computed by maximizing the cross-correlations of the Fe XII 195.119 Å line with images from the 193 Å band of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). By coaligning 3336 rasters with high signal-to-noise ratio, we estimate the rotation angle between EIS and AIA and explore the distribution of its values. We report an average value of (−0.387±0.007 ) ∘. We also provide a software implementation of this method that can be used to coalign any EIS raster. Title: First Measurement of the Hubble Constant from a Dark Standard Siren using the Dark Energy Survey Galaxies and the LIGO/Virgo Binary-Black-hole Merger GW170814 Authors: Soares-Santos, M.; Palmese, A.; Hartley, W.; Annis, J.; Garcia-Bellido, J.; Lahav, O.; Doctor, Z.; Fishbach, M.; Holz, D. E.; Lin, H.; Pereira, M. E. S.; Garcia, A.; Herner, K.; Kessler, R.; Peiris, H. V.; Sako, M.; Allam, S.; Brout, D.; Carnero Rosell, A.; Chen, H. Y.; Conselice, C.; deRose, J.; deVicente, J.; Diehl, H. T.; Gill, M. S. S.; Gschwend, J.; Sevilla-Noarbe, I.; Tucker, D. L.; Wechsler, R.; Berger, E.; Cowperthwaite, P. S.; Metzger, B. D.; Williams, P. K. G.; Abbott, T. M. C.; Abdalla, F. B.; Avila, S.; Bechtol, K.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Davis, C.; Desai, S.; Doel, P.; Drlica-Wagner, A.; Eifler, T. F.; Evrard, A. E.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gaztanaga, E.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Hollowood, D. L.; Hoyle, B.; James, D. J.; Jeltema, T.; Kuehn, K.; Kuropatkin, N.; Li, T. S.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Menanteau, F.; Miquel, R.; Neilsen, E.; Ogando, R. L. C.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Serrano, S.; Smith, M.; Smith, R. C.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, R. C.; Walker, A. R.; Wester, W.; Zuntz, J.; DES Collaboration; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abraham, S.; Acernese, F.; Ackley, K.; Adams, C.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, G.; Allocca, A.; Aloy, M. A.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Angelova, S. V.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arène, M.; Ascenzi, S.; Ashton, G.; Aston, S. M.; Astone, P.; Aubin, F.; Aufmuth, P.; AultONeal, K.; Austin, C.; Avendano, V.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Badaracco, F.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barkett, K.; Barnum, S.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Bawaj, M.; Bayley, J. C.; Bazzan, M.; Bécsy, B.; Bejger, M.; Bell, A. S.; Beniwal, D.; Bergmann, G.; Bernuzzi, S.; Bero, J. J.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhandare, R.; Bidler, J.; Bilenko, I. A.; Bilgili, S. A.; Billingsley, G.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Biscoveanu, S.; Bisht, A.; Bitossi, M.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bode, N.; Boer, M.; Boetzel, Y.; Bogaert, G.; Bondu, F.; Bonilla, E.; Bonnand, R.; Booker, P.; Boom, B. A.; Booth, C. D.; Bork, R.; Boschi, V.; Bose, S.; Bossie, K.; Bossilkov, V.; Bosveld, J.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Bramley, A.; Branchesi, M.; Brau, J. E.; Briant, T.; Briggs, J. H.; Brighenti, F.; Brillet, A.; Brinkmann, M.; Brockill, P.; Brooks, A. F.; Brown, D. D.; Brunett, S.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T. A.; Calloni, E.; Camp, J. B.; Campbell, W. A.; Cannon, K. C.; Cao, H.; Cao, J.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Carullo, G.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalieri, R.; Cella, G.; Cerdá-Durán, P.; Cerretani, G.; Cesarini, E.; Chaibi, O.; Chakravarti, K.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chase, E. A.; Chassande-Mottin, E.; Chatterjee, D.; Chaturvedi, M.; Chatziioannou, K.; Cheeseboro, B. D.; Chen, X.; Chen, Y.; Cheng, H. -P.; Cheong, C. K.; Chia, H. Y.; Chincarini, A.; Chiummo, A.; Cho, G.; Cho, H. S.; Cho, M.; Christensen, N.; Chu, Q.; Chua, S.; Chung, K. W.; Chung, S.; Ciani, G.; Ciobanu, A. A.; Ciolfi, R.; Cipriano, F.; Cirone, A.; Clara, F.; Clark, J. A.; Clearwater, P.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P. -F.; Colgan, R.; Colleoni, M.; Collette, C. G.; Collins, C.; Cominsky, L. R.; Constancio, M., Jr.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Cordero-Carrión, I.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Cotesta, R.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J. -P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Croquette, M.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Dálya, G.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; Da Silva Costa, C. F.; Datrier, L. E. H.; Dattilo, V.; Dave, I.; Davis, D.; Daw, E. J.; DeBra, D.; Deenadayalan, M.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; DeMarchi, L. M.; Demos, N.; Dent, T.; De Pietri, R.; Derby, J.; De Rosa, R.; De Rossi, C.; DeSalvo, R.; de Varona, O.; Dhurandhar, S.; Díaz, M. C.; Dietrich, T.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Ding, B.; Di Pace, S.; Di Palma, I.; Di Renzo, F.; Dmitriev, A.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Downes, T. P.; Drago, M.; Driggers, J. C.; Du, Z.; Dupej, P.; Dwyer, S. E.; Easter, P. J.; Edo, T. B.; Edwards, M. C.; Effler, A.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenmann, M.; Eisenstein, R. A.; Estelles, H.; Estevez, D.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fazio, M.; Fee, C.; Feicht, J.; Fejer, M. M.; Feng, F.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferreira, T. A.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Fishner, J. M.; Fitz-Axen, M.; Flaminio, R.; Fletcher, M.; Flynn, E.; Fong, H.; Font, J. A.; Forsyth, P. W. F.; Fournier, J. -D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garcia, A.; García-Quirós, C.; Garufi, F.; Gateley, B.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giacomazzo, B.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Giordano, G.; Glover, L.; Godwin, P.; Goetz, E.; Goetz, R.; Goncharov, B.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Grassia, P.; Gray, C.; Gray, R.; Greco, G.; Green, A. C.; Green, R.; Gretarsson, E. M.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Gulati, H. K.; Guo, Y.; Gupta, A.; Gupta, M. K.; Gustafson, E. K.; Gustafson, R.; Haegel, L.; Halim, O.; Hall, B. R.; Hall, E. D.; Hamilton, E. Z.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Haris, K.; Harms, J.; Harry, G. M.; Harry, I. W.; Haster, C. -J.; Haughian, K.; Hayes, F. J.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Hernandez Vivanco, Francisco; Heurs, M.; Hild, S.; Hinderer, T.; Hoak, D.; Hochheim, S.; Hofman, D.; Holgado, A. M.; Holland, N. A.; Holt, K.; Hopkins, P.; Horst, C.; Hough, J.; Howell, E. J.; Hoy, C. G.; Hreibi, A.; Huerta, E. A.; Hughey, B.; Hulko, M.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Idzkowski, B.; Iess, A.; Ingram, C.; Inta, R.; Intini, G.; Irwin, B.; Isa, H. N.; Isac, J. -M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jadhav, S. J.; Jani, K.; Janthalur, N. N.; Jaranowski, P.; Jenkins, A. C.; Jiang, J.; Johnson, D. S.; Jones, A. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kamai, B.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kashyap, R.; Kasprzack, M.; Katsanevas, S.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Keerthana, N. V.; Kéfélian, F.; Keitel, D.; Kennedy, R.; Key, J. S.; Khalili, F. Y.; Khan, H.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Khursheed, M.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, K.; Kim, W.; Kim, W. S.; Kim, Y. -M.; Kimball, C.; King, E. J.; King, P. J.; Kinley-Hanlon, M.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klika, J. H.; Klimenko, S.; Knowles, T. D.; Koch, P.; Koehlenbeck, S. M.; Koekoek, G.; Koley, S.; Kondrashov, V.; Kontos, A.; Koper, N.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnendu, N.; Królak, A.; Kuehn, G.; Kumar, A.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Lam, T. L.; Landry, M.; Lane, B. B.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lecoeuche, Y. K.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, J.; Lee, K.; Lehmann, J.; Lenon, A.; Letendre, N.; Levin, Y.; Li, J.; Li, K. J. L.; Li, T. G. F.; Li, X.; Lin, F.; Linde, F.; Linker, S. D.; Littenberg, T. B.; Liu, J.; Liu, X.; Lo, R. K. L.; Lockerbie, N. A.; London, L. T.; Longo, A.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Lower, M. E.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macas, R.; Macfoy, S.; MacInnis, M.; Macleod, D. M.; Macquet, A.; Magaña Hernandez, I.; Magaña-Sandoval, F.; Magaña Zertuche, L.; Magee, R. M.; Majorana, E.; Maksimovic, I.; Malik, A.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Markowitz, A.; Maros, E.; Marquina, A.; Marsat, S.; Martelli, F.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Mason, K.; Massera, E.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCann, J. J.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIver, J.; McManus, D. J.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Mehta, A. K.; Meidam, J.; Melatos, A.; Mendell, G.; Mercer, R. A.; Mereni, L.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, A.; Millhouse, M.; Mills, J. C.; Milovich-Goff, M. C.; Minazzoli, O.; Minenkov, Y.; Mishkin, A.; Mishra, C.; Mistry, T.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Mo, G.; Moffa, D.; Mogushi, K.; Mohapatra, S. R. P.; Montani, M.; Moore, C. J.; Moraru, D.; Moreno, G.; Morisaki, S.; Mours, B.; Mow-Lowry, C. M.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muñiz, E. A.; Muratore, M.; Murray, P. G.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Neilson, J.; Nelemans, G.; Nelson, T. J. N.; Nery, M.; Neunzert, A.; Ng, K. Y.; Ng, S.; Nguyen, P.; Nichols, D.; Nissanke, S.; Nocera, F.; North, C.; Nuttall, L. K.; Obergaulinger, M.; Oberling, J.; O'Brien, B. D.; O'Dea, G. D.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Ohta, H.; Okada, M. A.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ormiston, R. G.; Ortega, L. F.; O'Shaughnessy, R.; Ossokine, S.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Pagano, G.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, Huang-Wei; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Parida, A.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patil, M.; Patricelli, B.; Pearlstone, B. L.; Pedersen, C.; Pedraza, M.; Pedurand, R.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Pfeiffer, H. P.; Phelps, M.; Phukon, K. S.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pillant, G.; Pinard, L.; Pirello, M.; Pitkin, M.; Poggiani, R.; Pong, D. Y. T.; Ponrathnam, S.; Popolizio, P.; Porter, E. K.; Powell, J.; Prajapati, A. K.; Prasad, J.; Prasai, K.; Prasanna, R.; Pratten, G.; Prestegard, T.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Quetschke, V.; Quinonez, P. J.; Quintero, E. A.; Quitzow-James, R.; Radkins, H.; Radulescu, N.; Raffai, P.; Raja, S.; Rajan, C.; Rajbhandari, B.; Rakhmanov, M.; Ramirez, K. E.; Ramos-Buades, A.; Rana, Javed; Rao, K.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Ren, W.; Ricci, F.; Richardson, C. J.; Richardson, J. W.; Ricker, P. M.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romanelli, M.; Romano, R.; Romel, C. L.; Romie, J. H.; Rose, K.; Rosińska, D.; Rosofsky, S. G.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Rutins, G.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sanchez, L. E.; Sanchis-Gual, N.; Sandberg, V.; Sanders, J. R.; Santiago, K. A.; Sarin, N.; Sassolas, B.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Schale, P.; Scheel, M.; Scheuer, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sennett, N.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T.; Shahriar, M. S.; Shaner, M. B.; Shao, L.; Sharma, P.; Shawhan, P.; Shen, H.; Shink, R.; Shoemaker, D. H.; Shoemaker, D. M.; ShyamSundar, S.; Siellez, K.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, L. P.; Singh, N.; Singhal, A.; Sintes, A. M.; Sitmukhambetov, S.; Skliris, V.; Slagmolen, B. J. J.; Slaven-Blair, T. J.; Smith, J. R.; Smith, R. J. E.; Somala, S.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Sowell, E.; Spencer, A. P.; Srivastava, A. K.; Srivastava, V.; Staats, K.; Stachie, C.; Standke, M.; Steer, D. A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stevenson, S. P.; Stocks, D.; Stone, R.; Stops, D. J.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Strunk, A.; Sturani, R.; Stuver, A. L.; Sudhir, V.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Sur, A.; Suresh, J.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Tait, S. C.; Talbot, C.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Tasson, J. D.; Taylor, R.; Thies, F.; Thomas, M.; Thomas, P.; Thondapu, S. R.; Thorne, K. A.; Thrane, E.; Tiwari, Shubhanshu; Tiwari, Srishti; Tiwari, V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torres-Forné, A.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Tringali, M. C.; Trovato, A.; Trozzo, L.; Trudeau, R.; Tsang, K. W.; Tse, M.; Tso, R.; Tsukada, L.; Tsuna, D.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van Heijningen, J. V.; van der Schaaf, L.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vine, D. J.; Vinet, J. -Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, W. H.; Wang, Y. F.; Ward, R. L.; Warden, Z. A.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L. -W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wellmann, F.; Wen, L.; Wessel, E. K.; Weßels, P.; Westhouse, J. W.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Whittle, C.; Wilken, D. M.; Williams, D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wysocki, D. M.; Xiao, L.; Yamamoto, H.; Yancey, C. C.; Yang, L.; Yap, M. J.; Yazback, M.; Yeeles, D. W.; Yu, Hang; Yu, Haocun; Yuen, S. H. R.; Yvert, M.; Zadrożny, A. K.; Zanolin, M.; Zelenova, T.; Zendri, J. -P.; Zevin, M.; Zhang, J.; Zhang, L.; Zhang, T.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zimmerman, A.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration Bibcode: 2019ApJ...876L...7S Altcode: 2019arXiv190101540T We present a multi-messenger measurement of the Hubble constant H 0 using the binary-black-hole merger GW170814 as a standard siren, combined with a photometric redshift catalog from the Dark Energy Survey (DES). The luminosity distance is obtained from the gravitational wave signal detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration (LVC) on 2017 August 14, and the redshift information is provided by the DES Year 3 data. Black hole mergers such as GW170814 are expected to lack bright electromagnetic emission to uniquely identify their host galaxies and build an object-by-object Hubble diagram. However, they are suitable for a statistical measurement, provided that a galaxy catalog of adequate depth and redshift completion is available. Here we present the first Hubble parameter measurement using a black hole merger. Our analysis results in {H}0={75}-32+40 {km} {{{s}}}-1 {Mpc}}-1, which is consistent with both SN Ia and cosmic microwave background measurements of the Hubble constant. The quoted 68% credible region comprises 60% of the uniform prior range [20, 140] km s-1 Mpc-1, and it depends on the assumed prior range. If we take a broader prior of [10, 220] km s-1 Mpc-1, we find {H}0={78}-24+96 {km} {{{s}}}-1 {Mpc}}-1 (57% of the prior range). Although a weak constraint on the Hubble constant from a single event is expected using the dark siren method, a multifold increase in the LVC event rate is anticipated in the coming years and combinations of many sirens will lead to improved constraints on H 0. Title: Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare Authors: Baker, Deborah; van Driel-Gesztelyi, Lidia; Brooks, David H.; Valori, Gherardo; James, Alexander W.; Laming, J. Martin; Long, David M.; Démoulin, Pascal; Green, Lucie M.; Matthews, Sarah A.; Oláh, Katalin; Kővári, Zsolt Bibcode: 2019ApJ...875...35B Altcode: 2019arXiv190206948B Understanding elemental abundance variations in the solar corona provides an insight into how matter and energy flow from the chromosphere into the heliosphere. Observed variations depend on the first ionization potential (FIP) of the main elements of the Sun’s atmosphere. High-FIP elements (>10 eV) maintain photospheric abundances in the corona, whereas low-FIP elements have enhanced abundances. Conversely, inverse FIP (IFIP) refers to the enhancement of high-FIP or depletion of low-FIP elements. We use spatially resolved spectroscopic observations, specifically the Ar XIV/Ca XIV intensity ratio, from Hinode’s Extreme-ultraviolet Imaging Spectrometer to investigate the distribution and evolution of plasma composition within two confined flares in a newly emerging, highly sheared active region. During the decay phase of the first flare, patches above the flare ribbons evolve from the FIP to the IFIP effect, while the flaring loop tops show a stronger FIP effect. The patch and loop compositions then evolve toward the preflare basal state. We propose an explanation of how flaring in strands of highly sheared emerging magnetic fields can lead to flare-modulated IFIP plasma composition over coalescing umbrae which are crossed by flare ribbons. Subsurface reconnection between the coalescing umbrae leads to the depletion of low-FIP elements as a result of an increased wave flux from below. This material is evaporated when the flare ribbons cross the umbrae. Our results are consistent with the ponderomotive fractionation model for the creation of IFIP-biased plasma. Title: Properties of the Diffuse Emission around Warm Loops in Solar Active Regions Authors: Brooks, David H. Bibcode: 2019ApJ...873...26B Altcode: 2019arXiv190107741B Coronal loops in active regions are the subjects of intensive investigation, but the important diffuse unresolved emission in which they are embedded has received relatively little attention. Here I measure the densities and emission measure (EM) distributions of a sample of background-foreground regions surrounding warm (2 MK) coronal loops, and introduce two new aspects to the analysis. First, I infer the EM distributions only from temperatures that contribute to the same background emission. Second, I measure the background emission co-spatially with the loops so that the results are truly representative of the immediate loop environment. The second aspect also allows me to take advantage of the presence of embedded loops to infer information about the (unresolvable) magnetic field in the background. I find that about half of the regions in my sample have narrow but not quite isothermal EM distributions with a peak temperature of 1.4-2 MK. The other half have broad EM distributions (Gaussian width >3 × 105 K), and the width of the EM appears to be correlated with peak temperature. Densities in the diffuse background are log (n/cm-3) = 8.5-9.0. Significantly, these densities and temperatures imply that the co-spatial background is broadly compatible with static equilibrium theory (RTV scaling laws) provided that the unresolved field length is comparable to the embedded loop length. For this agreement to break down, the field length in most cases would have to be substantially longer than the loop length, a factor of 2-3 on average, which for the sample in this work approaches the dimensions of only the largest active regions. Title: A Diagnostic of Coronal Elemental Behavior during the Inverse FIP Effect in Solar Flares Authors: Brooks, David H. Bibcode: 2018ApJ...863..140B Altcode: 2018arXiv180704408B The solar corona shows a distinctive pattern of elemental abundances that is different from that of the photosphere. Low first ionization potential (FIP) elements are enhanced by factors of several. A similar effect is seen in the atmospheres of some solar-like stars, while late-type M stars show an inverse FIP effect. This inverse effect was recently detected on the Sun during solar flares, potentially allowing a very detailed look at the spatial and temporal behavior that is not possible from stellar observations. A key question for interpreting these measurements is whether both effects act solely on low-FIP elements (a true inverse effect predicted by some models), or whether the inverse FIP effect arises because high-FIP elements are enhanced. Here we develop a new diagnostic that can discriminate between the two scenarios, based on modeling of the radiated power loss, and apply the models to a numerical hydrodynamic simulation of coronal loop cooling. We show that when low-/high-FIP elements are depleted/enhanced, there is a significant difference in the cooling lifetime of loops that is greatest at lower temperatures. We apply this diagnostic to a post X1.8 flare loop arcade and inverse FIP region, and show that for this event, low-FIP elements are depleted. We discuss the results in the context of stellar observations, and models of the FIP and inverse FIP effect. We also provide the radiated power-loss functions for the two inverse FIP effect scenarios in machine readable form to facilitate further modeling. Title: Solar Cycle Observations of the Neon Abundance in the Sun-as-a-star Authors: Brooks, David H.; Baker, Deborah; van Driel-Gesztelyi, Lidia; Warren, Harry P. Bibcode: 2018ApJ...861...42B Altcode: 2018arXiv180507032B Properties of the Sun’s interior can be determined accurately from helioseismological measurements of solar oscillations. These measurements, however, are in conflict with photospheric elemental abundances derived using 3D hydrodynamic models of the solar atmosphere. This divergence of theory and helioseismology is known as the “solar modeling problem.” One possible solution is that the photospheric neon abundance, which is deduced indirectly by combining the coronal Ne/O ratio with the photospheric O abundance, is larger than generally accepted. There is some support for this idea from observations of cool stars. The Ne/O abundance ratio has also been found to vary with the solar cycle in the slowest solar wind streams and coronal streamers, and the variation from solar maximum to minimum in streamers (∼0.1-0.25) is large enough to potentially bring some of the solar models into agreement with the seismic data. Here we use daily sampled observations from the EUV Variability Experiment on the Solar Dynamics Observatory taken in 2010-2014, to investigate whether the coronal Ne/O abundance ratio shows a variation with the solar cycle when the Sun is viewed as a star. We find only a weak dependence on, and moderate anti-correlation with, the solar cycle with the ratio measured around 0.2-0.3 MK falling from 0.17 at solar minimum to 0.11 at solar maximum. The effect is amplified at higher temperatures (0.3-0.6 MK) with a stronger anti-correlation and the ratio falling from 0.16 at solar minimum to 0.08 at solar maximum. The values we find at solar minimum are too low to solve the solar modeling problem. Title: Coronal Elemental Abundances in Solar Emerging Flux Regions Authors: Baker, Deborah; Brooks, David H.; van Driel-Gesztelyi, Lidia; James, Alexander W.; Démoulin, Pascal; Long, David M.; Warren, Harry P.; Williams, David R. Bibcode: 2018ApJ...856...71B Altcode: 2018arXiv180108424B The chemical composition of solar and stellar atmospheres differs from the composition of their photospheres. Abundances of elements with low first ionization potential (FIP) are enhanced in the corona relative to high-FIP elements with respect to the photosphere. This is known as the FIP effect and it is important for understanding the flow of mass and energy through solar and stellar atmospheres. We used spectroscopic observations from the Extreme-ultraviolet Imaging Spectrometer on board the Hinode observatory to investigate the spatial distribution and temporal evolution of coronal plasma composition within solar emerging flux regions inside a coronal hole. Plasma evolved to values exceeding those of the quiet-Sun corona during the emergence/early-decay phase at a similar rate for two orders of magnitude in magnetic flux, a rate comparable to that observed in large active regions (ARs) containing an order of magnitude more flux. During the late-decay phase, the rate of change was significantly faster than what is observed in large, decaying ARs. Our results suggest that the rate of increase during the emergence/early-decay phase is linked to the fractionation mechanism that leads to the FIP effect, whereas the rate of decrease during the later decay phase depends on the rate of reconnection with the surrounding magnetic field and its plasma composition. Title: Spectroscopic Observations of Current Sheet Formation and Evolution Authors: Warren, Harry P.; Brooks, David H.; Ugarte-Urra, Ignacio; Reep, Jeffrey W.; Crump, Nicholas A.; Doschek, George A. Bibcode: 2018ApJ...854..122W Altcode: 2017arXiv171110826W We report on the structure and evolution of a current sheet that formed in the wake of an eruptive X8.3 flare observed at the west limb of the Sun on 2017 September 10. Using observations from the EUV Imaging Spectrometer (EIS) on Hinode and the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory, we find that plasma in the current sheet reaches temperatures of about 20 MK and that the range of temperatures is relatively narrow. The highest temperatures occur at the base of the current sheet, in the region near the top of the post-flare loop arcade. The broadest high temperature line profiles, in contrast, occur at the largest observed heights. Furthermore, line broadening is strong very early in the flare and diminishes over time. The current sheet can be observed in the AIA 211 and 171 channels, which have a considerable contribution from thermal bremsstrahlung at flare temperatures. Comparisons of the emission measure in these channels with other EIS wavelengths and AIA channels dominated by Fe line emission indicate a coronal composition and suggest that the current sheet is formed by the heating of plasma already in the corona. Taken together, these observations suggest that some flare heating occurs in the current sheet, while additional energy is released as newly reconnected field lines relax and become more dipolar. Title: The Origin of the Solar Wind Authors: Lee, Kyoung-Sun; Brooks, David H.; Imada, Shinsuke Bibcode: 2018ASSL..449...95L Altcode: No abstract at ADS Title: A gravitational-wave standard siren measurement of the Hubble constant Authors: Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Afrough, M.; Agarwal, B.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allen, G.; Allocca, A.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Angelova, S. V.; Antier, S.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Atallah, D. V.; Aufmuth, P.; Aulbert, C.; Aultoneal, K.; Austin, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barkett, K.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bawaj, M.; Bayley, J. C.; Bazzan, M.; Bécsy, B.; Beer, C.; Bejger, M.; Belahcene, I.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Bero, J. J.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Biscoveanu, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bode, N.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonilla, E.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bossie, K.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Bustillo, J. Calderón; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Canizares, P.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Diaz, J. Casanueva; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerdá-Durán, P.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chase, E.; Chassande-Mottin, E.; Chatterjee, D.; Chatziioannou, K.; Cheeseboro, B. D.; Chen, H. Y.; Chen, X.; Chen, Y.; Cheng, H. -P.; Chia, H.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, A. K. W.; Chung, S.; Ciani, G.; Ciolfi, R.; Cirelli, C. E.; Cirone, A.; Clara, F.; Clark, J. A.; Clearwater, P.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P. -F.; Cohen, D.; Colla, A.; Collette, C. G.; Cominsky, L. R.; Constancio, M.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Cordero-Carrión, I.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J. -P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Dálya, G.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; da Silva Costa, C. F.; Datrier, L. E. H.; Dattilo, V.; Dave, I.; Davier, M.; Davis, D.; Daw, E. J.; Day, B.; de, S.; Debra, D.; Degallaix, J.; de Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Demos, N.; Denker, T.; Dent, T.; de Pietri, R.; Dergachev, V.; De Rosa, R.; Derosa, R. T.; de Rossi, C.; Desalvo, R.; de Varona, O.; Devenson, J.; Dhurandhar, S.; Díaz, M. C.; di Fiore, L.; di Giovanni, M.; di Girolamo, T.; di Lieto, A.; di Pace, S.; di Palma, I.; di Renzo, F.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Dreissigacker, C.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dupej, P.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H. -B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Estevez, D.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fee, C.; Fehrmann, H.; Feicht, J.; Fejer, M. M.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finstad, D.; Fiori, I.; Fiorucci, D.; Fishbach, M.; Fisher, R. P.; Fitz-Axen, M.; Flaminio, R.; Fletcher, M.; Fong, H.; Font, J. A.; Forsyth, P. W. F.; Forsyth, S. S.; Fournier, J. -D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garcia-Quiros, C.; Garufi, F.; Gateley, B.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glover, L.; Goetz, E.; Goetz, R.; Gomes, S.; Goncharov, B.; González, G.; Castro, J. M. Gonzalez; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Gretarsson, E. M.; Groot, P.; Grote, H.; Grunewald, S.; Gruning, P.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Halim, O.; Hall, B. R.; Hall, E. D.; Hamilton, E. Z.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Haster, C. -J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hinderer, T.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Horst, C.; Hough, J.; Houston, E. A.; Howell, E. J.; Hreibi, A.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Inta, R.; Intini, G.; Isa, H. N.; Isac, J. -M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kamai, B.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katolik, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Kéfélian, F.; Keitel, D.; Kemball, A. J.; Kennedy, R.; Kent, C.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, K.; Kim, W.; Kim, W. S.; Kim, Y. -M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kinley-Hanlon, M.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Knowles, T. D.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Linker, S. D.; Littenberg, T. B.; Liu, J.; Liu, X.; Lo, R. K. L.; Lockerbie, N. A.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macas, R.; Macfoy, S.; Machenschalk, B.; Macinnis, M.; MacLeod, D. M.; Hernandez, I. Magaña; Magaña-Sandoval, F.; Zertuche, L. Magaña; Magee, R. M.; Majorana, E.; Maksimovic, I.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Markowitz, A.; Maros, E.; Marquina, A.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Mason, K.; Massera, E.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McNeill, L.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Mejuto-Villa, E.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, B. B.; Miller, J.; Millhouse, M.; Milovich-Goff, M. C.; Minazzoli, O.; Minenkov, Y.; Ming, J.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moffa, D.; Moggi, A.; Mogushi, K.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muñiz, E. A.; Muratore, M.; Murray, P. G.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Neilson, J.; Nelemans, G.; Nelson, T. J. N.; Nery, M.; Neunzert, A.; Nevin, L.; Newport, J. M.; Newton, G.; Ng, K. K. Y.; Nguyen, T. T.; Nichols, D.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; North, C.; Nuttall, L. K.; Oberling, J.; O'Dea, G. D.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Okada, M. A.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ormiston, R.; Ortega, L. F.; O'Shaughnessy, R.; Ossokine, S.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, Howard; Pan, Huang-Wei; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Parida, A.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patil, M.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pirello, M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Porter, E. K.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Pratten, G.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rajbhandari, B.; Rakhmanov, M.; Ramirez, K. E.; Ramos-Buades, A.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Ren, W.; Reyes, S. D.; Ricci, F.; Ricker, P. M.; Rieger, S.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romel, C. L.; Romie, J. H.; Rosińska, D.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Rutins, G.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sanchez, L. E.; Sanchis-Gual, N.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheel, M.; Scheuer, J.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T. J.; Shah, A. A.; Shahriar, M. S.; Shaner, M. B.; Shao, L.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, L. P.; Singh, A.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Somala, S.; Son, E. J.; Sonnenberg, J. A.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staats, K.; Staley, A.; Steer, D.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stevenson, S. P.; Stone, R.; Stops, D. J.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Strunk, A.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Suresh, J.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Tait, S. C.; Talbot, C.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Tasson, J. D.; Taylor, J. A.; Taylor, R.; Tewari, S. V.; Theeg, T.; Thies, F.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torres-Forné, A.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tsang, K. W.; Tse, M.; Tso, R.; Tsukada, L.; Tsuna, D.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; van den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J. -Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, W. H.; Wang, Y. F.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L. -W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessel, E. K.; Weßels, P.; Westerweck, J.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; Whiting, B. F.; Whittle, C.; Wilken, D.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J.; Wong, K. W. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wysocki, D. M.; Xiao, S.; Yamamoto, H.; Yancey, C. C.; Yang, L.; Yap, M. J.; Yazback, M.; Yu, Hang; Yu, Haocun; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zelenova, T.; Zendri, J. -P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y. -H.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S. J.; Zhu, X. J.; Zimmerman, A. B.; Zucker, M. E.; Zweizig, J.; Foley, R. J.; Coulter, D. A.; Drout, M. R.; Kasen, D.; Kilpatrick, C. D.; Madore, B. F.; Murguia-Berthier, A.; Pan, Y. -C.; Piro, A. L.; Prochaska, J. X.; Ramirez-Ruiz, E.; Rest, A.; Rojas-Bravo, C.; Shappee, B. J.; Siebert, M. R.; Simon, J. D.; Ulloa, N.; Annis, J.; Soares-Santos, M.; Brout, D.; Scolnic, D.; Diehl, H. T.; Frieman, J.; Berger, E.; Alexander, K. D.; Allam, S.; Balbinot, E.; Blanchard, P.; Butler, R. E.; Chornock, R.; Cook, E. R.; Cowperthwaite, P.; Drlica-Wagner, A.; Drout, M. R.; Durret, F.; Eftekhari, T.; Finley, D. A.; Fong, W.; Fryer, C. L.; García-Bellido, J.; Gill, M. S. S.; Gruendl, R. A.; Hanna, C.; Hartley, W.; Herner, K.; Huterer, D.; Kasen, D.; Kessler, R.; Li, T. S.; Lin, H.; Lopes, P. A. A.; Lourenço, A. C. C.; Margutti, R.; Marriner, J.; Marshall, J. L.; Matheson, T.; Medina, G. E.; Metzger, B. D.; Muñoz, R. R.; Muir, J.; Nicholl, M.; Nugent, P.; Palmese, A.; Paz-Chinchón, F.; Quataert, E.; Sako, M.; Sauseda, M.; Schlegel, D. J.; Secco, L. F.; Smith, N.; Sobreira, F.; Stebbins, A.; Villar, V. A.; Vivas, A. K.; Wester, W.; Williams, P. K. G.; Yanny, B.; Zenteno, A.; Abbott, T. M. C.; Abdalla, F. B.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Bridle, S. L.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Castander, F. J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Davis, C.; Depoy, D. L.; Desai, S.; Dietrich, J. P.; Estrada, J.; Fernandez, E.; Flaugher, B.; Fosalba, P.; Gaztanaga, E.; Gerdes, D. W.; Giannantonio, T.; Goldstein, D. A.; Gruen, D.; Gutierrez, G.; Hartley, W. G.; Honscheid, K.; Jain, B.; James, D. J.; Jeltema, T.; Johnson, M. W. G.; Kent, S.; Krause, E.; Kron, R.; Kuehn, K.; Kuhlmann, S.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Miller, C. J.; Miquel, R.; Neilsen, E.; Nord, B.; Ogando, R. L. C.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Suchyta, E.; Tarle, G.; Thomas, D.; Thomas, R. C.; Troxel, M. A.; Tucker, D. L.; Vikram, V.; Walker, A. R.; Weller, J.; Zhang, Y.; Haislip, J. B.; Kouprianov, V. V.; Reichart, D. E.; Tartaglia, L.; Sand, D. J.; Valenti, S.; Yang, S.; Arcavi, Iair; Hosseinzadeh, Griffin; Howell, D. Andrew; McCully, Curtis; Poznanski, Dovi; Vasylyev, Sergiy; Tanvir, N. R.; Levan, A. J.; Hjorth, J.; Cano, Z.; Copperwheat, C.; de Ugarte-Postigo, A.; Evans, P. A.; Fynbo, J. P. U.; González-Fernández, C.; Greiner, J.; Irwin, M.; Lyman, J.; Mandel, I.; McMahon, R.; Milvang-Jensen, B.; O'Brien, P.; Osborne, J. P.; Perley, D. A.; Pian, E.; Palazzi, E.; Rol, E.; Rosetti, S.; Rosswog, S.; Rowlinson, A.; Schulze, S.; Steeghs, D. T. H.; Thöne, C. C.; Ulaczyk, K.; Watson, D.; Wiersema, K.; Lipunov, V. M.; Gorbovskoy, E.; Kornilov, V. G.; Tyurina, N.; Balanutsa, P.; Vlasenko, D.; Gorbunov, I.; Podesta, R.; Levato, H.; Saffe, C.; Buckley, D. A. H.; Budnev, N. M.; Gress, O.; Yurkov, V.; Rebolo, R.; Serra-Ricart, M. Bibcode: 2017Natur.551...85A Altcode: 2017arXiv171005835A On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817—a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO-Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identification of an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first ‘multi-messenger’ astronomical observation. Such observations enable GW170817 to be used as a ‘standard siren’ (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic ‘distance ladder’: the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. This value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision. Title: Multi-messenger Observations of a Binary Neutron Star Merger Authors: Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Afrough, M.; Agarwal, B.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allen, G.; Allocca, A.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Angelova, S. V.; Antier, S.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Atallah, D. V.; Aufmuth, P.; Aulbert, C.; AultONeal, K.; Austin, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barkett, K.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Barthelmy, S. D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bawaj, M.; Bayley, J. C.; Bazzan, M.; Bécsy, B.; Beer, C.; Bejger, M.; Belahcene, I.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Bero, J. J.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Biscoveanu, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bode, N.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonilla, E.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bossie, K.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Canizares, P.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerdá-Durán, P.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chase, E.; Chassande-Mottin, E.; Chatterjee, D.; Chatziioannou, K.; Cheeseboro, B. D.; Chen, H. Y.; Chen, X.; Chen, Y.; Cheng, H. -P.; Chia, H.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, A. K. W.; Chung, S.; Ciani, G.; Ciolfi, R.; Cirelli, C. E.; Cirone, A.; Clara, F.; Clark, J. A.; Clearwater, P.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P. -F.; Cohen, D.; Colla, A.; Collette, C. G.; Cominsky, L. R.; Constancio, M., Jr.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Cordero-Carrión, I.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J. -P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Dálya, G.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davis, D.; Daw, E. J.; Day, B.; De, S.; DeBra, D.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Demos, N.; Denker, T.; Dent, T.; De Pietri, R.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; De Rossi, C.; DeSalvo, R.; de Varona, O.; Devenson, J.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Renzo, F.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Dreissigacker, C.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dupej, P.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Estevez, D.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fee, C.; Fehrmann, H.; Feicht, J.; Fejer, M. M.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finstad, D.; Fiori, I.; Fiorucci, D.; Fishbach, M.; Fisher, R. P.; Fitz-Axen, M.; Flaminio, R.; Fletcher, M.; Fong, H.; Font, J. A.; Forsyth, P. W. F.; Forsyth, S. S.; Fournier, J. -D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garcia-Quiros, C.; Garufi, F.; Gateley, B.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glover, L.; Goetz, E.; Goetz, R.; Gomes, S.; Goncharov, B.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Gretarsson, E. M.; Griswold, B.; Groot, P.; Grote, H.; Grunewald, S.; Gruning, P.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Halim, O.; Hall, B. R.; Hall, E. D.; Hamilton, E. Z.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Haster, C. -J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hinderer, T.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Horst, C.; Hough, J.; Houston, E. A.; Howell, E. J.; Hreibi, A.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Inta, R.; Intini, G.; Isa, H. N.; Isac, J. -M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kamai, B.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katolik, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Kéfélian, F.; Keitel, D.; Kemball, A. J.; Kennedy, R.; Kent, C.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, K.; Kim, W.; Kim, W. S.; Kim, Y. -M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kinley-Hanlon, M.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Knowles, T. D.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Larson, S. L.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Linker, S. D.; Littenberg, T. B.; Liu, J.; Lo, R. K. L.; Lockerbie, N. A.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macas, R.; Macfoy, S.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña Hernandez, I.; Magaña-Sandoval, F.; Magaña Zertuche, L.; Magee, R. M.; Majorana, E.; Maksimovic, I.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Markowitz, A.; Maros, E.; Marquina, A.; Marsh, P.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Mason, K.; Massera, E.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McNeill, L.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Mejuto-Villa, E.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, B. B.; Miller, J.; Millhouse, M.; Milovich-Goff, M. C.; Minazzoli, O.; Minenkov, Y.; Ming, J.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moffa, D.; Moggi, A.; Mogushi, K.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muñiz, E. A.; Muratore, M.; Murray, P. G.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Neilson, J.; Nelemans, G.; Nelson, T. J. N.; Nery, M.; Neunzert, A.; Nevin, L.; Newport, J. M.; Newton, G.; Ng, K. K. Y.; Nguyen, P.; Nguyen, T. T.; Nichols, D.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; North, C.; Nuttall, L. K.; Oberling, J.; O'Dea, G. D.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Okada, M. A.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ormiston, R.; Ortega, L. F.; O'Shaughnessy, R.; Ossokine, S.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, Howard; Pan, Huang-Wei; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Parida, A.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patil, M.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pirello, M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Porter, E. K.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Pratten, G.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rajbhandari, B.; Rakhmanov, M.; Ramirez, K. E.; Ramos-Buades, A.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Ren, W.; Reyes, S. D.; Ricci, F.; Ricker, P. M.; Rieger, S.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romel, C. L.; Romie, J. H.; Rosińska, D.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Rutins, G.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sanchez, L. E.; Sanchis-Gual, N.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheel, M.; Scheuer, J.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T. J.; Shah, A. A.; Shahriar, M. S.; Shaner, M. B.; Shao, L.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, L. P.; Singh, A.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Somala, S.; Son, E. J.; Sonnenberg, J. A.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staats, K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stevenson, S. P.; Stone, R.; Stops, D. J.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Strunk, A.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Suresh, J.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Tait, S. C.; Talbot, C.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Tasson, J. D.; Taylor, J. A.; Taylor, R.; Tewari, S. V.; Theeg, T.; Thies, F.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torres-Forné, A.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tsang, K. W.; Tse, M.; Tso, R.; Tsukada, L.; Tsuna, D.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J. -Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, W. H.; Wang, Y. F.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L. -W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessel, E. K.; Wessels, P.; Westerweck, J.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; Whiting, B. F.; Whittle, C.; Wilken, D.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J.; Wong, K. W. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wysocki, D. M.; Xiao, S.; Yamamoto, H.; Yancey, C. C.; Yang, L.; Yap, M. J.; Yazback, M.; Yu, Hang; Yu, Haocun; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zelenova, T.; Zendri, J. -P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y. -H.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S. J.; Zhu, X. J.; Zimmerman, A. B.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration; Wilson-Hodge, C. A.; Bissaldi, E.; Blackburn, L.; Briggs, M. S.; Burns, E.; Cleveland, W. H.; Connaughton, V.; Gibby, M. H.; Giles, M. M.; Goldstein, A.; Hamburg, R.; Jenke, P.; Hui, C. M.; Kippen, R. M.; Kocevski, D.; McBreen, S.; Meegan, C. A.; Paciesas, W. S.; Poolakkil, S.; Preece, R. D.; Racusin, J.; Roberts, O. J.; Stanbro, M.; Veres, P.; von Kienlin, A.; GBM, Fermi; Savchenko, V.; Ferrigno, C.; Kuulkers, E.; Bazzano, A.; Bozzo, E.; Brandt, S.; Chenevez, J.; Courvoisier, T. J. -L.; Diehl, R.; Domingo, A.; Hanlon, L.; Jourdain, E.; Laurent, P.; Lebrun, F.; Lutovinov, A.; Martin-Carrillo, A.; Mereghetti, S.; Natalucci, L.; Rodi, J.; Roques, J. -P.; Sunyaev, R.; Ubertini, P.; INTEGRAL; Aartsen, M. G.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Samarai, I. Al; Altmann, D.; Andeen, K.; Anderson, T.; Ansseau, I.; Anton, G.; Argüelles, C.; Auffenberg, J.; Axani, S.; Bagherpour, H.; Bai, X.; Barron, J. P.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Bernardini, E.; Besson, D. Z.; Binder, G.; Bindig, D.; Blaufuss, E.; Blot, S.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Bourbeau, E.; Bourbeau, J.; Bradascio, F.; Braun, J.; Brayeur, L.; Brenzke, M.; Bretz, H. -P.; Bron, S.; Brostean-Kaiser, J.; Burgman, A.; Carver, T.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Collin, G. H.; Conrad, J. M.; Cowen, D. F.; Cross, R.; Day, M.; de André, J. P. A. M.; De Clercq, C.; DeLaunay, J. J.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dujmovic, H.; Dumm, J. P.; Dunkman, M.; Dvorak, E.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Eller, P.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Felde, J.; Filimonov, K.; Finley, C.; Flis, S.; Franckowiak, A.; Friedman, E.; Fuchs, T.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Giang, W.; Glauch, T.; Glüsenkamp, T.; Goldschmidt, A.; Gonzalez, J. G.; Grant, D.; Griffith, Z.; Haack, C.; Hallgren, A.; Halzen, F.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Hokanson-Fasig, B.; Hoshina, K.; Huang, F.; Huber, M.; Hultqvist, K.; Hünnefeld, M.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jones, B. J. P.; Kalaczynski, P.; Kang, W.; Kappes, A.; Karg, T.; Karle, A.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kheirandish, A.; Kim, J.; Kim, M.; Kintscher, T.; Kiryluk, J.; Kittler, T.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Köpke, L.; Kopper, C.; Kopper, S.; Koschinsky, J. P.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, M.; Krückl, G.; Kunnen, J.; Kunwar, S.; Kurahashi, N.; Kuwabara, T.; Kyriacou, A.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lauber, F.; Lesiak-Bzdak, M.; Leuermann, M.; Liu, Q. R.; Lu, L.; Lünemann, J.; Luszczak, W.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mancina, S.; Maruyama, R.; Mase, K.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meier, M.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Micallef, J.; Momenté, G.; Montaruli, T.; Moore, R. W.; Moulai, M.; Nahnhauer, R.; Nakarmi, P.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; O'Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Peiffer, P.; Pepper, J. A.; Pérez de los Heros, C.; Pieloth, D.; Pinat, E.; Price, P. B.; Przybylski, G. T.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Rea, I. C.; Reimann, R.; Relethford, B.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Rysewyk, D.; Sälzer, T.; Sanchez Herrera, S. E.; Sandrock, A.; Sandroos, J.; Santander, M.; Sarkar, S.; Sarkar, S.; Satalecka, K.; Schlunder, P.; Schmidt, T.; Schneider, A.; Schoenen, S.; Schöneberg, S.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soedingrekso, J.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stachurska, J.; Stamatikos, M.; Stanev, T.; Stasik, A.; Stettner, J.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stössl, A.; Strotjohann, N. L.; Stuttard, T.; Sullivan, G. W.; Sutherland, M.; Taboada, I.; Tatar, J.; Tenholt, F.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Tung, C. F.; Turcati, A.; Turley, C. F.; Ty, B.; Unger, E.; Usner, M.; Vandenbroucke, J.; Van Driessche, W.; van Eijndhoven, N.; Vanheule, S.; van Santen, J.; Vehring, M.; Vogel, E.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandler, F. D.; Wandkowsky, N.; Waza, A.; Weaver, C.; Weiss, M. J.; Wendt, C.; Werthebach, J.; Whelan, B. J.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wills, L.; Wolf, M.; Wood, T. R.; Woolsey, E.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Yuan, T.; Zoll, M.; IceCube Collaboration; Balasubramanian, A.; Mate, S.; Bhalerao, V.; Bhattacharya, D.; Vibhute, A.; Dewangan, G. C.; Rao, A. R.; Vadawale, S. V.; AstroSat Cadmium Zinc Telluride Imager Team; Svinkin, D. S.; Hurley, K.; Aptekar, R. L.; Frederiks, D. D.; Golenetskii, S. V.; Kozlova, A. V.; Lysenko, A. L.; Oleynik, Ph. P.; Tsvetkova, A. E.; Ulanov, M. V.; Cline, T.; IPN Collaboration; Li, T. P.; Xiong, S. L.; Zhang, S. N.; Lu, F. J.; Song, L. M.; Cao, X. L.; Chang, Z.; Chen, G.; Chen, L.; Chen, T. X.; Chen, Y.; Chen, Y. B.; Chen, Y. P.; Cui, W.; Cui, W. W.; Deng, J. K.; Dong, Y. W.; Du, Y. Y.; Fu, M. X.; Gao, G. H.; Gao, H.; Gao, M.; Ge, M. Y.; Gu, Y. D.; Guan, J.; Guo, C. C.; Han, D. W.; Hu, W.; Huang, Y.; Huo, J.; Jia, S. M.; Jiang, L. H.; Jiang, W. C.; Jin, J.; Jin, Y. J.; Li, B.; Li, C. K.; Li, G.; Li, M. S.; Li, W.; Li, X.; Li, X. B.; Li, X. F.; Li, Y. G.; Li, Z. J.; Li, Z. W.; Liang, X. H.; Liao, J. Y.; Liu, C. Z.; Liu, G. Q.; Liu, H. W.; Liu, S. Z.; Liu, X. J.; Liu, Y.; Liu, Y. N.; Lu, B.; Lu, X. F.; Luo, T.; Ma, X.; Meng, B.; Nang, Y.; Nie, J. Y.; Ou, G.; Qu, J. L.; Sai, N.; Sun, L.; Tan, Y.; Tao, L.; Tao, W. H.; Tuo, Y. L.; Wang, G. F.; Wang, H. Y.; Wang, J.; Wang, W. S.; Wang, Y. S.; Wen, X. Y.; Wu, B. B.; Wu, M.; Xiao, G. C.; Xu, H.; Xu, Y. P.; Yan, L. L.; Yang, J. W.; Yang, S.; Yang, Y. J.; Zhang, A. M.; Zhang, C. L.; Zhang, C. M.; Zhang, F.; Zhang, H. M.; Zhang, J.; Zhang, Q.; Zhang, S.; Zhang, T.; Zhang, W.; Zhang, W. C.; Zhang, W. Z.; Zhang, Y.; Zhang, Y.; Zhang, Y. F.; Zhang, Y. J.; Zhang, Z.; Zhang, Z. L.; Zhao, H. S.; Zhao, J. L.; Zhao, X. F.; Zheng, S. J.; Zhu, Y.; Zhu, Y. X.; Zou, C. L.; Insight-HXMT Collaboration; Albert, A.; André, M.; Anghinolfi, M.; Ardid, M.; Aubert, J. -J.; Aublin, J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Belhorma, B.; Bertin, V.; Biagi, S.; Bormuth, R.; Bourret, S.; Bouwhuis, M. C.; Brânzaş, H.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Cherkaoui El Moursli, R.; Chiarusi, T.; Circella, M.; Coelho, J. A. B.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Díaz, A. F.; Deschamps, A.; De Bonis, G.; Distefano, C.; Di Palma, I.; Domi, A.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; El Khayati, N.; Elsässer, D.; Enzenhöfer, A.; Ettahiri, A.; Fassi, F.; Felis, I.; Fusco, L. A.; Gay, P.; Giordano, V.; Glotin, H.; Grégoire, T.; Ruiz, R. Gracia; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Hössl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C. W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kiessling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Lotze, M.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Mele, R.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Navas, S.; Nezri, E.; Organokov, M.; Păvălaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Quinn, L.; Racca, C.; Riccobene, G.; Sánchez-Losa, A.; Saldaña, M.; Salvadori, I.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Taiuti, M.; Tayalati, Y.; Trovato, A.; Turpin, D.; Tönnis, C.; Vallage, B.; Van Elewyck, V.; Versari, F.; Vivolo, D.; Vizzoca, A.; Wilms, J.; Zornoza, J. D.; Zúñiga, J.; ANTARES Collaboration; Beardmore, A. P.; Breeveld, A. A.; Burrows, D. N.; Cenko, S. B.; Cusumano, G.; D'Aì, A.; de Pasquale, M.; Emery, S. W. K.; Evans, P. A.; Giommi, P.; Gronwall, C.; Kennea, J. A.; Krimm, H. A.; Kuin, N. P. M.; Lien, A.; Marshall, F. E.; Melandri, A.; Nousek, J. A.; Oates, S. R.; Osborne, J. P.; Pagani, C.; Page, K. L.; Palmer, D. M.; Perri, M.; Siegel, M. H.; Sbarufatti, B.; Tagliaferri, G.; Tohuvavohu, A.; Swift Collaboration; Tavani, M.; Verrecchia, F.; Bulgarelli, A.; Evangelista, Y.; Pacciani, L.; Feroci, M.; Pittori, C.; Giuliani, A.; Del Monte, E.; Donnarumma, I.; Argan, A.; Trois, A.; Ursi, A.; Cardillo, M.; Piano, G.; Longo, F.; Lucarelli, F.; Munar-Adrover, P.; Fuschino, F.; Labanti, C.; Marisaldi, M.; Minervini, G.; Fioretti, V.; Parmiggiani, N.; Gianotti, F.; Trifoglio, M.; Di Persio, G.; Antonelli, L. A.; Barbiellini, G.; Caraveo, P.; Cattaneo, P. W.; Costa, E.; Colafrancesco, S.; D'Amico, F.; Ferrari, A.; Morselli, A.; Paoletti, F.; Picozza, P.; Pilia, M.; Rappoldi, A.; Soffitta, P.; Vercellone, S.; AGILE Team; Foley, R. J.; Coulter, D. A.; Kilpatrick, C. D.; Drout, M. R.; Piro, A. L.; Shappee, B. J.; Siebert, M. R.; Simon, J. D.; Ulloa, N.; Kasen, D.; Madore, B. F.; Murguia-Berthier, A.; Pan, Y. -C.; Prochaska, J. X.; Ramirez-Ruiz, E.; Rest, A.; Rojas-Bravo, C.; 1M2H Team; Berger, E.; Soares-Santos, M.; Annis, J.; Alexander, K. D.; Allam, S.; Balbinot, E.; Blanchard, P.; Brout, D.; Butler, R. E.; Chornock, R.; Cook, E. R.; Cowperthwaite, P.; Diehl, H. T.; Drlica-Wagner, A.; Drout, M. R.; Durret, F.; Eftekhari, T.; Finley, D. A.; Fong, W.; Frieman, J. A.; Fryer, C. L.; García-Bellido, J.; Gruendl, R. A.; Hartley, W.; Herner, K.; Kessler, R.; Lin, H.; Lopes, P. A. A.; Lourenço, A. C. C.; Margutti, R.; Marshall, J. L.; Matheson, T.; Medina, G. E.; Metzger, B. D.; Muñoz, R. R.; Muir, J.; Nicholl, M.; Nugent, P.; Palmese, A.; Paz-Chinchón, F.; Quataert, E.; Sako, M.; Sauseda, M.; Schlegel, D. J.; Scolnic, D.; Secco, L. F.; Smith, N.; Sobreira, F.; Villar, V. A.; Vivas, A. K.; Wester, W.; Williams, P. K. G.; Yanny, B.; Zenteno, A.; Zhang, Y.; Abbott, T. M. C.; Banerji, M.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Castander, F. J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Davis, C.; DePoy, D. L.; Desai, S.; Dietrich, J. P.; Eifler, T. F.; Fernandez, E.; Flaugher, B.; Fosalba, P.; Gaztanaga, E.; Gerdes, D. W.; Giannantonio, T.; Goldstein, D. A.; Gruen, D.; Gschwend, J.; Gutierrez, G.; Honscheid, K.; James, D. J.; Jeltema, T.; Johnson, M. W. G.; Johnson, M. D.; Kent, S.; Krause, E.; Kron, R.; Kuehn, K.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Martini, P.; McMahon, R. G.; Menanteau, F.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Nichol, R. C.; Ogando, R. L. C.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, M.; Smith, R. C.; Stebbins, A.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, R. C.; Troxel, M. A.; Tucker, D. L.; Vikram, V.; Walker, A. R.; Wechsler, R. H.; Weller, J.; Carlin, J. L.; Gill, M. S. S.; Li, T. S.; Marriner, J.; Neilsen, E.; Dark Energy Camera GW-EM Collaboration; DES Collaboration; Haislip, J. B.; Kouprianov, V. V.; Reichart, D. E.; Sand, D. J.; Tartaglia, L.; Valenti, S.; Yang, S.; DLT40 Collaboration; Benetti, S.; Brocato, E.; Campana, S.; Cappellaro, E.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Getman, F.; Ghirlanda, G.; Ghisellini, G.; Limatola, L.; Nicastro, L.; Palazzi, E.; Pian, E.; Piranomonte, S.; Possenti, A.; Rossi, A.; Salafia, O. S.; Tomasella, L.; Amati, L.; Antonelli, L. A.; Bernardini, M. G.; Bufano, F.; Capaccioli, M.; Casella, P.; Dadina, M.; De Cesare, G.; Di Paola, A.; Giuffrida, G.; Giunta, A.; Israel, G. L.; Lisi, M.; Maiorano, E.; Mapelli, M.; Masetti, N.; Pescalli, A.; Pulone, L.; Salvaterra, R.; Schipani, P.; Spera, M.; Stamerra, A.; Stella, L.; Testa, V.; Turatto, M.; Vergani, D.; Aresu, G.; Bachetti, M.; Buffa, F.; Burgay, M.; Buttu, M.; Caria, T.; Carretti, E.; Casasola, V.; Castangia, P.; Carboni, G.; Casu, S.; Concu, R.; Corongiu, A.; Deiana, G. L.; Egron, E.; Fara, A.; Gaudiomonte, F.; Gusai, V.; Ladu, A.; Loru, S.; Leurini, S.; Marongiu, L.; Melis, A.; Melis, G.; Migoni, Carlo; Milia, Sabrina; Navarrini, Alessandro; Orlati, A.; Ortu, P.; Palmas, S.; Pellizzoni, A.; Perrodin, D.; Pisanu, T.; Poppi, S.; Righini, S.; Saba, A.; Serra, G.; Serrau, M.; Stagni, M.; Surcis, G.; Vacca, V.; Vargiu, G. P.; Hunt, L. K.; Jin, Z. P.; Klose, S.; Kouveliotou, C.; Mazzali, P. A.; Møller, P.; Nava, L.; Piran, T.; Selsing, J.; Vergani, S. D.; Wiersema, K.; Toma, K.; Higgins, A. B.; Mundell, C. G.; di Serego Alighieri, S.; Gótz, D.; Gao, W.; Gomboc, A.; Kaper, L.; Kobayashi, S.; Kopac, D.; Mao, J.; Starling, R. L. C.; Steele, I.; van der Horst, A. J.; GRAWITA: GRAvitational Wave Inaf TeAm; Acero, F.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Berenji, B.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Bregeon, J.; Buehler, R.; Buson, S.; Cameron, R. A.; Caputo, R.; Caraveo, P. A.; Cavazzuti, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Cohen-Tanugi, J.; Cominsky, L. R.; Costantin, D.; Cuoco, A.; D'Ammando, F.; de Palma, F.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Dubois, R.; Fegan, S. J.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Green, D.; Grondin, M. -H.; Guillemot, L.; Guiriec, S.; Harding, A. K.; Horan, D.; Jóhannesson, G.; Kamae, T.; Kensei, S.; Kuss, M.; La Mura, G.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Magill, J. D.; Maldera, S.; Manfreda, A.; Mazziotta, M. N.; McEnery, J. E.; Meyer, M.; Michelson, P. F.; Mirabal, N.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Nuss, E.; Ojha, R.; Omodei, N.; Orienti, M.; Orlando, E.; Palatiello, M.; Paliya, V. S.; Paneque, D.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Rochester, L. S.; Saz Parkinson, P. M.; Sgrò, C.; Siskind, E. J.; Spada, F.; Spandre, G.; Suson, D. J.; Takahashi, M.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Torresi, E.; Troja, E.; Venters, T. M.; Vianello, G.; Zaharijas, G.; Fermi Large Area Telescope Collaboration; Allison, J. R.; Bannister, K. W.; Dobie, D.; Kaplan, D. L.; Lenc, E.; Lynch, C.; Murphy, T.; Sadler, E. M.; Australia Telescope Compact Array, ATCA:; Hotan, A.; James, C. W.; Oslowski, S.; Raja, W.; Shannon, R. M.; Whiting, M.; Australian SKA Pathfinder, ASKAP:; Arcavi, I.; Howell, D. A.; McCully, C.; Hosseinzadeh, G.; Hiramatsu, D.; Poznanski, D.; Barnes, J.; Zaltzman, M.; Vasylyev, S.; Maoz, D.; Las Cumbres Observatory Group; Cooke, J.; Bailes, M.; Wolf, C.; Deller, A. T.; Lidman, C.; Wang, L.; Gendre, B.; Andreoni, I.; Ackley, K.; Pritchard, T. A.; Bessell, M. S.; Chang, S. -W.; Möller, A.; Onken, C. A.; Scalzo, R. A.; Ridden-Harper, R.; Sharp, R. G.; Tucker, B. E.; Farrell, T. J.; Elmer, E.; Johnston, S.; Venkatraman Krishnan, V.; Keane, E. F.; Green, J. A.; Jameson, A.; Hu, L.; Ma, B.; Sun, T.; Wu, X.; Wang, X.; Shang, Z.; Hu, Y.; Ashley, M. C. B.; Yuan, X.; Li, X.; Tao, C.; Zhu, Z.; Zhang, H.; Suntzeff, N. B.; Zhou, J.; Yang, J.; Orange, B.; Morris, D.; Cucchiara, A.; Giblin, T.; Klotz, A.; Staff, J.; Thierry, P.; Schmidt, B. P.; OzGrav; (Deeper, DWF; Wider; program, Faster; AST3; CAASTRO Collaborations; Tanvir, N. R.; Levan, A. J.; Cano, Z.; de Ugarte-Postigo, A.; González-Fernández, C.; Greiner, J.; Hjorth, J.; Irwin, M.; Krühler, T.; Mandel, I.; Milvang-Jensen, B.; O'Brien, P.; Rol, E.; Rosetti, S.; Rosswog, S.; Rowlinson, A.; Steeghs, D. T. H.; Thöne, C. C.; Ulaczyk, K.; Watson, D.; Bruun, S. H.; Cutter, R.; Figuera Jaimes, R.; Fujii, Y. I.; Fruchter, A. S.; Gompertz, B.; Jakobsson, P.; Hodosan, G.; Jèrgensen, U. G.; Kangas, T.; Kann, D. A.; Rabus, M.; Schrøder, S. L.; Stanway, E. R.; Wijers, R. A. M. J.; VINROUGE Collaboration; Lipunov, V. M.; Gorbovskoy, E. S.; Kornilov, V. G.; Tyurina, N. V.; Balanutsa, P. V.; Kuznetsov, A. S.; Vlasenko, D. M.; Podesta, R. C.; Lopez, C.; Podesta, F.; Levato, H. O.; Saffe, C.; Mallamaci, C. C.; Budnev, N. M.; Gress, O. A.; Kuvshinov, D. A.; Gorbunov, I. A.; Vladimirov, V. V.; Zimnukhov, D. S.; Gabovich, A. V.; Yurkov, V. V.; Sergienko, Yu. P.; Rebolo, R.; Serra-Ricart, M.; Tlatov, A. G.; Ishmuhametova, Yu. V.; MASTER Collaboration; Abe, F.; Aoki, K.; Aoki, W.; Asakura, Y.; Baar, S.; Barway, S.; Bond, I. A.; Doi, M.; Finet, F.; Fujiyoshi, T.; Furusawa, H.; Honda, S.; Itoh, R.; Kanda, N.; Kawabata, K. S.; Kawabata, M.; Kim, J. H.; Koshida, S.; Kuroda, D.; Lee, C. -H.; Liu, W.; Matsubayashi, K.; Miyazaki, S.; Morihana, K.; Morokuma, T.; Motohara, K.; Murata, K. L.; Nagai, H.; Nagashima, H.; Nagayama, T.; Nakaoka, T.; Nakata, F.; Ohsawa, R.; Ohshima, T.; Ohta, K.; Okita, H.; Saito, T.; Saito, Y.; Sako, S.; Sekiguchi, Y.; Sumi, T.; Tajitsu, A.; Takahashi, J.; Takayama, M.; Tamura, Y.; Tanaka, I.; Tanaka, M.; Terai, T.; Tominaga, N.; Tristram, P. J.; Uemura, M.; Utsumi, Y.; Yamaguchi, M. S.; Yasuda, N.; Yoshida, M.; Zenko, T.; J-GEM; Adams, S. M.; Anupama, G. C.; Bally, J.; Barway, S.; Bellm, E.; Blagorodnova, N.; Cannella, C.; Chandra, P.; Chatterjee, D.; Clarke, T. E.; Cobb, B. E.; Cook, D. O.; Copperwheat, C.; De, K.; Emery, S. W. K.; Feindt, U.; Foster, K.; Fox, O. D.; Frail, D. A.; Fremling, C.; Frohmaier, C.; Garcia, J. A.; Ghosh, S.; Giacintucci, S.; Goobar, A.; Gottlieb, O.; Grefenstette, B. W.; Hallinan, G.; Harrison, F.; Heida, M.; Helou, G.; Ho, A. Y. Q.; Horesh, A.; Hotokezaka, K.; Ip, W. -H.; Itoh, R.; Jacobs, Bob; Jencson, J. E.; Kasen, D.; Kasliwal, M. M.; Kassim, N. E.; Kim, H.; Kiran, B. S.; Kuin, N. P. M.; Kulkarni, S. R.; Kupfer, T.; Lau, R. M.; Madsen, K.; Mazzali, P. A.; Miller, A. A.; Miyasaka, H.; Mooley, K.; Myers, S. T.; Nakar, E.; Ngeow, C. -C.; Nugent, P.; Ofek, E. O.; Palliyaguru, N.; Pavana, M.; Perley, D. A.; Peters, W. M.; Pike, S.; Piran, T.; Qi, H.; Quimby, R. M.; Rana, J.; Rosswog, S.; Rusu, F.; Sadler, E. M.; Van Sistine, A.; Sollerman, J.; Xu, Y.; Yan, L.; Yatsu, Y.; Yu, P. -C.; Zhang, C.; Zhao, W.; GROWTH; JAGWAR; Caltech-NRAO; TTU-NRAO; NuSTAR Collaborations; Chambers, K. C.; Huber, M. E.; Schultz, A. S. B.; Bulger, J.; Flewelling, H.; Magnier, E. A.; Lowe, T. B.; Wainscoat, R. J.; Waters, C.; Willman, M.; Pan-STARRS; Ebisawa, K.; Hanyu, C.; Harita, S.; Hashimoto, T.; Hidaka, K.; Hori, T.; Ishikawa, M.; Isobe, N.; Iwakiri, W.; Kawai, H.; Kawai, N.; Kawamuro, T.; Kawase, T.; Kitaoka, Y.; Makishima, K.; Matsuoka, M.; Mihara, T.; Morita, T.; Morita, K.; Nakahira, S.; Nakajima, M.; Nakamura, Y.; Negoro, H.; Oda, S.; Sakamaki, A.; Sasaki, R.; Serino, M.; Shidatsu, M.; Shimomukai, R.; Sugawara, Y.; Sugita, S.; Sugizaki, M.; Tachibana, Y.; Takao, Y.; Tanimoto, A.; Tomida, H.; Tsuboi, Y.; Tsunemi, H.; Ueda, Y.; Ueno, S.; Yamada, S.; Yamaoka, K.; Yamauchi, M.; Yatabe, F.; Yoneyama, T.; Yoshii, T.; MAXI Team; Coward, D. M.; Crisp, H.; Macpherson, D.; Andreoni, I.; Laugier, R.; Noysena, K.; Klotz, A.; Gendre, B.; Thierry, P.; Turpin, D.; Consortium, TZAC; Im, M.; Choi, C.; Kim, J.; Yoon, Y.; Lim, G.; Lee, S. -K.; Lee, C. -U.; Kim, S. -L.; Ko, S. -W.; Joe, J.; Kwon, M. -K.; Kim, P. -J.; Lim, S. -K.; Choi, J. -S.; KU Collaboration; Fynbo, J. P. U.; Malesani, D.; Xu, D.; Optical Telescope, Nordic; Smartt, S. J.; Jerkstrand, A.; Kankare, E.; Sim, S. A.; Fraser, M.; Inserra, C.; Maguire, K.; Leloudas, G.; Magee, M.; Shingles, L. J.; Smith, K. W.; Young, D. R.; Kotak, R.; Gal-Yam, A.; Lyman, J. D.; Homan, D. S.; Agliozzo, C.; Anderson, J. P.; Angus, C. R.; Ashall, C.; Barbarino, C.; Bauer, F. E.; Berton, M.; Botticella, M. T.; Bulla, M.; Cannizzaro, G.; Cartier, R.; Cikota, A.; Clark, P.; De Cia, A.; Della Valle, M.; Dennefeld, M.; Dessart, L.; Dimitriadis, G.; Elias-Rosa, N.; Firth, R. E.; Flörs, A.; Frohmaier, C.; Galbany, L.; González-Gaitán, S.; Gromadzki, M.; Gutiérrez, C. P.; Hamanowicz, A.; Harmanen, J.; Heintz, K. E.; Hernandez, M. -S.; Hodgkin, S. T.; Hook, I. M.; Izzo, L.; James, P. A.; Jonker, P. G.; Kerzendorf, W. E.; Kostrzewa-Rutkowska, Z.; Kromer, M.; Kuncarayakti, H.; Lawrence, A.; Manulis, I.; Mattila, S.; McBrien, O.; Müller, A.; Nordin, J.; O'Neill, D.; Onori, F.; Palmerio, J. T.; Pastorello, A.; Patat, F.; Pignata, G.; Podsiadlowski, P.; Razza, A.; Reynolds, T.; Roy, R.; Ruiter, A. J.; Rybicki, K. A.; Salmon, L.; Pumo, M. L.; Prentice, S. J.; Seitenzahl, I. R.; Smith, M.; Sollerman, J.; Sullivan, M.; Szegedi, H.; Taddia, F.; Taubenberger, S.; Terreran, G.; Van Soelen, B.; Vos, J.; Walton, N. A.; Wright, D. E.; Wyrzykowski, Ł.; Yaron, O.; pre="(">ePESSTO, 2 at a luminosity distance of {40}-8+8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 {M}. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∼ 40 {{Mpc}}) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position ∼ 9 and ∼ 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.

Any correspondence should be addressed to . Title: A Solar cycle correlation of coronal element abundances in Sun-as-a-star observations Authors: Brooks, David H.; Baker, Deborah; van Driel-Gesztelyi, Lidia; Warren, Harry P. Bibcode: 2017NatCo...8..183B Altcode: 2018arXiv180200563B The elemental composition in the coronae of low-activity solar-like stars appears to be related to fundamental stellar properties such as rotation, surface gravity, and spectral type. Here we use full-Sun observations from the Solar Dynamics Observatory, to show that when the Sun is observed as a star, the variation of coronal composition is highly correlated with a proxy for solar activity, the F10.7 cm radio flux, and therefore with the solar cycle phase. Similar cyclic variations should therefore be detectable spectroscopically in X-ray observations of solar analogs. The plasma composition in full-disk observations of the Sun is related to the evolution of coronal magnetic field activity. Our observations therefore introduce an uncertainty into the nature of any relationship between coronal composition and fixed stellar properties. The results highlight the importance of systematic full-cycle observations for understanding the elemental composition of solar-like stellar coronae. Title: On-Disc Observations of Flux Rope Formation Prior to Its Eruption Authors: James, A. W.; Green, L. M.; Palmerio, E.; Valori, G.; Reid, H. A. S.; Baker, D.; Brooks, D. H.; van Driel-Gesztelyi, L.; Kilpua, E. K. J. Bibcode: 2017SoPh..292...71J Altcode: 2017arXiv170310837J Coronal mass ejections (CMEs) are one of the primary manifestations of solar activity and can drive severe space weather effects. Therefore, it is vital to work towards being able to predict their occurrence. However, many aspects of CME formation and eruption remain unclear, including whether magnetic flux ropes are present before the onset of eruption and the key mechanisms that cause CMEs to occur. In this work, the pre-eruptive coronal configuration of an active region that produced an interplanetary CME with a clear magnetic flux rope structure at 1 AU is studied. A forward-S sigmoid appears in extreme-ultraviolet (EUV) data two hours before the onset of the eruption (SOL2012-06-14), which is interpreted as a signature of a right-handed flux rope that formed prior to the eruption. Flare ribbons and EUV dimmings are used to infer the locations of the flux rope footpoints. These locations, together with observations of the global magnetic flux distribution, indicate that an interaction between newly emerged magnetic flux and pre-existing sunspot field in the days prior to the eruption may have enabled the coronal flux rope to form via tether-cutting-like reconnection. Composition analysis suggests that the flux rope had a coronal plasma composition, supporting our interpretation that the flux rope formed via magnetic reconnection in the corona. Once formed, the flux rope remained stable for two hours before erupting as a CME. Title: IRIS, Hinode, SDO, and RHESSI Observations of a White Light Flare Produced Directly by Nonthermal Electrons Authors: Lee, Kyoung-Sun; Imada, Shinsuke; Watanabe, Kyoko; Bamba, Yumi; Brooks, David H. Bibcode: 2017ApJ...836..150L Altcode: 2017arXiv170106286L An X1.6 flare occurred in active region AR 12192 on 2014 October 22 at 14:02 UT and was observed by Hinode, IRIS, SDO, and RHESSI. We analyze a bright kernel that produces a white light (WL) flare with continuum enhancement and a hard X-ray (HXR) peak. Taking advantage of the spectroscopic observations of IRIS and Hinode/EIS, we measure the temporal variation of the plasma properties in the bright kernel in the chromosphere and corona. We find that explosive evaporation was observed when the WL emission occurred, even though the intensity enhancement in hotter lines is quite weak. The temporal correlation of the WL emission, HXR peak, and evaporation flows indicates that the WL emission was produced by accelerated electrons. To understand the WL emission process, we calculated the energy flux deposited by non-thermal electrons (observed by RHESSI) and compared it to the dissipated energy estimated from a chromospheric line (Mg II triplet) observed by IRIS. The deposited energy flux from the non-thermal electrons is about (3-7.7) × 1010 erg cm-2 s-1 for a given low-energy cutoff of 30-40 keV, assuming the thick-target model. The energy flux estimated from the changes in temperature in the chromosphere measured using the Mg II subordinate line is about (4.6-6.7) × 109 erg cm-2 s-1: ∼6%-22% of the deposited energy. This comparison of estimated energy fluxes implies that the continuum enhancement was directly produced by the non-thermal electrons. Title: Properties and Modeling of Unresolved Fine Structure Loops Observed in the Solar Transition Region by IRIS Authors: Brooks, David H.; Reep, Jeffrey W.; Warren, Harry P. Bibcode: 2016ApJ...826L..18B Altcode: 2016arXiv160605440B Recent observations from the Interface Region Imaging Spectrograph (IRIS) have discovered a new class of numerous low-lying dynamic loop structures, and it has been argued that they are the long-postulated unresolved fine structures (UFSs) that dominate the emission of the solar transition region. In this letter, we combine IRIS measurements of the properties of a sample of 108 UFSs (intensities, lengths, widths, lifetimes) with one-dimensional non-equilibrium ionization simulations, using the HYDRAD hydrodynamic model to examine whether the UFSs are now truly spatially resolved in the sense of being individual structures rather than being composed of multiple magnetic threads. We find that a simulation of an impulsively heated single strand can reproduce most of the observed properties, suggesting that the UFSs may be resolved, and the distribution of UFS widths implies that they are structured on a spatial scale of 133 km on average. Spatial scales of a few hundred kilometers appear to be typical for a range of chromospheric and coronal structures, and we conjecture that this could be an important clue for understanding the coronal heating process. Title: Transition Region Abundance Measurements During Impulsive Heating Events Authors: Warren, Harry P.; Brooks, David H.; Doschek, George A.; Feldman, Uri Bibcode: 2016ApJ...824...56W Altcode: 2015arXiv151204447W It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona, low-FIP elements such as Fe, Si, Mg, and Ca, are generally enriched relative to high-FIP elements such as C, N, O, Ar, and Ne. In this paper we report on measurements of plasma composition made during impulsive heating events observed at transition region temperatures with the Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode. During these events the intensities of O IV, v, and VI emission lines are enhanced relative to emission lines from Mg v, VI, and vii and Si VI and vii, and indicate a composition close to that of the photosphere. Long-lived coronal fan structures, in contrast, show an enrichment of low-FIP elements. We conjecture that the plasma composition is an important signature of the coronal heating process, with impulsive heating leading to the evaporation of unfractionated material from the lower layers of the solar atmosphere and higher-frequency heating leading to long-lived structures and the accumulation of low-FIP elements in the corona. Title: Measurements of Non-thermal Line Widths in Solar Active Regions Authors: Brooks, David H.; Warren, Harry P. Bibcode: 2016ApJ...820...63B Altcode: 2015arXiv151102313B Spectral line widths are often observed to be larger than can be accounted for by thermal and instrumental broadening alone. This excess broadening is a key observational constraint for both nanoflare and wave dissipation models of coronal heating. Here we present a survey of non-thermal velocities measured in the high temperature loops (1-4 MK) often found in the cores of solar active regions. This survey of Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) observations covers 15 non-flaring active regions that span a wide range of solar conditions. We find relatively small non-thermal velocities, with a mean value of 17.6 ± 5.3 km s-1, and no significant trend with temperature or active region magnetic flux. These measurements appear to be inconsistent with those expected from reconnection jets in the corona, chromospheric evaporation induced by coronal nanoflares, and Alfvén wave turbulence models. Furthermore, because the observed non-thermal widths are generally small, such measurements are difficult and susceptible to systematic effects. Title: A Comparison of Global Magnetic Field Skeletons and Active-Region Upflows Authors: Edwards, S. J.; Parnell, C. E.; Harra, L. K.; Culhane, J. L.; Brooks, D. H. Bibcode: 2016SoPh..291..117E Altcode: 2015SoPh..tmp..161E Plasma upflows have been detected in active regions using Doppler velocity maps. The origin and nature of these upflows is not well known with many of their characteristics determined from the examination of single events. In particular, some studies suggest these upflows occur along open field lines and, hence, are linked to sources of the solar wind. To investigate the relationship these upflows may have with the solar wind, and to probe what may be driving them, this paper considers seven active regions observed on the solar disc using the Extreme ultraviolet Imaging Spectrometer aboard Hinode between August 2011 and September 2012. Plasma upflows are observed in all these active regions. The locations of these upflows are compared to the global potential magnetic field extrapolated from the Solar Dynamics Observatory, Helioseismic and Magnetic Imager daily synoptic magnetogram taken on the day the upflows were observed. The structure of the magnetic field is determined by constructing its magnetic skeleton in order to help identify open-field regions and also sites where magnetic reconnection at global features is likely to occur. As a further comparison, measurements of the temperature, density and composition of the plasma are taken from regions with active-region upflows. In most cases the locations of the upflows in the active regions do not correspond to areas of open field, as predicted by a global coronal potential-field model, and therefore these upflows are not always sources of the slow solar wind. The locations of the upflows are, in general, intersected by separatrix surfaces associated with null points located high in the corona; these could be important sites of reconnection with global consequences. Title: Photospheric Abundances of Polar Jets on the Sun Observed by Hinode Authors: Lee, Kyoung-Sun; Brooks, David H.; Imada, Shinsuke Bibcode: 2015ApJ...809..114L Altcode: 2015arXiv150704075L Many jets are detected at X-ray wavelengths in the Sun's polar regions, and the ejected plasma along the jets has been suggested to contribute mass to the fast solar wind. From in situ measurements in the magnetosphere, it has been found that the fast solar wind has photospheric abundances while the slow solar wind has coronal abundances. Therefore, we investigated the abundances of polar jets to determine whether they are the same as that of the fast solar wind. For this study, we selected 22 jets in the polar region observed by Hinode/EUV Imaging Spectroscopy (EIS) and X-ray Telescope (XRT) simultaneously on 2007 November 1-3. We calculated the First Ionization Potential (FIP) bias factor from the ratio of the intensity between high (S) and low (Si, Fe) FIP elements using the EIS spectra. The values of the FIP bias factors for the polar jets are around 0.7-1.9, and 75% of the values are in the range of 0.7-1.5, which indicates that they have photospheric abundances similar to the fast solar wind. The results are consistent with the reconnection jet model where photospheric plasma emerges and is rapidly ejected into the fast wind. Title: FIP Bias Evolution in a Decaying Active Region Authors: Baker, D.; Brooks, D. H.; Démoulin, P.; Yardley, S. L.; van Driel-Gesztelyi, L.; Long, D. M.; Green, L. M. Bibcode: 2015ApJ...802..104B Altcode: 2015arXiv150107397B Solar coronal plasma composition is typically characterized by first ionization potential (FIP) bias. Using spectra obtained by Hinode’s EUV Imaging Spectrometer instrument, we present a series of large-scale, spatially resolved composition maps of active region (AR)11389. The composition maps show how FIP bias evolves within the decaying AR during the period 2012 January 4-6. Globally, FIP bias decreases throughout the AR. We analyzed areas of significant plasma composition changes within the decaying AR and found that small-scale evolution in the photospheric magnetic field is closely linked to the FIP bias evolution observed in the corona. During the AR’s decay phase, small bipoles emerging within supergranular cells reconnect with the pre-existing AR field, creating a pathway along which photospheric and coronal plasmas can mix. The mixing timescales are shorter than those of plasma enrichment processes. Eruptive activity also results in shifting the FIP bias closer to photospheric in the affected areas. Finally, the FIP bias still remains dominantly coronal only in a part of the AR’s high-flux density core. We conclude that in the decay phase of an AR’s lifetime, the FIP bias is becoming increasingly modulated by episodes of small-scale flux emergence, i.e., decreasing the AR’s overall FIP bias. Our results show that magnetic field evolution plays an important role in compositional changes during AR development, revealing a more complex relationship than expected from previous well-known Skylab results showing that FIP bias increases almost linearly with age in young ARs. Title: Full-Sun observations for identifying the source of the slow solar wind Authors: Brooks, David H.; Ugarte-Urra, Ignacio; Warren, Harry P. Bibcode: 2015NatCo...6.5947B Altcode: 2016arXiv160509514B; 2015NatCo...6E5947B Fast (>700 km s-1) and slow (~400 km s-1) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind source map of the entire Sun, which we construct from specially designed, full-disk observations from the Hinode satellite, and a magnetic field model. Our map provides a full-Sun observation that combines three key ingredients for identifying the sources: velocity, plasma composition and magnetic topology and shows them as solar wind composition plasma outflowing on open magnetic field lines. The area coverage of the identified sources is large enough that the sum of their mass contributions can explain a significant fraction of the mass loss rate of the solar wind. Title: Constraining hot plasma in a non-flaring solar active region with FOXSI hard X-ray observations Authors: Ishikawa, Shin-nosuke; Glesener, Lindsay; Christe, Steven; Ishibashi, Kazunori; Brooks, David H.; Williams, David R.; Shimojo, Masumi; Sako, Nobuharu; Krucker, Säm Bibcode: 2014PASJ...66S..15I Altcode: 2015arXiv150905288I; 2014PASJ..tmp..102I We present new constraints on the high-temperature emission measure of a non-flaring solar active region using observations from the recently flown Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload. FOXSI has performed the first focused hard X-ray (HXR) observation of the Sun in its first successful flight on 2012 November 2. Focusing optics, combined with small strip detectors, enable high-sensitivity observations with respect to previous indirect imagers. This capability, along with the sensitivity of the HXR regime to high-temperature emission, offers the potential to better characterize high-temperature plasma in the corona as predicted by nanoflare heating models. We present a joint analysis of the differential emission measure (DEM) of active region 11602 using coordinated observations by FOXSI, Hinode/XRT, and Hinode/EIS. The Hinode-derived DEM predicts significant emission measure between 1 MK and 3 MK, with a peak in the DEM predicted at 2.0-2.5 MK. The combined XRT and EIS DEM also shows emission from a smaller population of plasma above 8 MK. This is contradicted by FOXSI observations that significantly constrain emission above 8 MK. This suggests that the Hinode DEM analysis has larger uncertainties at higher temperatures and that > 8 MK plasma above an emission measure of 3 × 1044 cm-3 is excluded in this active region. Title: Hot Topic, Warm Loops, Cooling Plasma? Multithermal Analysis of Active Region Loops Authors: Schmelz, J. T.; Pathak, S.; Brooks, D. H.; Christian, G. M.; Dhaliwal, R. S. Bibcode: 2014ApJ...795..171S Altcode: We have found indications of a relationship between the differential emission measure (DEM) weighted temperature and the cross-field DEM width for coronal loops. The data come from the Hinode X-ray Telescope, the Hinode EUV Imaging Spectrometer, and the Solar Dynamics Observatory Atmospheric Imaging Assembly. These data show that cooler loops tend to have narrower DEM widths. If most loops observed by these instruments are composed of bundles of unresolved magnetic strands and are only observed in their cooling phase, as some studies have suggested, then this relationship implies that the DEM of a coronal loop narrows as it cools. This could imply that fewer strands are seen emitting in the later cooling phase, potentially resolving the long standing controversy of whether the cross-field temperatures of coronal loops are multithermal or isothermal. Title: Tracking Solar Active Region Outflow Plasma from Its Source to the Near-Earth Environment Authors: Culhane, J. L.; Brooks, D. H.; van Driel-Gesztelyi, L.; Démoulin, P.; Baker, D.; DeRosa, M. L.; Mandrini, C. H.; Zhao, L.; Zurbuchen, T. H. Bibcode: 2014SoPh..289.3799C Altcode: 2014SoPh..tmp...90C; 2014arXiv1405.2949C Seeking to establish whether active-region upflow material contributes to the slow solar wind, we examine in detail the plasma upflows from Active Region (AR) 10978, which crossed the Sun's disc in the interval 8 to 16 December 2007 during Carrington rotation (CR) 2064. In previous work, using data from the Hinode/EUV Imaging Spectrometer, upflow velocity evolution was extensively studied as the region crossed the disc, while a linear force-free-field magnetic extrapolation was used to confirm aspects of the velocity evolution and to establish the presence of quasi-separatrix layers at the upflow source areas. The plasma properties, temperature, density, and first ionisation potential bias [FIP-bias] were measured with the spectrometer during the disc passage of the active region. Global potential-field source-surface (PFSS) models showed that AR 10978 was completely covered by the closed field of a helmet streamer that is part of the streamer belt. Therefore it is not clear how any of the upflowing AR-associated plasma could reach the source surface at 2.5 R and contribute to the slow solar wind. However, a detailed examination of solar-wind in-situ data obtained by the Advanced Composition Explorer (ACE) spacecraft at the L1 point shows that increases in O7+/O6+, C6+/C5+, and Fe/O - a FIP-bias proxy - are present before the heliospheric current-sheet crossing. These increases, along with an accompanying reduction in proton velocity and an increase in density are characteristic of both AR and slow-solar-wind plasma. Finally, we describe a two-step reconnection process by which some of the upflowing plasma from the AR might reach the heliosphere. Title: FIP bias in a sigmoidal active region Authors: Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, Lidia; Green, L. M.; Steed, K.; Carlyle, J. Bibcode: 2014IAUS..300..222B Altcode: We investigate first ionization potential (FIP) bias levels in an anemone active region (AR) - coronal hole (CH) complex using an abundance map derived from Hinode/EIS spectra. The detailed, spatially resolved abundance map has a large field of view covering 359'' × 485''. Plasma with high FIP bias, or coronal abundances, is concentrated at the footpoints of the AR loops whereas the surrounding CH has a low FIP bias, ~1, i.e. photospheric abundances. A channel of low FIP bias is located along the AR's main polarity inversion line containing a filament where ongoing flux cancellation is observed, indicating a bald patch magnetic topology characteristic of a sigmoid/flux rope configuration. Title: Plasma Composition in a Sigmoidal Anemone Active Region Authors: Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, L.; Green, L. M.; Steed, K.; Carlyle, J. Bibcode: 2013ApJ...778...69B Altcode: 2013arXiv1310.0999B Using spectra obtained by the EUV Imaging Spectrometer (EIS) instrument onboard Hinode, we present a detailed spatially resolved abundance map of an active region (AR)-coronal hole (CH) complex that covers an area of 359'' × 485''. The abundance map provides first ionization potential (FIP) bias levels in various coronal structures within the large EIS field of view. Overall, FIP bias in the small, relatively young AR is 2-3. This modest FIP bias is a consequence of the age of the AR, its weak heating, and its partial reconnection with the surrounding CH. Plasma with a coronal composition is concentrated at AR loop footpoints, close to where fractionation is believed to take place in the chromosphere. In the AR, we found a moderate positive correlation of FIP bias with nonthermal velocity and magnetic flux density, both of which are also strongest at the AR loop footpoints. Pathways of slightly enhanced FIP bias are traced along some of the loops connecting opposite polarities within the AR. We interpret the traces of enhanced FIP bias along these loops to be the beginning of fractionated plasma mixing in the loops. Low FIP bias in a sigmoidal channel above the AR's main polarity inversion line, where ongoing flux cancellation is taking place, provides new evidence of a bald patch magnetic topology of a sigmoid/flux rope configuration. Title: High Spatial Resolution Observations of Loops in the Solar Corona Authors: Brooks, David H.; Warren, Harry P.; Ugarte-Urra, Ignacio; Winebarger, Amy R. Bibcode: 2013ApJ...772L..19B Altcode: 2013arXiv1305.2246B Understanding how the solar corona is structured is of fundamental importance to determine how the Sun's upper atmosphere is heated to high temperatures. Recent spectroscopic studies have suggested that an instrument with a spatial resolution of 200 km or better is necessary to resolve coronal loops. The High Resolution Coronal Imager (Hi-C) achieved this performance on a rocket flight in 2012 July. We use Hi-C data to measure the Gaussian widths of 91 loops observed in the solar corona and find a distribution that peaks at about 270 km. We also use Atmospheric Imaging Assembly data for a subset of these loops and find temperature distributions that are generally very narrow. These observations provide further evidence that loops in the solar corona are often structured at a scale of several hundred kilometers, well above the spatial scale of many proposed physical mechanisms. Title: Tracking Solar Active Region Outflow Plasma from its Source to the near-Earth Environment Authors: Culhane, J. L.; Brooks, D.; Zurbuchen, T.; van Driel-Gesztelyi, L.; Fazakerley, A. N.; DeRosa, M. L. Bibcode: 2012AGUFMSH53A2255C Altcode: In a recent study of persistent active region outflow from AR 10978 in the period 10 - 15, December, 2007, Brooks and Warren (2011), using the Hinode EUV Imaging Spectrometer (EIS) instrument showed the presence of a strong low-FIP element enhancement in the outflowing plasma that was replicated three days later in the in-situ solar wind measurements made by the ACE/SWICS instrument. In the present work, we examine the outflowing plasma properties (Te, Ne, v, abundances) as a function of time in greater detail as AR 10978 passes the Earth-Sun line. The structure of the magnetic field above the two outflow regions - E and W of the AR, is also examined. Following an assessment of the relevant magnetic structures between Sun and Earth, the properties of the solar wind plasma arriving at ACE approximately three days later are measured and compared with those of the outflowing AR plasma. The relationship of these measurements to the in-situ magnetic field observed by the ACE magnetometer is also studied. Finally the role of persistent AR outflows in contributing to the slow solar wind is assessed. Title: Hinode/EIS measurements of Abundances in Solar Active Region Outflows Authors: Brooks, D.; Warren, H. P. Bibcode: 2012AGUFMSH52A..04B Altcode: Peripheral outflows appear to be a common feature of active regions, and may be a significant source of the slow speed solar wind. Spectral line profiles from the Hinode EUV Imaging Spectrometer (EIS) show that the bulk outflows reach speeds of ~50km/s with a much faster component reaching hundreds of km/s. I will review recent measurements of the elemental composition of the outflows obtained by EIS, with particular attention paid to AR 10978 that was observed as it crossed the solar disk in December 2007. EIS measurements show that the temperature distribution of the outflows is dominated by coronal emission, and that plasma with a slow wind-like composition flowed from the edge of AR 10978 for at least five days. Furthermore, when the outflow from the Western side was favorably oriented in the Earth direction, the composition was found to match the value measured a few days later by ACE/SWICS. The composition of the high speed component of the outflows was also found to be similar to that of the slow speed wind, implying that it may also be a contributor. Observations and models indicate that it takes time for plasma to evolve to the enhanced composition typical of the slow wind, suggesting that the material in the outflows is trapped on closed loops before escaping, perhaps by interchange reconnection. The results, therefore, also identify the high speed component of the plasma as having a coronal origin. A significant constraint on the mechanisms that drive the outflows. Title: Magnetic Topology of Active Regions and Coronal Holes: Implications for Coronal Outflows and the Solar Wind Authors: van Driel-Gesztelyi, L.; Culhane, J. L.; Baker, D.; Démoulin, P.; Mandrini, C. H.; DeRosa, M. L.; Rouillard, A. P.; Opitz, A.; Stenborg, G.; Vourlidas, A.; Brooks, D. H. Bibcode: 2012SoPh..281..237V Altcode: 2012SoPh..tmp..228V During 2 - 18 January 2008 a pair of low-latitude opposite-polarity coronal holes (CHs) were observed on the Sun with two active regions (ARs) and the heliospheric plasma sheet located between them. We use the Hinode/EUV Imaging Spectrometer (EIS) to locate AR-related outflows and measure their velocities. Solar-Terrestrial Relations Observatory (STEREO) imaging is also employed, as are the Advanced Composition Explorer (ACE) in-situ observations, to assess the resulting impacts on the solar wind (SW) properties. Magnetic-field extrapolations of the two ARs confirm that AR plasma outflows observed with EIS are co-spatial with quasi-separatrix layer locations, including the separatrix of a null point. Global potential-field source-surface modeling indicates that field lines in the vicinity of the null point extend up to the source surface, enabling a part of the EIS plasma upflows access to the SW. We find that similar upflow properties are also observed within closed-field regions that do not reach the source surface. We conclude that some of plasma upflows observed with EIS remain confined along closed coronal loops, but that a fraction of the plasma may be released into the slow SW. This suggests that ARs bordering coronal holes can contribute to the slow SW. Analyzing the in-situ data, we propose that the type of slow SW present depends on whether the AR is fully or partially enclosed by an overlying streamer. Title: A Systematic Survey of High-temperature Emission in Solar Active Regions Authors: Warren, Harry P.; Winebarger, Amy R.; Brooks, David H. Bibcode: 2012ApJ...759..141W Altcode: 2012arXiv1204.3220W The recent analysis of observations taken with the EUV Imaging Spectrometer and X-Ray Telescope instruments on Hinode suggests that well-constrained measurements of the temperature distribution in solar active regions can finally be made. Such measurements are critical for constraining theories of coronal heating. Past analysis, however, has suffered from limited sample sizes and large uncertainties at temperatures between 5 and 10 MK. Here we present a systematic study of the differential emission measure distribution in 15 active region cores. We focus on measurements in the "inter-moss" region, that is, the region between the loop footpoints, where the observations are easier to interpret. To reduce the uncertainties at the highest temperatures we present a new method for isolating the Fe XVIII emission in the AIA/SDO 94 Å channel. The resulting differential emission measure distributions confirm our previous analysis showing that the temperature distribution in an active region core is often strongly peaked near 4 MK. We characterize the properties of the emission distribution as a function of the total unsigned magnetic flux. We find that the amount of high-temperature emission in the active region core is correlated with the total unsigned magnetic flux, while the emission at lower temperatures, in contrast, is inversely related. These results provide compelling evidence that high-temperature active region emission is often close to equilibrium, although weaker active regions may be dominated by evolving million degree loops in the core. Title: The Coronal Source of Extreme-ultraviolet Line Profile Asymmetries in Solar Active Region Outflows Authors: Brooks, David H.; Warren, Harry P. Bibcode: 2012ApJ...760L...5B Altcode: 2012arXiv1210.1274B High-resolution spectra from the Hinode EUV Imaging Spectrometer have revealed that coronal spectral line profiles are sometimes asymmetric, with a faint enhancement in the blue wing on the order of 100 km s-1. These asymmetries could be important since they may be subtle yet diagnostically useful signatures of coronal heating or solar wind acceleration processes. It has also been suggested that they are signatures of chromospheric jets supplying mass and energy to the corona. Until now, however, there have been no studies of the physical properties of the plasma producing the asymmetries. Here we identify regions of asymmetric profiles in the outflows of AR 10978 using an asymmetric Gaussian function and extract the intensities of the faint component using multiple Gaussian fits. We then derive the temperature structure and chemical composition of the plasma producing the asymmetries. We find that the asymmetries are dependent on temperature, and are clearer and stronger in coronal lines. The temperature distribution peaks around 1.4-1.8 MK with an emission measure at least an order of magnitude larger than that at 0.6 MK. The first ionization potential bias is found to be 3-5, implying that the high-speed component of the outflows may also contribute to the slow-speed wind. Observations and models indicate that it takes time for plasma to evolve to a coronal composition, suggesting that the material is trapped on closed loops before escaping, perhaps by interchange reconnection. The results, therefore, identify the plasma producing the asymmetries as having a coronal origin. Title: Solar Coronal Loops Resolved by Hinode and the Solar Dynamics Observatory Authors: Brooks, David H.; Warren, Harry P.; Ugarte-Urra, Ignacio Bibcode: 2012ApJ...755L..33B Altcode: Despite decades of studying the Sun, the coronal heating problem remains unsolved. One fundamental issue is that we do not know the spatial scale of the coronal heating mechanism. At a spatial resolution of 1000 km or more, it is likely that most observations represent superpositions of multiple unresolved structures. In this Letter, we use a combination of spectroscopic data from the Hinode EUV Imaging Spectrometer and high-resolution images from the Atmospheric Imaging Assembly on the Solar Dynamics Observatory to determine the spatial scales of coronal loops. We use density measurements to construct multi-thread models of the observed loops and confirm these models using the higher spatial resolution imaging data. The results allow us to set constraints on the number of threads needed to reproduce a particular loop structure. We demonstrate that in several cases million degree loops are revealed to be single monolithic structures that are fully spatially resolved by current instruments. The majority of loops, however, must be composed of a number of finer, unresolved threads, but the models suggest that even for these loops the number of threads could be small, implying that they are also close to being resolved. These results challenge heating models of loops based on the reconnection of braided magnetic fields in the corona. Title: Constraints on the Heating of High-temperature Active Region Loops: Observations from Hinode and the Solar Dynamics Observatory Authors: Warren, Harry P.; Brooks, David H.; Winebarger, Amy R. Bibcode: 2011ApJ...734...90W Altcode: 2010arXiv1009.5976W We present observations of high-temperature emission in the core of a solar active region using instruments on Hinode and the Solar Dynamics Observatory (SDO). These multi-instrument observations allow us to determine the distribution of plasma temperatures and follow the evolution of emission at different temperatures. We find that at the apex of the high-temperature loops the emission measure distribution is strongly peaked near 4 MK and falls off sharply at both higher and lower temperatures. Perhaps most significantly, the emission measure at 0.5 MK is reduced by more than two orders of magnitude from the peak at 4 MK. We also find that the temporal evolution in broadband soft X-ray images is relatively constant over about 6 hr of observing. Observations in the cooler SDO/Atmospheric Imaging Assembly (AIA) bandpasses generally do not show cooling loops in the core of the active region, consistent with the steady emission observed at high temperatures. These observations suggest that the high-temperature loops observed in the core of an active region are close to equilibrium. We find that it is possible to reproduce the relative intensities of high-temperature emission lines with a simple, high-frequency heating scenario where heating events occur on timescales much less than a characteristic cooling time. In contrast, low-frequency heating scenarios, which are commonly invoked to describe nanoflare models of coronal heating, do not reproduce the relative intensities of high-temperature emission lines and predict low-temperature emission that is approximately an order of magnitude too large. We also present an initial look at images from the SDO/AIA 94 Å channel, which is sensitive to Fe XVIII. Title: EUV Spectral Line Formation and the Temperature Structure of Active Region Fan Loops: Observations with Hinode/EIS and SDO/AIA Authors: Brooks, David H.; Warren, Harry P.; Young, Peter R. Bibcode: 2011ApJ...730...85B Altcode: 2011arXiv1101.5240B With the aim of studying active region fan loops using observations from the Hinode EUV Imaging Spectrometer (EIS) and Solar Dynamics Observatory Atmospheric Imaging Assembly (AIA), we investigate a number of inconsistencies in modeling the absolute intensities of Fe VIII and Si VII lines, and address why spectroheliograms formed from these lines look very similar despite the fact that ionization equilibrium calculations suggest that they have significantly different formation temperatures: log(Te /K) = 5.6 and 5.8, respectively. It is important to resolve these issues because confidence has been undermined in their use for differential emission measure (DEM) analysis, and Fe VIII is the main contributor to the AIA 131 Å channel at low temperatures. Furthermore, the strong Fe VIII 185.213 Å and Si VII 275.368 Å lines are the best EIS lines to use for velocity studies in the transition region, and for assigning the correct temperature to velocity measurements in the fans. We find that the Fe VIII 185.213 Å line is particularly sensitive to the slope of the DEM, leading to disproportionate changes in its effective formation temperature. If the DEM has a steep gradient in the log(Te /K) = 5.6-5.8 temperature range, or is strongly peaked, Fe VIII 185.213 Å and Si VII 275.368 Å will be formed at the same temperature. We show that this effect explains the similarity of these images in the fans. Furthermore, we show that the most recent ionization balance compilations resolve the discrepancies in absolute intensities. With these difficulties overcome, we combine EIS and AIA data to determine the temperature structure of a number of fan loops and find that they have peak temperatures of 0.8-1.2 MK. The EIS data indicate that the temperature distribution has a finite (but narrow) width < log (σ_{T_e}/K) = 5.5 which, in one detailed case, is found to broaden substantially toward the loop base. AIA and EIS yield similar results on the temperature, emission measure magnitude, and thermal distribution in the fans, though sometimes the AIA data suggest a relatively larger thermal width. The result is that both the Fe VIII 185.213 Å and Si VII 275.368 Å lines are formed at log(Te /K)~ 5.9 in the fans, and the AIA 131 Å response also shifts to this temperature. Title: Establishing a Connection Between Active Region Outflows and the Solar Wind: Abundance Measurements with EIS/Hinode Authors: Brooks, David H.; Warren, Harry P. Bibcode: 2011ApJ...727L..13B Altcode: 2010arXiv1009.4291B One of the most interesting discoveries from Hinode is the presence of persistent high-temperature high-speed outflows from the edges of active regions (ARs). EUV imaging spectrometer (EIS) measurements indicate that the outflows reach velocities of 50 km s-1 with spectral line asymmetries approaching 200 km s-1. It has been suggested that these outflows may lie on open field lines that connect to the heliosphere, and that they could potentially be a significant source of the slow speed solar wind. A direct link has been difficult to establish, however. We use EIS measurements of spectral line intensities that are sensitive to changes in the relative abundance of Si and S as a result of the first ionization potential (FIP) effect, to measure the chemical composition in the outflow regions of AR 10978 over a 5 day period in 2007 December. We find that Si is always enhanced over S by a factor of 3-4. This is generally consistent with the enhancement factor of low FIP elements measured in situ in the slow solar wind by non-spectroscopic methods. Plasma with a slow wind-like composition was therefore flowing from the edge of the AR for at least 5 days. Furthermore, on December 10 and 11, when the outflow from the western side was favorably oriented in the Earth direction, the Si/S ratio was found to match the value measured a few days later by the Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer. These results provide strong observational evidence for a direct connection between the solar wind, and the coronal plasma in the outflow regions. Title: Characteristics and Evolution of the Magnetic Field and Chromospheric Emission in an Active Region Core Observed by Hinode Authors: Brooks, David H.; Warren, Harry P.; Winebarger, Amy R. Bibcode: 2010ApJ...720.1380B Altcode: 2010arXiv1006.5776B We describe the characteristics and evolution of the magnetic field and chromospheric emission in an active region core observed by the Solar Optical Telescope (SOT) on Hinode. Consistent with previous studies, we find that the moss is unipolar, the spatial distribution of magnetic flux evolves slowly, and that the magnetic field is only moderately inclined. We also show that the field-line inclination and horizontal component are coherent, and that the magnetic field is mostly sheared in the inter-moss regions where the highest magnetic flux variability is seen. Using extrapolations from spectropolarimeter magnetograms, we show that the magnetic connectivity in the moss is different from that in the quiet Sun because most of the magnetic field extends to significant coronal heights. The magnetic flux, field vector, and chromospheric emission in the moss also appear highly dynamic but actually show only small-scale variations in magnitude on timescales longer than the cooling times for hydrodynamic loops computed from our extrapolations, suggesting high-frequency (continuous) heating events. Some evidence is found for flux (Ca II intensity) changes on the order of 100-200 G (DN) on timescales of 20-30 minutes that could be taken as indicative of low-frequency heating. We find, however, that only a small fraction (10%) of our simulated loops would be expected to cool on these timescales, and we do not find clear evidence that the flux changes consistently produce intensity changes in the chromosphere. Using observations from the EUV Imaging Spectrometer (EIS), we also determine that the filling factor in the moss is ~16%, consistent with previous studies and larger than the size of an SOT pixel. The magnetic flux and chromospheric intensity in most individual SOT pixels in the moss vary by less than ~20% and ~10%, respectively, on loop cooling timescales. In view of the high energy requirements of the chromosphere, we suggest that these variations could be sufficient for the heating of "warm" EUV loops, but that the high basal levels may be more important for powering the hot core loops rooted in the moss. The magnetic field and chromospheric emission appear to evolve gradually on spatial scales comparable to the cross-field scale of the fundamental coronal structures inferred from EIS measurements. Title: Evidence for Steady Heating: Observations of an Active Region Core with Hinode and TRACE Authors: Warren, Harry P.; Winebarger, Amy R.; Brooks, David H. Bibcode: 2010ApJ...711..228W Altcode: 2009arXiv0910.0458W The timescale for energy release is an important parameter for constraining the coronal heating mechanism. Observations of "warm" coronal loops (~1 MK) have indicated that the heating is impulsive and that coronal plasma is far from equilibrium. In contrast, observations at higher temperatures (~3 MK) have generally been consistent with steady heating models. Previous observations, however, have not been able to exclude the possibility that the high temperature loops are actually composed of many small-scale threads that are in various stages of heating and cooling and only appear to be in equilibrium. With new observations from the EUV Imaging Spectrometer and X-ray Telescope (XRT) on Hinode we have the ability to investigate the properties of high temperature coronal plasma in extraordinary detail. We examine the emission in the core of an active region and find three independent lines of evidence for steady heating. We find that the emission observed in XRT is generally steady for hours, with a fluctuation level of approximately 15% in an individual pixel. Short-lived impulsive heating events are observed, but they appear to be unrelated to the steady emission that dominates the active region. Furthermore, we find no evidence for warm emission that is spatially correlated with the hot emission, as would be expected if the high temperature loops are the result of impulsive heating. Finally, we also find that intensities in the "moss," the footpoints of high temperature loops, are consistent with steady heating models provided that we account for the local expansion of the loop from the base of the transition region to the corona. In combination, these results provide strong evidence that the heating in the core of an active region is effectively steady, that is, the time between heating events is short relative to the relevant radiative and conductive cooling times. Title: Signatures of Coronal Heating Mechanisms Authors: Antolin, P.; Shibata, K.; Kudoh, T.; Shiota, D.; Brooks, D. Bibcode: 2010ASSP...19..277A Altcode: 2010mcia.conf..277A; 2009arXiv0903.1766A Alfvén waves created by sub-photospheric motions or by magnetic reconnection in the low solar atmosphere seem good candidates for coronal heating. However, the corona is also likely to be heated more directly by magnetic reconnection, with dissipation taking place in current sheets. Distinguishing observationally between these two heating mechanisms is an extremely difficult task. We perform 1.5-dimensional MHD simulations of a coronal loop subject to each type of heating and derive observational quantities that may allow these to be differentiated. This work is presented in more detail in Antolin et al. (2008). Title: Hinode/Extreme-Ultraviolet Imaging Spectrometer Observations of the Temperature Structure of the Quiet Corona Authors: Brooks, David H.; Warren, Harry P.; Williams, David R.; Watanabe, Tetsuya Bibcode: 2009ApJ...705.1522B Altcode: 2009arXiv0905.3603B We present a differential emission measure (DEM) analysis of the quiet solar corona on disk using data obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on Hinode. We show that the expected quiet-Sun DEM distribution can be recovered from judiciously selected lines, and that their average intensities can be reproduced to within 30%. We present a subset of these selected lines spanning the temperature range log T = 5.6-6.4 K that can be used to derive the DEM distribution reliably, including a subset of iron lines that can be used to derive the DEM distribution free of the possibility of uncertainties in the elemental abundances. The subset can be used without the need for extensive measurements, and the observed intensities can be reproduced to within the estimated uncertainty in the pre-launch calibration of EIS. Furthermore, using this subset, we also demonstrate that the quiet coronal DEM distribution can be recovered on size scales down to the spatial resolution of the instrument (1'' pixels). The subset will therefore be useful for studies of small-scale spatial inhomogeneities in the coronal temperature structure, for example, in addition to studies requiring multiple DEM derivations in space or time. We apply the subset to 45 quiet-Sun data sets taken in the period 2007 January to April, and show that although the absolute magnitude of the coronal DEM may scale with the amount of released energy, the shape of the distribution is very similar up to at least log T ~ 6.2 K in all cases. This result is consistent with the view that the shape of the quiet-Sun DEM is mainly a function of the radiating and conducting properties of the plasma and is fairly insensitive to the location and rate of energy deposition. This universal DEM may be sensitive to other factors such as loop geometry, flows, and the heating mechanism, but if so they cannot vary significantly from quiet-Sun region to region. Title: Flows and Motions in Moss in the Core of a Flaring Active Region: Evidence for Steady Heating Authors: Brooks, David H.; Warren, Harry P. Bibcode: 2009ApJ...703L..10B Altcode: 2009arXiv0905.3462B We present new measurements of the time variability of intensity, Doppler, and nonthermal velocities in moss in an active region core observed by the EUV Imaging Spectrometer on Hinode in 2007 June. The measurements are derived from spectral profiles of the Fe XII 195 Å line. Using the 2'' slit, we repeatedly scanned 150'' by 150'' in a few minutes. This is the first time it has been possible to make such velocity measurements in the moss, and the data presented are the highest cadence spatially resolved maps of moss Doppler and nonthermal velocities ever obtained in the corona. The observed region produced numerous C- and M-class flares with several occurring in the core close to the moss. The magnetic field was therefore clearly changing in the active region core, so we ought to be able to detect dynamic signatures in the moss if they exist. Our measurements of moss intensities agree with previous studies in that a less than 15% variability is seen over a period of 16 hr. Our new measurements of Doppler and nonthermal velocities reveal no strong flows or motions in the moss, nor any significant variability in these quantities. The results confirm that moss at the bases of high temperature coronal loops is heated quasi-steadily. They also show that quasi-steady heating can contribute significantly even in the core of a flare productive active region. Such heating may be impulsive at high frequency, but if so it does not give rise to large flows or motions. Title: The Temperature and Density Structure of the Solar Corona. I. Observations of the Quiet Sun with the EUV Imaging Spectrometer on Hinode Authors: Warren, Harry P.; Brooks, David H. Bibcode: 2009ApJ...700..762W Altcode: 2009arXiv0901.1621W Measurements of the temperature and density structure of the solar corona provide critical constraints on theories of coronal heating. Unfortunately, the complexity of the solar atmosphere, observational uncertainties, and the limitations of current atomic calculations, particularly those for Fe, all conspire to make this task very difficult. A critical assessment of plasma diagnostics in the corona is essential to making progress on the coronal heating problem. In this paper, we present an analysis of temperature and density measurements above the limb in the quiet corona using new observations from the EUV Imaging Spectrometer (EIS) on Hinode. By comparing the Si and Fe emission observed with EIS we are able to identify emission lines that yield consistent emission measure distributions. With these data we find that the distribution of temperatures in the quiet corona above the limb is strongly peaked near 1 MK, consistent with previous studies. We also find, however, that there is a tail in the emission measure distribution that extends to higher temperatures. EIS density measurements from several density sensitive line ratios are found to be generally consistent with each other and with previous measurements in the quiet corona. Our analysis, however, also indicates that a significant fraction of the weaker emission lines observed in the EIS wavelength ranges cannot be understood with current atomic data. Title: Active Region Transition Region Loop Populations and Their Relationship to the Corona Authors: Ugarte-Urra, Ignacio; Warren, Harry P.; Brooks, David H. Bibcode: 2009ApJ...695..642U Altcode: 2009arXiv0901.1075U The relationships among coronal loop structures at different temperatures are not settled. Previous studies have suggested that coronal loops in the core of an active region (AR) are not seen cooling through lower temperatures and therefore are steadily heated. If loops were cooling, the transition region would be an ideal temperature regime to look for a signature of their evolution. The Extreme-ultraviolet Imaging Spectrometer on Hinode provides monochromatic images of the solar transition region and corona at an unprecedented cadence and spatial resolution, making it an ideal instrument to shed light on this issue. Analysis of observations of AR 10978 taken in 2007 December 8-19 indicates that there are two dominant loop populations in the AR: (1) core multitemperature loops that undergo a continuous process of heating and cooling in the full observed temperature range 0.4-2.5 MK and even higher as shown by the X-Ray Telescope and (2) peripheral loops which evolve mostly in the temperature range 0.4-1.3 MK. Loops at transition region temperatures can reach heights of 150 Mm in the corona above the limb and develop downflows with velocities in the range of 39-105 km s-1. Title: The Role of Transient Brightenings in Heating the Solar Corona Authors: Brooks, David H.; Ugarte-Urra, Ignacio; Warren, Harry P. Bibcode: 2008ApJ...689L..77B Altcode: Nanoflare reconnection events have been proposed as a mechanism for heating the corona. Parker's original suggestion was that frequent reconnection events occur in coronal loops due to the braiding of the magnetic field. Many observational studies, however, have focused on the properties of isolated transient brightenings unassociated with loops, but their cause, role, and relevance for coronal heating have not yet been established. Using Hinode SOT magnetograms and high-cadence EIS spectral data we study the relationship between chromospheric, transition region, and coronal emission and the evolution of the magnetic field. We find that hot, relatively steadily emitting coronal loops and isolated transient brightenings are both associated with magnetic flux regions that are highly dynamic. An essential difference, however, is that brightenings are typically found in regions of flux collision and cancellation whereas coronal loops are generally rooted in magnetic field regions that are locally unipolar with unmixed flux. This suggests that the type of heating (transient vs. steady) is related to the structure of the magnetic field, and that the heating in transient events may be fundamentally different than in coronal loops. This implies that they do not play an important role in heating the "quiescent" corona. Title: Predicting Observational Signatures of Coronal Heating by Alfvén Waves and Nanoflares Authors: Antolin, P.; Shibata, K.; Kudoh, T.; Shiota, D.; Brooks, D. Bibcode: 2008ApJ...688..669A Altcode: Alfvén waves can dissipate their energy by means of nonlinear mechanisms, and constitute good candidates to heat and maintain the solar corona to the observed few million degrees. Another appealing candidate is nanoflare reconnection heating, in which energy is released through many small magnetic reconnection events. Distinguishing the observational features of each mechanism is an extremely difficult task. On the other hand, observations have shown that energy release processes in the corona follow a power-law distribution in frequency whose index may tell us whether small heating events contribute substantially to the heating or not. In this work we show a link between the power-law index and the operating heating mechanism in a loop. We set up two coronal loop models: in the first model Alfvén waves created by footpoint shuffling nonlinearly convert to longitudinal modes which dissipate their energy through shocks; in the second model numerous heating events with nanoflare-like energies are input randomly along the loop, either distributed uniformly or concentrated at the footpoints. Both models are based on a 1.5-dimensional MHD code. The obtained coronae differ in many aspects; for instance, in the flow patterns along the loop and the simulated intensity profile that Hinode XRT would observe. The intensity histograms display power-law distributions whose indexes differ considerably. This number is found to be related to the distribution of the shocks along the loop. We thus test the observational signatures of the power-law index as a diagnostic tool for the above heating mechanisms and the influence of the location of nanoflares. Title: Modeling of the Extreme-Ultraviolet and Soft X-Ray Emission in a Solar Coronal Bright Point Authors: Brooks, David H.; Warren, Harry P. Bibcode: 2008ApJ...687.1363B Altcode: Previous studies have been able to reproduce both the observed intensities and the morphology of high-temperature solar plasma using steady state heating models. These models, however, have been unable to reproduce the lower temperature emission observed in active regions. Here we present results from numerical simulations of a coronal bright point. We use potential field extrapolations of a Kitt Peak magnetogram to compute the coronal field lines and populate them with solutions to the hydrostatic loop equations based on a volumetric heating function that scales as bar B/L, where bar B is the magnetic field strength averaged along a field line and L is the loop length. We consider the effects of altering the magnitude and scale height of the energy deposition and the effect of allowing the loop cross sections to expand proportionally to 1/bar B. We then use the computed densities and temperatures to calculate average intensities and simulated EUV and soft X-ray images and compared them to Yohkoh and SOHO observations. We find that our best-case model (apex heating of expanding loops) can reproduce the high-temperature emission, the general morphology of the lower temperature emission, and the majority of the average intensities of reliable lines over a wide range of temperatures to within ~20%. The morphology in the EUV visualizations, however, shows some differences from the observations. These results suggest the role of nonpotential or evolving magnetic fields, or dynamic processes, but indicate that departures from the potential field hydrostatic case may not be too large. Title: Observations of Active Region Loops with the EUV Imaging Spectrometer on Hinode Authors: Warren, Harry P.; Ugarte-Urra, Ignacio; Doschek, George A.; Brooks, David H.; Williams, David R. Bibcode: 2008ApJ...686L.131W Altcode: 2008arXiv0808.3227W Previous solar observations have shown that coronal loops near 1 MK are difficult to reconcile with simple heating models. These loops have lifetimes that are long relative to a radiative cooling time, suggesting quasi-steady heating. The electron densities in these loops, however, are too high to be consistent with thermodynamic equilibrium. Models proposed to explain these properties generally rely on the existence of smaller scale filaments within the loop that are in various stages of heating and cooling. Such a framework implies that there should be a distribution of temperatures within a coronal loop. In this paper we analyze new observations from the EUV Imaging Spectrometer (EIS) on Hinode. EIS is capable of observing active regions over a wide range of temperatures (Fe VIII-Fe XVII) at relatively high spatial resolution (1''). We find that most isolated coronal loops that are bright in Fe XII generally have very narrow temperature distributions (σT lesssim 3 × 105 K), but are not isothermal. We also derive volumetric filling factors in these loops of approximately 10%. Both results lend support to the filament models. Title: Predicting observational signatures of coronal heating by Alfvén waves and nanoflares Authors: Antolin, Patrick; Shibata, Kazunari; Kudoh, Takahiro; Shiota, Daiko; Brooks, David Bibcode: 2008IAUS..247..279A Altcode: 2007IAUS..247..279A Alfvén waves can dissipate their energy by means of nonlinear mechanisms, and constitute good candidates to heat and maintain the solar corona to the observed few million degrees. Another appealing candidate is the nanoflare-reconnection heating, in which energy is released through many small magnetic reconnection events. Distinguishing the observational features of each mechanism is an extremely difficult task. On the other hand, observations have shown that energy release processes in the corona follow a power law distribution in frequency whose index may tell us whether small heating events contribute substantially to the heating or not. In this work we show a link between the power law index and the operating heating mechanism in a loop. We set up two coronal loop models: in the first model Alfvén waves created by footpoint shuffling nonlinearly convert to longitudinal modes which dissipate their energy through shocks; in the second model numerous heating events with nanoflare-like energies are input randomly along the loop, either distributed uniformly or concentrated at the footpoints. Both models are based on a 1.5-D MHD code. The obtained coronae differ in many aspects, for instance, in the simulated intensity profile that Hinode/XRT would observe. The intensity histograms display power law distributions whose indexes differ considerably. This number is found to be related to the distribution of the shocks along the loop. We thus test the observational signatures of the power law index as a diagnostic tool for the above heating mechanisms and the influence of the location of nanoflares. Title: The Role of Isolated EUV Brightenings in Heating the Corona Authors: Brooks, D. H.; Warren, H. P.; Ugarte-Urra, I. Bibcode: 2008AGUSMSP43C..04B Altcode: Nanoflare reconnection events have been proposed as a mechanism for heating the solar corona. Parker's original suggestion was that frequent reconnection events occur in coronal loops due to the twisting and braiding of the magnetic field. Many observational studies, however, have focused on the radiating properties of isolated brightening events, but their cause, role, and relevance for coronal heating has not yet been established. Using Hinode Solar Optical Telescope (SOT) magnetograms and high cadence EUV Imaging Spectrometer (EIS) slot rasters we study the relationship between transition region and coronal emission and the evolution of the magnetic field. We find that hot, relatively steadily emitting coronal loops are generally rooted in magnetic field regions that are locally unipolar yet highly dynamic, whereas detailed analysis shows that ubiquitous EUV brightenings are found in regions of magnetic flux cancellation in the photosphere. This suggests that the heating in transient events may be fundamentally different than the heating in coronal loops and that they play no direct role in the heating of the quiescent corona. Title: Electron Densities in Active Region Loops Observed with Hinode/EIS Authors: Warren, H. P.; Winebarger, A. R.; Brooks, D. H. Bibcode: 2008AGUSMSP41C..02W Altcode: Active region observations with the Transition Region and Coronal Explorer (TRACE) showed that loops near 1 MK appear to have high densities relative to the predictions of scaling laws based on steady heating. These loops also persist much longer than a radiative cooling time. This lead to the formation of models based on the impulsive heating of small scale filaments. With the launch of the EUV Imaging Spectrometer (EIS) on Hinode we now have a much more detailed view of coronal loops at these temperatures. We find that the temperatures, densities, and filling factors inferred from the new spectroscopic data are largely consistent with our interpretation of the earlier TRACE observations. The impulsive heating models also predict low densities relative to the steady heating models at high temperatures, and we will discuss the EIS evidence for hot, underdense loops in solar active regions. Title: EIS: a new view of active region transition region loops Authors: Ugarte-Urra, I.; Warren, H. P.; Brooks, D. H. Bibcode: 2008AGUSMSP41C..03U Altcode: The EUV Imaging Spectrometer (EIS) on board Hinode is providing unprecedented diagnostics of solar coronal plasmas. One of its less exploited capabilities is the ability to make instantaneous spectrally pure images with the 40'' slot. Simultaneous transition region (Mg VI, Mg VII, Si VII) and coronal (Fe XI - Fe XVI) images allow us to observe active region loops as we have not been able to before, given the spatial resolution (1arcsec pixels), cadence (70s) and, most importantly, the broad temperature coverage. Under this scrutiny two distinct populations of active region transition region loops can be differentiated: core loops that result from the cooling of several million degree plasma; and fan structures with their main contribution in the 0.6-1 MK temperature range. These results suggest that the cores of active regions are not as steady as commonly assumed and reinforce the idea of coexistance of differentiated loop populations within the active region topology. We present the properties of the loops and we discuss the implications that these new observations have for current transition region and coronal models. Title: Observations of Transient Active Region Heating with Hinode Authors: Warren, Harry P.; Ugarte-Urra, Ignacio; Brooks, David H.; Cirtain, Jonathan W.; Williams, David R.; Hara, Hirohisa Bibcode: 2007PASJ...59S.675W Altcode: 2007arXiv0711.0357W We present observations of transient active region heating events observed with the Extreme Ultraviolet Imaging Spectrometer (EIS) and X-ray Telescope (XRT) on Hinode. This initial investigation focuses on NOAA active region 10940 as observed by Hinode on 2007 February 1 between 12 and 19UT. In these observations we find numerous examples of transient heating events within the active region. The high spatial resolution and broad temperature coverage of these instruments allows us to track the evolution of coronal plasma. The evolution of the emission observed with XRT and EIS during these events is generally consistent with loops that have been heated and are cooling. We have analyzed the most energetic heating event observed during this period, a small GOES B-class flare, in some detail and present some of the spectral signatures of the event, such as relative Doppler shifts at one of the loop footpoints and enhanced line widths during the rise phase of the event. While the analysis of these transient events has the potential to yield insights into the coronal heating mechanism, these observations do not rule out the possibility that there is a strong steady heating level in the active region. Detailed statistical analysis will be required to address this question definitively. Title: Hinode EUV Imaging Spectrometer Observations of Solar Active Region Dynamics Authors: Mariska, John T.; Warren, Harry P.; Ugarte-Urra, Ignacio; Brooks, David H.; Williams, David R.; Hara, Hirohisa Bibcode: 2007PASJ...59S.713M Altcode: 2007arXiv0708.4309M The EUV Imaging Spectrometer (EIS) on the Hinode satellite is capable of measuring emission line center positions for Gaussian line profiles to a fraction of a spectral pixel, resulting in relative solar Doppler-shift measurements with an accuracy of a less than a km s-1 for strong lines. We show an example of the application of that capability to an active region sit-and-stare observation in which the EIS slit is placed at one location on the Sun and many exposures are taken while the spacecraft tracking keeps the same solar location within the slit. For the active region examined (NOAA10930), we find that significant intensity and Doppler-shift fluctuations as a function of time are present at a number of locations. These fluctuations appear to be similar to those observed in high-temperature emission lines with other space-borne spectroscopic instruments. With its increased sensitivity over earlier spectrometers and its ability to image many emission lines simultaneously, EIS should provide significant new constraints on Doppler-shift oscillations in the corona. Title: The X10 Flare on 29 October 2003: Was It Triggered by Magnetic Reconnection between Counter-Helical Fluxes? Authors: Liu, Yu; Kurokawa, Hiroki; Liu, Chang; Brooks, David H.; Dun, Jingping; Ishii, Takako T.; Zhang, Hongqi Bibcode: 2007SoPh..240..253L Altcode: 2007astro.ph..1794L Vector magnetograms taken at Huairou Solar Observing Station (HSOS) and Mees Solar Observatory (MSO) reveal that the super active region (AR) NOAA 10486 was a complex region containing current helicity flux of opposite signs. The main positive sunspots were dominated by negative helicity fields, while positive helicity patches persisted both inside and around the main positive sunspots. Based on a comparison of two days of deduced current helicity density, pronounced changes associated with the occurrence of an X10 flare that peaked at 20:49 UT on 29 October 2003 were noticed. The average current helicity density (negative) of the main sunspots decreased significantly by about 50%. Accordingly, the helicity densities of counter-helical patches (positive) were also found to decay by the same proportion or more. In addition, two hard X-ray (HXR) "footpoints" were observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) during the flare in the 50 - 100 keV energy range. The cores of these two HXR footpoints were adjacent to the positions of two patches with positive current helicity that disappeared after the flare. This strongly suggested that the X10 flare on 29 October 2003 resulted from reconnection between magnetic flux tubes having opposite current helicity. Finally, the global decrease of current helicity in AR 10486 by ∼50% can be understood as the helicity launched away by the halo coronal mass ejection (CME) associated with the X10 flare. Title: An Hα Surge Provoked by Moving Magnetic Features near an Emerging Flux Region Authors: Brooks, D. H.; Kurokawa, H.; Berger, T. E. Bibcode: 2007ApJ...656.1197B Altcode: We present a detailed study of Hα surges from cotemporal high-resolution multiwavelength images of NOAA AR 8227 obtained by the 50 cm Swedish Vacuum Solar Telescope (formerly situated on La Palma, Spain) and TRACE. We find that two kinds of collisions between opposite polarity magnetic flux produce the surges. First, one edge of an emerging flux region (EFR) collides with the preexisting magnetic field and causes continual surge activities, which have already been named EFR surges by previous authors. Secondly, moving magnetic features (MMFs), which emerge near the sunspot penumbra, pass through the ambient plasma and eventually collide with the opposite polarity magnetic field of the EFR. During their passage from the sunspot penumbra to the EFR, the MMFs constantly interacted with other magnetic elements and had a close relationship and showed similar flow patterns to Ca II K bright points. These brightenings were located at the leading edges of the MMFs. Cancellation of opposite polarity magnetic flux at the surge footpoint is observed, accompanied by chromospheric and coronal brightenings. We explain the evolutionary and morphological characteristics of the multiwavelength features associated with the Hα surges in both cases by the extension of previous 2D schematic models of reconnection in surges. Furthermore, by measuring the expansion velocity and photospheric magnetic field around the surge footpoint, we estimate a dimensionless reconnection rate of 0.04 (ratio of inflow velocity to Alfvén velocity). This is sufficient to produce a significant surge that heats the chromospheric plasma to coronal temperatures. Title: The in-flight monitoring and validation of the SOHO CDS Normal Incidence Spectrometer radiometric calibration Authors: Lang, J.; Brooks, D. H.; Lanzafame, A. C.; Martin, R.; Pike, C. D.; Thompson, W. T. Bibcode: 2007A&A...463..339L Altcode: The scientific return from an extreme-ultraviolet spectrometer depends on the accuracy and precision of its radiometric calibration. For the Coronal Diagnostic Spectrometer on SOHO, radiometric calibration started pre-launch in the laboratory and continued after launch by making comparison measurements of the same area of the Sun with calibrated sounding rocket payloads and also by intercalibration with the SUMER instrument on SOHO. The present work uses the measurement of line ratios to monitor and validate the calibration over the first six years of observation. As well as using branching ratios and line ratios independent of the electron temperature and density, line ratios dependent on electron temperature or density have also been used successfully to validate and monitor the calibration. The results indicate that, within the uncertainties, the radiometric calibration has been validated and maintained over the first six years of observations apart from three specific wavelengths, 338.98 Å, 315.0 Å, and 311.8 Å. Problems with lines at 608.4 Å, 303.4 Å (seen in second order), 335.4 Å, and 360.7 Å are attributed to difficulties with the burn-in correction. Title: The Intercalibration of SOHO EIT, CDS-NIS, and TRACE Authors: Brooks, David H.; Warren, Harry P. Bibcode: 2006ApJS..164..202B Altcode: Using coordinated observations of a quiet coronal region, we study the intercalibration of the CDS and EIT instruments on board the Solar and Heliospheric Observatory (SOHO) and the Transition Region and Coronal Explorer (TRACE). We derive the differential emission measure (DEM) distribution from CDS spectral line intensities and convolve it with EIT and TRACE temperature response functions, calculated with the latest atomic data from the CHIANTI database, to predict count rates in their observing channels. We examine different analysis methods and briefly discuss some more advanced aspects of atomic modeling such as the density dependence of the ionization fractions. We investigate the implications for our study using data from the ADAS database. We find that our CDS DEM can predict the TRACE and EIT 171 and 195 Å channel count rates to within 25%. However, the accuracy of the predictions depends on the ionization fractions and elemental abundances used. The TRACE 284 Å and EIT 284 and 304 Å filter predictions do not agree well with the observations, even after taking the contribution from the optically thick He II 304 Å line to the TRACE 284 Å channel into account. The different CDS DEM solutions we derive using different ionization fractions produce fairly similar results: the majority of the CDS line intensities used are reproduced to within 20% with only around one-fifth reproduced to worse than 50%. However, the comparison provides us with further clues with which to explain the discrepancies found for some lines, and highlights the need for accurate equilibrium ionization balance calculations even at low density. Title: On Deriving Plasma Velocity Information from CDS/NIS Observations: Application to the Dynamics of Blinkers Authors: Brooks, David Hamilton; Bewsher, Danielle Bibcode: 2006SoPh..234..257B Altcode: Using standard instrument software and two independently developed data reduction and analysis procedures, we re-examine the accuracy of plasma velocity information derived from data obtained by the Solar and Heliospheric Observatory (SOHO)-Coronal Diagnostic Spectrometer (CDS). We discuss only the Ov 629 Å line data obtained by the Normal Incidence Spectrometer (NIS) and analyse a quiet Sun (QS) and active region (AR) dataset. Using the QS data, we demonstrate that the well-known North-South tilt in wavelength along the NIS slit varies significantly with time, which is not accounted for in the standard CDS correction procedures. In addition, when residual N - S trends exist in the data after processing, they may not be detected, nor removed, using the standard analysis software. This underscores the need for careful analysis of velocity results for individual datasets when using standard correction procedures. Furthermore, even when the results obtained by the two independent methods are well correlated (coefficients greater than 0.9), discrepancies in the values of the derived Doppler velocities can remain (95% within ±5 km s−1). Therefore, we apply the results to examine the velocities obtained for EUV blinkers by previous authors. It is found that a strong correlation exists in the patterns of variation of the blinker velocities (> 0.98), even though there may be differences in their magnitudes. That is, in a clear majority of cases, the methods agree that a blinker is red-shifted or blue-shifted, although the uncertainty in the absolute velocity may be large. Title: Horizontal and Vertical Flow Structure in Emerging Flux Regions Authors: Kozu, Hiromichi; Kitai, Reizaburo; Brooks, David H.; Kurokawa, Hiroki; Yoshimura, Keiji; Berger, Thomas E. Bibcode: 2006PASJ...58..407K Altcode: In order to obtain an overall view of the flow structure of convective gas in emerging flux regions (EFRs), we studied three EFRs in two solar active regions, NOAA 8218 and NOAA 10774. Using the Local Correlation Tracking method, we found several horizontally divergent flow structures, which were stable over a period of 1 hour, in 2 EFRs in NOAA 8218. The horizontal flow velocities and the sizes of the structures were around 500m s-1 and about 4Mm in radius, respectively. We analyzed another dataset of NOAA 10774 using spectroscopic methods and found temporarily stable up-ward gas flows in the central part of the EFR. The line-of-sight velocities were around 150m s-1 and the size of the flow patch was 2 to 5Mm in radius. These results support our previous findings that convective-cell-like flow appears in the central part of an EFR. We estimated from these results that the depth of the flow cell in EFRs is about 600km, and the turn-over time of the cell is about 2 hours. Title: Ionization state, excited populations and emission of impurities in dynamic finite density plasmas: I. The generalized collisional radiative model for light elements Authors: Summers, H. P.; Dickson, W. J.; O'Mullane, M. G.; Badnell, N. R.; Whiteford, A. D.; Brooks, D. H.; Lang, J.; Loch, S. D.; Griffin, D. C. Bibcode: 2006PPCF...48..263S Altcode: 2005astro.ph.11561S The paper presents an integrated view of the population structure and its role in establishing the ionization state of light elements in dynamic, finite density, laboratory and astrophysical plasmas. There are four main issues, the generalized collisional-radiative picture for metastables in dynamic plasmas with Maxwellian free electrons and its particularizing to light elements, the methods of bundling and projection for manipulating the population equations, the systematic production/use of state selective fundamental collision data in the metastable resolved picture to all levels for collisonal-radiative modelling and the delivery of appropriate derived coefficients for experiment analysis. The ions of carbon, oxygen and neon are used in illustration. The practical implementation of the methods described here is part of the ADAS Project. Title: Transition Region Downflows in the Impulsive Phase of Solar Flares Authors: Kamio, S.; Kurokawa, H.; Brooks, D. H.; Kitai, R.; UeNo, S. Bibcode: 2005ApJ...625.1027K Altcode: We present observations of four flares that occurred during coordinated observations between the Coronal Diagnostic Spectrometer (CDS) on board SOHO and the Domeless Solar Telescope (DST) at Hida Observatory. We studied the evolution of relative Doppler velocities in the flare kernels by using He I (3.5×104 K), O V (2.2×105 K), and Mg IX (1.0×106 K) spectra obtained with high time cadence (42 s) SOHO CDS observations and the Hα monochromatic images obtained with the DST. We found that the transition region plasma of O V showed strong downward velocities up to 87 km s-1 simultaneously with the downflows in the lower temperature chromospheric emissions in He I and Hα during the impulsive phase of all four flares. From these results we suggest that the downflows in the transition region and the chromosphere are a common feature in the impulsive phase of flares. For the Mg IX line we did not detect any significant change in velocity, which suggests that the 106 K plasma was close to the intermediate temperature between the upflowing plasma (107 K) and the downflowing plasma (104-105 K). These are important for understanding the dynamics of the solar atmosphere in response to the sudden energy deposition of a flare. Title: ADAS analysis of the differential emission measure structure of the inner solar corona. II. A study of the "quiet Sun" inhomogeneities from SOHO CDS-NIS spectra Authors: Lanzafame, A. C.; Brooks, D. H.; Lang, J. Bibcode: 2005A&A...432.1063L Altcode: 2004astro.ph.12118L We present a study of the differential emission measure (DEM) of a “quiet Sun” area observed in the extreme ultraviolet at normal incidence by the Coronal Diagnostic Spectrometer (CDS) on the SOHO spacecraft. The data used for this work were taken using the NISATS observing sequence. This takes the full wavelength ranges from both the NIS channels (308 381 Å and 513 633 Å) with the 2 arcsec by 240 arcsec slit, which is the narrowest slit available, yielding the best spectral resolution. In this work we contrast the DEM from subregions of 2 × 80 arcsec2 with that obtained from the mean spectrum of the whole raster (20 × 240 arcsec2). We find that the DEM maintains essentially the same shape in the subregions, differing by a constant factor between 0.5 and 2 from the mean DEM, except in areas were the electron density is below 2 × 107 cm-3 and downflow velocities of 50 km s-1 are found in the transition region. Such areas are likely to contain plasma departing from ionisation equilibrium, violating the basic assumptions underlying the DEM method. The comparison between lines of Li-like and Be-like ions may provide further evidence of departure from ionisation equilibrium. We find also that line intensities tend to be lower where velocities of the order of 30 km s-1 or higher are measured in transition region lines. The DEM analysis is also exploited to improve the line identification performed by [CITE] and to investigate possible elemental abundance variations from region to region. We find that the plasma has composition close to photospheric in all the subregions examined.

Table 5 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/432/1063 Title: A Study of a Tiny Two-Ribbon Flare Driven by Emerging Flux Authors: Sakajiri, Takuma; Brooks, David H.; Yamamoto, Tetsuya; Shiota, Daikou; Isobe, Hiroaki; Akiyama, Sachiko; Ueno, Satoru; Kitai, Reizaburo; Shibata, Kazunari Bibcode: 2004ApJ...616..578S Altcode: We present observations of the eruption of a miniature filament that occurred near NOAA Active Region 9537 on 2001 July 14. The eruption was observed by the Hida Observatory Domeless Solar Telescope, in the Hα line center and +/-0.4 Å wings, the Solar and Heliospheric Observatory EUV Imaging Telescope (EIT) and Michelson Doppler Imager, and the Yohkoh Soft X-Ray Telescope (SXT). The miniature filament began to form and was clearly visible in Hα images by around 06:50 UT. It erupted about 25 minutes later, accompanied by a small two-ribbon subflare (with an area of 61 arcsec2). The two ribbons were also found to approach each other at a speed of 3.33 km s-1. We found that this event was caused by the emergence of new magnetic flux in a quiet region. The emerging flux appeared as a bright region in the EIT and SXT images taken on the previous day. It moved southward into an area of preexisting opposite-polarity flux, where a cancelling magnetic flux region was formed. The miniature filament then appeared, and we suggest that it played some role in inhibiting the release of energy by delaying reconnection between the emerging and preexisting flux, as evidenced by the disappearance of the bright region between opposite polarities in the EUV and soft X-ray images. Consequently, magnetic energy was stored as a result of the slow converging motion of the two opposite-polarity flux regions (0.17 km s-1). Reconnection below the filament provoked the filament eruption, and the two-ribbon flare occurred. Miniature filaments are thought to be small-scale analogs of large-scale filaments. Our observations also suggest some common properties between small-scale and large-scale flares. These results support the view that a unified magnetic reconnection model may be able to explain all scales of flares. Title: Hida Domeless Solar Telescope and SOHO Coronal Diagnostic Spectrometer Observations of Short-Duration Active Region Blinkers. II. Extreme-Ultraviolet Properties Authors: Brooks, D. H.; Kurokawa, H. Bibcode: 2004ApJ...611.1125B Altcode: No abstract at ADS Title: Short-Duration Active Region Brightenings Observed in the Extreme Ultraviolet and Hα by the Solar and Heliospheric Observatory Coronal Diagnostic Spectrometer and Hida Domeless Solar Telescope Authors: Brooks, D. H.; Kurokawa, H.; Kamio, S.; Fludra, A.; Ishii, T. T.; Kitai, R.; Kozu, H.; Ueno, S.; Yoshimura, K. Bibcode: 2004ApJ...602.1051B Altcode: We present the first detection of an Hα counterpart to the EUV blinker. The observations come from a coordinated campaign between the Hida Observatory Domeless Solar Telescope (DST) and the Solar and Heliospheric Observatory Coronal Diagnostic Spectrometer (CDS) conducted in 2002 July and August. Utilizing studies designed for high-cadence observations, many short-duration brightenings (<3 minutes) were identified in the He I λ584.334 and O V λ629.732 spectral lines in CDS data of active region NOAA 10039/10044. These brightenings show similar characteristics (increases in intensity, size) to longer duration EUV blinkers previously reported in active regions and the quiet Sun. Focusing on two events that show pronounced emission in the upper chromosphere (He I), we have been able to identify cospatial bright points in the lower chromosphere (Hα center, +/-0.5 Å) that show enhanced emission during the EUV blinker. These bright features have lifetimes similar to those of their EUV counterparts, and their peak intensities occur nearly simultaneously with the peak blinker intensities in the He I and O V lines. In both cases the He I and O V lines show excess line broadening at the peak of the event (>15 km s-1). Our high-cadence observations also enabled us to examine the dimensions and lifetimes of short-duration active region blinkers in detail. We find that the instrumental spatial and temporal resolution can combine to distort their characteristics: even short-duration blinkers appear to be composed of elementary brightening events. The optical brightenings also appear to closely follow the behavior of the elementary brightenings. The spatial and temporal relationships between the brightenings indicate a causal link between the EUV and Hα blinkers. Title: A Reexamination of the Evidence for Reconnection Inflow Authors: Chen, P. F.; Shibata, K.; Brooks, D. H.; Isobe, H. Bibcode: 2004ApJ...602L..61C Altcode: In the flare event of 1999 March 18, a threadlike structure observed in EUV Imaging Telescope images was found to move inward and collapse to an X-shaped configuration below the ejecta, strongly suggestive of the occurrence of magnetic reconnection. On the basis of the numerical results of a coronal mass ejection (CME) flare model, a similar threadlike structure in the Fe XII 195 Å image is reproduced in this Letter. It is found that, as in the observations, the thread experiences an outward motion in the preflare phase, which is followed by an inward motion. Our simulation suggests that its formation and outward motion in the preflare phase result from the CME expansion; after the onset of the flare, the threadlike structure is always located on the upstream side of the interface between the reconnection inflow and outflow. Its apparent inward motion, which is several times slower than the in situ reconnection inflow, is mainly attributed to the rising motion of the reconnection X-point. Title: A study of the causal relationship between the emergence of a twisted magnetic flux rope and a small Hα two-ribbon flare Authors: Brooks, D. H.; Kurokawa, H.; Yoshimura, K.; Kozu, H.; Berger, T. E. Bibcode: 2003A&A...411..273B Altcode: We present results from an analysis of a small two-ribbon flare which occurred above emerging flux in solar active region NOAA 8218 on 1998, May 13th and which was observed by the Swedish Vacuum Solar Telescope (SVST) on the island of La Palma, Spain. The relatively simple magnetic morphology and small size of the flare together with the high quality of the SVST observations allow us to examine the essential properties of flares in emerging flux regions in greater detail than before.

In this paper we compare and contrast the flaring emerging flux region simultaneously with a non-flaring emerging flux region within the same field of view. Unusual magnetic footpoint motions are observed in the flaring region, coincident with the Hα kernels, which result in a high level of shearing of the magnetic neutral line between opposite polarities. The Hα images show dark filament structures which form an inverted S-like shape immediately prior to the flare and then separate after the energy release disrupts the magnetic field. We interpret the motions and structures as strong evidence for the emergence of a twisted magnetic flux rope which developed a sheared configuration with the overlying magnetic field. In contrast the companion region shows separating footpoints, with apparent arch-like filament connections in the Hα images, consistent with the expected appearance of emerging flux. The observations imply that the attachment of the inverted S-shaped structure may be an observational consequence of the magnetic reconnection or untwisting of the field which triggered the flare. We also find some evidence that the increase in magnetic flux is faster in the flaring region.

Finally, we propose a simple schematic model of the emergence of a twisted magnetic flux rope and attached branch which can account for the observed footpoint motions and Hα structures of the flaring region. Such a model can, in principle, induce partial magnetic reconnection in the overlying coronal field and we found some evidence of coronal loop footpoint brightenings which support our conclusions. Our high resolution study supports the results of previous authors that even a small twisted structure in an emerging flux tube can be important for flare production. Title: Spectroscopic diagnostics of UV power and accretion in T Tauri stars Authors: Brooks, D. H.; Costa, V. M. Bibcode: 2003MNRAS.339..467B Altcode: It is known that in the upper atmospheres of the Sun and some late-type stars there is a systematic relationship between the optically thin total radiated power and the power emitted by single spectral lines. Using recently derived emission-measure distributions from IUE spectra for BP Tau, CV Cha, RY Tau, RU Lupi and GW Ori, we demonstrate that this is also true for classical T Tauri stars (CTTSs). As in the solar case it is found that the CIV resonance doublet at 1548 Å is also the most accurate indicator of the total radiated power from the atmospheres of CTTSs. Since the total radiated-power density in CTTSs exceeds that of the Sun by over three orders of magnitude we derive new analytic expressions that can be used to estimate the values for these stars. We also discuss the implications of these results with regard to the influence or absence of accretion in this sample of stars and suggest that the method can be used to infer properties of the geometrical structure of the emission regions. As a demonstration case we also use archived HST-GHRS data to estimate the total radiative losses in the UV emitting region of BP Tau. We find values of 4.57 × 109 erg cm-2 s-1 and 5.11 × 1032 erg s-1 dependent on the geometry of the emission region. These results are several orders of magnitude larger than would be expected if the UV emission came primarily from an atmosphere covered in solar-like active regions and are closer to values associated with solar flares. They lead to luminosity estimates of 0.07 and 0.13 Lsolar, respectively, which are in broad agreement with results obtained from theoretical accretion shock models. Taken together they suggest that accretion may well be the dominant contributor to the UV emission in BP Tau. Title: ADAS analysis of the differential emission measure structure of the inner solar corona . Application of the data adaptive smoothing approach to the SERTS-89 active region spectrum Authors: Lanzafame, A. C.; Brooks, D. H.; Lang, J.; Summers, H. P.; Thomas, R. J.; Thompson, A. M. Bibcode: 2002A&A...384..242L Altcode: The differential emission measure (DEM) of a solar active region is derived from SERTS-89 rocket data between 170 and 450 Å (Thomas & Neupert \cite{Thomas_Neupert:94}). The integral inversion to infer the DEM distribution from spectral line intensities is performed by the data adaptive smoothing approach (Thompson \cite{Thompson:90}, \cite{Thompson:91}). Our analysis takes into account the density dependence of both ionisation fractions and excitation coefficients according to the collisional-radiative theory as implemented in ADAS, the Atomic Data and Analysis Structure (McWhirter & Summers \cite{McWhirter_Summers:84}; Summers \cite{Summers:94}; Summers \cite{Summers:01}). Our strategy aims at checking, using observational data, the validity and limitations of the DEM method used for analysing solar EUV spectra. We investigate what information it is possible to extract, within defined limitations, and how the method can assist in a number of cases, e.g. abundance determination, spectral line identification, intensity predictions, and validation of atomic cross-sections. Using the above data and theory, it is shown that a spurious multiple peak in the DEM distribution between log (Te)=6.1 and 6.7, where Te is the electron temperature, may derive from an inaccurate treatment of the population densities of the excited levels and ionisation fractions or from using an integral inversion technique with arbitrary smoothing. Therefore, complex DEM structures, like those proposed for solar and stellar coronae by several authors, must be considered with caution. We address also the issue of systematic differences between iso-electronic sequences and show that these cannot be unambiguously detected in the coronal lines observed by SERTS. Our results indicate that a substantial improvement is required in the atomic modelling of the complex element Fe. The elemental abundance ratio Si/Ne is found to be close to its photospheric value. The same result may be true for the Fe/Ne abundance, but this latter result is uncertain because of the problems found with Fe. Title: Solar Si XI Line Ratios Observed by the Normal Incidence Spectrometer on SOHO CDS Authors: Lang, J.; Brooks, D. H.; O'Mullane, M. G.; Pike, C. D.; Summers, H. P.; Thompson, W. T. Bibcode: 2001SoPh..201...37L Altcode: New measurements of line intensity ratios in the Be-like ion Si xi are presented for observations of the quiet Sun, active regions, coronal holes and above-limb regions obtained using the Coronal Diagnostic Spectrometer on the Solar and Heliospheric Observatory. A model ion, constructed using the best available atomic data, is used to predict the line intensity ratios for a wide range of electron temperatures and densities. Comparisons of the theoretical ratios with the new intensity ratios as well as with those from previous solar observations and laboratory measurements are given. The usefulness of the ratios for electron temperature and density diagnostics, as well as for spectrometer calibration, is discussed. Title: An Optical/ultraviolet Study of RW Aur Authors: Gameiro, J. F.; Costa, V. M.; Brooks, D. H. Bibcode: 2001AGM....18S0707G Altcode: 2001AGAb...18R..78G RW Aur is a classical T Tauri star showing unusually high activity and complex patterns of variability in all optical emission and absorption lines. Periodic variations in the photospheric absorption features were also found by Petrov et al. (2001). These authors suggest that axi-symmetric magnetospheric accretion can account for the periodic phenomena and most of the variations observed in the optical data. They also made estimates of physical parameters (such as electron density) in different regions of the accretion stream. It seems clear that most of the excess emission is related to a strong magnetic field. Here we extend their analysis into the ultraviolet region of the spectrum using data from the IUE satellite. We use emission measure analysis and diagnostic line ratios to estimate the electron density in the UV emission zone. We also assess the variability in the ultraviolet spectrum. The results are compared to those obtained from the optical observations and provide a further quantitative test of the proposed accretion models. Title: A study of opacity in SOHO-SUMER and SOHO-CDS spectral observations. I. Opacity deduction at the limb Authors: Brooks, D. H.; Fischbacher, G. A.; Fludra, A.; Harrison, R. A.; Innes, D. E.; Landi, E.; Landini, M.; Lang, J.; Lanzafame, A. C.; Loch, S. D.; McWhirter, R. W. P.; Summers, H. P. Bibcode: 2000A&A...357..697B Altcode: A study is presented of the optical thickness of spectral lines of carbon, nitrogen and oxygen ions in the quiet sun. The observations consist of cross limb scans by the SUMER and CDS spectrometers on the SOHO spacecraft. A maximum likelihood spectral line fitting code has been adapted to analyse the multiplet profiles and to provide an assessment of errors in the count rates, especially of close lying components. Branching multiplet component ratios are presented as a function of position across the limb and contrasted with theoretical ratios in the optically thin case. The emergent fluxes are analysed in an escape probability model to deduce the optical thicknesses in the various spectral lines. Different specifications of the escape probability are examined. These are used to compare the observations with a geometric model of the emitting layer thickness across the limb and the thinning of the emitting layer above the limb. Classification of the deviations of quiet sun spectral line intensities from the optically thin case is given to assist in the critical selection of lines for differential emission measure analysis. This is linked to a general purpose code for the calculation of the influence of the line radiation fields on the local excited state population structure of the selected ions so that the fluxes in any spectral lines can be predicted. The Atomic Data and Analysis Structure (ADAS) was used for the atomic calculations and data of the paper. Title: The quiet Sun extreme ultraviolet spectrum observed in normal incidence by the SOHO coronal diagnostic spectrometer Authors: Brooks, D. H.; Fischbacher, G. A.; Fludra, A.; Harrison, R. A.; Innes, D. E.; Landi, E.; Landini, M.; Lang, J.; Lanzafame, A. C.; Loch, S. D.; McWhirter, R. W. P.; Summers, H. P.; Thompson, W. T. Bibcode: 1999A&A...347..277B Altcode: The extreme ultraviolet quiet Sun spectrum, observed at normal incidence by the Coronal Diagnostic Spectrometer on the SOHO spacecraft, is presented. The spectrum covers the wavelength ranges 308-381 Ä and 513-633 Ä and is based on data recorded at various positions on the solar disk between October 1996 and February 1997. Datasets at twelve of these `positions' were judged to be free from active regions and data faults and selected for detailed study. A constrained maximum likelihood spectral line fitting code was used to analyse the spectral features. In all over 200 spectrum lines have been measured and about 50% identified. The line identification process consisted of a number of steps. Firstly assignment of well known lines was made and used to obtain the primary wavelength calibration. Variations of wavelengths with position were used to assess the precision of calibration achievable. Then, an analysis method first used in studies with the CHASE experiment, was applied to the new observations. The behaviour of the intensities of lines from like ions over the twelve positions, called `position patterns', were used to distinguish probable emitters of weaker lines and extend the identifications. Spectral line widths and expected multiplet intensities were examined to identify lines and probable blends. The product of the study is a table which includes all clearly observed emission lines, their measured wavelengths, widths and count rates. Adopted laboratory wavelengths, ion and transition designations are also presented for identified lines. The table has an estimate of the uncertainty of the count rates based on a statistical analysis of the variability of each line. A marked spectrum is also provided. Title: EUV Spectral Variability and Non-Equilibrium Ionisation in the 'Quiet' Sun Authors: Brooks, D. H.; Summers, H. P.; Harrison, R. A.; Lang, J.; Lanzafame, A. C. Bibcode: 1998Ap&SS.261...91B Altcode: 1999Ap&SS.261...91B Recent spectroscopic observations by the Solar and Heliospheric Observatory (SOHO) have revealed the dynamic nature of even the 'quiet' Sun. Spectral variability data clearly show that dynamics in the solar upper atmosphere take place on timescales shorter than those of ionisation relaxation. Accuracy in the interpretation of diagnostic spectral data can only be maintained through detailed quantitative modelling of the relevant atomic physics. In particular, dynamical plasma models of the solar plasma require matching dynamic atomic models to underpin conclusions drawn from the spectral reduction. The inclusion of important effects such as finite plasma electron density and the influence of metastable levels is essential to reduce the uncertainties associated with equilibrium assumptions.