Author name code: piskunov ADS astronomy entries on 2022-09-14 author:"Piskunov, Nikolai" ------------------------------------------------------------------------ Title: Evolution of brightness and magnetic features of young solar-type stars - I. The young G star HIP 89829 Authors: Perugini, G. M.; Marsden, S. C.; Waite, I. A.; Jeffers, S. V.; Piskunov, N.; Shaw, N.; Burton, D. M.; Mengel, M. W.; Hughes, J. E.; Hébrard, E. M. Bibcode: 2021MNRAS.508.3304P Altcode: 2021MNRAS.tmp.2515P The evolution in latitude of sunspots is a key feature of the cyclic solar dynamo. Here, we present the results of a spectroscopic and spectropolarimetric monitoring campaign on the young (~20 Myr old) early G star HIP 89829, in order to investigate potential evolution in the distribution of the star's spots and magnetic features. Our analysis of this G5V star spans eight epochs, from June 2010 to August 2015. The techniques of Doppler imaging and Zeeman-Doppler imaging were used to create brightness maps for each epoch and magnetic maps for two epochs. The brightness images show the star to have stable spot features with two main spot latitudes - a polar spot, often seen on young rapidly rotating stars such as this, and another highly unusual group of large spot features around the 20° and 30° latitudes. These lower spot latitudes appear to be rather stable over the 5 yr of observations. We included a solar-type differential rotation law into the imaging process and measured near-solid-body rotation for epochs where sufficient data exist for this analysis. The magnetic features show a dominant poloidal and a weaker toroidal magnetic field for both Stokes V epochs, which is unusual for a star with a rapid rotation period of 0.57 d. We conclude that HIP 89829 is an active young solar-type star with long-lived spots and near-solid-body rotation. Title: HIRES, the High-resolution Spectrograph for the ELT Authors: Marconi, A.; Abreu, M.; Adibekyan, V.; Aliverti, M.; Allende Prieto, C.; Amado, P.; Amate, M.; Artigau, E.; Augusto, S.; Barros, S.; Becerril, S.; Benneke, B.; Bergin, E.; Berio, P.; Bezawada, N.; Boisse, I.; Bonfils, X.; Bouchy, F.; Broeg, C.; Cabral, A.; Calvo-Ortega, R.; Canto Martins, B. L.; Chazelas, B.; Chiavassa, A.; Christensen, L.; Cirami, R.; Coretti, I.; Covino, S.; Cresci, G.; Cristiani, S.; Cunha Parro, V.; Cupani, G.; de Castro Leão, I.; Renan de Medeiros, J.; Furlande Souza, M. A.; Di Marcantonio, P.; Di Varano, I.; D'Odorico, V.; Doyon, R.; Drass, H.; Figueira, P.; Belen Fragoso, A.; Uldall Fynbo, J. P.; Gallo, E.; Genoni, M.; González Hernández, J.; Haehnelt, M.; Hlavacek-Larrondo, J.; Hughes, I.; Huke, P.; Humphrey, A.; Kjeldsen, H.; Korn, A.; Kouach, D.; Landoni, M.; Liske, J.; Lovis, C.; Lunney, D.; Maiolino, R.; Malo, L.; Marquart, T.; Martins, C.; Mason, E.; Molaro, P.; Monnier, J.; Monteiro, M.; Mordasini, C.; Morris, T.; Mucciarelli, A.; Murray, G.; Niedzielski, A.; Nunes, N.; Oliva, E.; Origlia, L.; Pallé, E.; Pariani, G.; Parr-Burman, P.; Peñate, J.; Pepe, F.; Pinna, E.; Piskunov, N.; Rasilla Piñeiro, J. L.; Rebolo, R.; Rees, P.; Reiners, A.; Riva, M.; Romano, D.; Rousseau, S.; Sanna, N.; Santos, N.; Sarajlic, M.; Shen, T. -C.; Sortino, F.; Sosnowska, D.; Sousa, S.; Stempels, E.; Strassmeier, K.; Tenegi, F.; Tozzi, A.; Udry, S.; Valenziano, L.; Vanzi, L.; Weber, M.; Woche, M.; Xompero, M.; Zackrisson, E.; Zapatero Osorio, M. R. Bibcode: 2021Msngr.182...27M Altcode: 2020arXiv201112317M HIRES will be the high-resolution spectrograph at optical and near-infrared (NIR) wavelengths for ESO's Extremely Large Telescope (ELT). It will consist of three fibre-fed spectrographs providing a wavelength coverage of 0.4-1.8 µm (with a goal of 0.35-1.8 µm) at a spectral resolution of ~ 100 000. Fibre-feeding allows HIRES to have several interchangeable observing modes, including a single-conjugate adaptive optics (SCAO) module and a small diffraction-limited integral field unit in the NIR. It will therefore be able to operate in both seeing- and diffraction-limited modes. HIRES will address a wide range of science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Some of the top science cases will be the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars (Pop III), tests on the stability of Nature's fundamental couplings, and the direct detection of the cosmic acceleration. The HIRES consortium is composed of more than 30 institutes from 14 countries, forming a team of more than 200 scientists and engineers. Title: Accurate Short-Characteristics Radiative Transfer in A Numerical Tool for Astrophysical RESearch (ANTARES) Authors: Kostogryz, Nadiia M.; Kupka, Friedrich; Piskunov, Nikolai; Fabbian, Damian; Krüger, Daniel; Gizon, Laurent Bibcode: 2021SoPh..296...46K Altcode: We aim to improve the accuracy of radiative energy transport in three-dimensional radiation hydrodynamical simulations in ANTARES (A Numerical Tool for Astrophysical RESearch). We implement in the ANTARES short-characteristics numerical schemes a modification of the Bézier interpolant solver. This method yields a smoother surface structure in simulations of solar convection and reduces the artifacts appearing due to the limited number of rays along which the integration is done. Reducing such artifacts leads to increased stability of the code. We show that our new implementation achieves a better agreement of the temperature structure and its gradient with a semi-empirical model derived from observations, as well as of synthetic spectral-line profiles with the observed solar spectrum. Title: Optimal extraction of echelle spectra: Getting the most out of observations Authors: Piskunov, Nikolai; Wehrhahn, Ansgar; Marquart, Thomas Bibcode: 2021A&A...646A..32P Altcode: 2020arXiv200805827P Context. The price of instruments and observing time on modern telescopes is quickly increasing. Therefore, it is worth revisiting the data reduction algorithms to extract every bit of scientific information from available observations. Echelle spectrographs are typical instruments used in high-resolution spectroscopy, but attempts to improve the wavelength coverage and versatility of these instruments has resulted in a complicated and variable footprint of the entrance slit projection onto the science detector. Traditional spectral extraction methods generally fail to perform a truly optimal extraction when the slit image is not aligned with the detector columns and, instead, is tilted or even curved.
Aims: Here, we present the mathematical algorithms and examples of their application to the optimal extraction and the following reduction steps for echelle spectrometers equipped with an entrance slit that is imaged with various distortions. The new method minimises the loss of spectral resolution, maximises the signal-to-noise ratio, and efficiently identifies local outliers. In addition to the new optimal extraction, we present order splicing and a more robust continuum normalisation algorithm.
Methods: We developed and implemented new algorithms that create a continuum-normalised spectrum. In the process, we account for the (variable) tilt or curvature of the slit image on the detector and achieve optimal extraction without prior assumptions about the slit illumination. Thus, the new method can handle arbitrary image slicers, slit scanning, and other observational techniques aimed at increasing the throughput or dynamic range.
Results: We compare our methods with other techniques for different instruments to illustrate the superior performance of the new algorithms compared to commonly used procedures.
Conclusions: Advanced modelling of the focal plane requires significant computational effort but it has proven worthwhile thanks to the retrieval of a greater store of science information from every observation. The described algorithms and tools are freely available as part of our PyReduce package. Title: ELT-HIRES, the high resolution spectrograph for the ELT: the Phase A study and the path to construction Authors: Marconi, A.; Abreu, M.; Adibekyan, V.; Aliverti, M.; Allende Prieto, C.; Amado, P.; Amate, M.; Artigau, E.; Augusto, S.; Barros, S.; Becerril, S.; Benneke, B.; Bergin, E.; Berio, P.; Bezawada, N.; Boisse, I.; Bonfils, X.; Bouchy, F.; Broeg, C.; Cabral, A.; Calvo-Ortega, R.; Canto Martins, B. L.; Chazelas, B.; Chiavassa, A.; Christensen, L.; Cirami, R.; Coretti, I.; Covino, S.; Cresci, G.; Cristiani, S.; Cunha Parro, V.; Cupani, G.; D'Odorico, V.; de Castro Leão, I.; de Medeiros, J. R.; de Souza, M.; Di Marcantonio, P.; Di Varano, I.; Doyon, R.; Drass, H.; Figueira, P.; Fragoso, A.; Fynbo, J.; Gallo, E.; Genoni, M.; González Hernández, J.; Gratton, R.; Haehnelt, M.; Hansen, C.; Hlavacek-Larrondo, J.; Hughes, I.; Huke, P.; Humphrey, A.; Kjeldsen, H.; Korn, A.; Kouach, D.; Landoni, M.; Liske, J.; Lovis, C.; Lunney, D.; Maiolino, R.; Malo, L.; Marquart, T.; Martins, C. J. A. P.; Maslowski, P.; Mason, E.; Micela, G.; Molaro, P.; Monnier, J.; Monteiro, M.; Mordasini, C.; Morris, T.; Mucciarelli, A.; Murray, G.; Niedzielski, A.; Niemczura, E.; Nisini, B.; Nunes, N.; Oliva, E.; Origlia, L.; Pallé, E.; Pariani, G.; Parr-Burman, P.; Pasquini, L.; Peñate, J.; Pepe, F.; Pietrzynski, G.; Pinna, E.; Piskunov, N.; Pollo, A.; Rasilla, J.; Rebolo, R.; Rees, P.; Reiners, A.; Riva, M.; Romano, D.; Rousseau, S.; Sanna, N.; Sarajlic, M.; Shen, T. -C.; Sortino, F.; Sosnowska, D.; Sousa, S.; Stempels, E.; Strassmeier, K.; Tenegi, F.; Tozzi, A.; Udry, S.; Valenziano, L.; Vanzi, L.; Weber, M.; Woche, M.; Xompero, M.; Zackrisson, E.; Zapatero Osorio, M. R. Bibcode: 2020SPIE11447E..26M Altcode: HIRES is the high-resolution spectrograph of the European Extremely Large Telescope at optical and near-infrared wavelengths. It consists of three fibre-fed spectrographs providing a wavelength coverage of 0.4-1.8 µm (goal 0.35-2.4 µm) at a spectral resolution of 100,000. The fibre-feeding allows HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU in the NIR. Therefore, it will be able to operate both in seeing- and diffraction-limited modes. Its modularity will ensure that HIRES can be placed entirely on the Nasmyth platform, if enough mass and volume is available, or part on the Nasmyth and part in the Coud`e room. ELT-HIRES has a wide range of science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars (PopIII), tests on the stability of Nature's fundamental couplings, and the direct detection of the cosmic acceleration. The HIRES consortium is composed of more than 30 institutes from 14 countries, forming a team of more than 200 scientists and engineers. Title: Shine BRITE: shedding light on stellar variability through advanced models Authors: Fabbian, D.; Kupka, F.; Krüger, D.; Kostogryz, N. M.; Piskunov, N. Bibcode: 2020svos.conf..155F Altcode: 2020arXiv200201560F The correct interpretation of the large amount of complex data from next-generation (in particular, space-based) observational facilities requires a very strong theoretical underpinning. One can predict that, in the near future, the use of atmospheric models obtained with three-dimensional (3-D) radiation magneto-hydrodynamics (RMHD) codes, coupled with advanced radiative transfer treatment including non-local thermodynamic equilibrium (non-LTE) effects and polarisation, will become the norm. In particular, stellar brightness variability in cool stars (i.e., spectral types F-- M) can be caused by several different effects besides pulsation. In this review we have briefly discussed some published results, and mentioned aspects of recent progress. It then attempted to peek into what the future may hold for understanding this important aspect of the lives of stars. Title: Hyperfine Splitting in the VALD Database of Spectral-line Parameters Authors: Pakhomov, Yu. V.; Ryabchikova, T. A.; Piskunov, N. E. Bibcode: 2019ARep...63.1010P Altcode: 2019arXiv191103189P The Vienna Atomic Line Database (VALD) has been supplemented with new data and new functionality—the possibility of taking into account the effect of hyperfine splitting (HFS) of atomic levels in the analysis of line profiles. This has been done through the creation of an ancillary SQL database with the HFS constants for atomic levels of 58 isotopes of 30 neutral and singly-ionized atoms. The completeness of the collected data and new opportunities for studies of stars of various spectral types is analyzed. The database enables analysis of splitting of up to 60% of lines with measurable effects in the ultraviolet (λ ≳ 1000 Å ), and up to 100% of such lines in the optical and infrared ranges (λ ≲ 25 000 Å ) for A-M stars. In the spectra of hot O-B stars, it is necessary to use laboratory measurements for atoms in the second and higher stages of ionization. Title: Evaluation of the Recent Atomic Data for Fe uc(i) Lines Based on Solar and Stellar Spectra Authors: Ryabchikova, T.; Piskunov, N.; Sitnova, T. Bibcode: 2019SoPh..294..156R Altcode: We performed an extensive comparative analysis of the recent experimental data on Fe I transition probabilities (TP) based on the observed solar and stellar spectra. This work is part of the Vienna Atomic Line database (VALD) activities. Our motivation is to keep the VALD line list as complete as possible and provide VALD users with substantiated recommendations for the most accurate atomic data. For assessment of data quality we choose the "normal" (as opposed to peculiar and/or magnetic) Main Sequence sharp-line stars of different effective temperatures with accurately known atmospheric parameters: Sun, Procyon, HD 32115, and 21 Peg. Theoretical spectra of these stars were synthesized for 1D plane-parallel model atmospheres accounting for non-local thermodynamic equilibrium (NLTE) effects, and then they were compared with the observations. For all of the stars we derived atmospheric abundances based on the new and previous experimental TP. When using the new TPs the best agreement for iron is achieved with the TP of the Hannover group (Bard, Kock, and Kock, Astron. Astrophys.248, 315, 1991; Bard and Kock, Astron. Astrophys.282, 1014, 1994). The Hannover set is recommended as the primary source of transition probabilities in stellar abundance analysis. The new TP data significantly increase the number of spectral lines of Fe I in the optical and red spectral regions available for accurate abundance analysis of stars in a wide range of temperatures and metallicities. Comparison with the observed stellar spectra invalidates some new experimental data despite the small given uncertainty of the laboratory measurements. Finally, we note the importance of accurate line-broadening data. Title: Model-free inverse method for transit imaging of stellar surfaces. Using transit surveys to map stellar spot coverage Authors: Aronson, Erik; Piskunov, Nikolai Bibcode: 2019A&A...630A.122A Altcode: 2019arXiv190206555A Context. We present a model-free method for mapping surface brightness variations.
Aims: We aim to develop a method that is not dependent on either stellar atmosphere models or limb-darkening equation. This method is optimized for exoplanet transit surveys such that a large database of stellar spot coverage can be created.
Methods: The method uses light curves from several transit events of the same system. These light curves are phase-folded and median-combined to for a high-quality light curve without temporal local brightness variations. Stellar specific intensities are extracted from this light curve using a model-free method. We search individual light curves for departures from the median-combined light curve. Such departures are interpreted as brightness variations on the stellar surface. A map of brightness variations on the stellar surface is produced by finding the brightness distribution that can produce a synthetic light curve that fits observations well. No assumptions about the size, shape, or contrast of brightness variations are made.
Results: We successfully reproduce maps of stellar disks from both synthetic data and archive observations from FORS2, the visual and near UV FOcal Reducer and low dispersion Spectrograph for the Very Large Telescope (VLT). Title: Spot evolution on LQ Hya from 2006-2017: temperature maps based on SOFIN and FIES data Authors: Cole-Kodikara, Elizabeth M.; Käpylä, Maarit J.; Lehtinen, Jyri J.; Hackman, Thomas; Ilyin, Ilya V.; Piskunov, Nikolai; Kochukhov, Oleg Bibcode: 2019A&A...629A.120C Altcode: 2019arXiv190408713C Context. LQ Hya is one of the most frequently studied young solar analogue stars. Recently, it has been observed to show intriguing behaviour when analysing long-term photometry. For instance, from 2003-2009, a coherent spot structure migrating in the rotational frame was reported by various authors. However, ever since, the star has entered a chaotic state where coherent structures seem to have disappeared and rapid phase jumps of the photometric minima occur irregularly over time.
Aims: LQ Hya is one of the stars included in the SOFIN/FIES long-term monitoring campaign extending over 25 yr. Here, we publish new temperature maps for the star during 2006-2017, covering the chaotic state of the star.
Methods: We used a Doppler imaging technique to derive surface temperature maps from high-resolution spectra.
Results: From the mean temperatures of the Doppler maps, we see a weak but systematic increase in the surface temperature of the star. This is consistent with the simultaneously increasing photometric magnitude. During nearly all observing seasons, we see a high-latitude spot structure which is clearly non-axisymmetric. The phase behaviour of this structure is very chaotic but agrees reasonably well with the photometry. Equatorial spots are also frequently seen, but we interpret many of them to be artefacts due to the poor to moderate phase coverage.
Conclusions: Even during the chaotic phase of the star, the spot topology has remained very similar to the higher activity epochs with more coherent and long-lived spot structures. In particular, we see high-latitude and equatorial spot activity, the mid latitude range still being most often void of spots. We interpret the erratic jumps and drifts in phase of the photometric minima to be caused by changes in the high-latitude spot structure rather than the equatorial spots.

Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. Title: Starspot activity of HD 199178. Doppler images from 1994-2017 Authors: Hackman, T.; Ilyin, I.; Lehtinen, J. J.; Kochukhov, O.; Käpylä, M. J.; Piskunov, N.; Willamo, T. Bibcode: 2019A&A...625A..79H Altcode: 2018arXiv181202013H Context. Studying the spots of late-type stars is crucial for distinguishing between the various proposed dynamo mechanisms believed to be the main cause of starspot activity. For this research it is important to collect observation time series that are long enough to unravel both long- and short-term spot evolution. Doppler imaging is a very efficient method for studying spots of stars that cannot be angularly resolved.
Aims: High-resolution spectral observations during 1994-2017 are analysed in order to reveal long- and short-term changes in the spot activity of the FK Comae-type subgiant HD 199178.
Methods: Most of the observations were collected with the Nordic Optical Telescope. The Doppler imaging temperature maps were calculated using an inversion technique based on Tikhonov regularisation and utilising multiple spectral lines.
Results: We present a unique series of 41 temperature maps spanning more than 23 years. All reliable images show a large cool spot region centred near the visible rotation pole. Some lower latitude cool features are also recovered, although the reliability of these is questionable. There is an expected anti-correlation between the mean surface temperature and the spot coverage. Using the Doppler images, we construct the equivalent of a solar butterfly diagram for HD 199178.
Conclusions: HD 199178 clearly has a long-term large and cool spot structure at the rotational pole. This spot structure dominated the spot activity during the years 1994-2017. The size and position of the structure has evolved with time, with a gradual increase during the last years. The lack of lower latitude features prevents the determination of a possible differential rotation.

The spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/625/A79Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. Title: VizieR Online Data Catalog: HD199178 1994-2017 spectra (Hackman+, 2019) Authors: Hackman, T.; Ilyin, I.; Lehtinen, J. J.; Kochukhov, O.; Kaepylae, M. J.; Piskunov, N.; Willamo, T. Bibcode: 2019yCat..36250079H Altcode: The instruments used where the Rozhen high resolution spectrograph (R=35000), SOFIN (R=80000, R=1400000) and FIES (R=67000). Observation times and S/N-ratios are given in the log-file. The spectral regions used for Doppler images varied with the instruments and seasons. The regions were centred around the following wavelengths (in Angstroms): 6265, 6411, 6431, 6439 6644, 6663 and 7511.

(2 data files). Title: 4MOST: Project overview and information for the First Call for Proposals Authors: de Jong, R. S.; Agertz, O.; Berbel, A. A.; Aird, J.; Alexander, D. A.; Amarsi, A.; Anders, F.; Andrae, R.; Ansarinejad, B.; Ansorge, W.; Antilogus, P.; Anwand-Heerwart, H.; Arentsen, A.; Arnadottir, A.; Asplund, M.; Auger, M.; Azais, N.; Baade, D.; Baker, G.; Baker, S.; Balbinot, E.; Baldry, I. K.; Banerji, M.; Barden, S.; Barklem, P.; Barthélémy-Mazot, E.; Battistini, C.; Bauer, S.; Bell, C. P. M.; Bellido-Tirado, O.; Bellstedt, S.; Belokurov, V.; Bensby, T.; Bergemann, M.; Bestenlehner, J. M.; Bielby, R.; Bilicki, M.; Blake, C.; Bland-Hawthorn, J.; Boeche, C.; Boland, W.; Boller, T.; Bongard, S.; Bongiorno, A.; Bonifacio, P.; Boudon, D.; Brooks, D.; Brown, M. J. I.; Brown, R.; Brüggen, M.; Brynnel, J.; Brzeski, J.; Buchert, T.; Buschkamp, P.; Caffau, E.; Caillier, P.; Carrick, J.; Casagrande, L.; Case, S.; Casey, A.; Cesarini, I.; Cescutti, G.; Chapuis, D.; Chiappini, C.; Childress, M.; Christlieb, N.; Church, R.; Cioni, M. -R. L.; Cluver, M.; Colless, M.; Collett, T.; Comparat, J.; Cooper, A.; Couch, W.; Courbin, F.; Croom, S.; Croton, D.; Daguisé, E.; Dalton, G.; Davies, L. J. M.; Davis, T.; de Laverny, P.; Deason, A.; Dionies, F.; Disseau, K.; Doel, P.; Döscher, D.; Driver, S. P.; Dwelly, T.; Eckert, D.; Edge, A.; Edvardsson, B.; Youssoufi, D. E.; Elhaddad, A.; Enke, H.; Erfanianfar, G.; Farrell, T.; Fechner, T.; Feiz, C.; Feltzing, S.; Ferreras, I.; Feuerstein, D.; Feuillet, D.; Finoguenov, A.; Ford, D.; Fotopoulou, S.; Fouesneau, M.; Frenk, C.; Frey, S.; Gaessler, W.; Geier, S.; Gentile Fusillo, N.; Gerhard, O.; Giannantonio, T.; Giannone, D.; Gibson, B.; Gillingham, P.; González-Fernández, C.; Gonzalez-Solares, E.; Gottloeber, S.; Gould, A.; Grebel, E. K.; Gueguen, A.; Guiglion, G.; Haehnelt, M.; Hahn, T.; Hansen, C. J.; Hartman, H.; Hauptner, K.; Hawkins, K.; Haynes, D.; Haynes, R.; Heiter, U.; Helmi, A.; Aguayo, C. H.; Hewett, P.; Hinton, S.; Hobbs, D.; Hoenig, S.; Hofman, D.; Hook, I.; Hopgood, J.; Hopkins, A.; Hourihane, A.; Howes, L.; Howlett, C.; Huet, T.; Irwin, M.; Iwert, O.; Jablonka, P.; Jahn, T.; Jahnke, K.; Jarno, A.; Jin, S.; Jofre, P.; Johl, D.; Jones, D.; Jönsson, H.; Jordan, C.; Karovicova, I.; Khalatyan, A.; Kelz, A.; Kennicutt, R.; King, D.; Kitaura, F.; Klar, J.; Klauser, U.; Kneib, J. -P.; Koch, A.; Koposov, S.; Kordopatis, G.; Korn, A.; Kosmalski, J.; Kotak, R.; Kovalev, M.; Kreckel, K.; Kripak, Y.; Krumpe, M.; Kuijken, K.; Kunder, A.; Kushniruk, I.; Lam, M. I.; Lamer, G.; Laurent, F.; Lawrence, J.; Lehmitz, M.; Lemasle, B.; Lewis, J.; Li, B.; Lidman, C.; Lind, K.; Liske, J.; Lizon, J. -L.; Loveday, J.; Ludwig, H. -G.; McDermid, R. M.; Maguire, K.; Mainieri, V.; Mali, S.; Mandel, H.; Mandel, K.; Mannering, L.; Martell, S.; Martinez Delgado, D.; Matijevic, G.; McGregor, H.; McMahon, R.; McMillan, P.; Mena, O.; Merloni, A.; Meyer, M. J.; Michel, C.; Micheva, G.; Migniau, J. -E.; Minchev, I.; Monari, G.; Muller, R.; Murphy, D.; Muthukrishna, D.; Nandra, K.; Navarro, R.; Ness, M.; Nichani, V.; Nichol, R.; Nicklas, H.; Niederhofer, F.; Norberg, P.; Obreschkow, D.; Oliver, S.; Owers, M.; Pai, N.; Pankratow, S.; Parkinson, D.; Paschke, J.; Paterson, R.; Pecontal, A.; Parry, I.; Phillips, D.; Pillepich, A.; Pinard, L.; Pirard, J.; Piskunov, N.; Plank, V.; Plüschke, D.; Pons, E.; Popesso, P.; Power, C.; Pragt, J.; Pramskiy, A.; Pryer, D.; Quattri, M.; Queiroz, A. B. d. A.; Quirrenbach, A.; Rahurkar, S.; Raichoor, A.; Ramstedt, S.; Rau, A.; Recio-Blanco, A.; Reiss, R.; Renaud, F.; Revaz, Y.; Rhode, P.; Richard, J.; Richter, A. D.; Rix, H. -W.; Robotham, A. S. G.; Roelfsema, R.; Romaniello, M.; Rosario, D.; Rothmaier, F.; Roukema, B.; Ruchti, G.; Rupprecht, G.; Rybizki, J.; Ryde, N.; Saar, A.; Sadler, E.; Sahlén, M.; Salvato, M.; Sassolas, B.; Saunders, W.; Saviauk, A.; Sbordone, L.; Schmidt, T.; Schnurr, O.; Scholz, R. -D.; Schwope, A.; Seifert, W.; Shanks, T.; Sheinis, A.; Sivov, T.; Skúladóttir, Á.; Smartt, S.; Smedley, S.; Smith, G.; Smith, R.; Sorce, J.; Spitler, L.; Starkenburg, E.; Steinmetz, M.; Stilz, I.; Storm, J.; Sullivan, M.; Sutherland, W.; Swann, E.; Tamone, A.; Taylor, E. N.; Teillon, J.; Tempel, E.; ter Horst, R.; Thi, W. -F.; Tolstoy, E.; Trager, S.; Traven, G.; Tremblay, P. -E.; Tresse, L.; Valentini, M.; van de Weygaert, R.; van den Ancker, M.; Veljanoski, J.; Venkatesan, S.; Wagner, L.; Wagner, K.; Walcher, C. J.; Waller, L.; Walton, N.; Wang, L.; Winkler, R.; Wisotzki, L.; Worley, C. C.; Worseck, G.; Xiang, M.; Xu, W.; Yong, D.; Zhao, C.; Zheng, J.; Zscheyge, F.; Zucker, D. Bibcode: 2019Msngr.175....3D Altcode: 2019arXiv190302464D We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R 20 000). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations. Title: VizieR Online Data Catalog: V-band differential photometry for V889 Her (Willamo+, 2019) Authors: Willamo, T.; Hackman, T.; Lehtinen, J. J.; Kapyla, M. J.; Ilyin, I.; Henry, G. W.; Jetsu, L.; Kochukhov, O.; Piskunov, N. Bibcode: 2019yCat..36220170W Altcode: We present the Johnson V-band differential photometry of V889 Her, obtained with the Tennessee State University T3 0.4m Automatic Photoelectric Telescope. The analysis of the data has been done using the comparison star HD 171286; the V-magnitude of V889 Her is gained by adding the V-magnitude of HD 171286 (V=6.84; Oja, 1987A&AS...71..561O) to each data point. For further analysis we use the Continous Period Search-method (CPS; Lehtinen et al., 2011A&A...527A.136L) to derive mean magnitudes for longer sets of data.

(1 data file). Title: Long-term spot monitoring of the young solar analogue V889 Herculis Authors: Willamo, T.; Hackman, T.; Lehtinen, J. J.; Käpylä, M. J.; Ilyin, I.; Henry, G. W.; Jetsu, L.; Kochukhov, O.; Piskunov, N. Bibcode: 2019A&A...622A.170W Altcode: 2018arXiv181105330W Context. Starspots are important manifestations of stellar magnetic activity. By studying their behaviour in young solar analogues, we can unravel the properties of their magnetic cycles. This gives crucial information of the underlying dynamo process. Comparisons with the solar cycle enable us to infer knowledge about how the solar dynamo has evolved during the Sun's lifetime.
Aims: Here we study the correlation between photometric brightness variations, spottedness, and mean temperature in V889 Her, a young solar analogue. Our data covers 18 years of spectroscopic and 25 years of photometric observations.
Methods: We use Doppler imaging to derive temperature maps from high-resolution spectra. We use the Continuous Period Search method to retrieve mean V-magnitudes from photometric data.
Results: Our Doppler imaging maps show a persistent polar spot structure varying in strength. This structure is centred slightly off the rotational pole. The mean temperature derived from the maps shows an overall decreasing trend, as does the photometric mean brightness, until it reaches its minimum around 2017. The filling factor of cool spots, however, shows only a weak tendency to anti-correlate with the decreasing mean brightness.
Conclusions: We interpret V889 Her to have entered into a grand maximum in its activity. The clear relation between the mean temperature of the Doppler imaging surface maps and the mean magnitude supports the reliability of the Doppler images. The lack of correlation between the mean magnitude and the spottedness may indicate that bright features in the Doppler images are real.

Photometric data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A170Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Based on observations made with the HARPSpol instrument on the ESO 3.6m telescope at La Silla (Chile), under the programme ID 091.D-0836. Title: VALD: The Meeting Point of Data Producers and Data Users Authors: Ryabchikova, Tatiana; Pakhomov, Yury; Piskunov, Nikolai Bibcode: 2018Galax...6...93R Altcode: Vienna Atomic Line Database (VALD) contains data on atomic and molecular energy levels and parameters of spectral lines required for stellar spectra analysis. Hundreds of millions of lines for fine spectral synthesis and for opacity calculations are collected in the present version of VALD (VALD3). Critical evaluation of the data and the diversity of extraction tools support the high popularity of VALD among users. The data model of VALD3 incorporates obligatory links to the bibliography making our database more attractive as a publishing platform for data producers. The VALD data quality and completeness are constantly improving allowing better reproduction of stellar spectra. To illustrate continuous evolution of the data content we present a comparative analysis of the recent experimental and theoretical atomic data for Fe-group elements, which will be included in the next VALD release. This release will also include a possibility for extracting the line data with full isotopic and hyperfine structures. Title: A unique infrared spectropolarimetric unit for CRIRES+ Authors: Piskunov, Nikolai; Stempels, Eric; Lavail, Alexis; Escuti, Michael; Snik, Frans; Dolgopolov, Andrey; Rozel, Milan; Durandet, Candice; Hatzes, Artie; Bristow, Paul; Brucalassi, Anna; Cumani, Claudio; Dorn, Reinhold J.; Haimerl, Andreas; Heiter, Ulrike; Hinterschuster, Renate; Follert, Roman; Ives, Derek; Jung, Yves; Kerber, Florian; Klein, Barbara; Lizon, Jean-Louis; Marquart, Thomas; Molina-Conde, Ignacio; Pasquini, Luca; Paufique, Jérôme; Oliva, Ernesto; Reiners, Ansgar; Seemann, Ulf; Stegmeier, Jörg; Tordo, Sebastien; Valenti, Elena Bibcode: 2018SPIE10702E..34P Altcode: High-resolution infrared spectropolarimetry has many science applications in astrophysics. One of them is measuring weak magnetic fields using the Zeeman effect. Infrared domain is particularly advantageous as Zeeman splitting of spectral lines is proportional to the square of the wavelength while the intrinsic width of the line cores increases only linearly. Important science cases include detection and monitoring of global magnetic fields on solar-type stars, study of the magnetic field evolution from stellar formation to the final stages of the stellar life with massive stellar winds, and the dynamo mechanism operation across the boundary between fully- and partially-convective stars. CRIRES+ (the CRIRES upgrade project) includes a novel spectropolarimetric unit (SPU) based on polar- ization gratings. The novel design allows to perform beam-splitting very early in the optical path, directly after the tertiary mirror of the telescope (the ESO Very Large Telescope, VLT), minimizing instrumental polariza- tion. The new SPU performs polarization beam-splitting in the near-infrared while keeping the telescope beam mostly unchanged in the optical domain, making it compatible with the adaptive optics system of the CRIRES+ instrument. The SPU consists of four beam-splitters optimized for measuring circular and linear polarization of spectral lines in YJ and HK bands. The SPU can perform beam switching allowing to correct for throughput in each beam and for variations in detector pixel sensitivity. Other new features of CRIRES+, such as substantially increased wavelength coverage, stability and advanced data reduction pipeline will further enhance the sensitivity of the polarimetric mode. The combination of the SPU, CRIRES+ and the VLT is a unique facility for making major progress in understanding stellar activity. In this article we present the design of the SPU, laboratory measurements of individual components and of the whole unit as well as the performance prediction for the operation at the VLT. Title: Analysis of the polarimetric performance of the HARPS3 Cassegrain adaptor unit Authors: Dorval, Patrick; Snik, Frans; Piskunov, Nikolai; Navarro, Ramon; Kragt, Jan; ter Horst, Rik; Kunst, Peter; Snellen, Ignas; Naylor, Tim; Thompson, Samantha Bibcode: 2018SPIE10702E..6BD Altcode: The third version of the High Accuracy Radial velocity Planet Searcher (HARPS3) instrument is built for a ten-year programme aimed at achieving 10 cm/sec radial velocity precision on nearby stars to search for Earth-like planets. HARPS3 will be commissioned on the to-be-roboticized 2.54-m Isaac Newton Telescope at La Palma in 2021. One of the main changes compared to its predecessors is the novel dual-beam Cassegrain focus, featuring a stabilised beam feed into the HARPS3 spectrograph and an insertable polarimetric sub-unit. This polarimetric sub-unit enables HARPS3 to directly measure stellar activity signatures, which can be useful for correcting activity-induced radial velocity jitter in the search for Earth-like planets. The sub-unit consists of superachromatic polymer quarter- and half-wave retarders for circular and linear polarizations respectively, designed to suppress polarized fringing, and a novel polarimetric beam splitter based on a wire-grid design, separating the two polarimetric beams by 30 mm and feeding two separate science fibers. The dual-beam exchange implementation in combination with the extreme stability of the HARPS3 spectrograph enables a polarimetric sensitivity of 10-5 on bright stars. One of the main challenges of such a system is in the characterization of instrumental polarization effects which limit the polarimetric accuracy of the polarimetric observing mode. By design and characterization of this subsystem and by pre-emptively mitigating possible noise sources, we can minimize the noise characteristics of the polarization sub-unit to allow for precise observations. In this paper we report on the design, realization, assembly, alignment, and testing of the polarimetric unit to be installed in the Cassegrain Adaptor Unit of the HARPS3 spectrograph Title: Full system test and early preliminary acceptance Europe results for CRIRES+ Authors: Brucalassi, Anna; Dorn, Reinhold J.; Follert, Roman; Hatzes, Artie; Bristow, Paul; Seemann, Ulf; Cumani, Claudio; Eschbaumer, Siegfried; Haimerl, Andreas; Haug, Marcus; Heiter, Ulrike; Hinterschuster, Renate; Ives, Derek J.; Jung, Yves; Kerber, Florian; Klein, Barbara; Lavail, Alexis; Lizon, Jean Louis; Marquart, Thomas; Moins, Christophe; Molina-Conde, Ignacio; Oliva, Ernesto; Pasquini, Luca; Paufique, Jérôme; Piskunov, Nikolai; Stegmeier, Jörg; Stempels, Eric; Tordo, Sebastien; Valenti, Elena; Anwand-Heerwart, Heiko; Hauptner, Katja; Jeep, Peter; Marvin, Christopher; Reiners, Ansgar; Rhode, Petra; Schmidt, Christof; Umlauf, Tim Bibcode: 2018SPIE10702E..39B Altcode: CRIRES+ is the new high-resolution NIR echelle spectrograph intended to be operated at the platform B of VLT Unit telescope UT3. It will cover from Y to M bands (0.95-5.3um) with a spectral resolution of R = 50000 or R=100000. The main scientific goals are the search of super-Earths in the habitable zone of low-mass stars, the characterisation of transiting planets atmosphere and the study of the origin and evolution of stellar magnetic fields. Based on the heritage of the old adaptive optics (AO) assisted VLT instrument CRIRES, the new spectrograph will present improved optical layout, a new detector system and a new calibration unit providing optimal performances in terms of simultaneous wavelength coverage and radial velocity accuracy (a few m/s). The total observing efficiency will be enhanced by a factor of 10 with respect to CRIRES. An innovative spectro-polarimetry mode will be also offered and a new metrology system will ensure very high system stability and repeatability. Fiinally, the CRIRES+ project will also provide the community with a new data reduction software (DRS) package. CRIRES+ is currently at the initial phase of its Preliminary Acceptance in Europe (PAE) and it will be commissioned early in 2019 at VLT. This work outlines the main results obtained during the initial phase of the full system test at ESO HQ Garching. Title: ELT-HIRES, the high resolution spectrograph for the ELT: results from the Phase A study Authors: Marconi, A.; Allende Prieto, C.; Amado, P. J.; Amate, M.; Augusto, S. R.; Becerril, S.; Bezawada, N.; Boisse, I.; Bouchy, F.; Cabral, A.; Chazelas, B.; Cirami, R.; Coretti, I.; Cristiani, S.; Cupani, G.; de Castro Leão, I.; de Medeiros, J. R.; de Souza, M. A. F.; Di Marcantonio, P.; Di Varano, I.; D'Odorico, V.; Drass, H.; Figueira, P.; Fragoso, A. B.; Fynbo, J. P. U.; Genoni, M.; González Hernández, J. I.; Haehnelt, M.; Hughes, I.; Huke, P.; Kjeldsen, H.; Korn, A. J.; Landoni, M.; Liske, J.; Lovis, C.; Maiolino, R.; Marquart, T.; Martins, C. J. A. P.; Mason, E.; Monteiro, M. A.; Morris, T.; Murray, G.; Niedzielski, A.; Oliva, E.; Origlia, L.; Pallé, E.; Parr-Burman, P.; Parro, V. C.; Pepe, F.; Piskunov, N.; Rasilla, J. L.; Rees, P.; Rebolo, R.; Riva, M.; Rousseau, S.; Sanna, N.; Santos, N. C.; Shen, T. -C.; Sortino, F.; Sosnowska, D.; Sousa, S.; Stempels, E.; Strassmeier, K.; Tenegi, F.; Tozzi, A.; Udry, S.; Valenziano, L.; Vanzi, L.; Weber, M.; Woche, M.; Xompero, M.; Zackrisson, E. Bibcode: 2018SPIE10702E..1YM Altcode: We present the results from the phase A study of ELT-HIRES, an optical-infrared High Resolution Spectrograph for ELT, which has just been completed by a consortium of 30 institutes from 12 countries forming a team of about 200 scientists and engineers. The top science cases of ELT-HIRES will be the detection of life signatures from exoplanet atmospheres, tests on the stability of Nature's fundamental couplings, the direct detection of the cosmic acceleration. However, the science requirements of these science cases enable many other groundbreaking science cases. The baseline design, which allows to fulfil the top science cases, consists in a modular fiber- fed cross-dispersed echelle spectrograph with two ultra-stable spectral arms providing a simultaneous spectral range of 0.4-1.8 μm at a spectral resolution of 100,000. The fiber-feeding allows ELT-HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU. Title: Model-independent Exoplanet Transit Spectroscopy Authors: Aronson, Erik; Piskunov, Nikolai Bibcode: 2018AJ....155..208A Altcode: 2018arXiv180305327A We propose a new data analysis method for obtaining transmission spectra of exoplanet atmospheres and brightness variation across the stellar disk from transit observations. The new method is capable of recovering exoplanet atmosphere absorption spectra and stellar specific intensities without relying on theoretical models of stars and planets. We simultaneously fit both stellar specific intensity and planetary radius directly to transit light curves. This allows stellar models to be removed from the data analysis. Furthermore, we use a data quality weighted filtering technique to achieve an optimal trade-off between spectral resolution and reconstruction fidelity homogenizing the signal-to-noise ratio across the wavelength range. Such an approach is more efficient than conventional data binning onto a low-resolution wavelength grid. We demonstrate that our analysis is capable of reproducing results achieved by using an explicit quadratic limb-darkening equation and that the filtering technique helps eliminate spurious spectral features in regions with strong telluric absorption. The method is applied to the VLT FORS2 observations of the exoplanets GJ 1214 b and WASP-49 b, and our results are in agreement with previous studies. Comparisons between obtained stellar specific intensity and numerical models indicates that the method is capable of accurately reconstructing the specific intensity. The proposed method enables more robust characterization of exoplanetary atmospheres by separating derivation of planetary transmission and stellar specific intensity spectra (that is model-independent) from chemical and physical interpretation. Title: Inside a VAMDC data node—putting standards into practical software Authors: Regandell, Samuel; Marquart, Thomas; Piskunov, Nikolai Bibcode: 2018PhyS...93c5001R Altcode: 2018arXiv180309217R Access to molecular and atomic data is critical for many forms of remote sensing analysis across different fields. Many atomic and molecular databases are however highly specialised for their intended application, complicating querying and combination data between sources. The Virtual Atomic and Molecular Data Centre, VAMDC, is an electronic infrastructure that allows each database to register as a ‘node’. Through services such as VAMDC’s portal website, users can then access and query all nodes in a homogenised way. Today all major Atomic and Molecular databases are attached to VAMDC This article describes the software tools we developed to help data providers create and manage a VAMDC node. It gives an overview of the VAMDC infrastructure and of the various standards it uses. The article then discusses the development choices made and how the standards are implemented in practice. It concludes with a full example of implementing a VAMDC node using a real-life case as well as future plans for the node software. Title: Deriving stellar parameters with the SME software package Authors: Piskunov, N. Bibcode: 2017sbcs.conf..209P Altcode: Photometry and spectroscopy are complementary tools for deriving accurate stellar parameters. Here I present one of the popular packages for stellar spectroscopy called SME with the emphasis on the latest developments and error assessment for the derived parameters. Title: Program Package for the Analysis of High Resolution High Signal-To-Noise Stellar Spectra Authors: Piskunov, N.; Ryabchikova, T.; Pakhomov, Yu.; Sitnova, T.; Alekseeva, S.; Mashonkina, L.; Nordlander, T. Bibcode: 2017ASPC..510..509P Altcode: 2017arXiv171010856P The program package SME (Spectroscopy Made Easy), designed to perform an analysis of stellar spectra using spectral fitting techniques, was updated due to adding new functions (isotopic and hyperfine splittins) in VALD and including grids of NLTE calculations for energy levels of few chemical elements. SME allows to derive automatically stellar atmospheric parameters: effective temperature, surface gravity, chemical abundances, radial and rotational velocities, turbulent velocities, taking into account all the effects defining spectral line formation. SME package uses the best grids of stellar atmospheres that allows us to perform spectral analysis with the similar accuracy in wide range of stellar parameters and metallicities - from dwarfs to giants of BAFGK spectral classes. Title: VALD3: Current Developments Authors: Pakhomov, Yu.; Piskunov, N.; Ryabchikova, T. Bibcode: 2017ASPC..510..518P Altcode: 2017arXiv171010854P Today Vienna Atomic Line Database (VALD) is one of main databases of atomic and molecular parameters required for stellar spectra analysis. We present the new features that recently appeared in the VALD3 release, including the effects of isotopic composition and hyperfine splitting. The latest version of VALD contains parameters for several isotopes of Li, Ca, Ti, Cu, Ba, Eu, and hyperfine splitting of 35 isotopes from Li to Eu. Title: Main High-Resolution Near-IR Spectrometer for the VLT Authors: Piskunov, N. Bibcode: 2017ASPC..510..514P Altcode: We present the ongoing CRISES+ project on the development of a cross-dispersed high resolution near-infrared spectrometer for the ESO Very Large Telescope. The presentation highlights the relation between science objectives, technical solutions, and the structure of the project. We also share some of the insights on the implementation and management of the project that are crucial for keeping the tight time-line through efficient interaction between consortium members. Title: Erratum: Spectral Properties of Cool Stars: Extended Abundance Analysis of 1617 Planet Search Stars (2016, ApJS, 225, 32) Authors: Brewer, John M.; Fischer, Debra A.; Valenti, Jeff A.; Piskunov, Nikolai Bibcode: 2017ApJS..230...12B Altcode: No abstract at ADS Title: Spectroscopy Made Easy: Evolution Authors: Piskunov, Nikolai; Valenti, Jeff A. Bibcode: 2017A&A...597A..16P Altcode: 2016arXiv160606073P; 2016A&A...597A..16P Context. The Spectroscopy Made Easy (SME) package has become a popular tool for analyzing stellar spectra, often in connection with large surveys or exoplanet research. SME has evolved significantly since it was first described in 1996, but many of the original caveats and potholes still haunt users. The main drivers for this paper are complexity of the modeling task, the large user community, and the massive effort that has gone into SME.
Aims: We do not intend to give a comprehensive introduction to stellar atmospheres, but will describe changes to key components of SME: the equation of state, opacities, and radiative transfer. We will describe the analysis and fitting procedure and investigate various error sources that affect inferred parameters.
Methods: We review the current status of SME, emphasizing new algorithms and methods. We describe some best practices for using the package, based on lessons learned over two decades of SME usage. We present a new way to assess uncertainties in derived stellar parameters.
Results: Improvements made to SME, better line data, and new model atmospheres yield more realistic stellar spectra, but in many cases systematic errors still dominate over measurement uncertainty. Future enhancements are outlined. Title: VizieR Online Data Catalog: Extended abundance analysis of cool stars (Brewer+, 2016) Authors: Brewer, J. M.; Fischer, D. A.; Valenti, J. A.; Piskunov, N. Bibcode: 2016yCat..22250032B Altcode: The stellar spectra in this study were all collected using the HIRES spectrograph (R~70000) on the Keck I telescope as part of one or more radial-velocity planet-search programs under the collaborative umbrella known as the California Planet Survey (CPS; Howard+ 2010ApJ...721.1467H).

In addition to stellar spectra, our data also include 20 spectra of four different asteroids (4 Vesta, 1036 Ganymed, 3 Juno, and 10 Hygiea) from five epochs throughout the 10-year period covered by the observations in our sample. These spectra provided disk-integrated solar spectra and were obtained to help calibrate our analysis by providing small zero-point offsets for solar parameters and abundances.

(4 data files). Title: Characterizing the cross dispersion reflection gratings of CRIRES+ Authors: Follert, Roman; Taubert, Dieter; Hollandt, Jörg; Monte, Christian; Oliva, Ernesto; Seemann, Ulf; Löwinger, Tom; Anwand-Heerwart, Heiko; Schmidt, Christof; Dorn, Reinhold J.; Bristow, Paul; Hatzes, Artie; Reiners, Ansgar; Piskunov, Nikolai; Heiter, Ulrike; Stempels, Eric; Marquart, Thomas; Lavail, Alexis; Cumani, Claudio; Grunhut, Jason; Haimerl, Andreas; Hinterschuster, Renate; Ives, Derek J.; Jung, Yves; Kerber, Florian; Klein, Barbara; Lizon, Jean Louis; Molina-Conde, Ignacio; Nicholson, Belinda; Origlia, Livia; Pasquini, Luca; Paufique, Jérôme; Stegmeier, Jörg; Tordo, Sebastien Bibcode: 2016SPIE.9912E..2BF Altcode: The CRIRES+ project attempts to upgrade the CRIRES instrument into a cross dispersed Echelle spectrograph with a simultaneous recording of 8-10 diffraction orders. In order to transform the CRIRES spectrograph into a cross-dispersing instrument, a set of six reflection gratings, each one optimized for one of the wavelength bands CRIRES+ will operate in (YJHKLM), will be used as cross dispersion elements in CRIRES+. Due to the upgrade nature of the project, the choice of gratings depends on the fixed geometry of the instrument. Thus, custom made gratings would be required to achieve the ambitious design goals. Custom made gratings have the disadvantage, though, that they come at an extraordinary price and with lead times of more than 12 months. To mitigate this, a set of off-the-shelf gratings was obtained which had grating parameters very close to the ones being identified as optimal. To ensure that the rigorous specifications for CRIRES+ will be fulfilled, the CRIRES+ team started a collaboration with the Physikalisch-Technische Bundesanstalt Berlin (PTB) to characterize gratings underconditions similar to the operating conditions in CRIRES+ (angle of incidence, wavelength range). The respective test setup was designed in collaboration between PTB and the CRIRES+ consortium. The PTB provided optical radiation sources and calibrated detectors for each wavelength range. With this setup, it is possible to measure the absolute efficiency of the gratings both wavelength dependent and polarization state dependent in a wavelength range from 0.9 μm to 6 μm. Title: VizieR Online Data Catalog: FGK dwarfs atmospheric parameters (Ryabchikova+, 2016) Authors: Ryabchikova, T.; Piskunov, N.; Pakhomov, Y.; Tsymbal, V.; Titarenko, A.; Sitnova, T.; Alexeeva, S.; Fossati, L.; Mashonkina, L. Bibcode: 2016yCat..74561221R Altcode: For the spectroscopic analysis, we choose the 13 MS stars including the Sun (Table 1) in the 4900-6600K temperature range and with metallicity between [Fe/H]=-1.5 and +0.3dex. All the stars, except HD 149026, have, at least, one interferometric determination of radius and effective temperature.

Spectra of the programme stars were obtained with different spectrographs. Most data were extracted from the following archives: the UVES/VLT and HARPS/3.6m spectrographs at ESO,2 the ELODIE/1.93-m spectrograph3 at the Observatoire de Haute Provence, and the ESPaDONs spectrograph at the Canada-France-Hawaii Telescope (CFHT). Spectra of beta Vir and HD 103095 were obtained with the FOCES spectrograph at 2.2-m telescope of the Calar Alto Observatory. One of the spectra of 61 Vir was obtained with the Hamilton Echelle Spectrograph attached to the Shane 3-m telescope of the Lick Observatory. Spectra of few stars, including that of the Sun reflected from Ganymede, were obtained with the HiReS/Keck spectrograph.

(3 data files). Title: HARPS3 for a roboticized Isaac Newton Telescope Authors: Thompson, Samantha J.; Queloz, Didier; Baraffe, Isabelle; Brake, Martyn; Dolgopolov, Andrey; Fisher, Martin; Fleury, Michel; Geelhoed, Joost; Hall, Richard; González Hernández, Jonay I.; ter Horst, Rik; Kragt, Jan; Navarro, Ramón; Naylor, Tim; Pepe, Francesco; Piskunov, Nikolai; Rebolo, Rafael; Sander, Louis; Ségransan, Damien; Seneta, Eugene; Sing, David; Snellen, Ignas; Snik, Frans; Spronck, Julien; Stempels, Eric; Sun, Xiaowei; Santana Tschudi, Samuel; Young, John Bibcode: 2016SPIE.9908E..6FT Altcode: 2016arXiv160804611T We present a description of a new instrument development, HARPS3, planned to be installed on an upgraded and roboticized Isaac Newton Telescope by end-2018. HARPS3 will be a high resolution (R≃115,000) echelle spectrograph with a wavelength range from 380-690 nm. It is being built as part of the Terra Hunting Experiment - a future 10- year radial velocity measurement programme to discover Earth-like exoplanets. The instrument design is based on the successful HARPS spectrograph on the 3.6m ESO telescope and HARPS-N on the TNG telescope. The main changes to the design in HARPS3 will be: a customised fibre adapter at the Cassegrain focus providing a stabilised beam feed and on-sky fibre diameter ≍1:4 arcsec, the implementation of a new continuous ow cryostat to keep the CCD temperature very stable, detailed characterisation of the HARPS3 CCD to map the effective pixel positions and thus provide an improved accuracy wavelength solution, an optimised integrated polarimeter and the instrument integrated into a robotic operation. The robotic operation will optimise our programme which requires our target stars to be measured on a nightly basis. We present an overview of the entire project, including a description of our anticipated robotic operation. Title: EELT-HIRES the high-resolution spectrograph for the E-ELT Authors: Marconi, A.; Di Marcantonio, P.; D'Odorico, V.; Cristiani, S.; Maiolino, R.; Oliva, E.; Origlia, L.; Riva, M.; Valenziano, L.; Zerbi, F. M.; Abreu, M.; Adibekyan, V.; Allende Prieto, C.; Amado, P. J.; Benz, W.; Boisse, I.; Bonfils, X.; Bouchy, F.; Buchhave, L.; Buscher, D.; Cabral, A.; Canto Martins, B. L.; Chiavassa, A.; Coelho, J.; Christensen, L. B.; Delgado-Mena, E.; de Medeiros, J. R.; Di Varano, I.; Figueira, P.; Fisher, M.; Fynbo, J. P. U.; Glasse, A. C. H.; Haehnelt, M.; Haniff, C.; Hansen, C. J.; Hatzes, A.; Huke, P.; Korn, A. J.; Leão, I. C.; Liske, J.; Lovis, C.; Maslowski, P.; Matute, I.; McCracken, R. A.; Martins, C. J. A. P.; Monteiro, M. J. P. F. G.; Morris, S.; Morris, T.; Nicklas, H.; Niedzielski, A.; Nunes, N. J.; Palle, E.; Parr-Burman, P. M.; Parro, V.; Parry, I.; Pepe, F.; Piskunov, N.; Queloz, D.; Quirrenbach, A.; Rebolo Lopez, R.; Reiners, A.; Reid, D. T.; Santos, N.; Seifert, W.; Sousa, S.; Stempels, H. C.; Strassmeier, K.; Sun, X.; Udry, S.; Vanzi, L.; Vestergaard, M.; Weber, M.; Zackrisson, E. Bibcode: 2016SPIE.9908E..23M Altcode: 2016arXiv160900497M The first generation of E-ELT instruments will include an optic-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long phase A study for EELT-HIRES has just started and will be performed by a consortium composed of institutes and organisations from Brazil, Chile, Denmark, France, Germany, Italy, Poland, Portugal, Spain, Sweden, Switzerland and United Kingdom. In this paper we describe the science goals and the preliminary technical concept for EELT-HIRES which will be developed during the phase A, as well as its planned development and consortium organisation during the study. Title: 4MOST: the 4-metre Multi-Object Spectroscopic Telescope project at preliminary design review Authors: de Jong, Roelof S.; Barden, Samuel C.; Bellido-Tirado, Olga; Brynnel, Joar G.; Frey, Steffen; Giannone, Domenico; Haynes, Roger; Johl, Diana; Phillips, Daniel; Schnurr, Olivier; Walcher, Jakob C.; Winkler, Roland; Ansorge, Wolfgang R.; Feltzing, Sofia; McMahon, Richard G.; Baker, Gabriella; Caillier, Patrick; Dwelly, Tom; Gaessler, Wolfgang; Iwert, Olaf; Mandel, Holger G.; Piskunov, Nikolai A.; Pragt, Johan H.; Walton, Nicholas A.; Bensby, Thomas; Bergemann, Maria; Chiappini, Cristina; Christlieb, Norbert; Cioni, Maria-Rosa L.; Driver, Simon; Finoguenov, Alexis; Helmi, Amina; Irwin, Michael J.; Kitaura, Francisco-Shu; Kneib, Jean-Paul; Liske, Jochen; Merloni, Andrea; Minchev, Ivan; Richard, Johan; Starkenburg, Else Bibcode: 2016SPIE.9908E..1OD Altcode: We present an overview of the 4MOST project at the Preliminary Design Review. 4MOST is a major new wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of ESO. 4MOST has a broad range of science goals ranging from Galactic Archaeology and stellar physics to the high-energy physics, galaxy evolution, and cosmology. Starting in 2021, 4MOST will deploy 2436 fibres in a 4.1 square degree field-of-view using a positioner based on the tilting spine principle. The fibres will feed one high-resolution (R 20,000) and two medium resolution (R 5000) spectrographs with fixed 3-channel designs and identical 6k x 6k CCD detectors. 4MOST will have a unique operations concept in which 5-year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept, showing that we can expect to observe more than 25 million objects in each 5-year survey period and will eventually be used to plan and conduct the actual survey. Title: Spectral Properties of Cool Stars: Extended Abundance Analysis of 1,617 Planet-search Stars Authors: Brewer, John M.; Fischer, Debra A.; Valenti, Jeff A.; Piskunov, Nikolai Bibcode: 2016ApJS..225...32B Altcode: 2016arXiv160607929B We present a catalog of uniformly determined stellar properties and abundances for 1,617 F, G, and K stars using an automated spectral synthesis modeling procedure. All stars were observed using the HIRES spectrograph at Keck Observatory. Our procedure used a single line list to fit model spectra to observations of all stars to determine effective temperature, surface gravity, metallicity, projected rotational velocity, and the abundances of 15 elements (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, and Y). Sixty percent of the sample had Hipparcos parallaxes and V-band photometry, which we combined with the spectroscopic results to obtain mass, radius, and luminosity. Additionally, we used the luminosity, effective temperature, metallicity and α-element enhancement to interpolate in the Yonsei-Yale isochrones to derive mass, radius, gravity, and age ranges for those stars. Finally, we determined new relations between effective temperature and macroturbulence for dwarfs and subgiants. Our analysis achieved precisions of 25 K in {T}{eff}, 0.01 dex in [M/H], 0.028 dex for {log}g, and 0.5 km s-1 in v\sin I based on multiple observations of the same stars. The abundance results were similarly precise, between ∼0.01 and ∼0.04 dex, though trends with respect to {T}{eff} remained for which we derived empirical corrections. The trends, though small, were much larger than our uncertainties and are shared with published abundances. We show that changing our model atmosphere grid accounts for most of the trend in [M/H] between 5000 and 5500 K, indicating a possible problem with the atmosphere models or opacities. Title: The "+" for CRIRES: enabling better science at infrared wavelength and high spectral resolution at the ESO VLT Authors: Dorn, Reinhold J.; Follert, Roman; Bristow, Paul; Cumani, Claudio; Eschbaumer, Siegfried; Grunhut, Jason; Haimerl, Andreas; Hatzes, Artie; Heiter, Ulrike; Hinterschuster, Renate; Ives, Derek J.; Jung, Yves; Kerber, Florian; Klein, Barbara; Lavail, Alexis; Lizon, Jean Louis; Löwinger, Tom; Molina-Conde, Ignacio; Nicholson, Belinda; Marquart, Thomas; Oliva, Ernesto; Origlia, Livia; Pasquini, Luca; Paufique, Jérôme; Piskunov, Nikolai; Reiners, Ansgar; Seemann, Ulf; Stegmeier, Jörg; Stempels, Eric; Tordo, Sebastien Bibcode: 2016SPIE.9908E..0ID Altcode: The adaptive optics (AO) assisted CRIRES instrument is an IR (0.92 - 5.2 μm) high-resolution spectrograph was in operation from 2006 to 2014 at the Very Large Telescope (VLT) observatory. CRIRES was a unique instrument, accessing a parameter space (wavelength range and spectral resolution) up to now largely uncharted. It consisted of a single-order spectrograph providing long-slit (40 arcsecond) spectroscopy with a resolving power up to R=100 000. However the setup was limited to a narrow, single-shot, spectral range of about 1/70 of the central wavelength, resulting in low observing efficiency for many scientific programmes requiring a broad spectral coverage. The CRIRES upgrade project, CRIRES+, transforms this VLT instrument into a cross-dispersed spectrograph to increase the simultaneously covered wavelength range by a factor of ten. A new and larger detector focal plane array of three Hawaii 2RG detectors with 5.3 μm cut-off wavelength will replace the existing detectors. For advanced wavelength calibration, custom-made absorption gas cells and an etalon system will be added. A spectro-polarimetric unit will allow the recording of circular and linear polarized spectra. This upgrade will be supported by dedicated data reduction software allowing the community to take full advantage of the new capabilities offered by CRIRES+. CRIRES+ has now entered its assembly and integration phase and will return with all new capabilities by the beginning of 2018 to the Very Large Telescope in Chile. This article will provide the reader with an update of the current status of the instrument as well as the remaining steps until final installation at the Paranal Observatory. Title: CRIRES+: A High Resolution Near-Infrared Spectro(Polari)Meter At The VLT Authors: Lavail, Alexis; Piskunov, Nikolai; Heiter, Ulrike; Marquart, Thomas; Stempels, Eric; Crires+ Consortium Bibcode: 2016csss.confE..48L Altcode: CRIRES, the CRyogenic high-resolution InfraRed Echelle Spectrograph has been removed from the ESO's Very Large Telescope in 2014 to undergo a massive upgrade. The upgraded CRIRES+ instrument will be a cross-dispersed spectrograph; gain a tenfold increase in simultaneous wavelength coverage; have new detectors, gas cells for wavelength calibration, polarimeter unit enabling spectropolarimeteric observations; and benefit from a new Data Reduction Software. Title: Hunting For Strong Magnetic Fields In Rapidly Rotating Sun-Like Stars With Stokes-I Observations Authors: Shulyak, Denis; Malo, Lison; Reiners, Ansgar; Kochukhov, Oleg; Jeffers, Sandra; Piskunov, Nikolai Bibcode: 2016csss.confE.118S Altcode: Stars with convective envelopes can generate strong magnetic fields
through rotationally driven dynamos. Theory suggests that the maximum
magnetic field strength depends on the energy budget stored in
the stellar convective shell and can reach values of several kilogauss
in fastest rotating stars. We test this predictions by measuring
total magnetic flux and polarization in a sample of sun-like stars
that rotate close to the activity saturation limit.
We detect average magnetic flux densities of several hundred G in several of our targets,with the strongest field of about 1 kG in a K type star V383 Lac showing that young sun-like starscan produce average fields on the kG level. Title: Hlinop: April 2016 Release Authors: Barklem, Paul; Piskunov, Nikolai Bibcode: 2016zndo.....50215B Altcode: First formal github release.  April 2016 version. Title: Highlights of IAU Commission 29: Recent Advances and Perspectives on Stellar Spectroscopy Authors: Cunha, Katia; Soderblom, David R.; Piskunov, Nikolai; Aoki, Wako; Asplund, Martin; Carpenter, Kenneth G.; Crowther, Paul; Melendez, Jorge; Venn, Kimberly; Hill, Vanessa; Yong, David Bibcode: 2016IAUTA..29..428C Altcode: IAU Commission 29 - Stellar Spectra has been one of the IAU commissions from the onset, until its dissolution at the most recent IAU General Assembly in Honolulu in 2015. This commission belonged to IAU Division G (``Stars and Stellar Physics''), the latter committed with fostering research in stellar astrophysics. Within the general field of stellar astrophysics, stellar spectroscopy plays a key role, as stellar spectra are a powerful tool providing a view into the detailed physical properties of stars and the physical processes occuring within them. Title: Accuracy of atmospheric parameters of FGK dwarfs determined by spectrum fitting Authors: Ryabchikova, T.; Piskunov, N.; Pakhomov, Yu.; Tsymbal, V.; Titarenko, A.; Sitnova, T.; Alexeeva, S.; Fossati, L.; Mashonkina, L. Bibcode: 2016MNRAS.456.1221R Altcode: 2015arXiv151106134R We performed extensive tests of the accuracy of atmospheric parameter determination for FGK stars based on the spectrum fitting procedure Spectroscopy Made Easy (SME). Our stellar sample consists of 13 objects, including the Sun, in the temperature range 5000-6600 K and metallicity range -1.4-+0.4. The analysed stars have the advantage of having parameters derived by interferometry. For each star, we use spectra obtained with different spectrographs and different signal-to-noise ratios (S/N). For the fitting, we adopted three different sets of constraints and test how the derived parameters depend upon the spectral regions (masks) used in SME. We developed and implemented in SME a new method for estimating uncertainties in the resulting parameters based on fitting residuals, partial derivatives, and data uncertainties. For stars in the 5700-6600 K range, the best agreement with the effective temperatures derived by interferometry is achieved when spectrum fitting includes the H α and H β lines, while for cooler stars the choice of the mask does not affect the results. The derived atmospheric parameters do not strongly depend on spectral resolution and S/N of the observations, while the uncertainties in temperature and surface gravity increase with increasing effective temperature, with minima at 50 K in Teff and 0.1 dex in log g, for spectra with S/N=150-200. A non-local thermodynamic equilibrium (NLTE) analysis of the Ti I/Ti II and Fe I/Fe II ionization equilibria and abundances determined from the atomic C I (NLTE) and molecular CH species supports the parameters we derived with SME by fitting the observed spectra including the hydrogen lines. Title: Scientific problems addressed by the Spektr-UV space project (world space Observatory—Ultraviolet) Authors: Boyarchuk, A. A.; Shustov, B. M.; Savanov, I. S.; Sachkov, M. E.; Bisikalo, D. V.; Mashonkina, L. I.; Wiebe, D. Z.; Shematovich, V. I.; Shchekinov, Yu. A.; Ryabchikova, T. A.; Chugai, N. N.; Ivanov, P. B.; Voshchinnikov, N. V.; Gomez de Castro, A. I.; Lamzin, S. A.; Piskunov, N.; Ayres, T.; Strassmeier, K. G.; Jeffrey, S.; Zwintz, S. K.; Shulyak, D.; Gérard, J. -C.; Hubert, B.; Fossati, L.; Lammer, H.; Werner, K.; Zhilkin, A. G.; Kaigorodov, P. V.; Sichevskii, S. G.; Ustamuich, S.; Kanev, E. N.; Kil'pio, E. Yu. Bibcode: 2016ARep...60....1B Altcode: The article presents a review of scientific problems and methods of ultraviolet astronomy, focusing on perspective scientific problems (directions) whose solution requires UV space observatories. These include reionization and the history of star formation in the Universe, searches for dark baryonic matter, physical and chemical processes in the interstellar medium and protoplanetary disks, the physics of accretion and outflows in astrophysical objects, from Active Galactic Nuclei to close binary stars, stellar activity (for both low-mass and high-mass stars), and processes occurring in the atmospheres of both planets in the solar system and exoplanets. Technological progress in UV astronomy achieved in recent years is also considered. The well advanced, international, Russian-led Spektr-UV (World Space Observatory—Ultraviolet) project is described in more detail. This project is directed at creating a major space observatory operational in the ultraviolet (115-310 nm). This observatory will provide an effective, and possibly the only, powerful means of observing in this spectral range over the next ten years, and will be an powerful tool for resolving many topical scientific problems. Title: The EChO science case Authors: Tinetti, Giovanna; Drossart, Pierre; Eccleston, Paul; Hartogh, Paul; Isaak, Kate; Linder, Martin; Lovis, Christophe; Micela, Giusi; Ollivier, Marc; Puig, Ludovic; Ribas, Ignasi; Snellen, Ignas; Swinyard, Bruce; Allard, France; Barstow, Joanna; Cho, James; Coustenis, Athena; Cockell, Charles; Correia, Alexandre; Decin, Leen; de Kok, Remco; Deroo, Pieter; Encrenaz, Therese; Forget, Francois; Glasse, Alistair; Griffith, Caitlin; Guillot, Tristan; Koskinen, Tommi; Lammer, Helmut; Leconte, Jeremy; Maxted, Pierre; Mueller-Wodarg, Ingo; Nelson, Richard; North, Chris; Pallé, Enric; Pagano, Isabella; Piccioni, Guseppe; Pinfield, David; Selsis, Franck; Sozzetti, Alessandro; Stixrude, Lars; Tennyson, Jonathan; Turrini, Diego; Zapatero-Osorio, Mariarosa; Beaulieu, Jean-Philippe; Grodent, Denis; Guedel, Manuel; Luz, David; Nørgaard-Nielsen, Hans Ulrik; Ray, Tom; Rickman, Hans; Selig, Avri; Swain, Mark; Banaszkiewicz, Marek; Barlow, Mike; Bowles, Neil; Branduardi-Raymont, Graziella; du Foresto, Vincent Coudé; Gerard, Jean-Claude; Gizon, Laurent; Hornstrup, Allan; Jarchow, Christopher; Kerschbaum, Franz; Kovacs, Géza; Lagage, Pierre-Olivier; Lim, Tanya; Lopez-Morales, Mercedes; Malaguti, Giuseppe; Pace, Emanuele; Pascale, Enzo; Vandenbussche, Bart; Wright, Gillian; Ramos Zapata, Gonzalo; Adriani, Alberto; Azzollini, Ruymán; Balado, Ana; Bryson, Ian; Burston, Raymond; Colomé, Josep; Crook, Martin; Di Giorgio, Anna; Griffin, Matt; Hoogeveen, Ruud; Ottensamer, Roland; Irshad, Ranah; Middleton, Kevin; Morgante, Gianluca; Pinsard, Frederic; Rataj, Mirek; Reess, Jean-Michel; Savini, Giorgio; Schrader, Jan-Rutger; Stamper, Richard; Winter, Berend; Abe, L.; Abreu, M.; Achilleos, N.; Ade, P.; Adybekian, V.; Affer, L.; Agnor, C.; Agundez, M.; Alard, C.; Alcala, J.; Allende Prieto, C.; Alonso Floriano, F. J.; Altieri, F.; Alvarez Iglesias, C. A.; Amado, P.; Andersen, A.; Aylward, A.; Baffa, C.; Bakos, G.; Ballerini, P.; Banaszkiewicz, M.; Barber, R. J.; Barrado, D.; Barton, E. J.; Batista, V.; Bellucci, G.; Belmonte Avilés, J. A.; Berry, D.; Bézard, B.; Biondi, D.; Błęcka, M.; Boisse, I.; Bonfond, B.; Bordé, P.; Börner, P.; Bouy, H.; Brown, L.; Buchhave, L.; Budaj, J.; Bulgarelli, A.; Burleigh, M.; Cabral, A.; Capria, M. T.; Cassan, A.; Cavarroc, C.; Cecchi-Pestellini, C.; Cerulli, R.; Chadney, J.; Chamberlain, S.; Charnoz, S.; Christian Jessen, N.; Ciaravella, A.; Claret, A.; Claudi, R.; Coates, A.; Cole, R.; Collura, A.; Cordier, D.; Covino, E.; Danielski, C.; Damasso, M.; Deeg, H. J.; Delgado-Mena, E.; Del Vecchio, C.; Demangeon, O.; De Sio, A.; De Wit, J.; Dobrijévic, M.; Doel, P.; Dominic, C.; Dorfi, E.; Eales, S.; Eiroa, C.; Espinoza Contreras, M.; Esposito, M.; Eymet, V.; Fabrizio, N.; Fernández, M.; Femenía Castella, B.; Figueira, P.; Filacchione, G.; Fletcher, L.; Focardi, M.; Fossey, S.; Fouqué, P.; Frith, J.; Galand, M.; Gambicorti, L.; Gaulme, P.; García López, R. J.; Garcia-Piquer, A.; Gear, W.; Gerard, J. -C.; Gesa, L.; Giani, E.; Gianotti, F.; Gillon, M.; Giro, E.; Giuranna, M.; Gomez, H.; Gomez-Leal, I.; Gonzalez Hernandez, J.; González Merino, B.; Graczyk, R.; Grassi, D.; Guardia, J.; Guio, P.; Gustin, J.; Hargrave, P.; Haigh, J.; Hébrard, E.; Heiter, U.; Heredero, R. L.; Herrero, E.; Hersant, F.; Heyrovsky, D.; Hollis, M.; Hubert, B.; Hueso, R.; Israelian, G.; Iro, N.; Irwin, P.; Jacquemoud, S.; Jones, G.; Jones, H.; Justtanont, K.; Kehoe, T.; Kerschbaum, F.; Kerins, E.; Kervella, P.; Kipping, D.; Koskinen, T.; Krupp, N.; Lahav, O.; Laken, B.; Lanza, N.; Lellouch, E.; Leto, G.; Licandro Goldaracena, J.; Lithgow-Bertelloni, C.; Liu, S. J.; Lo Cicero, U.; Lodieu, N.; Lognonné, P.; Lopez-Puertas, M.; Lopez-Valverde, M. A.; Lundgaard Rasmussen, I.; Luntzer, A.; Machado, P.; MacTavish, C.; Maggio, A.; Maillard, J. -P.; Magnes, W.; Maldonado, J.; Mall, U.; Marquette, J. -B.; Mauskopf, P.; Massi, F.; Maurin, A. -S.; Medvedev, A.; Michaut, C.; Miles-Paez, P.; Montalto, M.; Montañés Rodríguez, P.; Monteiro, M.; Montes, D.; Morais, H.; Morales, J. C.; Morales-Calderón, M.; Morello, G.; Moro Martín, A.; Moses, J.; Moya Bedon, A.; Murgas Alcaino, F.; Oliva, E.; Orton, G.; Palla, F.; Pancrazzi, M.; Pantin, E.; Parmentier, V.; Parviainen, H.; Peña Ramírez, K. Y.; Peralta, J.; Perez-Hoyos, S.; Petrov, R.; Pezzuto, S.; Pietrzak, R.; Pilat-Lohinger, E.; Piskunov, N.; Prinja, R.; Prisinzano, L.; Polichtchouk, I.; Poretti, E.; Radioti, A.; Ramos, A. A.; Rank-Lüftinger, T.; Read, P.; Readorn, K.; Rebolo López, R.; Rebordão, J.; Rengel, M.; Rezac, L.; Rocchetto, M.; Rodler, F.; Sánchez Béjar, V. J.; Sanchez Lavega, A.; Sanromá, E.; Santos, N.; Sanz Forcada, J.; Scandariato, G.; Schmider, F. -X.; Scholz, A.; Scuderi, S.; Sethenadh, J.; Shore, S.; Showman, A.; Sicardy, B.; Sitek, P.; Smith, A.; Soret, L.; Sousa, S.; Stiepen, A.; Stolarski, M.; Strazzulla, G.; Tabernero, H. M.; Tanga, P.; Tecsa, M.; Temple, J.; Terenzi, L.; Tessenyi, M.; Testi, L.; Thompson, S.; Thrastarson, H.; Tingley, B. W.; Trifoglio, M.; Martín Torres, J.; Tozzi, A.; Turrini, D.; Varley, R.; Vakili, F.; de Val-Borro, M.; Valdivieso, M. L.; Venot, O.; Villaver, E.; Vinatier, S.; Viti, S.; Waldmann, I.; Waltham, D.; Ward-Thompson, D.; Waters, R.; Watkins, C.; Watson, D.; Wawer, P.; Wawrzaszk, A.; White, G.; Widemann, T.; Winek, W.; Wiśniowski, T.; Yelle, R.; Yung, Y.; Yurchenko, S. N. Bibcode: 2015ExA....40..329T Altcode: 2015ExA...tmp...67T; 2015arXiv150205747T The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune—all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10-4 relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength coverage of at least 0.55 to 11 μm with a goal of covering from 0.4 to 16 μm. Only modest spectral resolving power is needed, with R ~ 300 for wavelengths less than 5 μm and R ~ 30 for wavelengths greater than this. The transit spectroscopy technique means that no spatial resolution is required. A telescope collecting area of about 1 m2 is sufficiently large to achieve the necessary spectro-photometric precision: for the Phase A study a 1.13 m2 telescope, diffraction limited at 3 μm has been adopted. Placing the satellite at L2 provides a cold and stable thermal environment as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. EChO has been conceived to achieve a single goal: exoplanet spectroscopy. The spectral coverage and signal-to-noise to be achieved by EChO, thanks to its high stability and dedicated design, would be a game changer by allowing atmospheric composition to be measured with unparalleled exactness: at least a factor 10 more precise and a factor 10 to 1000 more accurate than current observations. This would enable the detection of molecular abundances three orders of magnitude lower than currently possible and a fourfold increase from the handful of molecules detected to date. Combining these data with estimates of planetary bulk compositions from accurate measurements of their radii and masses would allow degeneracies associated with planetary interior modelling to be broken, giving unique insight into the interior structure and elemental abundances of these alien worlds. EChO would allow scientists to study exoplanets both as a population and as individuals. The mission can target super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300-3000 K) of F to M-type host stars. The EChO core science would be delivered by a three-tier survey. The EChO Chemical Census: This is a broad survey of a few-hundred exoplanets, which allows us to explore the spectroscopic and chemical diversity of the exoplanet population as a whole. The EChO Origin: This is a deep survey of a subsample of tens of exoplanets for which significantly higher signal to noise and spectral resolution spectra can be obtained to explain the origin of the exoplanet diversity (such as formation mechanisms, chemical processes, atmospheric escape). The EChO Rosetta Stones: This is an ultra-high accuracy survey targeting a subsample of select exoplanets. These will be the bright "benchmark" cases for which a large number of measurements would be taken to explore temporal variations, and to obtain two and three dimensional spatial information on the atmospheric conditions through eclipse-mapping techniques. If EChO were launched today, the exoplanets currently observed are sufficient to provide a large and diverse sample. The Chemical Census survey would consist of > 160 exoplanets with a range of planetary sizes, temperatures, orbital parameters and stellar host properties. Additionally, over the next 10 years, several new ground- and space-based transit photometric surveys and missions will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO's launch and enable the atmospheric characterisation of hundreds of planets. Title: Doppler imaging of LQ Hydrae for 1998-2002 Authors: Cole, E. M.; Hackman, T.; Käpylä, M. J.; Ilyin, I.; Kochukhov, O.; Piskunov, N. Bibcode: 2015A&A...581A..69C Altcode: 2015arXiv150403673C
Aims: We study the spot distribution on the surface of LQ Hya during the observing seasons October 1998-November 2002. We look for persistent active longitudes, trends in the level of spot activity and compare to photometric data.
Methods: We apply the Doppler imaging technique on photospheric spectral lines using an inversion code to retrieve images of the surface temperature.
Results: We present new temperature maps using multiple spectral lines for a total of 7 seasons.
Conclusions: We find no evidence for active longitudes persisting over multiple observing seasons. The spot activity appears to be concentrated to two latitude regions. Using the currently accepted rotation period, we find spot structures to show a trend in the phase-time plot, indicative of a need for a longer period. We conclude that the long-term activity of LQ Hya is more chaotic than that of some magnetically active binary stars analyzed with similar methods, but still with clear indications of an activity cycle from the photometry.

Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Table 2 is available in electronic form at http://www.aanda.org Title: Using near-infrared spectroscopy for characterization of transiting exoplanets (Corrigendum) Authors: Aronson, E.; Waldén, P.; Piskunov, N. Bibcode: 2015A&A...581C...1A Altcode: No abstract at ADS Title: HLINOP: Hydrogen LINe OPacity in stellar atmospheres Authors: Barklem, P. S.; Piskunov, N. Bibcode: 2015ascl.soft07008B Altcode: HLINOP is a collection of codes for computing hydrogen line profiles and opacities in the conditions typical of stellar atmospheres. It includes HLINOP for approximate quick calculation of any line of neutral hydrogen (suitable for model atmosphere calculations), based on the Fortran code of Kurucz and Peterson found in ATLAS9. It also includes HLINPROF, for detailed, accurate calculation of lower Balmer line profiles (suitable for detailed analysis of Balmer lines) and HBOP, to implement the occupation probability formalism of Daeppen, Anderson and Milhalas (1987) and thus account for the merging of bound-bound and bound-free opacity (used often as a wrapper to HLINOP for model atmosphere calculations). Title: Posters: Poster #73927: High-resolution transmission spectroscopy of exoplanets with the ground-based instruments Authors: Piskunov, Nikolai; Aronson, Erik Bibcode: 2015pthp.confE..54P Altcode: No abstract at ADS Title: Accurate Gravities of F, G, and K stars from High Resolution Spectra Without External Constraints Authors: Brewer, John M.; Fischer, Debra A.; Basu, Sarbani; Valenti, Jeff A.; Piskunov, Nikolai Bibcode: 2015ApJ...805..126B Altcode: 2015arXiv150307180B We demonstrate a new procedure to derive accurate and precise surface gravities from high resolution spectra without the use of external constraints. Our analysis utilizes Spectroscopy Made Easy with robust spectral line constraints and uses an iterative process to mitigate degeneracies in the fitting process. We adopt an updated radiative transfer code, a new treatment for neutral perturber broadening, a line list with multiple gravity constraints and separate fitting for global stellar properties and abundance determinations. To investigate the sources of temperature dependent trends in determining log {\mkern 1mu} g noted in previous studies, we obtained Keck HIRES spectra of 42 Kepler asteroseismic stars. In comparison to asteroseismically determined log {\mkern 1mu} g our spectroscopic analysis has a constant offset of 0.01 dex with a rms scatter of 0.05 dex. We also analyzed 30 spectra which had published surface gravities determined using the a/{{R}*} technique from planetary transits and found a constant offset of 0.06 dex and rms scatter of 0.07 dex. The two samples covered effective temperatures between 5000 and 6700 K with log {\mkern 1mu} g between 3.7 and 4.6. Title: On the Accuracy of Atmospheric Parameter Determination in BAFGK Stars Authors: Ryabchikova, T.; Piskunov, N.; Shulyak, D. Bibcode: 2015ASPC..494..308R Altcode: During the past few years, many papers determining the atmospheric parameters in FGK stars appeared in the literature where the accuracy of effective temperatures is given as 20-40 K. For main sequence stars within the 5 000-13 000 K temperature range, we have performed a comparative analysis of the parameters derived from the spectra by using the SME (Spectroscopy Made Easy) package and those found in the literature. Our sample includes standard stars Sirius, Procyon, δ Eri, and the Sun. Combining different spectral regions in the fitting procedure, we investigated an effect different atomic species have on the derived atmospheric parameters. The temperature difference may exceed 100 K depending on the spectral regions used in the SME procedure. It is shown that the atmospheric parameters derived with the SME procedure which includes wings of hydrogen lines in fitting agrees better with the results derived by the other methods and tools across a large part of the main sequence. For three stars—π Cet, 21 Peg, and Procyon—the atmospheric parameters were also derived by fitting a calculated energy distribution to the observed one. We found a substantial difference in the parameters inferred from different sets and combinations of spectrophotometric observations. An intercomparison of our results and literature data shows that the average accuracy of effective temperature determination for cool stars and for the early B-stars is 70-85 K and 170-200 K, respectively. Title: Stellar activity as noise in exoplanet detection - I. Methods and application to solar-like stars and activity cycles Authors: Korhonen, H.; Andersen, J. M.; Piskunov, N.; Hackman, T.; Juncher, D.; Järvinen, S. P.; Jørgensen, U. G. Bibcode: 2015MNRAS.448.3038K Altcode: 2015arXiv150100981K The detection of exoplanets using any method is prone to confusion due to the intrinsic variability of the host star. We investigate the effect of cool starspots on the detectability of the exoplanets around solar-like stars using the radial velocity method. For investigating this activity-caused `jitter' we calculate synthetic spectra using radiative transfer, known stellar atomic and molecular lines, different surface spot configurations and an added planetary signal. Here, the methods are described in detail, tested and compared to previously published studies. The methods are also applied to investigate the activity jitter in old and young solar-like stars, and over a solar-like activity cycles. We find that the mean full jitter amplitude obtained from the spot surfaces mimicking the solar activity varies during the cycle approximately between 1 and 9 m s-1. With a realistic observing frequency a Neptune-mass planet on a 1-yr orbit can be reliably recovered. On the other hand, the recovery of an Earth-mass planet on a similar orbit is not feasible with high significance. The methods developed in this study have a great potential for doing statistical studies of planet detectability, and also for investigating the effect of stellar activity on recovered planetary parameters. Title: Magnetic field topology and chemical spot distributions in the extreme Ap star HD 75049 Authors: Kochukhov, O.; Rusomarov, N.; Valenti, J. A.; Stempels, H. C.; Snik, F.; Rodenhuis, M.; Piskunov, N.; Makaganiuk, V.; Keller, C. U.; Johns-Krull, C. M. Bibcode: 2015A&A...574A..79K Altcode: 2014arXiv1411.7518K Context. Intermediate-mass, magnetic chemically peculiar (Ap) stars provide a unique opportunity to study the topology of stellar magnetic fields in detail and to investigate magnetically driven processes of spot formation.
Aims: Here we aim to derive the surface magnetic field geometry and chemical abundance distributions for the extraordinary Ap star HD 75049. This object hosts a surface field of ~30 kG, one of the strongest known for any non-degenerate star.
Methods: We used time-series of high-resolution HARPS intensity and circular polarisation observations. These data were interpreted with the help of magnetic Doppler imaging and model atmospheres incorporating effects of a non-solar chemical composition and a strong magnetic field.
Results: Based on high-precision measurements of the mean magnetic field modulus, we refined the rotational period of HD 75049 to Prot = 4.048267 ± 0.000036 d. We also derived basic stellar parameters, Teff = 10 250 ± 250 K and log g = 4.3 ± 0.1. Magnetic Doppler imaging revealed that the field topology of HD 75049 is poloidal and dominated by a dipolar contribution with a peak surface field strength of 39 kG. At the same time, deviations from the classical axisymmetric oblique dipolar configuration are significant. Chemical surface maps of Si, Cr, Fe, and Nd show abundance contrasts of 0.5-1.4 dex, which is low compared with many other Ap stars. Of the chemical elements, Nd is found to be enhanced close to the magnetic pole, whereas Si and Cr are concentrated predominantly at the magnetic equator. The iron distribution shows low-contrast features both at the magnetic equator and the pole.
Conclusions: The morphology of the magnetic field and the properties of chemical spots in HD 75049 are qualitatively similar to those of Ap stars with weaker fields. Consequently, whatever mechanism forms and sustains global magnetic fields in intermediate-mass main-sequence stars, it operates in the same way over the entire observed range of magnetic field strengths.

Based on observations collected at the European Southern Observatory, Chile (ESO programs 084.D-0338, 085.D-0296, 086.D-0240, 088.D-0066, 090.D-0256, 078.D-0192, 080.D-0170). Title: Serendipitous Discovery of a Dwarf Nova in the Kepler Field Near the G Dwarf KIC 5438845 Authors: Brown, Alexander; Neff, James E.; Ayres, Thomas R.; Kowalski, Adam; Hawley, Suzanne; Berdyugina, Svetlana; Harper, Graham M.; Korhonen, Heidi; Piskunov, Nikolai; Saar, Steven; Walkowicz, Lucianne; Wells, Mark A. Bibcode: 2015AJ....149...67B Altcode: The Kepler satellite provides a unique window into stellar temporal variability by observing a wide variety of stars with multi-year, near-continuous, high precision, optical photometric time series. While most Kepler targets are faint stars with poorly known physical properties, many unexpected discoveries should result from a long photometric survey of such a large area of sky. During our Kepler Guest Observer programs that monitored late-type stars for starspot and flaring variability, we discovered a previously unknown dwarf nova that lies within a few arcseconds of the mid-G dwarf star KIC 5438845. This dwarf nova underwent nine outbursts over a 4 year time span. The two largest outbursts lasted ∼17-18 days and show strong modulations with a 110.8 minute period and a declining amplitude during the outburst decay phase. These properties are characteristic of an SU UMa-type cataclysmic variable. By analogy with other dwarf nova light curves, we associate the 110.8 minute (1.847 hr) period with the superhump period, close to but slightly longer than the orbital period of the binary. No precursor outbursts are seen before the super-outbursts and the overall super-outburst morphology corresponds to Osaki & Meyer “Case B” outbursts, which are initiated when the outer edge of the disk reaches the tidal truncation radius. “Case B” outbursts are rare within the Kepler light curves of dwarf novae. The dwarf nova is undergoing relatively slow mass transfer, as evidenced by the long intervals between outbursts, but the mass transfer rate appears to be steady, because the smaller “normal” outbursts show a strong correlation between the integrated outburst energy and the elapsed time since the previous outburst. At super-outburst maximum the system was at V ∼ 18, but in quiescence it is fainter than V ∼ 22, which will make any detailed quiescent follow-up of this system difficult. Title: Stellar magnetic fields from four Stokes parameter observations Authors: Rusomarov, N.; Kochukhov, O.; Piskunov, N. Bibcode: 2015IAUS..307..395R Altcode: 2014arXiv1407.7912R Magnetic Doppler imaging (MDI) from observations of four Stokes parameters can uncover new information that is of interest to the evolution and structure of magnetic fields of intermediate and high-mass stars. Our MDI study of the chemically peculiar star HD 24712 from four Stokes parameter observations, obtained with the HARPSpol instrument at the 3.6-m ESO telescope, revealed a magnetic field with strong dipolar component and weak small-scale contributions. This finding gives evidence for the hypothesis that old Ap stars have predominantly dipolar magnetic fields. Title: Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712. II. Two-dimensional magnetic Doppler imaging in all four Stokes parameters Authors: Rusomarov, N.; Kochukhov, O.; Ryabchikova, T.; Piskunov, N. Bibcode: 2015A&A...573A.123R Altcode: 2014arXiv1409.6955R
Aims: We present a magnetic Doppler imaging study from all Stokes parameters of the cool, chemically peculiar star HD 24712. This is the very first such analysis performed at a resolving power exceeding 105.
Methods: The analysis is performed on the basis of phase-resolved observations of line profiles in all four Stokes parameters obtained with the HARPSpol instrument attached at the 3.6 m ESO telescope. We used the magnetic Doppler imaging code invers10, which allowed us to derive the magnetic field geometry and surface chemical abundance distributions simultaneously.
Results: We report magnetic maps of HD 24712 recovered from a selection of Fe i, Fe ii, Nd iii, and Na i lines with strong polarization signals in all Stokes parameters. Our magnetic maps successfully reproduce most of the details available from our observation data. We used these magnetic field maps to produce abundance distribution map of Ca. This new analysis shows that the surface magnetic field of HD 24712 has a dominant dipolar component with a weak contribution from higher-order harmonics. The surface abundance distributions of Fe and Ca show enhancements near the magnetic equator with an underabundant patch at the visible (positive) magnetic pole; Nd is highly abundant around the positive magnetic pole. The Na abundance map shows a high overabundance around the negative magnetic pole.
Conclusions: Based on our investigation and similar recent magnetic mapping studies that used four Stokes parameters, we present tentative evidence for the hypothesis that Ap stars with dipole-like fields are older than stars with magnetic fields that have more small-scale structures. We find that our abundance maps are inconsistent with recent theoretical calculations of atomic diffusion in presence of magnetic fields.

Based on observations collected at the European Southern Observatory, Chile (ESO programs 084.D-0338, 085.D-0296, 086.D-0240). Title: Methodology for measuring fundamental parameters and associated uncertainties for middle and cool main-sequence stars Authors: Piskunov, N.; Ryabchikova, T.; Titarenko, A.; Pakhomov, Yu. V.; Nizamov, B. Bibcode: 2014psce.conf..130P Altcode: We have performed a study of a representative group of main-sequence stars in the temperature range 5000-10000 K in order to test our methodology for determining fundamental parameters and for the assesment of associated uncertainties. The stars selected have reasonably well-established parameters. This paper presents all the steps of our method, from the selection of spectral intervals and atomic/molecular data, to the determination of effective temperatures, surface gravities and metallicities. Title: Magnetic fields of Ap stars from full Stokes spectropolarimetric observations Authors: Rusomarov, N.; Kochukhov, O.; Piskunov, N. Bibcode: 2014psce.conf..380R Altcode: 2013arXiv1310.0664R Current knowledge about stellar magnetic fields relies almost entirely on observations of circular polarization. Few objects have been observed in all four Stokes parameters. The magnetic Ap star HD 24712 (DO Eri, HR 1217) was recently observed in the Stokes IQUV parameters with the HARPSpol instrument at the 3.6-m ESO telescope as part of our project at investigating Ap stars in all four Stokes parameters. The resulting spectra have dense phase coverage, resolving power > 10^5, and S/N ratio of 300-600. These are the highest quality full Stokes observations obtained for any star other than the Sun. We present preliminary results from magnetic Doppler imaging of HD 24712. This analysis is the first step towards obtaining detailed 3-D maps of magnetic fields and abundance structures for HD 24712 and for other Ap stars that we are currently observing with HARPSpol. Title: Exoplanet Science with the European Extremely Large Telescope. The Case for Visible and Near-IR Spectroscopy at High Resolution Authors: Udry, S.; Lovis, C.; Bouchy, F.; Collier Cameron, A.; Henning, T.; Mayor, M.; Pepe, F.; Piskunov, N.; Pollacco, D.; Queloz, D.; Quirrenbach, A.; Rauer, H.; Rebolo, R.; Santos, N. C.; Snellen, I.; Zerbi, F. Bibcode: 2014arXiv1412.1048U Altcode: Exoplanet science is booming. In 20 years our knowledge has expanded considerably, from the first discovery of a Hot Jupiter, to the detection of a large population of Neptunes and super-Earths, to the first steps toward the characterization of exoplanet atmospheres. Between today and 2025, the field will evolve at an even faster pace with the advent of several space-based transit search missions, ground-based spectrographs, high-contrast imaging facilities, and the James Webb Space Telescope. Especially the ESA M-class PLATO mission will be a game changer in the field. From 2024 onwards, PLATO will find transiting terrestrial planets orbiting within the habitable zones of nearby, bright stars. These objects will require the power of Extremely Large Telescopes (ELTs) to be characterized further. The technique of ground-based high-resolution spectroscopy is establishing itself as a crucial pathway to measure chemical composition, atmospheric structure and atmospheric circulation in transiting exoplanets. A high-resolution spectrograph covering the visible and near-IR domains, mounted on the European ELT, will be able to detect molecules such as water vapour, carbon dioxide and oxygen in the atmospheres of habitable planets under favourable circumstances. E-ELT HiRES is the perfect ground-based match to the PLATO space mission and represents a unique opportunity for Europe to lead the world into the era of exploration of exoplanets with habitable conditions. HiRES will also be extremely complementary to other E-ELT planned instruments specialising in different kinds of planets, such as METIS and EPICS. Title: HIRES: the high resolution spectrograph for the E-ELT Authors: Zerbi, F. M.; Bouchy, F.; Fynbo, J.; Maiolino, R.; Piskunov, N.; Rebolo Lopez, R.; Santos, N.; Strassmeier, K.; Udry, S.; Vanzi, L.; Riva, M.; Basden, A.; Boisse, I.; Bonfils, X.; Buscher, D.; Cabral, A.; Dimarcantonio, P.; Di Varano, I.; Henry, D.; Monteiro, M.; Morris, T.; Murray, G.; Oliva, Ernesto; Parry, I.; Pepe, F.; Quirrenbach, A.; Rasilla, J. L.; Rees, P.; Stempels, E.; Valenziano, L.; Wells, M.; Wildi, F.; Origlia, L.; Allende Prieto, C.; Chiavassa, A.; Cristiani, S.; Figueira, P.; Gustafsson, B.; Hatzes, A.; Haehnelt, M.; Heng, K.; Israelian, G.; Kochukhov, O.; Lovis, C.; Marconi, A.; Martins, C. J. A. P.; Noterdaeme, P.; Petitjean, P.; Puzia, T.; Queloz, D.; Reiners, A.; Zoccali, M. Bibcode: 2014SPIE.9147E..23Z Altcode: The current instrumentation plan for the E-ELT foresees a High Resolution Spectrograph conventionally indicated as HIRES. Shaped on the study of extra-solar planet atmospheres, Pop-III stars and fundamental physical constants, HIRES is intended to embed observing modes at high-resolution (up to R=150000) and large spectral range (from the blue limit to the K band) useful for a large suite of science cases that can exclusively be tackled by the E-ELT. We present in this paper the solution for HIRES envisaged by the "HIRES initiative", the international collaboration established in 2013 to pursue a HIRES on E-ELT. Title: Magnetic fields in M-dwarfs from high-resolution infrared spectroscopy Authors: Shulyak, D.; Reiners, A.; Seemann, U.; Kochukhov, O.; Piskunov, N. Bibcode: 2014IAUS..302..170S Altcode: Accurate spectroscopic measurements of magnetic fields in low mass stars remain challenging because of their cool temperatures, strong line blending, and often fast rotation. This is why previous estimates were based either on the analysis of only a few lines or made use of some indirect techniques. This frequently led to noticeable scatter in obtained results. In this talk I will present and discuss new results on the determination of the intensity and geometry of the magnetic fields in M-dwarfs using IR observations obtained with CRIRES@VLT. The instrument provides unprecedented data of high resolution (R = 100 000) which is crucial for resolving individual magnetically broadened molecular and atomic lines. Such an in-depth analysis based on direct magnetic spectral synthesis opens a possibility to deduce both field intensity and geometry avoiding most of the limitation and assumptions made in previous studies. Title: Wavelength calibration from 1-5μm for the CRIRES+ high-resolution spectrograph at the VLT Authors: Seemann, U.; Anglada-Escude, G.; Baade, D.; Bristow, P.; Dorn, R. J.; Follert, R.; Gojak, D.; Grunhut, J.; Hatzes, A. P.; Heiter, U.; Ives, D. J.; Jeep, P.; Jung, Y.; Käufl, H. -U.; Kerber, F.; Klein, B.; Lizon, J. -L.; Lockhart, M.; Löwinger, T.; Marquart, T.; Oliva, E.; Paufique, J.; Piskunov, N.; Pozna, E.; Reiners, A.; Smette, A.; Smoker, J.; Stempels, E.; Valenti, E. Bibcode: 2014SPIE.9147E..5GS Altcode: CRIRES at the VLT is one of the few adaptive optics enabled instruments that offer a resolving power of 105 from 1 - 5 μm. An instrument upgrade (CRIRES+) is proposed to implement cross-dispersion capabilities, spectro-polarimetry modes, a new detector mosaic, and a new gas absorption cell. CRIRES+ will boost the simultaneous wavelength coverage of the current instrument (~ γ/70 in a single-order) by a factor of 10 in the cross-dispersed configuration, while still retaining a ~> 10 arcsec slit suitable for long-slit spectroscopy. CRIRES+ dramatically enhances the instrument's observing efficiency, and opens new scientific opportunities. These include high-precision radial-velocity studies on the 3 m/s level to characterize extra-solar planets and their athmospheres, which demand for specialized, highly accurate wavelength calibration techniques. In this paper, we present a newly developed absorption gas-cell to enable high-precision wavelength calibration for CRIRES+. We also discuss the strategies and developments to cover the full operational spectral range (1 - 5 μµm), employing cathode emission lamps, Fabry-Perot etalons, and absorption gas-cells. Title: Magnetic fields of Ap stars from full Stokes vector spectropolarimetric observations Authors: Rusomarov, N.; Kochukhov, O.; Piskunov, N. Bibcode: 2014IAUS..302..304R Altcode: 2013arXiv1310.0412R Current knowledge about stellar magnetic fields relies almost entirely on circular polarization observations, with very few objects having been observed in all four Stokes parameters. We are investigating a sample of Ap stars in all four Stokes parameters using the HARPSpol instrument at the 3.6-m ESO telescope. In the context of this project we recently observed the magnetic Ap star HD 24712 (DO Eri, HR 1217). The resulting spectra have dense phase coverage, resolving power > 105, and S/N ratio of 300-600. These are the highest quality full Stokes observations obtained for any star other than the Sun. Furthermore, we have achieved good phase coverage for HD 125248 and HD 119419. Typical four Stokes parameters HARPSpol spectra are shown in Fig. 1. An analysis of the full Stokes vector spectropolarimetric data set of HD 24712 has been published in Rusomarov et al. (2013). Title: Opto-mechanical design of a new cross dispersion unit for the CRIRES+ high resolution spectrograph for the VLT Authors: Lizon, Jean Louis; Klein, Barbara; Oliva, Ernesto; Löwinger, Tom; Anglada Escude, Guillem; Baade, Dietrich; Bristow, Paul; Dorn, Reinhold J.; Follert, Roman; Grunhut, Jason; Hatzes, Artie; Heiter, Ulrike; Ives, Derek; Jung, Yves; Kerber, Florian; Lockhart, Matt; Marquart, Thomas; Origlia, Livia; Pasquini, Luca; Paufique, Jerome; Piskunov, N.; Pozna, Eszter; Reiners, Ansgar; Smette, Alain; Smoker, Jonathan; Seemann, Ulf; Stempels, Eric; Valenti, Elena Bibcode: 2014SPIE.9147E..7SL Altcode: CRIRES is one of the few IR (0.92-5.2 μm) high-resolution spectrographs in operation at the VLT since 2006. Despite good performance it suffers a limitation that significantly hampers its ability: a small spectral coverage per exposure. The CRIRES upgrade (CRIRES+) proposes to transform CRIRES into a cross-dispersed spectrograph while maintaining the high resolution (100000) and increasing the wavelength coverage by a factor 10 compared to the current capabilities. A major part of the upgrade is the exchange of the actual cryogenic pre-disperser module by a new cross disperser unit. In addition to a completely new optical design, a number of important changes are required on key components and functions like the slit unit and detectors units. We will outline the design of these new units fitting inside a predefined and restricted space. The mechanical design of the new functions including a description and analysis will be presented. Finally we will present the strategy for the implementation of the changes. Title: Concept and optical design of the cross-disperser module for CRIRES+ Authors: Oliva, E.; Tozzi, A.; Ferruzzi, D.; Origlia, L.; Hatzes, A.; Follert, R.; Löwinger, T.; Piskunov, N.; Heiter, U.; Lockhart, M.; Marquart, T.; Stempels, E.; Reiners, A.; Anglada-Escude, G.; Seemann, Ulf; Dorn, R. J.; Bristow, P.; Baade, D.; Delabre, B.; Gojak, D.; Grunhut, J.; Klein, Barbara; Hilker, M.; Ives, D. J.; Jung, Y.; Kaeufl, H. -U.; Kerber, F.; Lizon, J. L.; Pasquini, L.; Paufique, J.; Pozna, Eszter; Smette, A.; Smoker, J.; Valenti, E. Bibcode: 2014SPIE.9147E..7RO Altcode: 2014arXiv1407.3057O CRIRES, the ESO high resolution infrared spectrometer, is a unique instrument which allows astronomers to access a parameter space which up to now was largely uncharted. In its current setup, it consists of a single-order spectrograph providing long-slit, single-order spectroscopy with resolving power up to R=100,000 over a quite narrow spectral range. This has resulted in sub-optimal efficiency and use of telescope time for all the scientific programs requiring broad spectral coverage of compact objects (e.g. chemical abundances of stars and intergalactic medium, search and characterization of extra-solar planets). To overcome these limitations, a consortium was set-up for upgrading CRIRES to a cross-dispersed spectrometer, called CRIRES+. This paper presents the updated optical design of the cross-dispersion module for CRIRES+. This new module can be mounted in place of the current pre-disperser unit. The new system yields a factor of >10 increase in simultaneous spectral coverage and maintains a quite long slit (10"), ideal for observations of extended sources and for precise sky-background subtraction. Title: CRIRES+: a cross-dispersed high-resolution infrared spectrograph for the ESO VLT Authors: Follert, R.; Dorn, R. J.; Oliva, E.; Lizon, J. L.; Hatzes, A.; Piskunov, N.; Reiners, A.; Seemann, U.; Stempels, E.; Heiter, U.; Marquart, T.; Lockhart, M.; Anglada-Escude, G.; Löwinger, T.; Baade, D.; Grunhut, J.; Bristow, P.; Klein, B.; Jung, Y.; Ives, D. J.; Kerber, F.; Pozna, E.; Paufique, J.; Kaeufl, H. U.; Origlia, L.; Valenti, E.; Gojak, D.; Hilker, M.; Pasquini, L.; Smette, A.; Smoker, J. Bibcode: 2014SPIE.9147E..19F Altcode: High-resolution infrared spectroscopy plays an important role in astrophysics from the search for exoplanets to cosmology. Yet, many existing infrared spectrographs are limited by a rather small simultaneous wavelength coverage. The AO assisted CRIRES instrument, installed at the ESO VLT on Paranal, is one of the few IR (0.92-5.2 μm) highresolution spectrographs in operation since 2006. However it has a limitation that hampers its efficient use: the wavelength range covered in a single exposure is limited to ~15 nanometers. The CRIRES Upgrade project (CRIRES+) will transform CRIRES into a cross-dispersed spectrograph and will also add new capabilities. By introducing crossdispersion elements the simultaneously covered wavelength range will be increased by at least a factor of 10 with respect to the present configuration, while the operational wavelength range will be preserved. For advanced wavelength calibration, new custom made absorption gas cells and etalons will be added. A spectro-polarimetric unit will allow one for the first time to record circularly polarized spectra at the highest spectral resolution. This will be all supported by a new data reduction software which will allow the community to take full advantage of the new capabilities of CRIRES+. Title: Novel infrared polarimeter for the ESO CRIRES+ instrument Authors: Lockhart, Matthew; Piskunov, Nikolai; Stempels, Eric; Escuti, Michael; Oliva, Ernesto; Käufl, Hans-Ulrich; Heiter, Ulrike; Marquart, Thomas; Anglada-Escude, Guillem; Baade, Dietrich; Bristow, Paul; Dorn, Reinhold J.; Follert, Roman; Gojak, Domingo; Grunhut, Jason H.; Hatzes, Artie; Hilker, Michael; Ives, Derek; Jung, Yves; Kerber, Florian; Klein, Barbara; Lizon, Jean-Louis; Löwinger, Tom; Origlia, Livia; Pasquini, Luca; Paufique, Jerome; Pozna, Eszter; Reiners, Ansgar; Seemann, Ulf; Smette, Alain; Smoker, Jonathan; Valenti, Elena Bibcode: 2014SPIE.9147E..8PL Altcode: The CRIRES infrared spectrograph at the European Southern Observatory (ESO) Very Large Telescope (VLT) facility will soon receive an upgrade. This upgrade will include the addition of a module for performing highresolution spectropolarimetry. The polarimetry module will incorporate a novel infrared beamsplitter based on polarization gratings (PGs). The beamsplitter produces a pair of infrared output beams, with opposite circular polarizations, which are then fed into the spectrograph. Visible light passes through the module virtually unaltered and is then available for use by the CRIRES adaptive optics system. We present the design of the polarimetry module and measurements of PG behavior in the 1 to 2.7 μm wavelength range. Title: CRIRES+: Exploring the Cold Universe at High Spectral Resolution Authors: Dorn, R. J.; Anglada-Escude, G.; Baade, D.; Bristow, P.; Follert, R.; Gojak, D.; Grunhut, J.; Hatzes, A.; Heiter, U.; Hilker, M.; Ives, D. J.; Jung, Y.; Käufl, H. -U.; Kerber, F.; Klein, B.; Lizon, J. -L.; Lockhart, M.; Löwinger, T.; Marquart, T.; Oliva, E.; Origlia, L.; Pasquini, L.; Paufique, J.; Piskunov, N.; Pozna, E.; Reiners, A.; Smette, A.; Smoker, J.; Seemann, U.; Stempels, E.; Valenti, E. Bibcode: 2014Msngr.156....7D Altcode: The CRIRES upgrade project, CRIRES+, transforms this VLT instrument into a cross-dispersed spectrograph to increase the wavelength range that is covered simultaneously by a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 μm cut-off wavelength will replace the existing detectors. For advanced wavelength calibration, custom-made absorption gas cells will be added. A spectropolarimetric unit will allow circularly polarised spectra to be recorded. These upgraded capabilities will be all supported by dedicated data reduction software which will allow the community to take full advantage of the new capabilities offered by CRIRES+. Title: Exploring the magnetic field complexity in M dwarfs at the boundary to full convection Authors: Shulyak, D.; Reiners, A.; Seemann, U.; Kochukhov, O.; Piskunov, N. Bibcode: 2014A&A...563A..35S Altcode: 2014arXiv1401.5250S Context. Magnetic fields play a pivotal role in the formation and evolution of low-mass stars, but the dynamo mechanisms generating these fields are poorly understood. Measuring cool star magnetism is a complicated task because of the complexity of cool star spectra and the subtle signatures of magnetic fields.
Aims: Based on detailed spectral synthesis, we carry out quantitative measurements of the strength and complexity of surface magnetic fields in the four well-known M dwarfs GJ 388, GJ 729, GJ 285, and GJ 406 that populate the mass regime around the boundary between partially and fully convective stars. Very high-resolution (R = 100 000), high signal-to-noise (up to 400), near-infrared Stokes I spectra were obtained with CRIRES at ESO's Very Large Telescope covering regions of the FeH Wing-Ford transitions at 1μm and Na i lines at 2.2μm.
Methods: A modified version of the Molecular Zeeman Library (MZL) was used to compute Landé g-factors for FeH lines. We determined the distribution of magnetic fields by magnetic spectral synthesis performed with the Synmast code. We tested two different magnetic geometries to probe the influence of field orientation effects.
Results: Our analysis confirms that FeH lines are excellent indicators of surface magnetic fields in low-mass stars of type M, particularly in comparison to profiles of Na i lines that are heavily affected by water lines and that suffer problems with continuum normalization. The field distributions in all four stars are characterized by three distinct groups of field components, and the data are consistent neither with a smooth distribution of different field strengths nor with one average field strength covering the full star. We find evidence of a subtle difference in the field distribution of GJ 285 compared to the other three targets. GJ 285 also has the highest average field of 3.5 kG and the strongest maximum field component of 7-7.5 kG. The maximum local field strengths in our sample seem to be correlated with rotation rate. While the average field strength is saturated, the maximum local field strengths in our sample show no evidence of saturation.
Conclusions: We find no difference between the field distributions of partially and fully convective stars. The one star with evidence of field distribution different from the other three is the most active star (i.e. with X-ray luminosity and mean surface magnetic field) rotating relatively fast. A possible explanation is that rotation determines the distribution of surface magnetic fields, and that local field strengths grow with rotation even in stars in which the average field is already saturated.

Based on observations collected at the European Southern Observatory, Paranal, Chile (programme 385.D-0273). Title: Doppler images of DI Piscium during 2004-2006 Authors: Lindborg, M.; Hackman, T.; Mantere, M. J.; Korhonen, H.; Ilyin, I.; Kochukhov, O.; Piskunov, N. Bibcode: 2014A&A...562A.139L Altcode:
Aims: DI Psc (HD 217352) is a Li-rich, rapidly rotating single K giant. We set out to study the spot configuration and activity level by calculating surface temperature maps of the star.
Methods: We apply the Doppler imaging method on high-resolution optical spectroscopy obtained during 2004-2006.
Results: In July-August 2004, no clear spot structures were visible, but the spot coverage increased in July 2005, and cool spots emerged, especially at intermediate latitudes. Later on in September 2006, the spot coverage increased and cool spots were visible on both sides of the equator. However, the map of 2006 suffers from bad phase coverage, meaning it is not possible to draw definite conclusions on the spot locations during that season.
Conclusions: Compared with earlier Doppler maps of DI Psc and temperature maps obtained for other late-type stars with similar rotation rates, DI Psc seems to be in a low activity state especially during the observing season of July-August 2004. During the 2005 and 2006 observing seasons, the spot activity seen in the spectral line profiles and inferred from Doppler images increases, and the temperature contrast in our last map is more comparable to what was reported in an earlier study. Therefore, it can be concluded that the spot activity level of the star is variable over time. However, the present and previous Doppler images form too short a time series to draw conclusions about a possible activity cycle in DI Psc.

Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. Title: A Gentle Introduction to SME Authors: Piskunov, Nikolai Bibcode: 2014dapb.book..287P Altcode: No abstract at ADS Title: Testing SME determination of stellar parameters Authors: Ryabchikova, T. A.; Mashonkina, L. I.; Titarenko, A. R.; Alexeeva, S. A.; Pakhomov, Yu. V.; Piskunov, N. E.; Sitnova, T. M.; Nizamov, B. A. Bibcode: 2014IAUS..298..436R Altcode: We present the results of special tests of the automatic procedure for atmospheric parameters determination based on spectroscopy. Title: Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712 . I. Spectropolarimetric observations in all four Stokes parameters Authors: Rusomarov, N.; Kochukhov, O.; Piskunov, N.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Makaganiuk, V.; Rodenhuis, M.; Snik, F.; Stempels, H. C.; Valenti, J. A. Bibcode: 2013A&A...558A...8R Altcode: 2013arXiv1306.0997R Context. High-resolution spectropolarimetric observations provide simultaneous information about stellar magnetic field topologies and three-dimensional distributions of chemical elements. High-quality spectra in the Stokes IQUV parameters are currently available for very few early-type magnetic chemically peculiar stars. Here we present analysis of a unique full Stokes vector spectropolarimetric data set, acquired for the cool magnetic Ap star HD 24712 with a recently commissioned spectropolarimeter.
Aims: The goal of our work is to examine the circular and linear polarization signatures inside spectral lines and to study variation of the stellar spectrum and magnetic observables as a function of rotational phase.
Methods: HD 24712 was observed with the HARPSpol instrument at the 3.6-m ESO telescope over a period of 2010-2011. We achieved full rotational phase coverage with 43 individual Stokes parameter observations. The resulting spectra have a signal-to-noise ratio of 300-600 and resolving power exceeding 105. The multiline technique of least-squares deconvolution (LSD) was applied to combine information from the spectral lines of Fe-peak and rare earth elements.
Results: We used the HARPSPol spectra of HD 24712 to study the morphology of the Stokes profile shapes in individual spectral lines and in LSD Stokes profiles corresponding to different line masks. From the LSD Stokes V profiles we measured the longitudinal component of the magnetic field, ⟨Bz⟩, with an accuracy of 5-10 G. We also determined the net linear polarization from the LSD Stokes Q and U profiles. Combining previous ⟨Bz⟩ measurements with our data allowed us to determine an improved rotational period of the star, Prot = 12.45812 ± 0.00019 d. We also measured the longitudinal magnetic field from the cores of Hα and Hβ lines. The analysis of ⟨Bz⟩ measurements showed no evidence for a significant radial magnetic field gradient in the atmosphere of HD 24712. We used our ⟨Bz⟩ and net linear polarization measurements to determine parameters of the dipolar magnetic field topology. We found that magnetic observables can be reasonably well reproduced by the dipolar model, although significant discrepancies remain at certain rotational phases. We discovered rotational modulation of the Hα core and related it to a non-uniform surface distribution of rare earth elements.

Based on observations collected at the European Southern Observatory, Chile (ESO programs 084.D-0338, 085.D-0296, 086.D-0240).Figure 3 and Appendix A are available in electronic form at http://www.aanda.org Title: Are there tangled magnetic fields on HgMn stars? Authors: Kochukhov, O.; Makaganiuk, V.; Piskunov, N.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Rodenhuis, M.; Snik, F.; Stempels, H. C.; Valenti, J. A. Bibcode: 2013A&A...554A..61K Altcode: 2013arXiv1304.6717K Context. Several recent spectrophotometric studies failed to detect significant global magnetic fields in late-B HgMn chemically peculiar stars, but some investigations have suggested the presence of strong unstructured or tangled fields in these objects.
Aims: We used detailed spectrum synthesis analysis to search for evidence of tangled magnetic fields in high-quality observed spectra of eight slowly rotating HgMn stars and one normal late-B star. We also evaluated recent sporadic detections of weak longitudinal magnetic fields in HgMn stars based on the moment technique.
Methods: Our spectrum synthesis code calculated the Zeeman broadening of metal lines in HARPS spectra, assuming an unstructured, turbulent magnetic field. A simple line formation model with a homogeneous radial field distribution was applied to assess compatibility between previous longitudinal field measurements and the observed mean circular polarization signatures.
Results: Our analysis of the Zeeman broadening of magnetically sensitive spectral lines reveals no evidence of tangled magnetic fields in any of the studied HgMn or normal stars. We infer upper limits of 200-700 G for the mean magnetic field modulus - much smaller than the field strengths implied by studies based on differential magnetic line intensification and quadratic field diagnostics. The new HARPSpol longitudinal field measurements for the extreme HgMn star HD 65949 and the normal late-B star 21 Peg are consistent with zero at a precision of 3-6 G. Re-analysis of our Stokes V spectra of the spotted HgMn star HD 11753 shows that the recent moment technique measurements retrieved from the same data are incompatible with the lack of circular polarization signatures in the spectrum of this star.
Conclusions: We conclude that there is no evidence for substantial tangled magnetic fields on the surfaces of studied HgMn stars. We cannot independently confirm the presence of very strong quadratic or marginal longitudinal fields for these stars, so results from the moment technique are likely to be spurious.

Based on observations collected at the European Southern Observatory, Chile (ESO programmes 084.D-0338, 085.D-0296, 086.D-0240). Title: Radial velocity signatures of Zeeman broadening Authors: Reiners, A.; Shulyak, D.; Anglada-Escudé, G.; Jeffers, S. V.; Morin, J.; Zechmeister, M.; Kochukhov, O.; Piskunov, N. Bibcode: 2013A&A...552A.103R Altcode: 2013arXiv1301.2951R Stellar activity signatures such as spots and plages can significantly limit the search for extrasolar planets. Current models of activity-induced radial velocity (RV) signals focus on the impact of temperature contrast in spots according to which they predict the signal to diminish toward longer wavelengths. The Zeeman effect on RV measurements counteracts this: the relative importance of the Zeeman effect on RV measurements should grow with wavelength because the Zeeman displacement itself grows with λ, and because a magnetic and cool spot contributes more to the total flux at longer wavelengths. In this paper, we model the impact of active regions on stellar RV measurements including both temperature contrast in spots and line broadening by the Zeeman effect. We calculate stellar line profiles using polarized radiative transfer models including atomic and molecular Zeeman splitting over large wavelength regions from 0.5 to 2.3 μm. Our results show that the amplitude of the RV signal caused by the Zeeman effect alone can be comparable to that caused by temperature contrast; a spot magnetic field of ~1000 G can produce a similar RV amplitude as a spot temperature contrast of ~1000 K. Furthermore, the RV signal caused by cool and magnetic spots increases with wavelength, in contrast to the expectation from temperature contrast alone. We also calculate the RV signal caused by variations in average magnetic field strength from one observation to the next, for example due to a magnetic cycle, but find it unlikely that this can significantly influence the search for extrasolar planets. As an example, we derive the RV amplitude of the active M dwarf AD Leo as a function of wavelength using data from the HARPS spectrograph. Across this limited wavelength range, the RV signal does not diminish at longer wavelengths but shows evidence for the opposite behavior, consistent with a strong influence of the Zeeman effect. We conclude that the RV signal of active stars does not vanish at longer wavelength but sensitively depends on the combination of spot temperature and magnetic field; in active low-mass stars, it is even likely to grow with wavelength. Title: Multi-element Doppler imaging of the CP2 star HD 3980 Authors: Nesvacil, N.; Lüftinger, T.; Shulyak, D.; Obbrugger, M.; Weiss, W.; Drake, N. A.; Hubrig, S.; Ryabchikova, T.; Kochukhov, O.; Piskunov, N.; Polosukhina, N. Bibcode: 2013arXiv1303.2703N Altcode: In atmospheres of magnetic main-sequence stars, the diffusion of chemical elements leads to a number of observed anomalies, such as abundance spots across the stellar surface. The aim of this study was to derive a detailed picture of the surface abundance distribution of the magnetic chemically peculiar star HD 3980. Based on high-resolution, phase-resolved spectroscopic observations of the magnetic A-type star HD 3980, the inhomogeneous surface distribution of 13 chemical elements (Li, O, Si, Ca, Cr, Mn, Fe, La, Ce, Pr, Nd, Eu, and Gd) has been reconstructed. The INVERS12 code was used to invert the rotational variability in line profiles to elemental surface distributions. Assuming a centered, dominantly dipolar magnetic field configuration, we find that Li, O, Mg, Pr, and Nd are mainly concentrated in the area of the magnetic poles and depleted in the regions around the magnetic equator. The high abundance spots of Si, La, Ce, Eu, and Gd are located between the magnetic poles and the magnetic equator. Except for La, which is clearly depleted in the area of the magnetic poles, no obvious correlation with the magnetic field has been found for these elements otherwise. Ca, Cr, and Fe appear enhanced along the rotational equator and the area around the magnetic poles. The intersection between the magnetic and the rotational equator constitutes an exception, especially for Ca and Cr, which are depleted in that region. No obvious correlation between the theoretically predicted abundance patterns and those determined in this study could be found. This can be attributed to a lack of up-to-date theoretical models, especially for rare earth elements. Title: Magnetically Controlled Accretion on the Classical T Tauri Stars GQ Lupi and TW Hydrae Authors: Johns-Krull, Christopher M.; Chen, Wei; Valenti, Jeff A.; Jeffers, Sandra V.; Piskunov, Nikolai E.; Kochukhov, Oleg; Makaganiuk, V.; Stempels, H. C.; Snik, Frans; Keller, Christoph; Rodenhuis, M. Bibcode: 2013ApJ...765...11J Altcode: 2013arXiv1301.3182J We present high spectral resolution (R ≈ 108, 000) Stokes V polarimetry of the classical T Tauri stars (CTTSs) GQ Lup and TW Hya obtained with the polarimetric upgrade to the HARPS spectrometer on the ESO 3.6 m telescope. We present data on both photospheric lines and emission lines, concentrating our discussion on the polarization properties of the He I emission lines at 5876 Å and 6678 Å. The He I lines in these CTTSs contain both narrow emission cores, believed to come from near the accretion shock region on these stars, and broad emission components which may come from either a wind or the large-scale magnetospheric accretion flow. We detect strong polarization in the narrow component of the two He I emission lines in both stars. We observe a maximum implied field strength of 6.05 ± 0.24 kG in the 5876 Å line of GQ Lup, making it the star with the highest field strength measured in this line for a CTTS. We find field strengths in the two He I lines that are consistent with each other, in contrast to what has been reported in the literature on at least one star. We do not detect any polarization in the broad component of the He I lines on these stars, strengthening the conclusion that they form over a substantially different volume relative to the formation region of the narrow component of the He I lines. Title: DELO-Bezier Formal Solutions of the Polarized Radiative Transfer Equation Authors: de la Cruz Rodríguez, J.; Piskunov, N. Bibcode: 2013ApJ...764...33D Altcode: 2012arXiv1212.2737D We present two new accurate and efficient methods to compute the formal solution of the polarized radiative transfer equation. In this work, the source function and the absorption matrix are approximated using quadratic and cubic Bezier spline interpolants. These schemes provide second- and third-order approximations, respectively, and do not suffer from erratic behavior of the polynomial approximation (overshooting). The accuracy and the convergence of the new method are studied along with other popular solutions of the radiative transfer equation, using stellar atmospheres with strong gradients in the line-of-sight velocity and in the magnetic-field vector. Title: MMT Hectochelle Spectral Variability of Active Late-type Stars in the Kepler Field (2013A) Authors: Brown, Alexander; Walkowicz, Lucianne; Saar, Steven; Hawley, Suzanne; Kowalski, Adam; Furesz, Gabor; Piskunov, Nikolai Bibcode: 2013noao.prop..286B Altcode: We have on-going it Kepler photometric monitoring of over 300 active late-type (mid-A - K) stars as part of our Cycles 1/2/3/4 Guest Observer (GO) programs with the aim of studying starspot evolution, differential rotation, activity cycles, and flares. We propose to use the MMT Hectochelle multiobject spectrograph to observe over 140 of these stars to determine a range of basic physical properties for the stars, such as radial velocity variations due to binarity, chromospheric activity levels from Ca II H+K and H(alpha), projected rotational velocities for comparison to the rotational periods measured directly by it Kepler, age/youth as indicated by Li I, and better effective temperature and luminosity estimates. In addition, to provide a superior sample for statistical studies another 800 GKM dwarf stars showing either starspot modulation from the it Kepler Team's data or from our deep XMM X-ray survey will be observed using the unassigned fibers in each field. These measurements require the 32,000 spectral resolution provided by Hectochelle, which is hard to obtain efficiently for 13-15th magnitude stars any other way. Title: A Large Sample of Magnetically-Active Stars Observed With Kepler Authors: Wells, Mark; Neff, J. E.; Brown, A.; Ayres, T. R.; Basri, G. S.; Berdyugina, S.; Harper, G.; Hawley, S. L.; Korhonen, H.; Kowalski, A.; Micela, G.; Piskunov, N. E.; Ramsey, L. W.; Saar, S. H.; Walkowicz, L. M. Bibcode: 2013AAS...22135415W Altcode: We have observed about 325 stars in our Kepler Guest Observer programs (Cycles 1 through 4). For most of these targets, we are analyzing extremely high-precision light curves that have been continuously sampled every 30 minutes for up to 3 years. Our sample of candidate magnetically-active stars was selected primarily using GALEX colors. Starspots, pulsations, and variations due to eclipsing and contact binaries combine to produce a rich variety of light curves. We have developed semi-automated procedures to characterize this variability and thus to classify the targets and identify the physical mechanisms that dominate their Kepler light curves. We will describe these procedures and discuss the range of physical properties covered by our final classification scheme. We are using this Kepler database of variability over timescales of minutes to years to provide diagnostics of flares, starspot formation, evolution, migration, and ultimately of stellar cycles in general. This work contains results obtained using the NASA Kepler satellite and from the Apache Point Observatory, the MMT (using NOAO community access time), and the Hobby-Eberly Telescope. Funding is provided by NASA Kepler grants NNX10AC51G, NNX11AC79G, and NNX12AC85G to the University of Colorado, by NSF grant AST-1109695 to the College of Charleston, and by a grant from the South Carolina Space Grant consortium. Title: HARPS Spectropolarimetry of the Classical T Tauri Stars GQ Lup and TW Hya Authors: Johns-Krull, Christopher M.; Chen, W.; Valenti, J. A.; Jeffers, S. V.; Piskunov, N. E.; Kochukhov, O.; Makaganiuk, V.; Stempels, H. C.; Snik, F.; Keller, C.; Rodenhuis, M. Bibcode: 2013AAS...22125614J Altcode: We present high spectral resolution Stokes V polarimetery of the Classical T Tauri stars (CTTSs) GQ Lup and TW Hya obtained with the polarimetric upgrade to the HARPS spectrometer on the ESO 3.6 m telescope. We present data on both photospheric lines and emission lines, concentrating our discussion on the polarization properties of the He I emission lines at 5876 A and 6678 A. The He I lines in both these CTTS contain both narrow emission cores, believed to come from near the accretion shock region on these stars, and broad emission components which may come from either a wind or the large scale magnetospheric accretion flow. We detect strong polarization in the narrow component of both the He I emission lines in both stars. We observe a maximum implied field strength of 5.8 +/- 0.3 kG in the 5876 A line of GQ Lup, the highest field strength measured to date in this line for a CTTS. We find field strengths in the two He I lines that are consistent with each other, unlike what has been reported in the literature on at least one star. We do not detect any polarization in the broad component of the He I lines on these stars, strengthening the conclusion that they form over a substantially different volume relative the formation region of the narrow component of the He I lines. Title: VizieR Online Data Catalog: Exoplanet Orbit Database (Wright+, 2011) Authors: Wright, J. T.; Kakhouri, O.; Marcy, G. W.; Han, E.; Feng, Y.; Johnson, J. A.; Howard, A. W.; Fischer, D. A.; Valenti, J. A.; Anderson, J.; Piskunov, N. Bibcode: 2013yCat..61230412W Altcode: We present a database of well determined orbital parameters of exoplanets, and their host stars' properties. This database comprises spectroscopic orbital elements measured for 427 planets orbiting 363 stars from radial velocity and transit measurements as reported in the literature. We have also compiled fundamental transit parameters, stellar parameters, and the method used for the planets discovery. This Exoplanet Orbit Database includes all planets with robust, well measured orbital parameters reported in peer-reviewed articles. The Database is available in a searcheable, filterable, and sortable form on the Web at http://exoplanets.org through the Exoplanets Data Explorer Table, and the data can be plotted and explored through the Exoplanet Data Explorer Plotter. We use the Data Explorer to generate publication-ready plots giving three examples of the signatures of exoplanet migration and dynamical evolution: We illustrate the character of the apparent correlation between mass and period in exoplanet orbits, the different selection biases between radial velocity and transit surveys, and that the multiplanet systems show a distinct semi-major axis distribution from apparently singleton systems.

(2 data files). Title: Young Star Populations in the Kepler Field Authors: Brown, Alexander; Neff, J. E.; Wells, M.; Saar, S.; Furesz, G.; Walkowicz, L. M.; Ayres, T. R.; Basri, G. S.; Berdyugina, S.; Harper, G.; Hawley, S. L.; Korhonen, H.; Kowalski, A.; Micela, G.; Piskunov, N. E.; Ramsey, L. W. Bibcode: 2013AAS...22135414B Altcode: The Kepler satellite is providing spectacular optical photometric light-curves of unprecedented precision and duration that routinely allow detailed studies of stellar magnetic activity on late-type stars that were difficult previously. Kepler provides multi-year duration light-curves that allow investigation of how activity phenomena -- such as the growth, migration, and decay of star-spots, differential rotation, activity cycles, and flaring -- operate on a wide variety of single and binary stars. The 105 square degree Kepler Field contains tens of thousands of late-type stars showing rotational modulation due to star-spots with periods ranging from one day to a ``solar-like'' month. Short rotation periods and high levels of magnetic activity are strongly correlated. However, there are only two basic reasons why stars with rotation periods of a few days possess such high angular momentum --- either they are close binaries or they are young stars. During Kepler GO Cycles 1 through 4 we have been studying the Long-cadence (30 minute sampling) photometry of hundreds of active late-type stars and as an absolutely essential complement we have been obtaining high resolution optical spectra to understand the physical properties of these stars. We present results from a spectroscopic survey using the MMT Hectochelle multi-object echelle of 4 square degrees of the Kepler Field. We have discovered a significant population of young stars with Li I absorption indicating ages of ~100 Myr or less at a spatial density of at least 20 stars per square degree. Our detected young star sample comprises at least 80 stars and represents a dramatic advance compared to the previously known sample over the full Kepler Field of three stars in this age range. Roughly one sixth of the stars observed are young and a similar number short-period binaries based on 2-4 radial velocities. We show how the rotational properties of the stars and their physical properties are related. This work is based on data obtained with the NASA Kepler satellite and the MMT Hectochelle spectrograph using NOAO community access time. Support by NASA Kepler grants to the University of Colorado and by NSF grant to the College of Charleston. Title: Upgrading CRIRES-VLT to cross-dispersed mode Authors: Oliva, E.; Hatzes, A.; Piskunov, N.; Reiners, A.; Käufl, H. U.; Ferruzzi, D.; Tozzi, A.; Origlia, L. Bibcode: 2012SPIE.8446E..2NO Altcode: The cryogenic high resolution IR echelle spectrograph CRIRES is the ESO infrared (0.95&#87225.4 μm) high resolution spectrograph operating at the Nasmyth A focus of VLT-UT1. The instrument provides long-slit (31") spectroscopy with resolving power up to R=100,000 over a quite narrow wavelengths range, about 1/70 of the central wavelength. Observations of compact objects (e.g. stellar photospheres) could be made much more efficient by implementing a cross-dispersed mode, which increases the simultaneous spectral coverage by an order of magnitude or more. This paper presents the design of a relatively simple system to add cross-dispersed modes to CRIRES with a minimum impact on the instrument optics and mechanics. Title: ``Virtual Atomic and Molecular Data Centre'' and Astrophysics: Level 2 Release Authors: Doronin, M.; Dubernet, M. L.; Walton, N.; Mason, N.; Rixon, G.; Sidaner, P. L.; Schlemmer, S.; Piskunov, N.; Tennyson, J.; Akram, A.; Endres, C.; Hill, C.; Marquart, T.; Nenadovic, L.; Smith, K.; Vamdc Consortium Bibcode: 2012ASPC..461..331D Altcode: 2012adass..21..331D The Virtual Atomic and Molecular Data Centre (VAMDC, <a href='http://www.vamdc.eu/'>http://www.vamdc.eu/</a>) is a consortium between groups involved in the generation, evaluation, and use of atomic and molecular data, funded by the European Union. VAMDC aims to build a reliable, open, flexible and interoperable e-science interface to existing atomic and molecular data. The project will cover establishing the core consortium, the development and deployment of the infrastructure and the development of interfaces to the existing atomic and molecular databases. This paper describes the organisation of the project and the achievements at the end of its second year. Title: M-dwarf metallicities. A high-resolution spectroscopic study in the near infrared Authors: Önehag, A.; Heiter, U.; Gustafsson, B.; Piskunov, N.; Plez, B.; Reiners, A. Bibcode: 2012A&A...542A..33O Altcode: 2011arXiv1112.0141O Context. The relatively wide spread in the derived metallicities ([Fe/H]) of M dwarfs shows that various approaches have not yet converged to consistency. The presence of strong molecular features and incomplete line lists for the corresponding molecules have made determining the metallicity of M dwarfs difficult. Furthermore, the faint M dwarfs require long exposure times for the signal-to-noise ratio needed for a detailed spectroscopic abundance analysis.
Aims: We present a high-resolution (R ~ 50 000) spectroscopic study of a sample of eight single M dwarfs and three wide-binary systems observed in the infrared J band.
Methods: The absence of large molecular contributions allows for a precise continuum placement. We derived metallicities based on the best fit of synthetic spectra to the observed spectra. To verify the accuracy of the applied atmospheric models and test our synthetic spectrum approach, three binary systems with a K-dwarf primary and an M-dwarf companion were observed and analysed along with the single M dwarfs.
Results: We obtain good agreement between the metallicities derived for the primaries and secondaries of our test binaries, thereby confirming the reliability of our method of analysing M dwarfs. Our metallicities agree well with some earlier determinations, and deviate from others.
Conclusions: We conclude that spectroscopic abundance analysis in the J band is a reliable method for establishing the metallicity scale for M dwarfs. We recommend its application to a larger sample covering lower, as well as higher, metallicities. Further prospects for the method include abundance determinations for individual elements.

Based on data obtained at ESO-VLT, Paranal Observatory, Chile, Program ID 082.D-0838(A) and 084.D-1042(A).Table 2 is available in electronic form at http://www.aanda.orgElectronic version of the spectra is only available at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/542/A33 Title: VizieR Online Data Catalog: 3 M dwarfs near-infrared spectra (Onehag+, 2012) Authors: Onehag, A.; Heiter, U.; Gustafsson, B.; Piskunov, N.; Plez, B.; Reiners, A. Bibcode: 2012yCat..35420033O Altcode: 2012yCat..35429033O The observations were carried out in service mode with the infrared spectrometer CRIRES at ESO-VLT.

In total 14 targets were observed during periods 82 (1st of October 2008 to 31st of March 2009) and 84 (1st of October 2009 to 31st of March 2010).

(4 data files). Title: HARPS spectropolarimetry of classical T Tauri stars Authors: Johns-Krull, C. M.; Valenti, J. A.; Jeffers, S. V.; Piskunov, N. E.; Kochukhov, O.; Keller, C.; Snik, F.; Rodenhuis, M.; Makaganiuk, V.; Stempels, H. Bibcode: 2012AIPC.1429...43J Altcode: We present high spectral resolution Stokes V polarimetery of the Classical T Tauri stars (CTTSs) GQ Lup and TW Hya obtained with the polarimetric upgrade to the HARPS spectrometer on the ESO 3.6 m telescope. We present data on both photospheric lines and emission lines, concentrating our discussion on the polarization properties of the He I emission lines at 5876 A and 6678 A. The He I lines in both these CTTS contain both narrow emission cores, believed to come from near the accretion shock region on these stars, and broad emission components which may come from either a wind or the large scale magnetospheric accretion flow. We detect strong polarization in the narrow component of both the He I emission lines in both stars. We observe a maximum implied field strength of 5.8 +/- 0.3 kG in the 5876 A˚ line of GQ Lup, the highest field strength measured to date in this line for a CTTS. We find field strengths in the two He I lines that are consistent with each other, unlike what has been reported in the literature on at least one star. We do not detect any polarization in the broad component of the He I lines on these stars, strengthening the conclusion that they form over a substantially different volume relative the formation region of the narrow component of the He I lines. Title: Commission 29: Stellar Spectra Authors: Piskunov, Nikolai; Cunha, Katia; Parthasarathy, Mudumba; Aoki, Wako; Asplund, Martin; Bohlender, David; Carpenter, Kenneth; Melendez, Jorge; Rossi, Silvia; Smith, Verne; Soderblom, David; Wahlgren, Glenn Bibcode: 2012IAUTA..28..157P Altcode: Commission 29 consists of members of the International Astronomical Union carrying out theoretical and observational studies of stars using spectroscopy, developing instrumentation for spectroscopy and producing and collecting data for interpretation of spectra. Title: Division Iv: Stars Authors: Corbally, Christopher; D'Antona, Francesca; Spite, Monique; Asplund, Martin; Charbonnel, Corinne; Docobo, Jose Angel; Gray, Richard O.; Piskunov, Nikolai E. Bibcode: 2012IAUTA..28..147C Altcode: This Division IV was started on a trial basis at the General Assembly in The Hague 1994 and was formally accepted at the Kyoto General Assembly in 1997. Its broad coverage of ``Stars'' is reflected in its relatively large number of Commissions and so of members (1266 in late 2011). Its kindred Division V, ``Variable Stars'', has the same history of its beginning. The thinking at the time was to achieve some kind of balance between the number of members in each of the 12 Divisions. Amid the current discussion of reorganizing the number of Divisions into a more compact form it seems advisable to make this numerical balance less of an issue than the rationalization of the scientific coverage of each Division, so providing more effective interaction within a particular field of astronomy. After all, every star is variable to a certain degree and such variability is becoming an ever more powerful tool to understand the characteristics of every kind of normal and peculiar star. So we may expect, after hearing the reactions of members, that in the restructuring a single Division will result from the current Divisions IV and V. Title: Divisions Iv-V / Working Group ap & Related Stars Authors: Mathys, Gautier; Cunha, Margarida; Dworetsky, Michael; Kochukhov, Oleg; Kupka, Friedrich; LeBlanc, Francis; Monier, Richard; Paunzen, Ernst; Pintado, Olga; Piskunov, Nikolai; Ziznovsky, Jozef Bibcode: 2012IAUTA..28..203M Altcode: The purpose of the Working Group on Ap and Related Stars (ApWG) is to promote and facilitate research about stars in the spectral type range from B to early F that exhibit surface chemical peculiarities and related phenomena. This is a very active field of research, in which a wide variety of new developments have taken place since 2009, as illustrated by the following selected highlights. Title: Magnetism, chemical spots, and stratification in the HgMn star ϕ Phoenicis Authors: Makaganiuk, V.; Kochukhov, O.; Piskunov, N.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Rodenhuis, M.; Snik, F.; Stempels, H. C.; Valenti, J. A. Bibcode: 2012A&A...539A.142M Altcode: 2011arXiv1111.6065M Context. Mercury-manganese (HgMn) stars have been considered as non-magnetic and non-variable chemically peculiar (CP) stars for a long time. However, recent discoveries of the variability in spectral line profiles have suggested an inhomogeneous surface distribution of chemical elements in some HgMn stars. From the studies of other CP stars it is known that magnetic field plays a key role in the formation of surface spots. All attempts to find magnetic fields in HgMn stars have yielded negative results.
Aims: In this study, we investigate the possible presence of a magnetic field in ϕ Phe (HD 11753) and reconstruct surface distribution of chemical elements that show variability in spectral lines. We also test a hypothesis that a magnetic field is concentrated in chemical spots and look into the possibility that some chemical elements are stratified with depth in the stellar atmosphere.
Methods: Our analysis is based on high-quality spectropolarimetric time-series observations, covering a full rotational period of the star. Spectra were obtained with the HARPSpol at the ESO 3.6-m telescope. To increase the sensitivity of the magnetic field search, we employed the least-squares deconvolution (LSD) technique. Using Doppler imaging code INVERS10, we reconstructed surface chemical distributions by utilising information from multiple spectral lines. The vertical stratification of chemical elements was calculated with the DDAFit program.
Results: Combining information from all suitable spectral lines, we set an upper limit of 4 G on the mean longitudinal magnetic field. For chemical spots, an upper limit on the longitudinal field varies between 8 and 15 G. We confirmed the variability of Y, Sr, and Ti and detected variability in Cr lines. Stratification analysis showed that Y and Ti are not concentrated in the uppermost atmospheric layers.
Conclusions: Our spectropolarimetric observations rule out the presence of a strong, globally-organised magnetic field in ϕ Phe. This implies an alternative mechanism of spot formation, which could be related to a non-equilibrium atomic diffusion. However, the typical time scales of the variation in stratification predicted by the recent time-dependent diffusion models exceed significantly the spot evolution time-scale reported for ϕ Phe.

Based on observations collected at the European Southern Observatory, Chile (ESO programme 084.D-0338). Figures 9-12 are available in electronic form at http://www.aanda.org Title: SME: Spectroscopy Made Easy Authors: Valenti, J. A.; Piskunov, N. Bibcode: 2012ascl.soft02013V Altcode: Spectroscopy Made Easy (SME) is IDL software and a compiled external library that fits an observed high-resolution stellar spectrum with a synthetic spectrum to determine stellar parameters. The SME external library is available for Mac, Linux, and Windows systems. Atomic and molecular line data formatted for SME may be obtained from VALD. SME can solve for empirical log(gf) and damping parameters, using an observed spectrum of a star (usually the Sun) as a constraint. Title: Doppler images of II Pegasi for 2004-2010 Authors: Hackman, T.; Mantere, M. J.; Lindborg, M.; Ilyin, I.; Kochukhov, O.; Piskunov, N.; Tuominen, I. Bibcode: 2012A&A...538A.126H Altcode: 2011arXiv1106.6237H
Aims: We study the spot activity of II Peg during the years 2004-2010 to determine long- and short-term changes in the magnetic activity. In a previous study, we detected a persistent active longitude, as well as major changes in the spot configuration occurring on a timescale of shorter than a year. The main objective of this study is to determine whether the same phenomena persist in the star during these six years of spectroscopic monitoring.
Methods: The observations were collected with the high-resolution SOFIN spectrograph at the Nordic Optical Telescope. The temperature maps were calculated using a Doppler imaging code based on Tikhonov regularization.
Results: We present 12 new temperature maps that show spots distributed mainly over high and intermediate latitudes. In each image, 1-3 main active regions can be identified. The activity level of the star is clearly lower than during our previous study for the years 1994-2002. In contrast to the previous observations, we detect no clear drift of the active regions with respect to the rotation of the star.
Conclusions: Having shown a systematic longitudinal drift of the spot-generating mechanism during 1994-2002, the star has clearly switched to a low-activity state for 2004-2010, during which the spot locations appear more random over phase space. It could be that the star is near to a minimum of its activity cycle.

Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Title: M2K. II. A Triple-planet System Orbiting HIP 57274 Authors: Fischer, Debra A.; Gaidos, Eric; Howard, Andrew W.; Giguere, Matthew J.; Johnson, John A.; Marcy, Geoffrey W.; Wright, Jason T.; Valenti, Jeff A.; Piskunov, Nikolai; Clubb, Kelsey I.; Isaacson, Howard; Apps, Kevin; Lepine, Sebastien; Mann, Andrew; Moriarty, John; Brewer, John; Spronck, Julien F. P.; Schwab, Christian; Szymkowiak, Andrew Bibcode: 2012ApJ...745...21F Altcode: 2011arXiv1109.2926F Doppler observations from Keck Observatory have revealed a triple-planet system orbiting the nearby K4V star, HIP 57274. The inner planet, HIP 57274b, is a super-Earth with Msin i = 11.6 M ⊕ (0.036 M Jup), an orbital period of 8.135 ± 0.004 days, and slightly eccentric orbit e = 0.19 ± 0.1. We calculate a transit probability of 6.5% for the inner planet. The second planet has Msin i = 0.4 M Jup with an orbital period of 32.0 ± 0.02 days in a nearly circular orbit (e = 0.05 ± 0.03). The third planet has Msin i = 0.53 M Jup with an orbital period of 432 ± 8 days (1.18 years) and an eccentricity e = 0.23 ± 0.03. This discovery adds to the number of super-Earth mass planets with M sin i < 12 M ⊕ that have been detected with Doppler surveys. We find that 56% ± 18% of super-Earths are members of multi-planet systems. This is certainly a lower limit because of observational detectability limits, yet significantly higher than the fraction of Jupiter mass exoplanets, 20% ± 8%, that are members of Doppler-detected, multi-planet systems.

Based on observations obtained at the Keck Observatory, which is operated by the University of California. Title: Multi-element Doppler imaging of the CP2 star HD 3980 Authors: Nesvacil, N.; Lüftinger, T.; Shulyak, D.; Obbrugger, M.; Weiss, W.; Drake, N. A.; Hubrig, S.; Ryabchikova, T.; Kochukhov, O.; Piskunov, N.; Polosukhina, N. Bibcode: 2012A&A...537A.151N Altcode: Context. In atmospheres of magnetic main-sequence stars, the diffusion of chemical elements leads to a number of observed anomalies, such as abundance spots across the stellar surface.
Aims: The aim of this study was to derive a detailed picture of the surface abundance distribution of the magnetic chemically peculiar star HD 3980.
Methods: Based on high-resolution, phase-resolved spectroscopic observations of the magnetic A-type star HD 3980, the inhomogeneous surface distribution of 13 chemical elements (Li, O, Si, Ca, Cr, Mn, Fe, La, Ce, Pr, Nd, Eu, and Gd) has been reconstructed. The INVERS12 code was used to invert the rotational variability in line profiles to elemental surface distributions.
Results: Assuming a centered, dominantly dipolar magnetic field configuration, we find that Li, O, Mg, Pr, and Nd are mainly concentrated in the area of the magnetic poles and depleted in the regions around the magnetic equator. The high abundance spots of Si, La, Ce, Eu, and Gd are located between the magnetic poles and the magnetic equator. Except for La, which is clearly depleted in the area of the magnetic poles, no obvious correlation with the magnetic field has been found for these elements otherwise. Ca, Cr, and Fe appear enhanced along the rotational equator and the area around the magnetic poles. The intersection between the magnetic and the rotational equator constitutes an exception, especially for Ca and Cr, which are depleted in that region.
Conclusions: No obvious correlation between the theoretically predicted abundance patterns and those determined in this study could be found. This can be attributed to a lack of up-to-date theoretical models, especially for rare earth elements.

Table 1 is available in electronic form at http://www.aanda.org Title: New Insights into Stellar Magnetism from the Spectropolarimetry in All Four Stokes Parameters Authors: Kochukhov, O.; Snik, F.; Piskunov, N.; Jeffers, S. V.; Keller, C. U.; Makaganiuk, V.; Valenti, J. A.; Johns-Krull, C. M.; Rodenhuis, M.; Stempels, H. C. Bibcode: 2011ASPC..448..245K Altcode: 2011csss...16..245K Development of high-resolution spectropolarimetry has stimulated a major progress in our understanding of the magnetism and activity of late-type stars. During the last decade magnetic fields were discovered and mapped for various types of active stars using spectropolarimetric methods. However, these observations and modeling attempts are inherently incomplete since they are based on the interpretation of the stellar circular polarization alone. Taking advantage of the recently commissioned HARPS polarimeter, we obtained the first systematic observations of cool active stars in all four Stokes parameters. Here we report detection of the magnetically induced linear polarization in the RS CVn binary HR 1099 and phase-resolved full Stokes vector observations of varepsilon Eri. For the latter star we measured the field strength with the precision of ∼0.1 G over a complete rotation cycle and reconstructed the global field topology with the help of magnetic Doppler imaging. Our observations of the inactive solar-like star α Cen A indicate the absence of the global field stronger than 0.2 G. Title: Rotation, magnetism and metallicity of M dwarf systems Authors: Shulyak, D.; Seifahrt, A.; Reiners, A.; Kochukhov, O.; Piskunov, N. Bibcode: 2011MNRAS.418.2548S Altcode: 2011MNRAS.tmp.1579S; 2011arXiv1108.3465S Close M dwarf binaries and higher multiples allow the investigation of rotational evolution and mean magnetic flux unbiased from scatter in inclination angle and age since the orientation of the spin axis of the components is most likely parallel and the individual systems are coeval. Systems composed of an early-type (M0.0-M4.0) and a late-type (M4.0-M8.0) component offer the possibility to study differences in rotation and magnetism between partially and fully convective stars. We have selected 10 of the closest dM systems to determine the rotation velocities and the mean magnetic field strengths based on spectroscopic analysis of FeH lines of Wing-Ford transitions at 1 μm observed with Very Large Telescope/CRIRES. We also studied the quality of our spectroscopic model regarding atmospheric parameters including metallicity. A modified version of the Molecular Zeeman Library (MZL) was used to compute Landég-factors for FeH lines. Magnetic spectral synthesis was performed with the SYNMAST code. We confirmed previously reported findings that less massive M dwarfs are braked less effectively than objects of earlier types. Strong surface magnetic fields were detected in primaries of four systems (GJ 852, GJ 234, LP 717-36 and GJ 3322), and in the secondary of the triple system GJ 852. We also confirm strong 2-kG magnetic field in the primary of the triple system GJ 2005. No fields could be accurately determined in rapidly rotating stars with υ sin i > 10 km s-1. For slowly and moderately rotating stars, we find the surface magnetic field strength to increase with the rotational velocity υ sin i which is consistent with other results from studying field stars. Based on observations made with European Southern Observatory (ESO) Telescopes at the Paranal Observatories under programme ID 81.D-0189. Title: Magnetic Fields in M-dwarfs: Quantitative Results from Detailed Spectral Synthesis in FeH Lines Authors: Shulyak, D.; Reiners, A.; Wende, S.; Kochukhov, O.; Piskunov, N.; Seifahrt, A. Bibcode: 2011ASPC..448.1263S Altcode: 2011csss...16.1263S; 2010arXiv1012.1435S Strong surface magnetic fields are ubiquitously found in M-dwarfs with mean intensities on the order of few thousand Gauss -- three orders of magnitude higher than the mean surface magnetic field of the Sun. These fields and their interaction with photospheric convection are the main source of stellar activity, which is of big interest to study links between parent stars and their planets. Moreover, the understanding of stellar magnetism, as well as the role of different dynamo-actions in particular, is impossible without explaining magnetic fields in M-dwarfs. Measuring magnetic field intensities and geometries in such cool objects, however, is strongly limited to our ability to simulate the Zeeman effect in molecular lines. In this work, we present quantitative results of modelling and analysis of the magnetic fields in selected M-dwarfs in FeH Wing-Ford lines and strong atomic lines. Some particular FeH lines are found to be the excellent probes of the magnetic field. Title: Spot activity of II Peg Authors: Hackman, T.; Mantere, M. J.; Jetsu, L.; Ilyin, I.; Kajatkari, P.; Kochukhov, O.; Lehtinen, J.; Lindborg, M.; Piskunov, N.; Tuominen, I. Bibcode: 2011AN....332..859H Altcode: We have studied the long-term spot activity of the RS CVn star II Peg by means of Doppler imaging based on spectroscopy and time series analysis of photometry. We present 28 Doppler imaging temperature maps spanning the years 1994-2010, of which 14 were calculated for the present study. The longitudinal spot distribution, derived from the surface temperature maps, is compared with epochs of the light curve minima, derived from photometric observations. We detect a longitudinal drift in the major spot structure during 1995-2003. After this there is a clear decrease in the activity level and no clear drift can be seen. We conclude that the variations could be caused by a cyclic behaviour of the underlying magnetic dynamo.

Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Title: No magnetic field in the spotted HgMn star μ Leporis Authors: Kochukhov, O.; Makaganiuk, V.; Piskunov, N.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Rodenhuis, M.; Snik, F.; Stempels, H. C.; Valenti, J. A. Bibcode: 2011A&A...534L..13K Altcode: 2011arXiv1110.0829K Context. Chemically peculiar stars of the mercury-manganese (HgMn) type represent a new class of spotted late-B stars, in which evolving surface chemical inhomogeneities are apparently unrelated to the presence of strong magnetic fields but are produced by some hitherto unknown astrophysical mechanism.
Aims: The goal of this study is to perform a detailed line profile variability analysis and carry out a sensitive magnetic field search for one of the brightest HgMn stars - μ Lep.
Methods: We acquired a set of very high-quality intensity and polarization spectra of μ Lep with the HARPSpol polarimeter. These data were analyzed with the multiline technique of least-squares deconvolution in order to extract information on the magnetic field and line profile variability.
Results: Our spectra show very weak but definite variability in the lines of Sc, all Fe-peak elements represented in the spectrum of μ Lep, as well as Y, Sr, and Hg. Variability might also be present in the lines of Si and Mg. Anomalous profile shapes of Ti ii and Y ii lines suggest a dominant axisymmetric distribution of these elements. At the same time, we found no evidence of the magnetic field in μ Lep, with the 3σ upper limit of only 3 G for the mean longitudinal magnetic field. This is the most stringent upper limit on the possible magnetic field derived for a spotted HgMn star.
Conclusions: The very weak variability detected for many elements in the spectrum μ Lep suggests that low-contrast chemical inhomogeneities may be common in HgMn stars and that they have not been recognized until now due to the limited precision of previous spectroscopic observations and a lack of time-series data. The null result of the magnetic field search reinforces the conclusion that formation of chemical spots in HgMn stars is not magnetically driven.

Based on observations collected at the European Southern Observatory, Chile (ESO programs 084.D-0338, 086.D-0240). Title: Analyzing low signal-to-noise FUSE spectra. Confirmation of Lyman continuum escape from Haro 11 Authors: Leitet, E.; Bergvall, N.; Piskunov, N.; Andersson, B. -G. Bibcode: 2011A&A...532A.107L Altcode: 2011arXiv1106.1178L Context. Galaxies are believed to be the main providers of Lyman continuum (LyC) photons during the early phases of the cosmic reionization. Little is known however, when it comes to escape fractions and the mechanisms behind the leakage. To learn more, one may look at local objects, but so far only one low-z galaxy has shown any signs of emitting LyC radiation. With data from the Far Ultraviolet Spectroscopic Explorer (FUSE), we previously found an absolute escape fraction of ionizing photons (fesc) of 4-10% for the blue compact galaxy Haro 11. However, using a revised version of the reduction pipeline on the same data set, Grimes and collaborators were unable to confirm this and derived an upper limit of fesc ≲ 2% .
Aims: We attempt to determine whether Haro 11 is emitting ionizing radiation to a significant level or not. We also investigate the performance of the reduction pipeline for faint targets such as Haro 11, and introduce a new approach to the background subtraction.
Methods: The final version of the reduction pipeline, CalFUSE v3.2, was applied to the same Haro 11 data set as the two previous authors used. At these faint flux levels, both FUSE and CalFUSE are pushed to their limits, and a detailed analysis was undertaken to monitor the performance of the pipeline. We show that non-simultaneous background estimates are insuffient when working with data of low signal-to-noise ratio (S/N), and a new background model was developed based on a direct fit to the detector response.
Results: We find that one has to be very careful when using CalFUSE v3.2 on low S/N data, and especially when dealing with sources where signal might originate from off-center regions. Applying the new background fit, a significant signal is detected in the LyC in both detector segments covering these wavelengths. Thus, the leakage is confirmed with a flux density of f900 = 4.0 × 10-15 erg s-1 cm-2 Å-1 (S/N = 4.6), measured on the airglow free regions in the LyC for the night-only data. This corresponds to an absolute escape fraction of ionizing photons from Haro 11 of fesc = 3.3 ± 0.7%. We confirm these results by investigating the two-dimensional data, the count rates, and the residual flux in C ii λ1036 Å.

Appendix A is available in electronic form at http://www.aanda.org Title: Starspot variability and evolution from modeling Kepler photometry of active late-type stars Authors: Brown, Alexander; Korhonen, Heidi; Berdyugina, Svetlana; Tofany, Barton; Ayres, Thomas R.; Kowalski, Adam; Hawley, Suzanne; Harper, Graham; Piskunov, Nikolai Bibcode: 2011IAUS..273...78B Altcode: The Kepler satellite provides a unique opportunity to study the detailed optical photometric variability of late-type stars with unprecedentedly long (several year) continuous monitoring and sensitivity to very small-scale variations. We are studying a sample of over two hundred cool (mid-A - late-K spectral type) stars using Kepler long-cadence (30 minute sampling) observations. These stars show a remarkable range of photometric variability, but in this paper we concentrate on rotational modulation due to starspots and flaring. Modulation at the 0.1% level is readily discernable. We highlight the rapid timescales of starspot evolution seen on solar-like stars with rotational periods between 2 and 7 days. Title: VAMDC: The Virtual Atomic and Molecular Data Center Authors: Walton, N. A.; Dubernet, M. L.; Mason, N. J.; Piskunov, N.; Rixon, G. T.; Vamdc Consortium Bibcode: 2011ASPC..442...89W Altcode: 2011adass..20...89W The Virtual Atomic and Molecular Data Center (VAMDC) is a European Union funded collaboration between groups involved in the generation, evaluation, and use of atomic and molecular data. VAMDC aims to build a secure, documented, flexible and interoperable e-science environment-based interface to existing atomic and molecular data. The project will cover establishing the core consortium, the development and deployment of the infrastructure and the development of interfaces to the existing atomic and molecular databases. This paper describes the organization, its objectives and introduces the VAMDC level one service release. Title: The search for magnetic fields in mercury-manganese stars Authors: Makaganiuk, Vitalii; Kochukhov, Oleg; Piskunov, Nikolai; Jeffers, Sandra V.; Johns-Krull, Christopher M.; Keller, Christoph U.; Rodenhuis, Michiel; Snik, Frans; Stempels, Henricus C.; Valenti, Jeff A. Bibcode: 2011IAUS..272..202M Altcode: Mercury-manganese (HgMn) stars were considered to be non-magnetic, showing no evidence of surface spots. However, recent investigations revealed that some stars in this class possess an inhomogeneous distribution of chemical elements on their surfaces. According to our current understanding, the most probable mechanism of spot formation involves magnetic fields. Taking the advantage of a newly-built polarimeter attached to the HARPS spectrometer at the ESO 3.6m-telescope, we performed a high-precision spectropolarimetric survey of a large group of HgMn stars. The main purpose of this study was to find out how typical it is for HgMn stars to have weak magnetic fields. We report no magnetic field detection for any of the studied objects, with a typical precision of the longitudinal field measurements of 10 G and down to 1 Gauss for some of the stars. We conclude that HgMn stars lack large-scale magnetic fields typical of spotted magnetic Ap stars and probably lack any fields capable of creating and sustaining chemical spots. Our study confirms that alongside the magnetically altered atomic diffusion, there must be other structure formation mechanism operating in the atmospheres of late-B main sequence stars. Title: Chemical spots in the absence of magnetic field in the binary HgMn star 66 Eridani Authors: Makaganiuk, V.; Kochukhov, O.; Piskunov, N.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Rodenhuis, M.; Snik, F.; Stempels, H. C.; Valenti, J. A. Bibcode: 2011A&A...529A.160M Altcode: 2011arXiv1102.4661M Context. According to our current understanding, a subclass of the upper main-sequence chemically peculiar stars, called mercury-manganese (HgMn), is non-magnetic. Nevertheless, chemical inhomogeneities were recently discovered on their surfaces. At the same time, no global magnetic fields stronger than 1-100 G are detected by systematic studies.
Aims: The goals of our study are to search for a magnetic field in the HgMn binary system 66 Eri and to investigate chemical spots on the stellar surfaces of both components.
Methods: Our analysis is based on high-quality spectropolarimetric time-series observations obtained during 10 consecutive nights with the HARPSpol instrument at the ESO 3.6-m telescope. To increase the sensitivity of the magnetic field search we employed a least-squares deconvolution (LSD). We used spectral disentangling to measure radial velocities and study the line profile variability. Chemical spot geometry was reconstructed using multi-line Doppler imaging.
Results: We report a non-detection of magnetic field in 66 Eri, with error bars 10-24 G for the longitudinal field. Circular polarization profiles also do not indicate any signatures of complex surface magnetic fields. For a simple dipolar field configuration we estimated an upper limit of the polar field strength to be 60-70 G. For the HgMn component we found variability in spectral lines of Ti, Ba, Y, and Sr with the rotational period equal to the orbital one. The surface maps of these elements reconstructed with the Doppler imaging technique show a relative underabundance on the hemisphere facing the secondary component. The contrast of chemical inhomogeneities ranges from 0.4 for Ti to 0.8 for Ba.

Based on observations collected at the European Southern Observatory, Chile (ESO program 084.D-0338). Title: First Detection of Linear Polarization in the Line Profiles of Active Cool Stars Authors: Kochukhov, O.; Makaganiuk, V.; Piskunov, N.; Snik, F.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Rodenhuis, M.; Valenti, J. A. Bibcode: 2011ApJ...732L..19K Altcode: 2011arXiv1103.6028K The application of high-resolution spectropolarimetry has led to major progress in understanding the magnetism and activity of late-type stars. During the last decade, magnetic fields have been discovered and mapped for many types of active cool stars using spectropolarimetric data. However, these observations and modeling attempts are fundamentally incomplete since they are based on the interpretation of the circular polarization alone. Taking advantage of the newly built HARPS polarimeter, we have obtained the first systematic observations of several cool active stars in all four Stokes parameters. Here we report the detection of magnetically induced linear polarization for the primary component of the very active RS CVn binary HR 1099 and for the moderately active K dwarf ɛ Eri. For both stars the amplitude of linear polarization signatures is measured to be ~10-4 of the unpolarized continuum, which is approximately a factor of 10 lower than for circular polarization. This is the first detection of the linear polarization in line profiles of cool active stars. Our observations of the inactive solar-like star α Cen A show neither circular nor linear polarization above the level of ~10-5, indicating the absence of a net longitudinal magnetic field stronger than 0.2 G.

Based on observations obtained at the European Southern Observatory (ESO programs 083.D-1000(A) and 084.D-0338(A)). Title: Kepler Observations of Starspot Evolution, Differential Rotation, and Flares on Late-Type Stars Authors: Brown, Alexander; Korhonen, H.; Berdyugina, S.; Walkowicz, L.; Kowalski, A.; Hawley, S.; Neff, J.; Ramsey, L.; Redman, S.; Saar, S.; Furesz, G.; Piskunov, N.; Harper, G.; Ayres, T.; Tofany, B. Bibcode: 2011AAS...21820502B Altcode: 2011BAAS..43G20502B The Kepler satellite is providing spectacular optical photometric light-curves of unprecedented precision and duration that routinely allow detailed studies of stellar magnetic activity on late-type stars that were difficult, if not impossible, to attempt previously. Rotational modulation due to starspots is commonly seen in the Kepler light-curves of late-type stars, allowing detailed study of the surface distribution of their photospheric magnetic activity. Kepler is providing multi-year duration light-curves that allow us to investigate how activity phenomena -- such as the growth, migration, and decay of starspots, differential rotation, activity cycles, and flaring -- operate on single and binary stars with a wide range of mass and convection zone depth.

We present the first results from detailed starspot modeling using newly-developed light-curve inversion codes for a range of GALEX-selected stars with typical rotation periods of a few days, that we have observed as part of our 200 target Kepler Cycle 1/2 Guest Observer programs. The physical properties of the stars have been measured using high resolution optical spectroscopy, which allows the Kepler results to be placed within the existing framework of knowledge regarding stellar magnetic activity. These results demonstrate the powerful diagnostic capability provided by tracking starspot evolution essentially continuously for more than 16 months. The starspots are clearly sampling the stellar rotation rate at different latitudes, enabling us to measure the differential rotation and starspot lifetimes. As would be expected, stars with few day rotation show frequent flaring that is easily seen as "white-light" flares in Kepler light-curves. We compare the observed flare rates and occurrence with the starspot properties.

This work contains results obtained using the NASA Kepler satellite and from the Apache Point Observatory, the MMT (using NOAO community access time), and the Hobby-Eberly Telescope. Funding is provided by NASA Kepler grants NNX10AC51G and NNX11AC79G. Title: The HARPS Polarimeter Authors: Snik, F.; Kochukhov, O.; Piskunov, N.; Rodenhuis, M.; Jeffers, S.; Keller, C.; Dolgopolov, A.; Stempels, E.; Makaganiuk, V.; Valenti, J.; Johns-Krull, C. Bibcode: 2011ASPC..437..237S Altcode: 2010arXiv1010.0397S We recently commissioned the polarimetric upgrade of the HARPS spectrograph at ESO's 3.6-m telescope at La Silla, Chile. The HARPS polarimeter is capable of full Stokes spectropolarimetry with large sensitivity and accuracy, taking advantage of the large spectral resolution and stability of HARPS. In this paper we present the instrument design and its polarimetric performance. The first HARPSpol observations show that it can attain a polarimetric sensitivity of ∼10-5 (after addition of many lines) and that no significant instrumental polarization effects are present. Title: The Exoplanet Orbit Database Authors: Wright, J. T.; Fakhouri, O.; Marcy, G. W.; Han, E.; Feng, Y.; Johnson, John Asher; Howard, A. W.; Fischer, D. A.; Valenti, J. A.; Anderson, J.; Piskunov, N. Bibcode: 2011PASP..123..412W Altcode: 2010arXiv1012.5676W We present a database of well-determined orbital parameters of exoplanets, and their host stars’ properties. This database comprises spectroscopic orbital elements measured for 427 planets orbiting 363 stars from radial velocity and transit measurements as reported in the literature. We have also compiled fundamental transit parameters, stellar parameters, and the method used for the planets discovery. This Exoplanet Orbit Database includes all planets with robust, well measured orbital parameters reported in peer-reviewed articles. The database is available in a searchable, filterable, and sortable form online through the Exoplanets Data Explorer table, and the data can be plotted and explored through the Exoplanet Data Explorer plotter. We use the Data Explorer to generate publication-ready plots, giving three examples of the signatures of exoplanet migration and dynamical evolution: We illustrate the character of the apparent correlation between mass and period in exoplanet orbits, the different selection biases between radial velocity and transit surveys, and that the multiplanet systems show a distinct semimajor-axis distribution from apparently singleton systems. Title: The NASA-UC Eta-Earth Program. III. A Super-Earth Orbiting HD 97658 and a Neptune-mass Planet Orbiting Gl 785 Authors: Howard, Andrew W.; Johnson, John Asher; Marcy, Geoffrey W.; Fischer, Debra A.; Wright, Jason T.; Henry, Gregory W.; Isaacson, Howard; Valenti, Jeff A.; Anderson, Jay; Piskunov, Nikolai E. Bibcode: 2011ApJ...730...10H Altcode: 2010arXiv1011.0414H We report the discovery of planets orbiting two bright, nearby early K dwarf stars, HD 97658 and Gl 785. These planets were detected by Keplerian modeling of radial velocities measured with Keck-HIRES for the NASA-UC Eta-Earth Survey. HD 97658 b is a close-in super-Earth with minimum mass Msin i = 8.2 ± 1.2 M ⊕, orbital period P = 9.494 ± 0.005 days, and an orbit that is consistent with circular. Gl 785 b is a Neptune-mass planet with Msin i = 21.6 ± 2.0 M ⊕, P = 74.39 ± 0.12 days, and orbital eccentricity e = 0.30 ± 0.09. Photometric observations with the T12 0.8 m automatic photometric telescope at Fairborn Observatory show that HD 97658 is photometrically constant at the radial velocity period to 0.09 mmag, supporting the existence of the planet.

Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time has been granted by both NASA and the University of California. Title: HARPSpol — The New Polarimetric Mode for HARPS Authors: Piskunov, N.; Snik, F.; Dolgopolov, A.; Kochukhov, O.; Rodenhuis, M.; Valenti, J.; Jeffers, S.; Makaganiuk, V.; Johns-Krull, C.; Stempels, E.; Keller, C. Bibcode: 2011Msngr.143....7P Altcode: The HARPS spectrograph can now perform a full polarisation analysis of spectra. It has been equipped with a polarimetric unit, HARPSpol, which was jointly designed and produced by Uppsala, Utrecht and Rice Universities and by the STScI. Here we present the new instrument, demonstrate its polarisation capabilities and show the first scientific results. Title: Doppler images of the RS CVn binary II Pegasi during the years 1994-2002 Authors: Lindborg, M.; Korpi, M. J.; Hackman, T.; Tuominen, I.; Ilyin, I.; Piskunov, N. Bibcode: 2011A&A...526A..44L Altcode:
Aims: We publish 16 Doppler imaging temperature maps for the years 1994-2002 of the active RS CVn star II Peg. The six maps from 1999-2002 are based on previously unpublished observations. Through Doppler imaging we want to study the spot evolution of the star and in particular compare this with previous results showing a cyclic spot behaviour and persistent, active longitudes.
Methods: The observations were collected with the SOFIN spectrograph at the Nordic Optical Telescope. The temperature maps were calculated using a Doppler imaging code based on Tikhonov regularization.
Results: During 1994-2001, our results show a consistent trend in the derived longitudes of the principal and secondary temperature minima over time such that the magnetic structure appears to rotate somewhat more rapidly than the orbital period of this close binary. A sudden phase jump in the active region occurred between the observing seasons of 2001 and 2002. No clear trend over time is detected in the derived latitudes of the spots, indicating that the systematic motion could be related to the drift of the spot-generating mechanism rather than to differential rotation. The derived temperature maps are quite similar to the ones obtained earlier with different methods and the main differences occur in the spot latitudes and relative strength of the spot structures.
Conclusions: We observe both longitude and latitude shifts in the spot activity of II Peg. However, our results are not consistent with the periodic behaviour presented in previous studies.

Full Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/526/A44 Title: The NASA-UC Eta-Earth Program. II. A Planet Orbiting HD 156668 with a Minimum Mass of Four Earth Masses Authors: Howard, Andrew W.; Johnson, John Asher; Marcy, Geoffrey W.; Fischer, Debra A.; Wright, Jason T.; Henry, Gregory W.; Isaacson, Howard; Valenti, Jeff A.; Anderson, Jay; Piskunov, Nikolai E. Bibcode: 2011ApJ...726...73H Altcode: 2010arXiv1003.3444H We report the discovery of HD 156668 b, an extrasolar planet with a minimum mass of MP sin i = 4.15 M ⊕. This planet was discovered through Keplerian modeling of precise radial velocities from Keck-HIRES and is the second super-Earth to emerge from the NASA-UC Eta-Earth Survey. The best-fit orbit is consistent with circular and has a period of P = 4.6455 days. The Doppler semi-amplitude of this planet, K = 1.89 m s-1, is among the lowest ever detected, on par with the detection of GJ 581 e using HARPS. A longer period (P ≈ 2.3 years), low-amplitude signal of unknown origin was also detected in the radial velocities and was filtered out of the data while fitting the short-period planet. Additional data are required to determine if the long-period signal is due to a second planet, stellar activity, or another source. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 156668 (an old, quiet K3 dwarf) is photometrically constant over the radial velocity period to 0.1 mmag, supporting the existence of the planet. No transits were detected down to a photometric limit of ~3 mmag, ruling out transiting planets dominated by extremely bloated atmospheres, but not precluding a transiting solid/liquid planet with a modest atmosphere.

Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time has been granted by both NASA and the University of California. Title: The search for magnetic fields in mercury-manganese stars Authors: Makaganiuk, V.; Kochukhov, O.; Piskunov, N.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Rodenhuis, M.; Snik, F.; Stempels, H. C.; Valenti, J. A. Bibcode: 2011A&A...525A..97M Altcode: 2010arXiv1010.3931M Context. A subclass of the upper main-sequence chemically peculiar stars, mercury-manganese (HgMn) stars were traditionally considered to be non-magnetic, showing no evidence of variability in their spectral line profiles. However, discoveries of chemical inhomogeneities on their surfaces imply that this assumption should be investigated. In particular, spectroscopic time-series of AR Aur, α And, and five other HgMn stars indicate the presence of chemical spots. At the same time, no signatures of global magnetic fields have been detected.
Aims: We attempt to understand the physical mechanism that causes the formation of chemical spots in HgMn stars and gain insight into the potential magnetic field properties at their surfaces; we performed a highly sensitive search for magnetic fields for a large set of HgMn stars.
Methods: With the aid of a new polarimeter attached to the HARPS spectrometer at the ESO 3.6 m-telescope, we obtained high-quality circular polarization spectra of 41 single and double HgMn stars. Using a multi-line analysis technique on each star, we co-added information from hundreds of spectral lines to ensure significantly greater sensitivity to the presence of magnetic fields, including very weak fields.
Results: For the 47 individual objects studied, including six components of SB2 systems, we do not detect any magnetic fields at greater than the 3σ level. The lack of detection in the circular polarization profiles indicates that if strong fields are present on these stars, they must have complex surface topologies. For simple global fields, our detection limits imply upper limits to the fields present of 2-10 Gauss in the best cases.
Conclusions: We conclude that HgMn stars lack large-scale magnetic fields, which is typical of spotted magnetic Ap stars, of sufficient strength to form and sustain the chemical spots observed on HgMn stars. Our study confirms that in addition to magnetically altered atomic diffusion, there exists another differentiation mechanism operating in the atmospheres of late-B main sequence stars that can produce compositional inhomogeneities on their surfaces.

Based on observations collected at the European Southern Observatory, Chile (ESO programs 083.D-1000, 084.D-0338, 085.D-0296).Figure 5 is only available in electronic form at http://www.aanda.org Title: Magnetic Fields of M-Dwarfs from the Molecular and Atomic Diagnostics Authors: Shulyak, D.; Reiners, A.; Wende, S.; Kochukhov, O.; Piskunov, N.; Seifahrt, A. Bibcode: 2011mast.conf..280S Altcode: Strong surface magnetic fields are frequently found in the spectra of M-dwarfs, with the mean intensities on the order of a few thousand Gauss - three orders of magnitude higher than the mean surface magnetic field of the Sun. The appearance of such fields in both partially and fully convective M-dwarfs provides strong constraints on the theoretical models of stellar magnetism. The accurate estimates of the magnetic field intensity and geometry in these cool objects, however, is strongly limited to our ability to simulate the Zeeman effect in molecular lines. Here we present the first quantitative results of modelling and analysis of the magnetic fields in selected M-dwarfs in FeH Wing-Ford F^4Δ-X^4Δ transitions and some strong atomic lines from polarised radiative transfer. Title: New release of Vienna Atomic Line Database (VALD) and its integration in Virtual Atomic and Molecular Data Centre (VAMDC) Authors: Ryabchikova, T. A.; Pakhomov, Yu. V.; Piskunov, N. E. Bibcode: 2011KIzKU.153...61R Altcode: No abstract at ADS Title: Least-squares deconvolution of the stellar intensity and polarization spectra Authors: Kochukhov, O.; Makaganiuk, V.; Piskunov, N. Bibcode: 2010A&A...524A...5K Altcode: 2010arXiv1008.5115K Context. Least-squares deconvolution (LSD) is a powerful method of extracting high-precision average line profiles from the stellar intensity and polarization spectra. This technique is widely used for detection, characterization, and detailed mapping of the temperature, magnetic, and chemical abundance structures on the surfaces of stars.
Aims: Despite its common usage, the LSD method is poorly documented and has never been tested with realistic synthetic spectra. In this study we revisit the key assumptions of the LSD technique, clarify its numerical implementation, discuss possible improvements and give recommendations of how to make LSD results understandable and reproducible. We also address the problem of interpretation of the moments and shapes of the LSD profiles in terms of physical parameters.
Methods: We have developed an improved, multiprofile version of LSD (iLSD) and have extended the deconvolution procedure to linear polarization analysis taking into account anomalous Zeeman splitting of spectral lines. The iLSD method is applied to the theoretical Stokes parameter spectra computed for a wide wavelength interval containing all relevant spectral lines. We test various methods of interpreting the mean profiles, investigating how coarse approximations of the multiline technique translate into errors of the derived parameters.
Results: We find that, generally, the Stokes parameter LSD profiles do not behave as a real spectral line with respect to the variation of magnetic field and elemental abundance. This problem is especially prominent for the Stokes I (intensity) variation with abundance and Stokes Q (linear polarization) variation with magnetic field. At the same time, the Stokes V (circular polarization) LSD spectra closely resemble the profile of a properly chosen synthetic line for the magnetic field strength up to 1 kG. The longitudinal field estimated from the Stokes V LSD profile is accurate to within 10% for the field strength below 5 kG and to within a few percent for the fields weaker than 1 kG. Our iLSD technique offers clear advantages over the standard LSD method in the individual analysis of different chemical elements.
Conclusions: We conclude that the usual method of interpreting the LSD profiles by assuming that they are equivalent to a real spectral line gives satisfactory results only in a limited parameter range and thus should be applied with caution. A more trustworthy approach is to abandon the single-line approximation of the average profiles and apply LSD consistently to observations and synthetic spectra. Title: VizieR Online Data Catalog: Observations of II Peg (Lindborg+, 2011) Authors: Lindborg, M.; Korpi, M. J.; Hackman, T.; Tuominen, I.; Ilyin, I.; Piskunov, N. Bibcode: 2010yCat..35260044L Altcode: 2010yCat..35269044L The observations were collected with the SOFIN spectrograph at the Nordic Optical Telescope. The temperature maps were calculated using a Doppler imaging code based on Tikhonov regularization.

(1 data file). Title: Modelling the molecular Zeeman-effect in M-dwarfs: methods and first results Authors: Shulyak, D.; Reiners, A.; Wende, S.; Kochukhov, O.; Piskunov, N.; Seifahrt, A. Bibcode: 2010A&A...523A..37S Altcode: 2010arXiv1008.2512S
Aims: We present first quantitative results of the surface magnetic field measurements in selected M-dwarfs based on detailed spectra synthesis conducted simultaneously in atomic and molecular lines of the FeH Wing-Ford F4 Δ - X4 Δ transitions.
Methods: A modified version of the Molecular Zeeman Library (MZL) was used to compute Landé g-factors for FeH lines in different Hund's cases. Magnetic spectra synthesis was performed with the Synmast code.
Results: We show that the implementation of different Hund's case for FeH states depending on their quantum numbers allows us to achieve a good fit to the majority of lines in a sunspot spectrum in an automatic regime. Strong magnetic fields are confirmed via the modelling of atomic and FeH lines for three M-dwarfs YZ CMi, EV Lac, and AD Leo, but their mean intensities are found to be systematically lower than previously reported. A much weaker field (1.7-2 kG against 2.7 kG) is required to fit FeH lines in the spectra of GJ 1224.
Conclusions: Our method allows us to measure average magnetic fields in very low-mass stars from polarized radiative transfer. The obtained results indicate that the fields reported in earlier works were probably overestimated by about 15-30%. Higher quality observations are needed for more definite results. Title: The California Planet Survey. I. Four New Giant Exoplanets Authors: Howard, Andrew W.; Johnson, John Asher; Marcy, Geoffrey W.; Fischer, Debra A.; Wright, Jason T.; Bernat, David; Henry, Gregory W.; Peek, Kathryn M. G.; Isaacson, Howard; Apps, Kevin; Endl, Michael; Cochran, William D.; Valenti, Jeff A.; Anderson, Jay; Piskunov, Nikolai E. Bibcode: 2010ApJ...721.1467H Altcode: 2010arXiv1003.3488H We present precise Doppler measurements of four stars obtained during the past decade at Keck Observatory by the California Planet Survey (CPS). These stars, namely, HD 34445, HD 126614, HD 13931, and Gl 179, all show evidence for a single planet in Keplerian motion. We also present Doppler measurements from the Hobby-Eberly Telescope (HET) for two of the stars, HD 34445 and Gl 179, that confirm the Keck detections and significantly refine the orbital parameters. These planets add to the statistical properties of giant planets orbiting near or beyond the ice line, and merit follow-up by astrometry, imaging, and space-borne spectroscopy. Their orbital parameters span wide ranges of planetary minimum mass (M sin i = 0.38-1.9 M Jup), orbital period (P = 2.87-11.5 yr), semimajor axis (a = 2.1-5.2 AU), and eccentricity (e = 0.02-0.41). HD 34445 b (P = 2.87 yr, M sin i = 0.79 M Jup, e = 0.27) is a massive planet orbiting an old, G-type star. We announce a planet, HD 126614 Ab, and an M dwarf, HD 126614 B, orbiting the metal-rich star HD 126614 (which we now refer to as HD 126614 A). The planet, HD 126614 Ab, has minimum mass M sin i = 0.38 M Jup and orbits the stellar primary with period P = 3.41 yr and orbital separation a = 2.3 AU. The faint M dwarf companion, HD 126614 B, is separated from the stellar primary by 489 mas (33 AU) and was discovered with direct observations using adaptive optics and the PHARO camera at Palomar Observatory. The stellar primary in this new system, HD 126614 A, has the highest measured metallicity ([Fe/H] = +0.56) of any known planet-bearing star. HD 13931 b (P = 11.5 yr, M sin i = 1.88 M Jup, e = 0.02) is a Jupiter analog orbiting a near solar twin. Gl 179 b (P = 6.3 yr, M sin i = 0.82 M Jup, e = 0.21) is a massive planet orbiting a faint M dwarf. The high metallicity of Gl 179 is consistent with the planet-metallicity correlation among M dwarfs, as documented recently by Johnson & Apps.

Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time has been granted by both NASA and the University of California. Two of the planets announced here are also based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen. Title: VAMDC: The Virtual Atomic and Molecular Data Centre: a Service Orientated Data Infrastructure for e- Research Authors: Mason, N. J.; Dubernet, M. L.; Benson, K. M.; Bureau, J.; Heiter, U.; Kupka, F.; Le Sidaner, P.; Piskunov, N.; Rixon, G. T.; Schlemmer, S.; Shih, A.; Tennyson, J.; Walton, N.; Witherick, D. W. Bibcode: 2010epsc.conf..861M Altcode: No abstract at ADS Title: Stability of spectroscopic data reduction Authors: Piskunov, Nikolai Bibcode: 2010aepr.confE..42P Altcode: No abstract at ADS Title: SIMPLE: a high-resolution near-infrared spectrometer for the E-ELT Authors: Origlia, Livia; Oliva, Ernesto; Maiolino, Roberto; Gustafsson, Bengt; Piskunov, Nikolai; Kochucov, Oleg; Vanzi, Leonardo; Minniti, Dante; Zoccali, Manuela; Hatzes, Artie; Guenther, Eike Bibcode: 2010SPIE.7735E..2BO Altcode: 2010SPIE.7735E..78O SIMPLE is an optimized near IR echelle spectrograph for the E-ELT assisted by adaptive optics. It delivers a complete 0.84-2.5μm spectrum in one exposure with resolution up to R=130,000, nearly diffraction limited pixel scale and limiting magnitudes down to JHK~20. Its most prominent science cases include the study of the intergalactic medium in the early Universe (z>6) and of the atmospheres of exo-planet transiting nearby low mass stars. Title: Doppler images of the RS CVn binary II Pegasi during the years 1994-2002 Authors: Lindborg; M.; Korpi; J., M.; Hackman; T.; Tuominen; I.; Ilyin; I.; Piskunov; N Bibcode: 2010arXiv1006.3060L Altcode: We publish 16 Doppler imaging temperature maps for the years 1994-2002 of the active RS CVn star II Peg. The six maps from 1999-2002 are based on previously unpublished observations. Through Doppler imaging we want to study the spot evolution of the star and in particular compare this with previous results showing a cyclic spot behaviour and persistent active longitudes. The observations were collected with the SOFIN spectrograph at the Nordic Optical Telescope. The temperature maps were calculated using a Doppler imaging code based on Tikhonov regularization. During 1994-2001, our results show a consistent trend in the derived longitudes of the principal and secondary temperature minima over time such that the magnetic structure appears to rotate somewhat more rapidly than the orbital period of this close binary. A sudden phase jump of the active region occured between the observing seasons of 2001 and 2002. No clear trend over time is detected in the derived latitudes of the spots, indicating that the systematic motion could be related to the drift of the spot generating mechanism rather than to differential rotation. The derived temperature maps are quite similar to the ones obtained earlier with a different methods, the main differences occurring in the spot latitudes and relative strength of the spot structures. We observe both longitude and latitude shifts in the spot activity of II Peg. However, our results are not consistent with the periodic behaviour presented in previous studies. Title: Commission 29: Stellar Spectra Authors: Piskunov, Nikolai; Cunha, Katia; Parthasarathy, Mudumba; Aoki, Wako; Asplund, Martin; Bohlender, David; Carpenter, Kenneth; Melendez, Jorge; Parthasarathy, Mudumba; Rossi, Silvia; Smith, Verne; Soderblom, David; Wahlgren, Glenn Bibcode: 2010IAUTB..27..193P Altcode: The business meeting was attended by 23 members of the Commission. The meeting started at 16:00 a short report of the activities during the triennium 2006-2009. The focus of the activities was the sharing of expertise between spectroscopic techniques in various areas of astronomical research. In particular, the progress in instrumentation, detectors, data reduction, data analysis and archiving. The second activity was the analysis of to IAU meeting proposals followed by recommendations for improvements and eventually support. The sponsored symposia included Sponsoring symposia The Ages of Stars and The Disk Galaxy Evolution in the Cosmological Context. The Commission was also disseminating information about the Commission activities and relevant meetings to the Commission members. In this respect the Commission web page is playing a crucial role. Title: INTER-DIVISION IV-V WORKING GROUP on Ap and Related Stars Authors: Cunha, Margarida S.; Weiss, Werner; Dworetsky, Mike; Kochukhov, Oleg; Kupka, Friedrich; Leblanc, Francis; Monier, Richard; Paunzen, Ernst; Piskunov, Nikolai; Shibahashi, Hiromoto; Smalley, Barry; Ziznovsky, Jozef Bibcode: 2010IAUTB..27..205C Altcode: The business meeting started at 11h00, in the presence of 18 members, with a brief summary of the activities and achievements of the Working group during the triennium 2006-2009. Title: Surface temperature maps for II Peg during 1999-2002 Authors: Lindborg, M.; Korpi, M. J.; Tuominen, I.; Hackman, T.; Ilyin, I.; Piskunov, N. Bibcode: 2010IAUS..264..213L Altcode: 2009arXiv0911.0198L The active RS CVn star II Peg has been spectroscopically monitored for almost 18 years with the SOFIN spectrograph at NOT, La Palma, Spain. In this paper we present five new surface temperature maps of the object for the years 1999 (two maps), 2001 (one map) and 2002 (two maps). Title: Surface structure of the CoRoT CP2 target star HD 50773 Authors: Lüftinger, T.; Fröhlich, H. -E.; Weiss, W. W.; Petit, P.; Aurière, M.; Nesvacil, N.; Gruberbauer, M.; Shulyak, D.; Alecian, E.; Baglin, A.; Baudin, F.; Catala, C.; Donati, J. -F.; Kochukhov, O.; Michel, E.; Piskunov, N.; Roudier, T.; Samadi, R. Bibcode: 2010A&A...509A..43L Altcode: 2009arXiv0911.3791L
Aims: We compare surface maps of the chemically peculiar star HD 50773 produced with a Bayesian technique and based on high quality CoRoT photometry with those derived from rotation phase resolved spectropolarimetry. The goal is to investigate the correlation of surface brightness with surface chemical abundance distribution and the stellar magnetic surface field.
Methods: The rotational period of the star was determined from a nearly 60 days long continuous light curve obtained during the initial run of CoRoT. Using a Bayesian approach to star-spot modelling, which in this work is applied for the first time for the photometric mapping of a CP star, we derived longitudes, latitudes and radii of four different spot areas. Additional parameters like stellar inclination and the spot's intensities were also determined. The CoRoT observations triggered an extensive ground-based spectroscopic and spectropolarimetric observing campaign and enabled us to obtain 19 different high resolution spectra in Stokes parameters I and V with NARVAL, ESPaDOnS, and SemelPol spectropolarimeters. Doppler and Magnetic Doppler imaging techniques allowed us to derive the magnetic field geometry of the star and the surface abundance distributions of Mg, Si, Ca, Ti, Cr, Fe, Ni, Y, and Cu.
Results: We find a dominant dipolar structure of the surface magnetic field. The CoRoT light curve variations and abundances of most elements mapped are correlated with the aforementioned geometry: Cr, Fe, and Si are enhanced around the magnetic poles and coincide with the bright regions on the surface of HD 50773 as predicted by our light curve synthesis and confirmed by photometric imaging.

The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Pograms, Austria, Belgium, Brazil, Germany, and Spain. Title: Time-resolved photometric and spectroscopic analysis of the luminous Ap star HD103498 Authors: Joshi, S.; Ryabchikova, T.; Kochukhov, O.; Sachkov, M.; Tiwari, S. K.; Chakradhari, N. K.; Piskunov, N. Bibcode: 2010MNRAS.401.1299J Altcode: 2009MNRAS.tmp.1638J; 2009arXiv0909.3906J We present the results of the photometric and spectroscopic monitoring of the luminous Ap star HD103498. The time-series photometric observations were carried out on 17 nights using a three-channel fast photometer attached to the 1.04-m optical telescope at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital. The photometric data from five nights in 2007 show a clear signature of 15-min periodicity. However, the follow-up observations during 2007-2009 did not reproduce any such periodicity. To confirm the photometric light variations, time-series spectroscopic observations were carried out with the 2.56-m Nordic Optical Telescope (NOT) at La Palma on 2009 February 2. No radial velocity variations were present in this data set, which is in full agreement with the photometric observations taken around the same date. Model atmosphere and abundance analysis of HD103498 show that the star is evolved from the main sequence and its atmospheric abundances are similar to those of two other evolved Ap stars, HD133792 and HD204411: large overabundances of Si, Cr and Fe and moderate overabundances of the rare-earth elements. These chemical properties and a higher effective temperature distinguish HD103498 from any known roAp star. Title: The Eta-Earth Survey for Low-Mass Exoplanets Authors: Howard, Andrew; Marcy, G.; Fischer, D.; Johnson, J.; Wright, J.; Valenti, J.; Anderson, J.; Piskunov, N.; Isaacson, H.; Brewer, J.; Clubb, K.; Lin, D.; Ida, S. Bibcode: 2010AAS...21534806H Altcode: 2010BAAS...42..530H The NASA-UC Eta-Earth Survey by the California Planet Search (CPS) group is a systematic search for low-mass planets ( 3-30 Earth masses) orbiting the nearest 230 GKM stars suitable for high-precision Doppler observations at Keck Observatory. These 1 m/s measurements of a well-defined sample of nearby stars will provide one of the first estimates of the fraction of stars with Earth-like planets. The talk will describe recently announced super-Earths and Neptune-mass planets from the Eta-Earth Survey, including the 9 Earth mass planet HD 7924b and others. These low-mass planets are extraordinarily valuable in their own right, as targets for transit and other follow-up studies, and as windows into the mechanisms of planet formation. Low mass planets show several emerging trends in their orbital parameters and in the characteristics of their host stars. For example, super-Earth and Neptune-mass planets preferentially orbit stars with lower mass (Mstar < 0.8 solar masses), in contrast to the trend seen in higher mass planets. The survey observations are nearly complete, allowing us to place initial constraints on the population of super-Earth and Neptune-mass planets, and, using planet-formation theory, to extrapolate to the fraction of Earth-mass planets and 1 year orbits. Title: Magnetic Doppler imaging of the roAp star HD 24712 Authors: Lüftinger, T.; Kochukhov, O.; Ryabchikova, T.; Piskunov, N.; Weiss, W. W.; Ilyin, I. Bibcode: 2010A&A...509A..71L Altcode: 2009arXiv0910.5556L
Aims: We present the first magnetic Doppler images of a rapidly oscillating Ap (roAp) star.
Methods: We deduce information about magnetic field geometry and abundance distributions of a number of chemical elements on the surface of the hitherto best studied roAp star, HD 24712, using the magnetic Doppler imaging (MDI) code, invers10, which allows us to reconstruct simultaneously and consistently the magnetic field geometry and elemental abundance distributions on a stellar surface. For this purpose we analyse time series spectra obtained in Stokes I and V parameters with the SOFIN polarimeter at the Nordic Optical Telescope and recover surface abundance structures of sixteen different chemical elements, respectively ions, including Mg, Ca, Sc, Ti, Cr, Fe, Co, Ni, Y, La, Ce, Pr, Nd, Gd, Tb, and Dy. For the rare earth elements (REE) Pr and Nd separate maps were obtained using lines of the first and the second ionization stage.
Results: We find and confirm a clear dipolar structure of the surface magnetic field and an unexpected correlation of elemental abundance with respect to this field: one group of elements accumulates solely where the positive magnetic pole is visible, whereas the other group avoids this region and is enhanced where the magnetic equatorial region dominates the visible stellar surface. We also observe relative shifts of abundance enhancement- or depletion regions between the various elements exhibiting otherwise similar behaviour.

Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Title: Detection of dusty plasma near the E-ring of Saturn Authors: Wahlund, J. -E.; André, M.; Eriksson, A. I. E.; Lundberg, M.; Morooka, M. W.; Shafiq, M.; Averkamp, T. F.; Gurnett, D. A.; Hospodarsky, G. B.; Kurth, W. S.; Jacobsen, K. S.; Pedersen, A.; Farrell, W.; Ratynskaia, S.; Piskunov, N. Bibcode: 2009P&SS...57.1795W Altcode: We present several independent in-situ measurements, which provide evidence that charged dust in the E-ring interacts collectively with the dense surrounding plasma disk of Saturn, i.e., form a system of dust-plasma interaction. The results are based on data sampled by the Radio and Plasma Wave Science (RPWS) investigation onboard Cassini, which allows for interferometry of plasma density inhomogeneities (δ n/ n) with two antenna elements and a Langmuir probe sensor. The interferometer experiment detects two ion populations; one co-rotating with the planetary magnetic field and another moving with near Keplerian speed around Saturn. The full range of RPWS measurements indicates that the Keplerian population consists of colder ions ( Ti<few eV), which would interact with the electrical potential cavities associated with the few volts negatively charged E-ring water-rich dust grains. The presence of the charged dust inhibits E× B pick-up of freshly ionized particles by the rotating magnetic field of Saturn, since the local potential gradients near the dust grains are stronger than the large-scale co-rotation electric field. Even so, most ions are eventually energised to energies above the dust potentials of a few volts and become part of a hotter co-rotating ion population. The observed results have direct relevance to the interactions occurring in planet forming accretion disks around young stars, since the physical environment is similar. Title: Magnetic Doppler Imaging of Active Stars Authors: Kochukhov, O.; Piskunov, N. Bibcode: 2009ASPC..405..539K Altcode: We present a new implementation of the magnetic Doppler imaging technique, which aims at self-consistent temperature and magnetic mapping of the surface structures in cool active stars. Our magnetic imaging procedure is unique in its capability to model individual spectral features in all four Stokes parameters. We discuss performance and intrinsic limitations of the new magnetic Doppler imaging method. A special emphasis is given to the simultaneous modeling of the magnetically sensitive lines in the optical and infrared regions and to combining information from both atomic and molecular spectral features. These two techniques may, for the first time, give us a tool to study magnetic fields in the starspot interiors. Title: The NASA-UC Eta-Earth Program. I. A Super-Earth Orbiting HD 7924 Authors: Howard, Andrew W.; Johnson, John Asher; Marcy, Geoffrey W.; Fischer, Debra A.; Wright, Jason T.; Henry, Gregory W.; Giguere, Matthew J.; Isaacson, Howard; Valenti, Jeff A.; Anderson, Jay; Piskunov, Nikolai E. Bibcode: 2009ApJ...696...75H Altcode: 2009arXiv0901.4394H We report the discovery of the first low-mass planet to emerge from the NASA-UC Eta-Earth Program, a super-Earth orbiting the K0 dwarf HD 7924. Keplerian modeling of precise Doppler radial velocities reveals a planet with minimum mass MP sin i = 9.26 M ⊕ in a P = 5.398 d orbit. Based on Keck-HIRES measurements from 2001 to 2008, the planet is robustly detected with an estimated false alarm probability of less than 0.001. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 7924 is photometrically constant over the radial velocity period to 0.19 mmag, supporting the existence of the planetary companion. No transits were detected down to a photometric limit of ~0.5 mmag, eliminating transiting planets with a variety of compositions. HD 7924b is one of only eight planets detected by the radial velocity technique with MP sin i < 10 M ⊕ and as such is a member of an emerging family of low-mass planets that together constrain theories of planet formation.

Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time has been granted by both NASA and the University of California. Title: Cartography of the magnetic fields and chemical spots of Ap stars Authors: Silvester, James; Kochukhov, O.; Wade, G. A.; Piskunov, N.; Landstreet, J. D.; Bagnulo, S. Bibcode: 2009IAUS..259..403S Altcode: We will introduce a project using Magnetic Doppler Imaging (MDI) to create assumption-free vector magnetic field maps and chemical surface structure maps of chemically peculiar A and B type (or Ap) stars. We are exploiting the latest generation of spectropolarimeters (NARVAL at the Pic du Midi observatory, and ESPaDOnS at the Canada-France-Hawaii telescope), to obtain high-resolution time series of Stokes IQUV spectra of a selection of Ap stars. The spectra have superior signal-to-noise ratio, resolution and wavelength coverage to those used previously. This combined with the ground-breaking inversion techniques introduced by Kochukhov et al. (2002) results in maps which represent the state-of-the-art in the field of stellar cartography. These maps will allow us to better understand the links between the magnetic field and the physical processes leading to the formation of chemical structures in the photosphere and allow us to address questions surrounding the detailed magnetic field geometry of Ap stars. Title: Planet formation bursts at the borders of the dead zone in 2D numerical simulations of circumstellar disks Authors: Lyra, W.; Johansen, A.; Zsom, A.; Klahr, H.; Piskunov, N. Bibcode: 2009A&A...497..869L Altcode: 2009arXiv0901.1638L Context: As accretion in protoplanetary disks is enabled by turbulent viscosity, the border between active and inactive (dead) zones constitutes a location where there is an abrupt change in the accretion flow. The gas accumulation that ensues triggers the Rossby wave instability, which in turn saturates into anticyclonic vortices. It has been suggested that the trapping of solids within them leads to a burst of planet formation on very short timescales.
Aims: We study in the formation and evolution of the vortices in greater detail, focusing on the implications for the dynamics of embedded solid particles and planet formation.
Methods: We performed two-dimensional global simulations of the dynamics of gas and solids in a non-magnetized thin protoplanetary disk with the Pencil code. We used multiple particle species of radius 1, 10, 30, and 100 cm. We computed the particles' gravitational interaction by a particle-mesh method, translating the particles' number density into surface density and computing the corresponding self-gravitational potential via fast Fourier transforms. The dead zone is modeled as a region of low viscosity. Adiabatic and locally isothermal equations of state are used.
Results: The Rossby wave instability is triggered under a variety of conditions, thus making vortex formation a robust process. Inside the vortices, fast accumulation of solids occurs and the particles collapse into objects of planetary mass on timescales as short as five orbits. Because the drag force is size-dependent, aerodynamical sorting ensues within the vortical motion, and the first bound structures formed are composed primarily of similarly-sized particles. In addition to erosion due to ram pressure, we identify gas tides from the massive vortices as a disrupting agent of formed protoplanetary embryos. We find evidence that the backreaction of the drag force from the particles onto the gas modifies the evolution of the Rossby wave instability, with vortices being launched only at later times if this term is excluded from the momentum equation. Even though the gas is not initially gravitationally unstable, the vortices can grow to Q ≈ 1 in locally isothermal runs, which halts the inverse cascade of energy towards smaller wavenumbers. As a result, vortices in models without self-gravity tend to rapidly merge towards a m = 2 or m =1 mode, while models with self-gravity retain dominant higher order modes (m = 4 or m = 3) for longer times. Non-selfgravitating disks thus show fewer and stronger vortices. We also estimate the collisional velocity history of the particles that compose the most massive embryo by the end of the simulation, finding that the vast majority of them never experienced a collision with another particle at speeds faster than 1 m s-1. This result lends further support to previous studies showing that vortices provide a favorable environment for planet formation. Title: Magnetic Doppler imaging of II Peg Authors: Kochukhov, Oleg; Piskunov, N.; Ilyin, I.; Tuominen, I. Bibcode: 2009IAUS..259..439K Altcode: Rotational modulation of the intensity and polarization spectra of magnetic stars offers a unique possibility to reconstruct the structure of surface magnetic fields and to investigate their relation to cool starspots. We have developed a new magnetic Doppler imaging code which aims at self-consistent temperature and magnetic mapping of cool active stars. Here we present magnetic Doppler imaging analysis of high-resolution circular polarization observations of the active star II Peg. We demonstrate that a self-consistent approach to magnetic inversion unveils stronger magnetic fields than found previously through disjoint analyses of polarization and intensity observations of active stars. Title: Magnetic Doppler Imaging of Active Stars Authors: Kochukhov, O.; Piskunov, N.; Ilyin, I.; Tuominen, I. Bibcode: 2009AIPC.1094..720K Altcode: 2007arXiv0712.2745K; 2009csss...15..720K We present a new magnetic Doppler imaging code which aims at self-consistent temperature and magnetic mapping of cool active stars. Our magnetic imaging procedure is unique in its capability to interpret rotational modulation of individual spectral features in all four Stokes parameters. We discuss performance and intrinsic limitations of our magnetic Doppler imaging method and present results of the simultaneous reconstruction of temperature spots and magnetic field on active star II Peg. Title: Magnetic fields in M dwarf stars from high-resolution infrared spectra Authors: Kochukhov, O.; Heiter, U.; Piskunov, N.; Ryde, N.; Gustafsson, B.; Bagnulo, S.; Plez, B. Bibcode: 2009AIPC.1094..124K Altcode: 2009csss...15..124K Magnetic fields play a central role in the atmospheric properties and variability of active M dwarfs. Information on the strength and structure of magnetic fields in these objects is vital for understanding dynamo mechanisms and magnetically-driven activity of low-mass stars, and for constraining theories of star formation and evolution. We have initiated the first systematic high-resolution survey of magnetically sensitive infrared spectral lines in M dwarf stars using the CRIRES instrument at the ESO VLT. We have completed observations for a sample of 35 active and inactive M dwarfs. Here we report first results of our project, demonstrating a clear detection of magnetic splitting of lines in the spectra of several M dwarfs. We assess diagnostic potential of different Zeeman-sensitive lines in the observed spectral region and apply spectrum synthesis modelling to infer magnetic field properties of selected M dwarfs. Title: Transiting Planets in the Galactic Bulge from SWEEPS Survey and Implications Authors: Sahu, Kailash C.; Casertano, Stefano; Valenti, Jeff; Bond, Howard E.; Brown, Thomas M.; Smith, T. Ed; Clarkson, Will; Minniti, Dante; Zoccali, Manuela; Livio, Mario; Renzini, Alvio; Rich, R. M.; Panagia, Nino; Lubow, Stephen; Brown, Timothy; Piskunov, Nikolai Bibcode: 2009IAUS..253...45S Altcode: The SWEEPS (Sagittarius Window Eclipsing Extrasolar Planet Search) program was aimed at detecting planets around stars in the Galactic bulge, not only to determine their physical properties, but also to determine whether the properties of planets found in the solar neighborhood, such as their frequency and the metallicity dependence, also hold for the planets in the Galactic bulge. We used the Hubble Space Telescope to monitor 180,000 F, G, K, and M dwarfs in the Galactic bulge continuously for 7 days in order to look for transiting planets. We discovered 16 candidate transiting extrasolar planets with periods of 0.6 to 4.2 days, including a possible new class of ultra-short period planets (USPPs) with P < 1 day. The facts that (i) the coverage in the monitoring program is continuous, (ii) most of the stars are at a known distance (in the Galctic bulge), (iii) monitoring was carried out in 2 passbands, and (iv) the images have high spatial resolution, were crucial in minimizing and estimating the false positive rates. We estimate that at least 45% of the candidates are genuine planets. Radial velocity observations of the two brightest host stars further support the planetary nature of the transiting companions. These results suggest that the planet frequency in the Galactic bulge is similar to that in the solar neighborhood. They also suggest that higher metallicity favors planet formation even in the Galactic bulge. The USPPs occur only around low-mass stars which may suggest that close-in planets around higher-mass stars are irradiately evaporated, or that planets are able to migrate to and survive in close-in orbits only around such old and low-mass stars. Title: Standing on the shoulders of giants. Trojan Earths and vortex trapping in low mass self-gravitating protoplanetary disks of gas and solids Authors: Lyra, W.; Johansen, A.; Klahr, H.; Piskunov, N. Bibcode: 2009A&A...493.1125L Altcode: 2008arXiv0810.3192L Context: Centimeter and meter-sized solid particles in protoplanetary disks are trapped within long-lived, high-pressure regions, creating opportunities for collapse into planetesimals and planetary embryos.
Aims: We aim to study the effect of the high-pressure regions generated in the gaseous disks by a giant planet perturber. These regions consist of gas retained in tadpole orbits around the stable Lagrangian points as a gap is carved, and the Rossby vortices launched at the edges of the gap.
Methods: We performed global simulations of the dynamics of gas and solids in a low mass non-magnetized self-gravitating thin protoplanetary disk. We employed the Pencil code to solve the Eulerian hydro equations, tracing the solids with a large number of Lagrangian particles, usually 100 000. To compute the gravitational potential of the swarm of solids, we solved the Poisson equation using particle-mesh methods with multiple fast Fourier transforms.
Results: Huge particle concentrations are seen in the Lagrangian points of the giant planet, as well as in the vortices they induce at the edges of the carved gaps. For 1 cm to 10 cm radii, gravitational collapse occurs in the Lagrangian points in less than 200 orbits. For 5 cm particles, a 2M⊕ planet is formed. For 10 cm, the final maximum collapsed mass is around 3M⊕. The collapse of the 1 cm particles is indirect, following the timescale of gas depletion from the tadpole orbits. Vortices are excited at the edges of the gap, primarily trapping particles of 30 cm radii. The rocky planet that is formed is as massive as 17M⊕, constituting a Super-Earth. Collapse does not occur for 40 cm onwards. By using multiple particle species, we find that gas drag modifies the streamlines in the tadpole region around the classical L4 and L5 points. As a result, particles of different radii have their stable points shifted to different locations. Collapse therefore takes longer and produces planets of lower mass. Three super-Earths are formed in the vortices, the most massive having 4.5M⊕.
Conclusions: A Jupiter-mass planet can induce the formation of other planetary embryos at the outer edge of its gas gap. Trojan Earth-mass planets are readily formed; although not existing in the solar system, might be common in the exoplanetary zoo. Title: Commission 29: Stellar Spectra Authors: Parthasarathy, Mudumba; Piskunov, Nikolai E.; Sneden, Christopher; Carpenter, Kenneth G.; Castelli, Fiorella; Cunha, Katia; Eenens, Phillippe R. J.; Hubeny, Ivan; Rossi, Silvia; Takada-Hidai, Masahide; Wahlgren, Glenn M.; Weiss, Werner W. Bibcode: 2009IAUTA..27..209P Altcode: The members of IAU Commission 29 Stellar Spectra are actively engaged in the quantitative analysis of spectra of various types of stars. With large and medium size telescopes equipped with high resolution spectrographs LTE and Non-LTE analysis of spectra of all types stars are being carried out. Spectra of stars in our Galaxy, in globular and open clusters, stars in LMC and SMC and in nearby galaxies are being studied. Accurate chemical composition analysis of various types of stars has been carried out during the past three years. Now the analysis of stellar spectra covers the wavelength range from X-ray region to IR and sub-millimeter range. Recently stellar spectra are being analysed using time-dependent, 3D, hydrodynamical model atmospheres to derive accurate stellar abundances. Title: Inter-Division IV-V / Working Group Ap and Related Stars Authors: Cunha, Margarida S.; Weiss, Werner W.; Dworetsky, Michael M.; Kochukhov, Oleg; Kupka, Friedrich; Leblanc, Francis; Monier, Richard; Paunzen, Ernst; Piskunov, Nikolai E.; Shibahashi, Hiromoto; Smalley, Barry; Ziznovsky, Jozef Bibcode: 2009IAUTA..27..245C Altcode: The diversity of physical phenomena embraced by the study of Chemically Peculiar (CP) stars results in an associated research community with interests that are equally diverse. This fact became once more evident during the CP#Ap Workshop that took place in Vienna (Austria) in September 2007, and which gathered over 80 members of this research community. Besides the excellent scientific outcome of the meeting, during the workshop the community had the opportunity to discuss its organization and plans for the future. Following on those plans, the Working Group has submitted a proposal for a Joint Discussion during the IAU XXVII General Assembly, in Rio de Janeiro, which has meanwhile been accepted. Moreover, through an ApN newsletter forum, the Working Group has compiled requests from the community concerning atomic and related data. These requests have been put together and will be shared with Commission 14. Title: Embryos grown in the dead zone. Assembling the first protoplanetary cores in low mass self-gravitating circumstellar disks of gas and solids Authors: Lyra, W.; Johansen, A.; Klahr, H.; Piskunov, N. Bibcode: 2008A&A...491L..41L Altcode: 2008arXiv0807.2622L Context: In the borders of the dead zones of protoplanetary disks, the inflow of gas produces a local density maximum that triggers the Rossby wave instability. The vortices that form are efficient in trapping solids.
Aims: We aim to assess the possibility of gravitational collapse of the solids within the Rossby vortices.
Methods: We perform global simulations of the dynamics of gas and solids in a low mass non-magnetized self-gravitating thin protoplanetary disk with the Pencil Code. We use multiple particle species of radius 1, 10, 30, and 100 cm. The dead zone is modelled as a region of low viscosity.
Results: The Rossby vortices excited in the edges of the dead zone are efficient particle traps. Within 5 orbits after their appearance, the solids achieve critical density and undergo gravitational collapse into Mars sized objects. The velocity dispersions are of the order of 10 m s-1 for newly formed embryos, later lowering to less than 1 m s-1 by drag force cooling. After 200 orbits, over 300 gravitationally bound embryos were formed, 20 of them being more massive than Mars. Their mass spectrum follows a power law of index -2.3 ± 0.2.

Appendices A-C are only available in electronic form at http://www.aanda.org Title: Doppler imaging Authors: Piskunov, N. Bibcode: 2008PhST..133a4017P Altcode: In this paper, I present a short review of the history and modern status of Doppler imaging techniques, highlighting their dependence on the knowledge of the fundamental stellar parameters, the quality of stellar atmospheric models and the accuracy of spectral synthesis. Title: Vald Authors: Obbrugger, M.; Heiter, U.; Kupka, F.; Lüftinger, T.; Nesvacil, N.; Piskunov, N.; Ryabchikova, T. A.; Stempels, H. C.; Stütz, Ch.; Weiss, W. W. Bibcode: 2008asvo.proc..215O Altcode: VALD is a collection of atomic transition parameters and supporting extraction software. VALD services are available via Email (VALD-EMS) and the Web interface. Different kinds of requests are useful for several needs like abundance analysis, radial velocity measurements, or line identification. Since 1994, the early days of VALD, the database has been constantly improved and the release of VALD-3 - incorporating, e.g., molecular data and new line lists - is in preparation. With meanwhile more than 5 000 000 requests VALD developed to a much appreciated tool. Title: VALD — an atomic and molecular database for astrophysics Authors: Heiter, U.; Barklem, P.; Fossati, L.; Kildiyarova, R.; Kochukhov, O.; Kupka, F.; Obbrugger, M.; Piskunov, N.; Plez, B.; Ryabchikova, T.; Stempels, H. C.; Stütz, Ch; Weiss, W. W. Bibcode: 2008JPhCS.130a2011H Altcode: The VALD database of atomic and molecular data aims to ensure a robust and consistent analysis of astrophysical spectra. We offer a convenient e-mail and web-based user interface to a vast collection of spectral line parameters for all chemical elements and in the future also for molecules. An international team is working on the following tasks: collecting line parameters from relevant theoretical and experimental publications, computing line parameters, evaluating the data quality by comparison of similar data from different sources and by comparison with astrophysical observations, and incorporating the data into VALD. A unique feature of VALD is its capability to provide the most comprehensive spectral line lists for specific astrophysical plasma conditions defined by the user. Title: A comparative analysis of the laboratory and theoretical transition probabilities of the Fe-peak elements for a new release of VALD Authors: Ryabchikova, T.; Kildiyarova, R.; Piskunov, N.; Heiter, U.; Fossati, L.; Weiss, W. W. Bibcode: 2008JPhCS.130a2017R Altcode: We carried out a comparative analysis of the recent atomic data for iron-peak elements, mainly Ti, Cr and Fe, for a new release of the Vienna Atomic Line Database (VALD3). New data were compared with those available in VALD2 and were checked using high-resolution, high signal-to-noise spectra of sharp-lined chemically normal stars including the Sun, and the zero-rotation extremely Cr- and Fe-rich chemically peculiar star HD 133792. The observed spectrum of the latter star allowed for comparison with transition probability calculations based on the orthogonal operator technique with the Cowan code for Cr II and Fe II lines for lower level energies between 2 eV and 11 eV in the wavelength region 3100 to 9000 Å.

In general, the agreement between the new experimental transition probabilities and those currently available in VALD2 is fairly good, which helps to validate the stellar abundance data derived with the VALD2 atomic parameters. We also found that, for a few important Ti II and Fe II lines in the visible spectral region, new transition probabilities are not consistent within their quoted accuracy.

In a series of recent works on experimental f-values for Fe II it was shown that calculations based on the orthogonal operator technique agree better with the experimental data than the Cowan code calculations and, hence, should have preference for stellar spectroscopy. Our analysis of the Ap star HD 133792 spectrum clearly demonstrates that there are quite a number of high-excitation Cr II and Fe II lines which are fitted reasonably well when using the transition probabilities calculated with the Cowan code. As a rule these lines have their upper energy levels classified differently in both methods of calculations. Title: The upgrade of HARPS to a full-Stokes high-resolution spectropolarimeter Authors: Snik, Frans; Jeffers, Sandra; Keller, Christoph; Piskunov, Nikolai; Kochukhov, Oleg; Valenti, Jeff; Johns-Krull, Christopher Bibcode: 2008SPIE.7014E..0OS Altcode: 2008SPIE.7014E..22S We present the design of a compact module that converts the HARPS instrument at the 3.6-m telescope at La Silla to a full-Stokes high-resolution spectropolarimeter. The polarimeter will replace the obsolete Iodine cell inside the HARPS Cassegrain adapter. Utilizing the two fibers going into the spectrograph, two dual-beam systems can be positioned in the beam: one with a rotating superachromatic quarter-wave plate for circular polarimetry and one with a rotating superachromatic half-wave plate for linear polarimetry. A large polarimetric precision is ensured by the beam-exchange technique and a minimal amount of instrumental polarization. The polarimeter, in combination with the ultra-precise HARPS spectrograph, enables unprecedented observations of stellar magnetic fields and circumstellar material without compromising the successful planet-finding program. Title: INTRODUCTION: Nobel Symposium 135: Physics of Planetary Systems (18 22 June 2007, Lidingö, Stockholm, Sweden) Authors: Piskunov, Nikolai; Rickman, Hans; Gustafsson, Bengt Bibcode: 2008PhST..130a1001P Altcode: Since the discovery of the first planet, orbiting a sun-like star outside of our solar system, astronomy has changed dramatically. This event inspired a wide spectrum of activities not just in observational astronomy but in all fields related to planets from star formation to astrobiology. The discovery itself was the result of long and systematic work on perfecting measuring techniques and collecting data. Once the required level of precision was reached news about extrasolar planets started to appear frequently not just in scientific journals but also in the general media.

Although fast progress is quite obvious in many areas related to planetary sciences for this Nobel symposium, dedicated to the Physics of Planetary Systems, we selected five topics where a number of particularly important breakthroughs happened in the last decade. These are:

detection of exoplanets planet birthplaces: observations and modelling planet formation evolution of planetary systems planet characterization.

We dedicated a full session, consisting of a few review talks and a joint discussion, to each of these topics. The format was a success, but what made this meeting so remarkable was the quality of the talks. We are very thankful to the world leading scientists for coming to Lidingö and making this symposium a truly memorable event. This book contains most of their contributions for you to enjoy.

We are very thankful to the Nobel Foundation for generous sponsorship which made this symposium possible. Title: Abundance analysis and searching for nonradial pulsations in the atmosphere of the chemically peculiar star HD 115708 Authors: Semenko, E. A.; Sachkov, M. E.; Ryabchikova, T. A.; Kudryavtsev, D. O.; Piskunov, N. E. Bibcode: 2008AstL...34..413S Altcode: 2008PAZh...34..455S We present the results of our abundance analysis for the magnetic chemically peculiar star HD 115708 based on high-resolution spectra. The atmospheric chemical composition of HD 115708 ( T eff = 7550 K) is shown to be typical of cool Ap stars with a significant ionization disequilibrium for the first and second rare earth ions, which is commonly observed in the atmospheres of pulsating Ap (roAp) stars. Our study of the vertical distribution of elements has shown that Mg, Ca, Cr, and Fe concentrate in deeper atmospheric layers, with their abundances decreasing sharply in the upper layers. The jumps in abundance are 1.5 3 orders of magnitude. Silicon is distributed in depth almost uniformly in the atmosphere of HD 115708. The derived empirical Cr and Fe distributions agree qualitatively with the results of diffusion calculations. Since the atmospheric chemical peculiarities in HD 115708 correspond to roAp stars, we have performed a spectroscopic monitoring to find nonradial pulsations. We have been able to determine only an upper limit for the amplitude of the possible radial velocity pulsations, ∼100 m s-1, due to the insufficient temporal resolution and instability of the main stellar spectrograph (MSS) of the 6-m telescope. Title: 3D atmospheric structure of the prototypical roAp star HD 24712 (HR1217) Authors: Lüftinger, T.; Kochukhov, O.; Ryabchikova, T.; Piskunov, N.; Weiss, W. W.; Ilyin, I. Bibcode: 2008CoSka..38..335L Altcode: The first analysis of the structure of the surface magnetic field of a rapidly oscillating Ap (roAp) star is presented. We obtain information about abundance distributions of a number of chemical elements on the surface of the prototypical roAp star HD 24712 and about magnetic field geometry. Inverting rotationally modulated spectra in Stokes parameters I and V obtained with the SOFIN spectropolarimeter attached to the NOT, we recover surface abundance structures of sixteen different chemical elements, including Mg, Ca, Sc, Ti, Cr, Fe, Co, Ni, Y, La, Ce, Pr, Nd, Gd, Tb, and Dy. Our analysis reveal a pure dipolar structure of the stellar magnetic field and surprising and unexpected correlations of the various elemental surface abundance structures to this field geometry. Stratification analysis at phases of both magnetic extrema enable us to obtain the vertical dimension in the atmosphere of HD 24712. High time resolved spectroscopic data and observations obtained with the MOST space photometer give us the possibility to compare (Lüftinger, 2007) our results to detailed pulsational analysis. Title: Global magnetohydrodynamical models of turbulence in protoplanetary disks. I. A cylindrical potential on a Cartesian grid and transport of solids Authors: Lyra, W.; Johansen, A.; Klahr, H.; Piskunov, N. Bibcode: 2008A&A...479..883L Altcode: 2007arXiv0705.4090L Aims:We present global 3D MHD simulations of disks of gas and solids, aiming at developing models that can be used to study various scenarios of planet formation and planet-disk interaction in turbulent accretion disks. A second goal is to demonstrate that Cartesian codes are comparable to cylindrical and spherical ones in handling the magnetohydrodynamics of the disk simulations while offering advantages, such as the absence of a grid singularity, for certain applications, e.g., circumbinary disks and disk-jet simulations.
Methods: We employ the Pencil Code, a 3D high-order finite-difference MHD code using Cartesian coordinates. We solve the equations of ideal MHD with a local isothermal equation of state. Planets and stars are treated as particles evolved with an N-body scheme. Solid boulders are treated as individual superparticles that couple to the gas through a drag force that is linear in the local relative velocity between gas and particle.
Results: We find that Cartesian grids are well-suited for accretion disk problems. The disk-in-a-box models based on Cartesian grids presented here develop and sustain MHD turbulence, in good agreement with published results achieved with cylindrical codes. Models without an inner boundary do not show the spurious build-up of magnetic pressure and Reynolds stress seen in the models with boundaries, but the global stresses and alpha viscosities are similar in the two cases. We investigate the dependence of the magnetorotational instability on disk scale height, finding evidence that the turbulence generated by the magnetorotational instability grows with thermal pressure. The turbulent stresses depend on the thermal pressure obeying a power law of 0.24 ± 0.03, compatible with the value of 0.25 found in shearing box calculations. The ratio of Maxwell to Reynolds stresses decreases with increasing temperature, dropping from 5 to 1 when the sound speed was raised by a factor 4, maintaing the same field strength. We also study the dynamics of solid boulders in the hydromagnetic turbulence, by making use of 106 Lagrangian particles embedded in the Eulerian grid. The effective diffusion provided by the turbulence prevents settling of the solids in a infinitesimally thin layer, forming instead a layer of solids of finite vertical thickness. The measured scale height of this diffusion-supported layer of solids implies turbulent vertical diffusion coefficients with globally averaged Schmidt numbers of 1.0 ± 0.2 for a model with α≈10-3 and 0.78 ± 0.06 for a model with α≈10-1. That is, the vertical turbulent diffusion acting on the solids phase is comparable to the turbulent viscosity acting on the gas phase. The average bulk density of solids in the turbulent flow is quite low (ρp = 6.0×10-11 kg m-3), but in the high pressure regions, significant overdensities are observed, where the solid-to-gas ratio reached values as great as 85, corresponding to 4 orders of magnitude higher than the initial interstellar value of 0.01. Title: Planets in the Galactic Bulge: Results from the SWEEPS Project Authors: Sahu, K. C.; Casertano, S.; Valenti, J.; Bond, H. E.; Brown, T. M.; Smith, T. E.; Clarkson, W.; Minniti, D.; Zoccali, M.; Livio, M.; Renzini, A.; Rich, R. M.; Panagia, N.; Lubow, S.; Brown, T.; Piskunov, N. Bibcode: 2008ASPC..398...93S Altcode: 2007arXiv0711.4059S The exoplanets discovered so far have been mostly around relatively nearby and bright stars. As a result, the host stars are mostly (i) in the Galactic disk, (ii) relatively massive, and (iii) relatively metal rich. The aim of the SWEEPS project is to extend our knowledge to stars which (i) are in a different part of the Galaxy, (ii) have low masses, and (iii) have a large range of metallicities. To achieve this goal, we used the Hubble Space Telescope and its Advanced Camera for Surveys to look for transiting planets around F, G, K, and and M dwarfs in the Galactic bulge. We photometrically monitored ∼180,000 stars in a dense stellar field in the Galactic bulge continuously for 7 days. We discovered 16 candidate transiting extrasolar planets with periods of 0.6 to 4.2 days, including a new class of ultra-short period planets (USPPs) with P<1.2 days. Radial velocity observations of two brightest candidates support the planetary nature. These results suggest that planets are equally abundant in the Galactic bulge and around low-mass stars (within a factor ∼2), and the metallicity distribution holds even for the stars in the Galactic bulge. The USPPs occur only around low-mass stars which suggest that close-in planets around higher-mass stars are either irradiately evaporated, or that the size of the inner disk hole decreases with decreasing mass of the host stars. Title: Optimal Extraction of Echelle Spectra Authors: Piskunov, Nikolai Bibcode: 2008psa..conf..129P Altcode: The extraction of the echelle spectra registered with a CCD detector represents a big challenge because of three reasons: (1) the pixel sampling is often close or worse then optimal, (2) spectral orders are curved and tilted with respect to the CCD rows (or columns) and (3) every pixel contains additional noise coming from various sources as illustrated in Figure 1. The main goal of an optimal extraction is to recover as much of the science signal while minimizing the contribution of the noise. Here we present the Slit Function Decomposition algorithm which replaces the summation in a sliding window with a reconstruction of the slit illumination profile. The reconstruction is formulated as an inverse problem solved by iterations and it is robust against most of the systematic problems including cosmic rays and cosmetic defects. Title: Atomic Diffusion and Mixing in Old Stars. I. Very Large Telescope FLAMES-UVES Observations of Stars in NGC 6397 Authors: Korn, A. J.; Grundahl, F.; Richard, O.; Mashonkina, L.; Barklem, P. S.; Collet, R.; Gustafsson, B.; Piskunov, N. Bibcode: 2007ApJ...671..402K Altcode: 2007arXiv0709.0639K We present a homogeneous photometric and spectroscopic analysis of 18 stars along the evolutionary sequence of the metal-poor globular cluster NGC 6397 ([Fe/H]~-2), from the main-sequence turnoff point to red giants below the bump. The spectroscopic stellar parameters, in particular stellar parameter differences between groups of stars, are in good agreement with broadband and Strömgren photometry calibrated on the infrared flux method. The spectroscopic abundance analysis reveals, for the first time, systematic trends of iron abundance with evolutionary stage. Iron is found to be 30% less abundant in the turnoff point stars than in the red giants. An abundance difference in lithium is seen between the turnoff point and warm subgiant stars. The impact of potential systematic errors on these abundance trends (stellar parameters, the hydrostatic and LTE approximations) is quantitatively evaluated and found not to alter our conclusions significantly. Trends for various elements (Li, Mg, Ca, Ti, and Fe) are compared with stellar structure models including the effects of atomic diffusion and radiative acceleration. Such models are found to describe the observed element-specific trends well, if extra (turbulent) mixing just below the convection zone is introduced. It is concluded that atomic diffusion and turbulent mixing are largely responsible for the subprimordial stellar lithium abundances of warm halo stars. Other consequences of atomic diffusion in old metal-poor stars are also discussed.

Based on observations carried out at the European Southern Observatory (ESO), Paranal, Chile, under program ID 075.D-0125(A). Title: Weather in stellar atmosphere revealed by the dynamics of mercury clouds in α Andromedae Authors: Kochukhov, Oleg; Adelman, Saul J.; Gulliver, Austin F.; Piskunov, Nikolai Bibcode: 2007NatPh...3..526K Altcode: 2007arXiv0705.4469K The formation of long-lasting structures at the surfaces of stars is commonly ascribed to the action of strong magnetic fields. This paradigm is supported by observations of evolving cool spots in the Sun and active late-type stars, and stationary chemical spots in the early-type magnetic stars. However, results of our seven-year monitoring of mercury spots in non-magnetic early-type star α Andromedae show that the picture of magnetically driven structure formation is fundamentally incomplete. Using an indirect stellar-surface mapping technique, we construct a series of two-dimensional images of starspots and discover a secular evolution of the mercury cloud cover in this star. This remarkable structure-formation process, observed for the first time in any star, is plausibly attributed to a non-equilibrium, dynamical evolution of the heavy-element clouds created by atomic diffusion, and may have the same underlying physics as the weather patterns on terrestrial and giant planets. Title: 3-D hydrodynamic simulations of convection in A stars Authors: Kochukhov, O.; Freytag, B.; Piskunov, N.; Steffen, M. Bibcode: 2007IAUS..239...68K Altcode: 2006astro.ph.10111K Broadening and asymmetry of spectral lines in slowly rotating late A-type stars provide evidence for high-amplitude convective motions. The properties of turbulence observed in the A-star atmospheres are not understood theoretically and contradict results of previous numerical simulations of convection. Here we describe an ongoing effort to understand the puzzling convection signatures of A stars with the help of 3-D hydrodynamic simulations. Our approach combines realistic spectrum synthesis and non-grey hydrodynamic models computed with the CO5BOLD code. We discuss these theoretical predictions and confront them with high-resolution spectra of A stars. Our models have, for the first time, succeeded in reproducing the observed profiles of weak spectral lines without introducing fudge broadening parameters. Title: Search for the radial magnetic-field gradient in the CP star α 2 CVn Authors: Romanyuk, I. I.; Panchuk, V. E.; Piskunov, N. E.; Kudryavtsev, D. O. Bibcode: 2007AstBu..62...26R Altcode: The possibility of investigating the vertical structure of the magnetic field in chemically peculiar main-sequence stars is discussed. The nonuniform distribution of chemical elements over the surface complicates the problem substantially. The most efficient measurements are shown to be those of the longitudinal field components based on spectral lines with wavelengths longer and shorter than 3646 Å (shortward and longward of the Balmer jump), which form at different optical depths in the atmosphere. Various methodological problems are addressed that must be overcome in order to accomplish the task. The brightest magnetic star α 2 CVn is observed with the echelle spectrometer equipped with an Uppsala CCD chip. New observations corroborate our previous result: the longitudinal component of the magnetic field B e of the α 2 CVn star increases with depth by about 30% over the atmosphere thickness scale. Title: Commission 29: Stellar Spectra Authors: Sneden, Christopher; Parthasarathy, M.; Castelli, Fiorella; Cunha, Katia; Eenens, Philippe; Friel, Eileen; Gratton, Raffaele; Hubeny, Ivan; Landstreet, John D.; Mathys, Gautier; Piskunov, Nikolai; Primas, Francesca; Takada-Hidai, Masahide; Weiss, Werner Bibcode: 2007IAUTA..26..203S Altcode: Participants in Commission 29 study various aspects of stellar spectra and the information that can be extracted from spectra. The list of fields of interest of the Organizing Committee members suggest some major current research topics in this area are stellar chemical compositions and surface/envelope phenomena. Some of the topics of this commission have overlap with other commissions, such as Commission 14 (Atomic and Molecular Data), 26 (Double and Multiple Stars), 27 (Variable Stars), 30 (Radial Velocities), 36 (Theory of Stellar Atmospheres), and 37 (Star Clusters and Associations). Many Commission 29 members are also members of these other commissions. Title: Transiting extrasolar planetary candidates in the Galactic bulge Authors: Sahu, Kailash C.; Casertano, Stefano; Bond, Howard E.; Valenti, Jeff; Ed Smith, T.; Minniti, Dante; Zoccali, Manuela; Livio, Mario; Panagia, Nino; Piskunov, Nikolai; Brown, Thomas M.; Brown, Timothy; Renzini, Alvio; Rich, R. Michael; Clarkson, Will; Lubow, Stephen Bibcode: 2006Natur.443..534S Altcode: 2006astro.ph.10098S More than 200 extrasolar planets have been discovered around relatively nearby stars, primarily through the Doppler line shifts owing to reflex motions of their host stars, and more recently through transits of some planets across the faces of the host stars. The detection of planets with the shortest known periods, 1.2-2.5 days, has mainly resulted from transit surveys which have generally targeted stars more massive than 0.75Msolar, where Msolar is the mass of the Sun. Here we report the results from a planetary transit search performed in a rich stellar field towards the Galactic bulge. We discovered 16 candidates with orbital periods between 0.4 and 4.2 days, five of which orbit stars of masses in the range 0.44-0.75Msolar. In two cases, radial-velocity measurements support the planetary nature of the companions. Five candidates have orbital periods below 1.0 day, constituting a new class of ultra-short-period planets, which occur only around stars of less than 0.88Msolar. This indicates that those orbiting very close to more-luminous stars might be evaporatively destroyed or that jovian planets around stars of lower mass might migrate to smaller radii. Title: New Abundances for Old Stars - Atomic Diffusion at Work in NGC 6397 Authors: Korn, A.; Grundahl, F.; Richard, O.; Barklem, P.; Mashonkina, L.; Collet, R.; Piskunov, N.; Gustafsson, B. Bibcode: 2006Msngr.125....6K Altcode: 2006astro.ph.10077K; 2006Msngr.125...10K A homogeneous spectroscopic analysis of unevolved and evolved stars in the metal-poor globular cluster NGC 6397 with FLAMES-UVES reveals systematic trends of stellar surface abundances that are likely caused by atomic diffusion. This finding helps to understand, among other issues, why the lithium abundances of old halo stars are significantly lower than the abundance found to be produced shortly after the Big Bang. Title: A probable stellar solution to the cosmological lithium discrepancy Authors: Korn, A. J.; Grundahl, F.; Richard, O.; Barklem, P. S.; Mashonkina, L.; Collet, R.; Piskunov, N.; Gustafsson, B. Bibcode: 2006Natur.442..657K Altcode: 2006astro.ph..8201K The measurement of the cosmic microwave background has strongly constrained the cosmological parameters of the Universe. When the measured density of baryons (ordinary matter) is combined with standard Big Bang nucleosynthesis calculations, the amounts of hydrogen, helium and lithium produced shortly after the Big Bang can be predicted with unprecedented precision. The predicted primordial lithium abundance is a factor of two to three higher than the value measured in the atmospheres of old stars. With estimated errors of 10 to 25%, this cosmological lithium discrepancy seriously challenges our understanding of stellar physics, Big Bang nucleosynthesis or both. Certain modifications to nucleosynthesis have been proposed, but found experimentally not to be viable. Diffusion theory, however, predicts atmospheric abundances of stars to vary with time, which offers a possible explanation of the discrepancy. Here we report spectroscopic observations of stars in the metal-poor globular cluster NGC6397 that reveal trends of atmospheric abundance with evolutionary stage for various elements. These element-specific trends are reproduced by stellar-evolution models with diffusion and turbulent mixing. We thus conclude that diffusion is predominantly responsible for the low apparent stellar lithium abundance in the atmospheres of old stars by transporting the lithium deep into the star. Title: Magnetic Doppler Imaging of Active Stars Authors: Kochukhov, O.; Piskunov, N. Bibcode: 2006IAUJD...8E...7K Altcode: Rotational modulation of the intensity and polarization spectra of magnetic stars offers a unique possibility to reconstruct the structure of surface magnetic fields and investigate their relation to the temperature and chemical spots in stellar atmospheres. The complex task of obtaining self-consistent and accurate maps of photospheric magnetic fields can finally be addressed with the Magnetic Doppler imaging technique. We present the new version of our magnetic Doppler imaging code which aims at temperature and magnetic mapping of cool active stars. Our magnetic imaging procedure is unique in its capability to model individual spectral features in several Stokes parameters simultaneously. We discuss performance and intrinsic limitations of our magnetic Doppler imaging method. A special emphasis is given to the mapping using both atomic and molecular spectral lines. The latter may, for the first time, give us a tool to learn about magnetic fields in the interior of starspots. Title: Global 3-D solar-type star-disc dynamo systems: I. MHD modeling Authors: von Rekowski, B.; Piskunov, N. Bibcode: 2006AN....327..340V Altcode: We have carried out global three-dimensional magnetohydrodynamic simulations of the star-disc interaction region around a young solar-type star. The magnetic field is generated and maintained by dynamos in the star as well as in the disc. The developing mass flows possess non-periodic time-variable azimuthal structure and are controlled by the nonaxisymmetric magnetic fields. Since the stellar field drives a strong stellar wind, accretion is anti-correlated with the stellar field strength and disc matter is spiraling onto the star at low latitudes, both contrary to the generally assumed accretion picture. Title: Pinning Down Gravitational Settling Authors: Korn, A. J.; Piskunov, N.; Grundahl, F.; Barklem, P.; Gustafsson, B. Bibcode: 2006cams.book..294K Altcode: 2006astro.ph..8338K We analyse high-resolution archival UVES data of turnoff and subgiant stars in the nearby globular cluster NGC6397 ([Fe/H]≈-2). Balmer-profile analyses are performed to derive reddening-free effective temperatures. Due to the limited S/N and uncertainties related to blaze removal, we find the data quality insufficient to exclude the existence of gravitational settling. If the newly derived effective temperatures are taken as a basis for an abundance analysis, the photospheric iron (Fe ii) abundance in the turnoff stars is 0.11 dex lower than in the (well-mixed) subgiants. Title: Inhomogeneous distribution of mercury on the surfaces of rapidly rotating HgMn stars Authors: Kochukhov, O.; Piskunov, N.; Sachkov, M.; Kudryavtsev, D. Bibcode: 2005A&A...439.1093K Altcode: 2005astro.ph..5124K Starspots are usually associated with the action of magnetic fields at stellar surfaces. However, an inhomogeneous chemical distribution of mercury was found recently for the mercury-manganese (HgMn) star α And - a well-established member of a non-magnetic subclass of the chemically peculiar stars of the upper main sequence. In this study we present first results of the high-resolution survey of the Hg II 3984 Å resonance line in the spectra of rapidly rotating HgMn stars with atmospheric parameters similar to those of α And. We use spectrum synthesis modelling and take advantage of the Doppler resolution of stellar surfaces to probe the horizontal structure of mercury distribution. Clear signatures of spots are found in the Hg II 3984 Å line profiles of HR 1185 and HR 8723. Two observations of the latter star separated by two days give evidence for line profile variability. We conclude that inhomogeneous distribution of Hg is a common phenomenon for the rapidly rotating HgMn stars in the 13 000-13 800 K effective temperature range independent of the stellar evolutionary stage. These results establish the existence of a new class of spectrum variable spotted B-type stars. It is suggested that the observed Hg inhomogeneities arise from dynamical instabilities in the chemical diffusion processes and are unrelated to magnetic phenomena. Title: Cool stars in the Gaia photometric system Authors: Heiter, U.; Piskunov, N.; Gustafsson, B.; Jordi, C.; Carrasco, J. M. Bibcode: 2005ESASP.560..635H Altcode: 2005csss...13..635H No abstract at ADS Title: Magnetic Doppler Imaging: Mathematical Basis Authors: Piskunov, N. Bibcode: 2005EAS....17..245P Altcode: We address important mathematical properties of solutions of the Magnetic Doppler Imaging problem. We show that the underlying inverse problem based on all 4 Stokes parameters is well-posed and thus has a unique solution. The only purpose of regularization is to suppress instabilities induced by sparse sampling of phase and/or wavelength when dealing with practical data. Therefore, the final solution is stable with respect to the initial guess and is not affected by the selection of a specific type of regularization. Title: Magnetic Fields and Stellar Surface Structures Authors: Piskunov, Nikolai Bibcode: 2005hris.conf..315P Altcode: We discuss the use of high-resolution spectroscopy for studying inhomogeneities on stellar surfaces. Examples of such inhomogeneities include chemical and temperature spots, pulsation waves and magnetic fields. Presence of surface structures reflects important physical processes occurring in much deeper layers than can be observed and, therefore, they contain valuable information for theoretical modelling of stars. Title: Panel discussion section B Authors: Piskunov, N. Bibcode: 2004IAUS..224..115P Altcode: No abstract at ADS Title: Multi-element abundance Doppler imaging of the rapidly oscillating Ap star HR 3831 Authors: Kochukhov, O.; Drake, N. A.; Piskunov, N.; de la Reza, R. Bibcode: 2004A&A...424..935K Altcode: We investigate magnetic field geometry and surface distribution of chemical elements in the rapidly oscillating Ap star HR 3831. Results of the model atmosphere analysis of the spectra of this star are combined with the Hipparcos parallax and evolutionary models to obtain new accurate estimates of the fundamental stellar parameters: Teffv{7650}, log L/L⊙=1.09, M/M⊙= 1.77 and an inclination angle i=68° of the stellar axis of rotation. We find that the variation of the longitudinal magnetic field of HR 3831 and the results of our analysis of the magnetic intensification of Fe I lines in the spectrum of this star are consistent with a dipolar magnetic topology with a magnetic obliquity β=87° and a polar strength Bp=2.5 kG. We apply a multi-element abundance Doppler imaging inversion code for the analysis of the spectrum variability of HR 3831, and recover surface distributions of 17 chemical elements, including Li, C, O, Na, Mg, Si, Ca, Ti, Cr, Mn, Fe, Co, Ba, Y, Pr, Nd, Eu. Our study represents the most thorough examination of the surface chemical structure in a magnetic Ap star and provides important observational constraints for modelling radiative diffusion in magnetic stars. The exceedingly high quality of some of our spectroscopic data allowed us to reconstruct unprecedented details of abundance distributions, demonstrating a high level of complexity in the surface structure down to the resolution limit of the Doppler maps. The Doppler imaging analysis of HR 3831 forms a basis for subsequent detailed observational investigations and theoretical modelling of non-radial oscillations in this star. We discuss the compound effect of the chemical nonuniformities and pulsational velocity field on the rapid line profile variations, and assess the possibility of identifying pulsation modes by using spatial filtering produced by an inhomogeneous abundance distribution. The results of our study of the surface chemical structure suggest that differences in pulsational behaviour of lines of different ions observed for HR 3831 are not a consequence of horizontal atmospheric inhomogeneities, but predominantly a depth effect.

Based on observations obtained at the European Southern Observatory, La Silla, Chile. Title: The influence of magnetic fields on the hydrostatic structure of the atmospheres of chemically peculiar stars Authors: Valyavin, G.; Kochukhov, O.; Piskunov, N. Bibcode: 2004A&A...420..993V Altcode: We discuss the properties of atmospheres of chemically peculiar magnetic stars. The slow evolution of global magnetic fields leads to the development of an induced electric current in all conductive atmospheric layers. The Lorentz force, which results from the interaction between a magnetic field and the induced current, may change the atmospheric structure and provide insight into the formation and evolution of stellar magnetic fields. We developed a model atmosphere code that takes into account the Lorentz force in the equation of hydrostatic equilibrium, and computed a number of model atmospheres for magnetic A and B stars. The surface distribution of a magnetic field was assumed to be a dipole, slightly distorted by the induced atmospheric electric current. The interaction between the magnetic field and electric current is modelled in detail, taking into account microscopic properties of the stellar plasma. The presence of a significant Lorentz force leads to substantial modification of the atmospheric structure and in particular the pressure stratification, which in turn influences the formation of absorption spectral features, especially hydrogen Balmer lines. Furthermore, we find that rotational modulation of the disk-average parameters of a global stellar magnetic field causes characteristic rotational variability of hydrogen lines. With our model, observable effects correspond to induced electric currents of the order of 10-11 cgs, which requires characteristic field evolution times 2-3 orders of magnitude shorter than the field decay time estimated for magnetic A and B stars assuming fossil dipolar field topology in the stellar interior. Using the computations of our model atmospheres we consider an observational aspect of the problem and attempt to interpret photometric data on the variability of hydrogen lines within the framework of simplest model of the evolution of global magnetic fields. With the hydrogen line data we find tentative support for the presence of a non-negligible Lorentz force in the atmospheres of some magnetic chemically peculiar stars. Title: Near-Polar Starspots and Polar Dynamo Waves Authors: Novikov, S. V.; Piskunov, N. E.; Sokoloff, D. D. Bibcode: 2004ARep...48..522N Altcode: A possible mechanism for the formation of near-polar magnetic spots on some stars with convective envelopes is proposed. The mechanism is based on the idea that the maximum of the dynamo waves that are excited in thin convective shells by the dynamo mechanism is shifted appreciably from the maximum of the magnetic-field sources in the direction of motion of the dynamo wave. If there is no region of super-rotation near the equator for some reason (as a consequence of disruption due to tidal interaction with a companion in a binary system, for example) and the wave of stellar activity propagates toward the poles rather than toward the equator, this maximum will be in the near-polar regions. Title: No magnetic field variation with pulsation phase in the roAp star γ Equulei Authors: Kochukhov, O.; Ryabchikova, T.; Piskunov, N. Bibcode: 2004A&A...415L..13K Altcode: 2004astro.ph..1048K We present an analysis of 210 high-resolution time-resolved spectropolarimetric observations of the roAp star γ Equ obtained over three nights in August and September 2003. Radial velocity variations due to p-mode non-radial pulsations are clearly detected in the lines of rare-earth elements, in particular Pr III, Nd II and Nd III. In contrast, we find absolutely no evidence for the variation of the mean longitudinal magnetic field over the pulsation period in γ Equ at the level of 110-240 G which was recently reported by Leone & Kurtz (\cite{LK03}). Our investigation of the variability of circularly polarized profiles of 13 Nd III lines demonstrates that, at the 3σ confidence level, no magnetic field variation with an amplitude above ≈40-60 G was present in γ Equ during our monitoring of this star. Title: Magnetic Doppler imaging of 53 Camelopardalis in all four Stokes parameters Authors: Kochukhov, O.; Bagnulo, S.; Wade, G. A.; Sangalli, L.; Piskunov, N.; Landstreet, J. D.; Petit, P.; Sigut, T. A. A. Bibcode: 2004A&A...414..613K Altcode: We present the first investigation of the structure of the stellar surface magnetic field using line profiles in all four Stokes parameters. We extract the information about the magnetic field geometry and abundance distributions of the chemically peculiar star 53 Cam by modelling time-series of high-resolution spectropolarimetric observations with the help of a new magnetic Doppler imaging code. This combination of the unique four Stokes parameter data and state-of-the-art magnetic imaging technique makes it possible to infer the stellar magnetic field topology directly from the rotational variability of the Stokes spectra. In the magnetic imaging of 53 Cam we discard the traditional multipolar assumptions about the structure of magnetic fields in Ap stars and explore the stellar magnetic topology without introducing any global a priori constraints on the field structure. The complex magnetic model of 53 Cam derived with our magnetic Doppler imaging method achieves a good fit to the observed intensity, circular and linear polarization profiles of strong magnetically sensitive Fe II spectral lines. Such an agreement between observations and model predictions was not possible with any earlier multipolar magnetic models, based on modelling Stokes I spectra and fitting surface averaged magnetic observables (e.g., longitudinal field, magnetic field modulus, etc.). Furthermore, we demonstrate that even the direct inversion of the four Stokes parameters of 53 Cam assuming a low-order multipolar magnetic geometry is incapable of achieving an adequate fit to our spectropolarimetric observations. Thus, as a main result of our investigation, we discover that the magnetic field topology of 53 Cam is considerably more complex than any low-order multipolar expansion, raising a general question about the validity of the multipolar assumption in the studies of magnetic field structures of Ap stars. In addition to the analysis of the magnetic field of 53 Cam, we reconstruct surface abundance distributions of Si, Ca, Ti, Fe and Nd. These abundance maps confirm results of the previous studies of 53 Cam, in particular dramatic antiphase variation of Ca and Ti abundances.

Based on observations obtained with the Bernard Lyot telescope of the Pic du Midi Observatory and Isaac Newton Telescope of the La Palma Observatory. Title: He and Si surface inhomogeneities of four Bp variable stars Authors: Briquet, M.; Aerts, C.; Lüftinger, T.; De Cat, P.; Piskunov, N. E.; Scuflaire, R. Bibcode: 2004A&A...413..273B Altcode: We present ground-based multi-colour Geneva photometry and high-resolution spectra of four variable B-type stars: HD 105382, HD 131120, HD 138769 and HD 55522. All sets of data reveal monoperiodic stars. A comparison of moment variations of two spectral lines, one silicon line and one helium line, allows us to exclude the pulsation model as being the cause of the observed variability of the four stars. We therefore delete the four stars from the list of candidate slowly pulsating B stars. We attribute the line-profile variations to non-homogeneous distributions of elements on the stellar surface and we derive abundance maps for both elements on the stellar surface by means of the Doppler Imaging technique. We confirm HD 131120 to be a He-weak star and we classify HD 105382, HD 138769 as new He-weak stars. HD 55522 has the solar helium abundance but the mean abundance value of He varies by 0.8 dex during the stellar rotation. For HD 131120 and HD 105382, helium is enhanced in regions of the stellar surface where silicon is depleted and depleted in regions where silicon is enhanced.

Based on observations obtained with the Swiss photometric telescope and ESO's CAT/CES telescope, both situated at La Silla, Chile.

Appendix A, Tables 1 and 2 and Figs. 9, 11, 13 are only available in electronic form at http://www.edpsciences.org Title: Balmer Lines and Effective Temperatures in Cool Stars Authors: Barklem, P. S.; Stempels, H. C.; Kochukhov, O.; Piskunov, N.; O'Mara, B. J. Bibcode: 2003csss...12.1103B Altcode: Theoretical work on the self-broadening of Balmer lines by us predicts a large impact on model profiles, and therefore effective temperature determinations, particularly in metal-poor stars. We present initial results of the application to observations of a sample of cool dwarf stars. The effective temperatures determined for our sample show much improved agreement with the infra-red flux method results in the literature when compared with analysis using the previously available broadening theory. Title: Probing Magnetospheric Infall onto CTTS with Time-resolved Veiling Measurements. Authors: Stempels, H. C.; Piskunov, N. Bibcode: 2003csss...12..735S Altcode: We show that time-resolved veiling measurements over a large wavelength range can probe individual accretion events onto Classical T Tauri Stars (CTTS). We demonstrate two methods of measuring veiling. Using these measurements, we model CTTS spectra as a superposition of two components representing stellar and accretion emission. The simple but functional method allows us to estimate the temperature of the accretion shock and the relative surface area of the accretion regions on the star. We apply this method to a series of spectra of the CTTS RU Lupi and present our first results. Title: The photosphere and veiling spectrum of T Tauri stars Authors: Stempels, H. C.; Piskunov, N. Bibcode: 2003A&A...408..693S Altcode: Using recent high signal-to-noise and high spectral resolution (R ~ 60 000) observations with VLT/UVES, we have analysed the photosphere and veiling spectrum of five T Tauri stars. With a grid of 1-dimensional plane-parallel hydrostatic model atmospheres from the MARCS consortium we have determined their atmospheric properties, calculated synthetic spectra and determined the spectrum of the veiling continuum. Our analysis of the veiling spectrum supports the view that veiling can be represented by a combination of continuum sources. However, for the most strongly accreting stars we find a broad region around 5300 Å where the derived level of veiling is consistently higher than expected from continuum sources.

Based on observations collected at the European Southern Observatory, Chile (proposal 65.I-0404). Title: Doppler Imaging of the Ap star epsilon Ursae Majoris: Ca, Cr, Fe, Mg, Mn, Ti, Sr Authors: Lueftinger, T.; Kuschnig, R.; Piskunov, N. E.; Weiss, W. W. Bibcode: 2003A&A...406.1033L Altcode: The surface abundance structure of seven elements of the brightest chemically peculiar A-type star, epsilon Ursae Majoris (epsilon UMa, HD 112185, HR 4905) has been determined. Cr, Fe and, Mn are enhanced at the magnetic polar region of epsilon UMa while they avoid the magnetic equator. Sr seems to behave like Cr, Fe, and Mn, but is concentrated only at one of the two magnetic poles. Ti, in contrast, is accumulated at the magnetic equator and is depleted where Cr and Fe are accumulated, in accordance with theoretical predictions. Mg and Ca do not correlate with the distribution of Cr, Fe, Mn, and Sr or with Ti. The surface distribution of Mn, Sr, Ti, and Mg was determined for the first time for this star. A Doppler Imaging code was used that allows to analyse elements present in complex spectral line blends and thus to increase significantly the potential to map more elements. We compare our Cr and Fe distributions to already published maps. The high consistency of our results, based on different observations and Doppler Imaging codes, proves the reliability of the different methods. Title: PEPSI spectro-polarimeter for the LBT Authors: Strassmeier, Klaus G.; Hofmann, Axel; Woche, Manfred F.; Rice, John B.; Keller, Christoph U.; Piskunov, N. E.; Pallavicini, Roberto Bibcode: 2003SPIE.4843..180S Altcode: PEPSI (Postham Echelle Polarimetric and Spectroscopic Instrument) is to use the unique feature of the LBT and its powerful double mirror configuration to provide high and extremely high spectral resolution full-Stokes four-vector spectra in the wavelength range 450-1100nm. For the given aperture of 8.4m in single mirror mode and 11.8m in double mirror mode, and at a spectral resolution of 40,000-300,000 as designed for the fiber-fed Echelle spectrograph, a polarimetric accuracy between 10-4 and 10-2 can be reached for targets with visual magnitudes of up to 17th magnitude. A polarimetric accuracy better than 10-4 can only be reached for either targets brighter than approximately 10th magnitude together wiht a substantial trade-off wiht the spectral resolution or with spectrum deconvolution techniques. At 10-2, however, we will be able to observe the brightest AGNs down to 17th magnitude. Title: Round Table Summary: Radiative Transfer Problems Authors: Piskunov, N. Bibcode: 2003IAUS..210..107P Altcode: No abstract at ADS Title: Doppler and Zeeman Doppler Imaging of roAp Stars Authors: Lueftinger, T.; Ryabchikova, T. A.; Weiss, W. W.; Khochukhov, O.; Piskunov, N. E.; Kuschnig, R.; Wade, G. A. Bibcode: 2003ASPC..305...92L Altcode: 2003mfob.conf...92L No abstract at ADS Title: Modelling of Stellar Atmospheres Authors: Piskunov, N.; Weiss, W. W.; Gray, D. F. Bibcode: 2003IAUS..210.....P Altcode: No abstract at ADS Title: Magnetic Doppler Imaging of Chemically Peculiar Stars Authors: Kochukhov, O.; Piskunov, N.; Bagnulo, S.; Landstreet, J. D.; Sigut, T. A. A.; Petit, P.; Wade, G. A. Bibcode: 2003ASPC..307..549K Altcode: No abstract at ADS Title: Parametric Resonance and Magnetic Activity in Close Binary Systems Authors: Sokoloff, D.; Piskunov, N. Bibcode: 2003IAUS..210P.E43S Altcode: No abstract at ADS Title: Hydrogen Balmer Lines as Probes of Stellar Atmospheres Authors: Barklem, P. S.; Piskunov, N. Bibcode: 2003IAUS..210P.E28B Altcode: No abstract at ADS Title: Magnetic Doppler Imaging of Early-Type Stars Authors: Piskunov, N. E.; Kochukhov, O. Bibcode: 2003ASPC..305...83P Altcode: 2003mfob.conf...83P No abstract at ADS Title: The Influence of the Global Magnetic Field Evolution on the Structure of Atmospheres of Early-Type Stars Authors: Valyavin, G.; Kochukhov, O.; Piskunov, N. Bibcode: 2003IAUS..210P.A14V Altcode: No abstract at ADS Title: Magnetic Doppler Imaging of Solar-type Stars Authors: Piskunov, N.; Kochukhov, O. Bibcode: 2003ASPC..307..539P Altcode: No abstract at ADS Title: Tools and Methods for Abundance Analysis Authors: Knoglinger, P.; Nesvacil, N.; Kupka, F.; Mittermayer, P.; Piskunov, N.; Weiss, W. W.; Bruntt, H. Bibcode: 2003IAUS..210P.E66K Altcode: No abstract at ADS Title: Nonaxisymmetric cool spot distributions and dynamo action in close binaries Authors: Moss, D.; Piskunov, N.; Sokoloff, D. Bibcode: 2002A&A...396..885M Altcode: We investigate the nonaxisymmetric magnetic field distribution in the components of close binary systems, generated by a stellar dynamo with a nonaxisymmetric distribution of the alpha -coefficient, proportional to the mean helicity of the convective motions in the stellar convective envelope. The nonaxisymmetry of alpha is assumed to be connected with interaction with the binary companion, i.e. the reflection effect and tidal interaction. The degree of asymmetry is estimated from the known parameters of ER Vulpeculae, an active RS CVn-type star. We demonstrate that the synchronization of rotation and orbital motion of ER Vulpeculae due to tidal interaction is sufficient to allow nonaxisymmetric magnetic structures to survive in the presence of smoothing by differential rotation. The dynamo driven nonaxisymmetric magnetic structures are usually steady in the reference frame connected with the alpha -spot. However, we found a resonant excitation of an oscillatory, strongly nonaxisymmetric, configuration, driven by the joint action of the alpha -effect and differential rotation. The magnetic structures obtained are predominantly manifested on the stellar surface in the form of spots of radial magnetic field. Their form and size are similar to the form and size of cool spots observed on the surfaces of both components of ER Vulpeculae, and their displacements from the alpha -spots are comparable to that of the observed cool spots from the hot spots connected with the reflection effect. Possible relevant observations are discussed. Title: Spectroscopy of T Tauri stars with UVES. Observations and analysis of RU Lup Authors: Stempels, H. C.; Piskunov, N. Bibcode: 2002A&A...391..595S Altcode: We present the first results of our observations of classical T Tauri Stars with UVES/VLT. The data consists of high signal-to-noise (ge 150) and high spectral resolution (R ~ 60 000) spectra. A large simultaneous wavelength coverage throughout most of the visible spectrum and comparatively short integration times allow us to study variability on short time-scales, using a number of diagnostics reflecting a wide range of physical processes. In particular we concentrate on the properties and geometry of the accretion process in the strongly accreting and highly variable CTTS RU Lup. We use the evolution of the level of veiling, the shapes of absorption and emission lines, and correlations between these diagnostics, to make new measurements of the fundamental stellar parameters as well as constraints on the accretion process and its geometry. We also derive the shortest time-scale of incoherent changes, which has implications for the nature of the accretion process in RU Lup. Based on observations collected at the European Southern Observatory, Chile (proposal 65.I-0404). Title: Swing excitation and magnetic activity in close binary systems Authors: Sokoloff, D.; Piskunov, N. Bibcode: 2002MNRAS.334..925S Altcode: Parametric resonance between the perturbation of a stellar convective zone affected by a companion of a close binary system and non-axisymmetric dynamo modes can play an important role in close binary systems. This process in combination with the previously suggested α2-mechanism is probably responsible for strongly non-axisymmetric magnetic activity observed in several close binaries. The conditions required for swing excitation to occur in such systems are directly related to the status of rotational synchronization between the orbital motion and rotation of the star, which can be used as a tool to discover such objects. One potential candidate - an active RS CVn-type star ER Vulpeculae - shows indications of the swing excitation. Title: Doppler Imaging of stellar magnetic fields. III. Abundance distribution and magnetic field geometry of alpha 2 CVn Authors: Kochukhov, O.; Piskunov, N.; Ilyin, I.; Ilyina, S.; Tuominen, I. Bibcode: 2002A&A...389..420K Altcode: We used the new magnetic Doppler Imaging code to reconstruct the magnetic field geometry and surface abundance distributions for the classical magnetic CP star alpha 2 CVn. High-resolution spectropolarimetric observations in the Stokes I and V parameters were collected with the SOFIN échelle spectrograph at the Nordic Optical Telescope. This superb observational material in combination with the advanced modelling technique allowed to achieve the first simultaneous self-consistent mapping of the vector magnetic field and the abundance distributions of six chemical elements. In recovering the stellar magnetic distribution no prior assumptions about the field geometry or strength were made. Instead, we restricted possible solutions of the inverse problem by means of the multipolar regularization method which searches for the field map close to a general non-axisymmetric multipolar configuration but allows departures from this geometry if that is required by the observational data. We found that the magnetic field of alpha 2 CVn/ is dominated by a dipolar component and has a minor quadrupole contribution. The surface distributions of the chemical species form symmetric patterns which closely follow the magnetic geometry. This discovery constitutes one of the first direct observational constraints on the horizontal diffusion processes acting in the upper envelope of a strongly magnetized stellar atmosphere. In addition to the extensive magnetic Doppler Imaging analysis, we derived new accurate estimates of the atmospheric parameters and basic physical properties of alpha 2 CVn/ using the energy distribution, hydrogen line profiles and the recent Hipparchos parallax. Based on observations obtained with the Nordic Optical Telescope (NOT) and Isaac Newton Telescope (INT), La Palma, Spain. Title: Spectropolarimetry of starspots Authors: Piskunov, N. Bibcode: 2002AN....323..257P Altcode: We use the simulations of Stokes profiles for active late-type stars in order to assess the requirements to the observations and select the best observing strategy for these objects. The synthetic spectropolarimetry was computed using models of magnetic fields distribution for several rotational phases throughout the activity cycle. The simulations show that cyclic variations of the polarization profiles are more systematic and easier to observe and that averaging over single rotation periods may be used to increase the signal-to-noise ratio. Title: Doppler Imaging of stellar magnetic fields. II. Numerical experiments Authors: Kochukhov, O.; Piskunov, N. Bibcode: 2002A&A...388..868K Altcode: We present numerical experiments designed to evaluate the performance of the new Magnetic Doppler Imaging (MDI) code INVERS10. Numerous test runs demonstrate what can be achieved with the MDI method and allow assessment of the systematic errors that can cause distortions of the maps. Our numerical experiments showed that given high-resolution observations in four Stokes parameters the code is capable of reconstructing abundance and magnetic field vector distributions simultaneously and without any prior assumptions about the magnetic field geometry. At the same time we found that in order to achieve reliable reconstruction using only circular polarization data it is necessary to impose additional constraints on the possible structure of the magnetic field. Numerical tests also reveal surprisingly different properties of the MDI maps from conventional scalar maps which we attribute to the complex relation between the orientation of the field and the polarization signal. We conclude that the information about the field is primarily extracted from the changes in magnetic orientation due to rotation rather than from the Doppler shifts critical for scalar Doppler Imaging maps making it possible to apply the MDI to even very slow rotators. Title: New algorithms for reducing cross-dispersed echelle spectra Authors: Piskunov, N. E.; Valenti, J. A. Bibcode: 2002A&A...385.1095P Altcode: We describe advanced image processing algorithms, implemented in a data analysis package for conventional and cross-dispersed echelle spectra. Comparisons with results from other packages illustrate the outstanding quality of the new REDUCE package, particularly in terms of resulting noise level and treatment of CCD defects and cosmic ray spikes. REDUCE can be adapted relatively easily to handle a variety of instrument types, including spectrographs with prism or grating cross-dispersers, possibly fed by a fiber or image slicer, etc. In addition to reduced spectra, an accurate spatial profile is recovered, providing valuable information about the spectrograph PSF and simplifying scattered light corrections. Based on data obtained with the VLT UVES and SAAO Giraffe spectrometers. Title: Detailed analysis of Balmer lines in cool dwarf stars Authors: Barklem, P. S.; Stempels, H. C.; Allende Prieto, C.; Kochukhov, O. P.; Piskunov, N.; O'Mara, B. J. Bibcode: 2002A&A...385..951B Altcode: 2002astro.ph..1537B An analysis of Hα and Hβ spectra in a sample of 30 cool dwarf and subgiant stars is presented using MARCS model atmospheres based on the most recent calculations of the line opacities. A detailed quantitative comparison of the solar flux spectra with model spectra shows that Balmer line profile shapes, and therefore the temperature structure in the line formation region, are best represented under the mixing length theory by any combination of a low mixing-length parameter alpha and a low convective structure parameter y. A slightly lower effective temperature is obtained for the sun than the accepted value, which we attribute to errors in models and line opacities. The programme stars span temperatures from 4800 to 7100 K and include a small number of population II stars. Effective temperatures have been derived using a quantitative fitting method with a detailed error analysis. Our temperatures find good agreement with those from the Infrared Flux Method (IRFM) near solar metallicity but show differences at low metallicity where the two available IRFM determinations themselves are in disagreement. Comparison with recent temperature determinations using Balmer lines by Fuhrmann (\cite{fuhrmann98, fuhrmann00}), who employed a different description of the wing absorption due to self-broadening, does not show the large differences predicted by Barklem et al. (\cite{bpo:hyd}). In fact, perhaps fortuitously, reasonable agreement is found near solar metallicity, while we find significantly cooler temperatures for low metallicity stars of around solar temperature. Based on observations collected at the Isaac Newton Telescope, La Palma, Spain, and McDonald Observatory, Texas, USA. Title: Abundance stratification and pulsation in the atmosphere of the roAp star boldmath gamma Equulei Authors: Ryabchikova, T.; Piskunov, N.; Kochukhov, O.; Tsymbal, V.; Mittermayer, P.; Weiss, W. W. Bibcode: 2002A&A...384..545R Altcode: We present the evidence for abundance stratification in the atmosphere of the rapidly oscillating Ap star gamma Equ. Ca, Cr, Fe, Ba, Si, Na seem to be overabundant in deeper atmospheric layers, but normal to underabundant in the upper layers with a transition in the typical line forming region of -1.5<log tau 5000<-0.5. This stratification profile agrees well with diffusion theory for Ca and Cr, developed for cool magnetic stars with a weak mass loss of {~}2.5*E-15 Msun yr-1. Pr and Nd from the rare earth elements have an opposite profile. Their abundance is more than 6 dex higher above log tau 5000 ~ -8.0 than in the deeper atmospheric layers. We further discuss the implications of abundance stratification in the context of radial velocity amplitudes and phases observed by Kochukhov & Ryabchikova (2001) for a variety of spectral lines and elements using high spectral and time resolved, high S/N observations. Based on observations obtained at the European Southern Observatory (La Silla, Chile), and the South African Astronomical Observatory. Title: Spectroscopy of Rapidly Oscillating Ap Stars Authors: Weiss, W. W.; Ryabchikova, T. A.; Savanov, I.; Piskunov, N.; Tsymbal, V.; Mittermayer, P.; Martinez, P.; Kochukhov, O.; Nesvacil, N. Bibcode: 2002ASPC..259..280W Altcode: 2002IAUCo.185..280W; 2002rnpp.conf..280W No abstract at ADS Title: Doppler Imaging of stellar magnetic fields. I. Techniques Authors: Piskunov, N.; Kochukhov, O. Bibcode: 2002A&A...381..736P Altcode: We describe our latest Magnetic Doppler Imaging (MDI) code capable of simultaneously reconstructing the magnetic field vector and chemical composition distribution over the stellar surface. Input data consists of polarization measurements in the line profiles and the reconstruction is performed by solving the regularized inverse problem. The code incorporates the latest developments in the radiative transfer, the optimization and parallel computing techniques. We have also developed a new regularization method that allows application of our MDI code to incomplete data sets (e.g. only intensity and circular polarization) by restricting possible configurations of the field. Numerical experiments to be presented in a forthcoming paper demonstrate what can be achieved with MDI and allow studying of systematic errors that can cause serious distortions of the maps. Title: VizieR Online Data Catalog: LTE spectrum synthesis in magnetic atmospheres (Wade+, 2001) Authors: Wade, G. A.; Bagnulo, S.; Kochukhov, O.; Landstreet, J. D.; Piskunov, N.; Stift, M. J. Bibcode: 2001yCat..33740265W Altcode: Files table4.dat contain calculated Stokes IQUV local line profiles of Fe II 4923.9 shown in Fig. 4 of this paper. Profile sets are provided for 0.1, 5 and 20kG magnetic fields, with vector orientation ψ=40°, φ=0°, disc centre and epsfe=4.6. (3 data files). Title: LTE spectrum synthesis in magnetic stellar atmospheres. The interagreement of three independent polarised radiative transfer codes Authors: Wade, G. A.; Bagnulo, S.; Kochukhov, O.; Landstreet, J. D.; Piskunov, N.; Stift, M. J. Bibcode: 2001A&A...374..265W Altcode: With the aim of establishing a benchmark for the detailed calculation of the polarised line profiles of magnetic stars, we describe an intercomparison of LTE Stokes profiles calculated using three independent, state-of-the-art magnetic spectrum synthesis codes: Cossam, Invers10 and Zeeman2. We find, upon establishing a homogeneous basis for the calculations (identical definitions of the Stokes parameters and the magnetic and stellar reference frames, identical input model stellar atmosphere, identical input atomic data, and identical chemical element abundances and magnetic field distributions), that local and disc-integrated Stokes IQUV profiles of Fe II lambda 4923.9 calculated using the three codes agree very well. For the illustrative case of disc-integrated profiles calculated for abundance log nFe/ntot=-4.60, dipole magnetic field intensity Bd=5 kG, and projected rotational velocity v_esin i=20 km s-1, Stokes I profiles (depth ~ 40% of the continuum flux Ic) agree to within about 0.05% rms of Ic, Stokes V profiles (full amplitude ~ 10%) to within about 0.02% rms of Ic, and Stokes Q and U profiles (full amplitudes ~ 2%) at the sub-0.01% rms level. These differences are sufficiently small so as to allow for congruent interpretation of the best spectropolarimetric data available, as well as for any data likely to become available during the near future. This indicates that uncertainties in modeling Stokes profiles result overwhelmingly from uncertainties in input atomic and physical data, especially the state and structure of model stellar atmospheres. Title: Formation of Fe X-Fe XIV coronal lines in the accretion shock of T Tauri stars Authors: Lamzin, S. A.; Stempels, H. C.; Piskunov, N. E. Bibcode: 2001A&A...369..965L Altcode: Specific intensities of the strongest Fe x-Fe xiV\ coronal lines were calculated in the framework of our accretion shock model (Lamzin \cite{Lamzin1998}). These lines are formed in a region immediately behind the front of the accretion shock, therefore, the gas velocity in the line formation region is close to 1/4 of the infall velocity. It appears that iron coronal lines in the optical band (e.g. [Fe x] 6376 Å and [Fe xiV] 5304 Å) are too weak to be observed in spectra of T Tauri stars, but the UV lines (e.g. [Fe xi] 1467 Å and [Fe xiI] 1349 Å) can possibly be detected. In agreement with our calculations we could not detect the [Fe x] 6376 Å and [Fe xiV] 5304 Å lines in low noise UVES spectra of RU Lup where the accretion luminosity is ten times larger than the bolometric luminosity of the underlying star. At the same time we detected the [Fe xi] 1467 Å line in a HST/GHRS spectrum of RY Tau which suggests that the accretion rate of the star in its quiescent state is ~2 10-9 M_sun/yr. As a byproduct of the study we found that for RY Tau the interstellar extinction coefficient A_V is closer to 0.5{m} than to 1.0{m}. For DF Tau, the observed upper limit for the flux of the [Fe xiI] 1349 Å line in HST/GHRS spectra is in agreement with an accretion rate of 2 10-9 M_sun/yr as found by Lamzin et al. (\cite{Lamzin2000}). As a critical test of our calculations we predict that the [Fe xi] 1467 Å line in the spectrum of RU Lupi should be relatively strong: we expect the flux to be near 10-15 erg/s/cm2. Title: The core-wing anomaly of cool Ap stars. Abnormal Balmer Profiles Authors: Cowley, C. R.; Hubrig, S.; Ryabchikova, T. A.; Mathys, G.; Piskunov, N.; Mittermayer, P. Bibcode: 2001A&A...367..939C Altcode: 2000astro.ph.12102C The profiles of Hα in a number of cool Ap stars are anomalous. Broad wings, indicative of temperatures in the range 7000-8000 K end abruptly in narrow cores. The widths of these cores are compatible with those of dwarfs with temperatures of 6000 K or lower. This profile has been known for Przybylski's star, but it is seen in other cool Ap stars. The Hβ profile in several of these stars shows a similar core-wing anomaly (CWA). In Przybylski's star, the CWA is probably present at higher Balmer members. We are unable to account for these profiles within the context of LTE and normal dwarf atmospheres. We conclude that the atmospheres of these stars are not ``normal''. This is contrary to a notion that has long been held. Based on observations obtained at the European Southern Observatory, Paranal, Chile (ESO programme No. 65.I-0644) and the South African Astronomical Observatory (SAAO).} Title: Model Atmospheres with Individualized Abundances Authors: Piskunov, N.; Kupka, F. Bibcode: 2001ApJ...547.1040P Altcode: We describe a new method for computing opacity distribution functions (ODFs) for model atmosphere calculations. The method is tailored to model the atmospheres of individual stars on a modern workstation. Our goal is the computation of model atmospheres for stars with abundances significantly different from the solar or scaled solar composition typically used for grid calculations. As a consistency test, we show that the new procedure is able to reproduce the ODFs and existing model atmospheres for solar abundances, and we describe models for stars with peculiar abundances. We demonstrate that while mild chemical peculiarities can be well represented by scaled solar models, the extreme cases result in a very different atmospheric structure with no analogs in scaled solar grids. Such a structure influences the emerging spectrum as is clearly seen both in the observed flux distribution and in the line ratios that are much better represented by the new models. Title: Magnetic Doppler Imaging of α CVn Authors: Kochukhov, O.; Piskunov, N.; Ilyin, I.; Ilyina, S.; Tuominen, I. Bibcode: 2001ASPC..248..321K Altcode: 2001mfah.conf..321K No abstract at ADS Title: Chemical Stratification in Magnetic Ap Stars Authors: Wade, G. A.; Ryabchikova, T. A.; Bagnulo, S.; Piskunov, N. Bibcode: 2001ASPC..248..373W Altcode: 2001mfah.conf..373W No abstract at ADS Title: Magnetic Doppler Imaging of CP Stars Authors: Piskunov, N. Bibcode: 2001ASPC..248..293P Altcode: 2001mfah.conf..293P No abstract at ADS Title: The Search and Modeling of Magnetic Fields on M dwarfs (CD-ROM Directory: contribs/kochuk) Authors: Kochukhov, O. P.; Piskunov, N. E.; Valenti, J. A.; Johns-Krull, C. M. Bibcode: 2001ASPC..223..985K Altcode: 2001csss...11..985K No abstract at ADS Title: Using FeH to Measure Magnetic Fields on Cool Stars and Brown Dwarfs (CD-ROM Directory: contribs/valenti) Authors: Valenti, J. A.; Johns-Krull, C. M.; Piskunov, N. E. Bibcode: 2001ASPC..223.1579V Altcode: 2001csss...11.1579V No abstract at ADS Title: Recent Developments of the VALD Database (CD-ROM Directory: contribs/stempels) Authors: Stempels, H. C.; Piskunov, N.; Barklem, P. S. Bibcode: 2001ASPC..223..878S Altcode: 2001csss...11..878S No abstract at ADS Title: Doppler Imaging of Eclipsing Binary Systems ER Vul and TY Pyx (CD-ROM Directory: contribs/piskunov) Authors: Piskunov, N.; Vincent, A.; Duemmler, R.; Ilyin, I.; Tuominen, I. Bibcode: 2001ASPC..223.1285P Altcode: 2001csss...11.1285P No abstract at ADS Title: Magnetic Doppler Imaging of Chemically Peculiar Stars Authors: Piskunov, N.; Kochukhov, O. Bibcode: 2001LNP...573..238P Altcode: 2001astr.conf..238P We present the results of numerical experiments and real applications of our new Magnetic Doppler Imaging code INVERS10. The code is capable of simultaneously reconstructing the surface distribution of magnetic field vectors and one chemical element from a time sequence of line profiles measured in four Stokes parameters. The application of the code to a well studied magnetic Ap star 2 °CVn recovered a field distribution, resembling an oblique dipole with the strength and orientation consistent with those derived with other techniques. Title: Time-Resolved Spectroscopy of the roAp Star γ Equ Authors: Kochukhov, O.; Ryabchikova, T.; Piskunov, N. Bibcode: 2001ASPC..248..341K Altcode: 2001mfah.conf..341K No abstract at ADS Title: Hydrogen Line Formation in Cool Stars (CD-ROM Directory: contribs/barklem1) Authors: Barklem, P. S.; Kochukhov, O.; Piskunov, N.; O'Mara, B. J.; Stempels, H. C. Bibcode: 2001ASPC..223..766B Altcode: 2001csss...11..766B No abstract at ADS Title: New Measurements of T Tauri Magnetic Fields: Testing Magnetospheric Accretion Authors: Johns-Krull, C. M.; Valenti, J. A.; Piskunov, N. E.; Saar, S. H.; Hatzes, A. P. Bibcode: 2001ASPC..248..527J Altcode: 2001mfah.conf..527J No abstract at ADS Title: The Search and Modelling of Magnetic Fields on M Dwarfs Authors: Kochukhov, O.; Piskunov, N.; Valenti, J.; Johns-Krull, C. Bibcode: 2001ASPC..248..219K Altcode: 2001mfah.conf..219K No abstract at ADS Title: Self-broadening in Balmer line wing formation in stellar atmospheres Authors: Barklem, P. S.; Piskunov, N.; O'Mara, B. J. Bibcode: 2000A&A...363.1091B Altcode: 2000astro.ph.10022B Details of a theory of self-broadening of hydrogen lines are presented. The main features of the new theory are that the dispersive-inductive components of the interaction (van der Waals forces) have been included, and the resonance components have been computed by perturbation theory without the use of the multipole expansion. The theory is applied to lower Balmer lines and the theoretical and observational impact of the new broadening theory is examined. It is shown that this theory leads to considerable differences in the predicted line profiles in cool stars when compared with previous theories which include only resonance interactions. In particular, the effect is found to be very important in metal poor stars. The theory provides a natural explanation for the behaviour of effective temperatures derived from Balmer lines by others using a theory which includes only resonance broadening. When applied to Balmer lines in the solar spectrum the theory predicts an improved agreement between observed and computed profiles for models which also match limb darkening curves and rules out a model which does not. However significant discrepancies still remain which could be due to inadequacies in our theory or the atmospheric model or both. Title: Abundance analysis of roAp stars. V. HD 166473 Authors: Gelbmann, M.; Ryabchikova, T.; Weiss, W. W.; Piskunov, N.; Kupka, F.; Mathys, G. Bibcode: 2000A&A...356..200G Altcode: This fifth paper in a sequence on abundance analyses of roAp stars features several improvements and complements over the previous investigations: i. The new VALD-2 atomic data base was used which significantly improves the analysis of C, N, O, and rare earth elements (REE) and in particular includes also some doubly ionized REE species. ii. An individual opacity distribution function table was generated for a successful synthesis of photometric indices of this very peculiar star. iii. The influence of a (rather strong) magnetic field on abundance determinations is studied and presented for 30 elements. iv. Our investigation of 33 elements (45 ions) is the hitherto most complete chemical analysis of a chemically peculiar star, using modern tools. Similar to the four roAp stars analysed by us so far (alpha Cir: Kupka et al. 1996, HD 203932: Gelbmann et al. 1997, gamma Equ: Ryabchikova et al. 1997a, and HD 24712: Ryabchikova et al. 1997b) we find nearly solar abundances of Fe and Ni, and a definite overabundance of Cr and especially Co. Rare earth elements have large overabundances, whereas C and O are underabundant relative to the Sun. This pattern seems to be a common property of the chemically peculiar (CP2, Ap) stars. A new and most striking result is the discovery of the anomalous line strengths of the second ions of REE resulting in an abundance increase of up to +1.5 dex, compared to values obtained from lines of the first ions. This anomaly is not found in non-roAp and ``normal'' stars. Based on observations obtained at the European Southern Observatory (La Silla, Chile) Title: A list of data for the broadening of metallic lines by neutral hydrogen collisions Authors: Barklem, P. S.; Piskunov, N.; O'Mara, B. J. Bibcode: 2000A&AS..142..467B Altcode: A list of data for the broadening by neutral hydrogen collisions of many astrophysically important spectral lines, which has been incorporated into the Vienna Atomic Line Database (VALD), is presented. Data for lines of neutral atoms are interpolated from the tabulated data of Anstee & O'Mara (\cite{ao:sp}), Barklem & O'Mara (\cite{bo:pd}), and Barklem et al. (\cite{bor:df}). Data for lines of singly ionised atoms are compiled from the calculations by Barklem & O'Mara (\cite{bo:ion1,bo:ion2}). The list at present contains data for 4891 lines between 2300 and 13000 Ä of elements from Li to Ni. We examine the statistical impact of the new theory by comparison with the previously available data. We also demonstrate the direct effect on spectral synthesis calculations. Table~1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via anonymous ftp to ftp.astro.uu.se/pub/Spectra/barklem/hlist/ Title: VizieR Online Data Catalog: Broadening of metallic lines by H collisions (Barklem+ 2000) Authors: Barklem, P. S.; Piskunov, N.; O'Mara, B. J. Bibcode: 2000yCat..41420467B Altcode: File table1 is a list of theoretical data for the broadening of metallic lines by collisions with neutral hydrogen atoms. The list contains data for 4891 spectral lines between 2300 and 13000 Angstroms of elements from Li to Ni. (1 data file). Title: Self broadening of hydrogen lines: initial results Authors: Barklem, P. S.; Piskunov, N.; O'Mara, B. J. Bibcode: 2000A&A...355L...5B Altcode: For the first time broadening by both resonance and dispersive-inductive interactions with H-atoms are included in the formation of Balmer lines in cool stars, without the use of a multipole expansion. Comparison of synthetic profiles with observed profiles for the Sun and two late F dwarfs shows that this improvement in broadening theory accounts for some of the problems found in previous work. It is anticipated that planned future developments in the theory of self broadening will lead to further improve ments in the modelling of cool star atmospheres. Title: VALD-2 -- The New Vienna Atomic Line Database Authors: Kupka, F. G.; Ryabchikova, T. A.; Piskunov, N. E.; Stempels, H. C.; Weiss, W. W. Bibcode: 2000BaltA...9..590K Altcode: 2000OAst....9..590K We provide a brief outline of the concepts and facilities of the Vienna Atomic Line DataBase in its new version 2. A summary of contents and recommendations how to use the VALD-2 are given. We conclude by a few applications planned for future releases of VALD. Title: Spectral and polarimetric observations of the star HD 37022 (θ1 Ori C) Authors: Kudryavtsev, D. O.; Piskunov, N. E.; Romanyuk, I. I.; Chountonov, G. A.; Shtol', V. G. Bibcode: 2000mfcp.proc...64K Altcode: HD 37022 (θ1 Ori C) is a young star of spectral type O7 V, the brightest star in the Trapezium of the Orion Nebulae (M42). It has a synchronous spectral variability in the optical, ultraviolet and X--rays regions with a period P=15.422d. For the explanation of this variability many authors suggest a magnetic rotator modulating the stellar wind. During 1996-97 we made a series of observations of θ1 Ori C at the 6 m telescope of SAO RAS, using the circular polarization analyzer and hydrogen--line magnetometer, to make sure that a magnetic field exists in this star. In this paper we publish the results of measurements of the effective magnetic field and Stokes parameters. The value of the effective magnetic field is within the measurement errors and apparently not more than 500G. Title: The new magnetic Doppler imaging code Authors: Piskunov, N. Bibcode: 2000mfcp.proc...96P Altcode: In this paper we describe a new Magnetic Doppler Imaging (MDI) code INVERS10 designed to reconstruct magnetic fields on the surfaces of CP stars. The code is based on a state-of-the-art radiative transfer solver and efficient minimization technique. It is aimed at multi-processor calculations. This new tool is capable of reconstructing the distribution of magnetic field vectors and abundance of one chemical element from a time sequence of four Stokes parameters, observed with sufficient time and spectral resolution. No assumptions about field geometry (e.g. multipolar, radial etc.) are necessary. In addition, INVERS10 is capable of simulating the observed profiles for a given field geometry and abundance distribution. We also show some results of numerical experiments and discuss future applications of the new code. Title: The Three-dimensional Structure of the Warm Local Interstellar Medium. I. Methodology Authors: Linsky, Jeffrey L.; Redfield, Seth; Wood, Brian E.; Piskunov, Nikolai Bibcode: 2000ApJ...528..756L Altcode: In this first in a series of papers, we develop a methodology for constructing three-dimensional models of the local interstellar cloud (LIC) and adjacent warm clouds in the local interstellar medium (LISM). Our models are based on the column density of neutral hydrogen gas (NHI) inferred primarily from measurements of the deuterium column density toward nearby stars obtained from the analysis of Hubble Space Telescope ultraviolet spectra. We also use values of NHI inferred from spectra of hot white dwarfs and B-type stars obtained by the Extreme Ultraviolet Explorer satellite. These very different methods give consistent results for the three white dwarf stars in common. We assume that along each line of sight all interstellar gas moving with a speed consistent with the LIC velocity vector has a constant density, NHI=0.10 cm-3, and extends from the heliosphere to an edge determined by the value of NHI moving at this speed. A number of stars have velocities and/or depletions that indicate absorption by other warm clouds in their lines of sight. On this basis α Cen A and B and probably also ɛ Ind lie inside the Galactic center (G) cloud, HZ 43 and 31 Com lie inside what we call the north Galactic pole cloud, and β Cet is located inside what we call the south Galactic pole cloud. We show the locations of these clouds in Galactic coordinates. The Sun is located very close to the edge of the LIC toward the Galactic center and the north Galactic pole. The absence of Mg II absorption at the LIC velocity toward α Cen indicates that the distance to the edge of the LIC in this direction is <=0.05 pc and the Sun should leave the LIC and perhaps enter the G cloud in less than 3000 yr. Comparison of LIC and total values of NHI toward pairs of stars with separations between 0.9d and 20° reveals a pattern of good agreement so long as both stars lie within 60 pc of the Sun. Thus the LIC and perhaps also other nearby warm clouds have shapes that are smooth on these angular scales. In our second paper we will therefore fit the shape of the LIC with a set of smooth basis functions (spherical harmonics).

Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Title: The news about Vienna Atomic Line Data Base Authors: Piskunov, N.; Ryabchikova, T. A.; Weiss, W. W. Bibcode: 2000mfcp.proc..194P Altcode: We describe the main changes in the ``Vienna Atomic Line Data Base'' (VALD, Piskunov et al., 1995 and Piskunov, 1996) that have been made since the first release in 1994. The original VALD lists have been complemented with critically evaluated data obtained from experimental measurements and theoretical calculations which are necessary for computing state-of-the-art line opacities in stellar atmospheres, as well as for spectral synthesis for high precision studies (e.g. abundances, radial velocities etc.). In this paper we present new and improved data sets for chemical elements that have already been included in VALD, for new elements and for additional higher ionized species. Software modifications allow remote users of VALD to specify individual extraction parameters as an alternative to the default settings of the VALD team and to have direct control over the quality ranking of line data. The new World--Wide--Web interface provides easy access to all new features. The support for the mirror site permitted opening of two additional VALD servers at Hoddard Space Flight Center (USA) and at Uppsala Astronomical Observatory (Sweden). For proper crediting of all authors of atomic data, VALD now includes a compilation of all publications used to any replies. Title: Multi element Doppler imaging of AP stars. I. He, Mg, Si, CR and Fe surface distribution for CU Virginis Authors: Kuschnig, R.; Ryabchikova, T. A.; Piskunov, N. E.; Weiss, W. W.; Gelbmann, M. J. Bibcode: 1999A&A...348..924K Altcode: We present the distribution of helium, magnesium, silicon, chromium and iron on the surface of the fast rotating magnetic B9p Si star CU Virginis, obtained with a Doppler Imaging inversion code. A clearly defined helium spot coincides with the position of one magnetic pole whereas silicon, chromium and iron accumulate in regions where the magnetic field lines are dominantly horizontal in the stellar atmosphere. The distribution of magnesium is significantly different compared to the other elements. The Hdelta line varies in phase with the helium spot and the magnetic pole and the line profiles can be fitted within the observational errors with model atmospheres of constant {T_eff } of 12500 K, but different surface gravity. We compare our observations with current concepts for diffusion in magnetic chemically peculiar stars and find good agreement. Based on observation obtained at the Observatoire d'Haute-Provence. Title: VALD-2: Progress of the Vienna Atomic Line Data Base Authors: Kupka, F.; Piskunov, N.; Ryabchikova, T. A.; Stempels, H. C.; Weiss, W. W. Bibcode: 1999A&AS..138..119K Altcode: We describe the updated version of the Vienna Atomic Line Data Base (VALD, \cite[Piskunov et al. 1995)]{pis95} which represents a considerable improvement over the first installation from 1994. The original line lists have been complemented with critically evaluated data obtained from experimental measurements and theoretical calculations which are necessary for computing state-of-the-art line opacities in stellar atmospheres, as well as for synthesizing spectra for high precision analyses. In this paper, we present new and improved data sets for neutral species and ions of Si, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ru, Xe, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Re, Pt, Au, Hg, and Pb. For some species data are available in VALD for the first time. We explain our choice of quality rankings by reviewing the literature for the new data and by comparison with source lists included into VALD. For some cases, we produced new line data by weighted averaging of data from different sources with individual error estimates in order to increase the reliability of VALD line lists. Software modifications allow remote users of VALD to specify individual extraction parameters as an alternative to the default settings of the VALD team and to have direct control over the quality ranking of line data. A World-Wide-Web interface is described which provides easy access to all new features. To simplify proper crediting of all authors of atomic data, VALD now includes a compilation of all publications used in each type of reply. Finally, we briefly discuss the future roadmap of VALD developments, including the incorporation of molecular transitions and integration with external data bases. http://www.astro.univie.ac.at/~vald http://www.astro.uu.se/~vald Title: Eu III identification and Eu abundance in CP stars Authors: Ryabchikova, T.; Piskunov, N.; Savanov, I.; Kupka, F.; Malanushenko, V. Bibcode: 1999A&A...343..229R Altcode: We report the first identification of the Eu iii lambda 6666.347 line in optical spectra of CP stars. This line is clearly present in the spectra of HR 4816, 73 Dra, HR 7575, beta CrB, and alpha (2) CVn, while it is marginally present or absent in spectra of the roAp stars (rapidly oscillating Ap stars, cf. Kurtz 1990) alpha Cir, gamma Equ, HD 203932, GZ Lib (33 Lib), and HD 24712. Careful synthetic spectrum calculations for the Eu ii lambda 6645.11 line taking into account hyperfine, isotopic, and magnetic splittings allow us to obtain more accurate Eu abundances in the atmospheres of 9 CP stars. In most cases the derived abundances are significantly lower than the previous results reported for some of the stars based on coarse analysis of the famous blue Eu ii lines. Assuming an ionization balance in the stellar atmospheres we give an estimate of the astrophysical oscillator strength log (gf)=1.18 +/- 0.14 for the Eu iii lambda 6666.347 line. This value is obtained without taking into account a possible hyperfine-splitting which is unknown for this Eu iii line. We also provide astrophysical gf-values for Eu iii lambda lambda 7221.838, 7225.151, and 8079.071. Title: Study of Delta and Roper resonances excitation in light nuclei induced reactions Authors: Strokovsky, E. A.; Azhgirey, L. S.; Malinina, L. V.; Piskunov, N. M.; Sitnik, I. M.; Boivin, M.; Hennino, T.; Kunne, R.; Kagarlis, M.; Radvanyi, P.; Tomasi-Gustaffson, E.; Boyard, J. -L.; Farhi, L.; Jourdain, J. C.; Ramstein, B.; Roy-Stephan, M.; Alkhazov, G. D.; Kravtsov, A. V.; Mylnikov, V. A.; Orichtchin, E. M.; Prokofiev, A. N.; Razmyslovich, B. V.; Tkach, I. I.; Volkov, S. S.; Zhdanov, A. A.; Dahl, R.; Drews, M.; Ellegaard, F. C.; Gaarde, C.; Larsen, J. S.; Skousen, M.; Morsch, P.; Augustiniak, W.; Zupranski, P.; Perdrisat, C. F.; Punjabi, V. Bibcode: 1999fbpp.conf..495S Altcode: No abstract at ADS Title: Observing Hot Stars in all Four Stokes Parameters Authors: Eversberg, Thomas; Moffat, Anthony F. J.; Debruyne, Michael; Rice, John B.; Piskunov, Nikolai; Bastien, Pierre; Wehlau, William H.; Chesneau, Olivier Bibcode: 1999LNP...523..107E Altcode: 1999IAUCo.169..107E; 1999vnss.conf..107E We introduce a new polarimeter unit which, mounted at the Cassegrain focus of any telescope and fiber-connected to a fixed CCD spectrograph, as able to measure all Stokes parameters I, Q, U and V photon-noise limited across spectral lines of bright stellar targets and other point sources in a quasi-simultaneous manner. We briefly outline the technical design of the polarimeter unit and the linear algebraic Mueller calculus for obtaining polarization parameters of any point source. In addition, practical limitations of the optical elements are discussed. We present first results obtained with our spectropolarimeter for three prototype hot-star. Title: Stellar activity and magnetism Authors: Piskunov, N. Bibcode: 1999anot.conf..204P Altcode: No abstract at ADS Title: Modeling magnetic fields on stars other than the Sun Authors: Piskunov, N. Bibcode: 1999ASSL..243..515P Altcode: 1999sopo.conf..515P No abstract at ADS Title: The William-Wehlau Spectropolarimeter: Observing Hot Stars in All Four Stokes Parameters Authors: Eversberg, Thomas; Moffat, Anthony F. J.; Debruyne, Michael; Rice, John B.; Piskunov, Nikolai; Bastien, Pierre; Wehlau, William H.; Chesneau, Olivier Bibcode: 1998PASP..110.1356E Altcode: We introduce a new polarimeter unit, which, mounted at the Cassegrain focus of any telescope and fiber-connected to a fixed CCD spectrograph, is able to measure all Stokes parameters I, Q, U, and V across spectral lines of bright stellar targets and other point sources in a quasi-simultaneous manner. Applying standard reduction techniques for linearly and circularly polarized light, we are able to obtain photon noise-limited line polarization. We briefly outline the technical design of the polarimeter unit and the linear algebraic Mueller calculus for obtaining polarization parameters of any point source. In addition, practical limitations of the optical elements are outlined. We present first results obtained with our spectropolarimeter for four bright, hot-star targets. We confirm previous results for Hα in the bright Be star gamma Cas and find linear depolarization features across the emission-line complex C III/C IV (5696/5808 Å) of the WR + O binary gamma^2 Vel. We also find circular line polarization in the strongly magnetic Ap star 53 Cam across its Hα absorption line. No obvious line polarization features are seen across Hα in the variable O star theta^1 Ori C above the sigma~0.2% instrumental level. Title: Spectral Synthesis of TiO Lines Authors: Valenti, Jeff A.; Piskunov, Nikolai; Johns-Krull, Christopher M. Bibcode: 1998ApJ...498..851V Altcode: We explore the extent to which current titanium oxide (TiO) line data and M dwarf model atmospheres can be used to reproduce an R = 120,000 optical spectrum of the relatively inactive star Gliese 725B (M3.5 V). We find that tabulated TiO wavelengths have errors large enough to complicate line identification, especially for transitions involving higher vibrational states. We determine empirical wavelength corrections for 12 strong γ-bands near 6680 and 7090 Å. For the sequence of orbital quantum numbers, J, within any one of these bands, our observations confirm the predicted line spacing, thereby validating the rotational constants for low vibrational levels. However, the predicted wavelengths have zero-point errors that differ for each overlapping band. Next, we compare observed and synthetic spectra near 8463 Å, where an ɛ Q3 0-0 band head is expected, demonstrating that the electronic oscillator strength of 0.014 advocated by Jørgensen is too large by at least a factor of 5. This has a minor effect on the structure of theoretical model atmospheres. Using our empirically corrected TiO wavelengths, we compute a grid of synthetic spectra for Allard & Hauschildt models spanning a range in effective temperature (Teff), surface gravity (log g), and metallicity ([M/H]). Interpolating in this grid of synthetic spectra, we simultaneously fit observations of the TiO band head region near 7088 Å and five Ti I and Fe I lines near 8683 Å. For Gl 725B, we find Teff = 3170 +/- 71 K, log g = 4.77 +/- 0.14, [M/H] = -0.92 +/- 0.07, and vmac = 1.1 +/- 0.7 km s-1. We show that by using both atomic and molecular lines as constraints, systematic uncertainties in derived stellar parameters can be reduced. These parameters are consistent with published values obtained by other means, but more stringent tests would be useful. In the Appendix, we tabulate wavelengths, identifications, relative line strengths, and other properties of the strongest band heads in the α, β, γ, γ', δ, ɛ, and φ electronic systems of TiO. Title: Astronephography: the 3-D shape of the Local Interstellar Cloud Authors: Linsky, J. L.; Piskunov, N.; Wood, B. E. Bibcode: 1998AAS...192.1018L Altcode: 1998BAAS...30..830L GHRS spectra of 19 mostly late-type stars provide interstellar hydrogen and metal column densities along these lines of sight with sufficient resolution to resolve individual clouds. For 16 of these lines of sight we can infer the hydrogen column density at the projected velocity of the Local Interstellar Cloud (LIC). We construct a 3 dimensional representation of the LIC by assuming that the neutral hydrogen density in the cloud is the same as the highest mean density observed, about 0.1 cm(-3) , and that the LIC extends continuously along each line of sight to a distance determined by the hydrogen column density and the assumed density. We will present our model of the LIC as an animated video that shows its shape from different directions. We find that the hydrogen column densities obtained from EUVE spectra of white dwarfs are in excellent agreement with the GHRS column densities for the stars. Also, some other nearby white dwarfs fit our LIC model well and are included in the model. As viewed from the North Galactic Pole, the LIC has an irregular shape with the Sun very near the edge toward the Galactic Center and very little column density in the first and fourth Galactic quadrants. As viewed from in the Galactic plane, there is more material to the south and the cloud has narrow extensions toward the Galactic Center and toward Galactic longitude 270 Degrees. We propose that the study of the structure of interstellar clouds be called "astronephography" based on the Greek word for cloud, "nephos". This work is supported by NASA grants to the University of Colorado. Title: CP star atmospheres based on individual ODFs Authors: Kupka, F.; Piskunov, N. E. Bibcode: 1998CoSka..27..228K Altcode: 1998astro.ph..5057K We describe a new method for the computation of opacity distribution functions (ODFs) useful to calculate one-dimensional model atmospheres in local thermal equilibrium (LTE). The new method is fast enough to be applied on current workstations and allows the computation of model atmospheres which deviate significantly from (scaled) solar chemical composition. It has reproduced existing ODFs and model atmospheres for solar abundances. Depending on the type of chemical peculiarity the "individual" model atmosphere may have a structure and surface fluxes similar to atmospheres based on (scaled) solar abundances or deviate in a way that cannot be reproduced by any of the conventional models. Examples are given to illustrate this behavior. The availability of models with "individualized" abundances is crucial for abundance analyses and Doppler imaging of extreme CP stars. Title: IOTA Cas: Multi-element Doppler imaging and magnetic field geometry Authors: Kuschnig, R.; Wade, G. A.; Hill, G. M.; Piskunov, N. Bibcode: 1998CoSka..27..470K Altcode: 1998astro.ph..5243K In order to clarify the role of the magnetic field in generating abundance inhomogeneities in the atmospheres of Ap stars, we present new abundance Doppler images and an approximate magnetic field geometry for the Ap star iota Cas. Title: Radiative transfer in Doppler Imaging Authors: Piskunov, N. Bibcode: 1998CoSka..27..374P Altcode: 1998astro.ph..5048P The modern Doppler Imaging (DI) technique allows the reconstruction of different stellar surface structures based on accurate calculation of spectra of specific intensity. New applications like the mapping of the magnetic field vector put very stringent requirements on the radiative transfer (RT) solver which should be accurate, fast, and robust against numerical errors. We describe the evaluation of three different algorithms for our new magnetic DI code INVERS10. We also show the first results of numerical experiments made with the new code. Title: EU III identification and EU abundance in cool CP stars Authors: Ryabchikova, T.; Piskunov, N.; Savanov, I.; Kupka, F. Bibcode: 1998CoSka..27..359R Altcode: 1998astro.ph..5206R We report the first identification of the Eu III lambda 6666.317 line in optical spectra of CP stars. This line is clearly present in the spectra of HR 4816, 73 Dra, HR 7575, and beta CrB, while it is marginally present or absent in spectra of the roAp stars alpha Cir, gamma Equ, BI Mic, 33 Lib, and HD 24712. Title: Linear spectropolarimetry of AP stars: a new degree of constraint on magnetic structure Authors: Wade, G. A.; Donati, J. -F.; Mathys, G.; Piskunov, N. Bibcode: 1998CoSka..27..436W Altcode: 1998astro.ph..5069W We present preliminary results from a programme aimed at acquiring linear spectropolarimetry of magnetic A and B stars. Linear polarization in the spectral lines of these objects is due to the Zeeman effect, and should provide detailed new information regarding the structure of their strong magnetic fields. To illustrate the impact of these new data, we compare observed circular and linear polarization line profiles of 53 Cam with the profiles predicted by the magnetic model by Landstreet. Linear polarization in the spectral lines of all stars studied is extremely weak; in most cases, below the threshold of detectability even for very high SNRs. In order to overcome this problem, we employ the Least-Squares Deconvolution (LSD) multi-line analysis technique in order to extract low-noise mean line profiles and polarization signatures from our echelle spectra. Tests show that these mean signatures can be modelled as real spectral lines, and have the potential to lead to high-resolution maps of the magnetic and chemical abundance surface distributions. Title: Multi-element Doppler imaging of kappa PSC Authors: Piskunov, N.; Stempels, H. C.; Ryabchikova, T. A.; Malanushenko, V.; Savanov, I. Bibcode: 1998CoSka..27..482P Altcode: 1998astro.ph..5250P kappa Psc (HD 220825) is a typical Chromium Ap star that happens to have optimal parameters for Doppler imaging (DI). Its short rotational period of less than 2 days, rotational velocity of approx. 40 km/s, and a moderate inclination of the rotational axis put modest requirements on spectroscopic observations. Anomalies of iron peak elements are clearly present, but small enough to cause significant deviations from model atmospheres with scaled solar abundances. We applied DI to kappa Psc once before, determining the distribution of Cr. However, due to strong blending of Fe, the image was based on two short (approx. 2 A) spectral intervals, dominated by Cr lines. Since the first paper we obtained additional spectra and developed a new code that allows to perform multi-element DI and thus to use larger spectral interval(s). We demonstrate the abilities of the new code and present new maps of Cr and Fe. A much larger time base allowed us to improve the rotational period of kappa Psc as well. Title: A Fiber-Linked Four Stokes-Parameter Polarimeter for the SOFIN Spectrometer on the Nordic Optical Telescope Authors: Pettersson, B.; Stempels, E.; Piskunov, N. Bibcode: 1998ASPC..152..343P Altcode: 1998fopa.proc..343P No abstract at ADS Title: Observational Constraints on the Dynamo in Flare Stars Authors: Valenti, Jeff A.; Johns-Krull, Christopher M.; Piskunov, Nikolai Bibcode: 1998ASPC..154.1357V Altcode: 1998csss...10.1357V There is increasing evidence that the dynamo mechanism in dMe flare stars differs from the alphaOmega dynamo believed to operate in the Sun. We review existing observational constraints on the dynamo and then present new constraints. In particular, we show that the magnetic field on Gliese 729 has been constant for 1.5 years, despite large variations in Hα equivalent width. This has implications for chromospheric heating and the existence of stellar cycles in flare stars. We also present preliminary polarimetry of AD Leo, demonstrating the the field is not globally organized. We discuss these results in the context of existing dynamo models. Title: INVERS10: A New Code for Magnetic Doppler Imaging Authors: Piskunov, N. Bibcode: 1998ASPC..154.2029P Altcode: 1998csss...10.2029P We present a new Magnetic Doppler Imaging computer code designed to simultaneously reconstruct both the 3D structure of magnetic fields and the temperature structure of active regions on the surfaces of late-type stars. We show results from numerical experiments and demonstrate that the full set Stokes parameters is needed for proper reconstruction of the magnetic field vector. Title: The Vienna Atomic Line Database : Present State and Future Development Authors: Ryabchikova, T. A.; Piskunov, N. E.; Kupka, F.; Weiss, W. W. Bibcode: 1997BaltA...6..244R Altcode: 1997OAst....6..244R We describe the main structure of the Vienna Atomic Line Database, the tools provided for the users and the statistics of its use in the last two years. Our plans for future developments of the database are discussed. Title: Local Interstellar Medium Properties and Deuterium Abundances for the Lines of Sight toward HR 1099, 31 Comae, β Ceti, and β Cassiopeiae Authors: Piskunov, Nikolai; Wood, Brian E.; Linsky, Jeffrey L.; Dempsey, Robert C.; Ayres, R. Bibcode: 1997ApJ...474..315P Altcode: We analyze Goddard High-Resolution Spectrograph data to infer the properties of local interstellar gas and the deuterium/hydrogen (D/H) ratio for lines of sight toward four nearby late-type stars--HR 1099, 31 Comae, β Ceti, and β Cassiopeiae. The data consist of spectra of the hydrogen and deuterium Lyα lines, and echelle spectra of the Mg II h and k lines toward all stars except β Cas. Spectra of the RS CVn-type spectroscopic binary system HR 1099 were obtained near opposite quadratures to determine the intrinsic stellar emission line profile and the interstellar absorption separately. Multiple-velocity components were found toward HR 1099 and β Cet. The spectra of 31 Com and β Cet are particularly interesting because they sample lines of sight toward the north and south Galactic poles, respectively, for which H I and D I column densities were not previously available.

The north Galactic pole appears to be a region of low hydrogen density like the ``interstellar tunnel'' toward ɛ CMa. The temperature and turbulent velocities of the local interstellar medium (LISM) that we measure for the lines of sight toward HR 1099, 31 Com, β Cet, and β Cas are similar to previously measured values (T ~ 7000 K and ξ = 1.0-1.6 km s-1). The deuterium/hydrogen ratios found for these lines of sight are also consistent with previous measurements of other short lines of sight, which suggest D/H ~ 1.6 × 10-5. In contrast, the Mg abundance measured for the β Cet line of sight [implying a logarithmic depletion of D(Mg) = +0.30 +/- 0.15] is about 5 times larger than the Mg abundance previously observed toward α Cen, and about 20 times larger than all other previous measurements for the LISM. These results demonstrate that metal abundances in the LISM vary greatly over distances of only a few parsecs.

Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Title: Surface distribution of chromium on the CP2 star HD 220825 (κ Psc) Authors: Ryabchikova, T. A.; Pavlova, V. M.; Davydova, E. S.; Piskunov, N. E. Bibcode: 1996AstL...22..822R Altcode: 1996AstL...22..821R; 1996PAZh...22..917R No abstract at ADS Title: Spectroscopy made easy: A new tool for fitting observations with synthetic spectra. Authors: Valenti, J. A.; Piskunov, N. Bibcode: 1996A&AS..118..595V Altcode: We describe a new software package that may be used to determine stellar and atomic parameters by matching observed spectra with synthetic spectra generated from parameterized atmospheres. A nonlinear least squares algorithm is used to solve for any subset of allowed parameters, which include atomic data (log gf and van der Waals damping constants), model atmosphere specifications (T_ eff_, logg), elemental abundances, and radial, turbulent, and rotational velocities. LTE synthesis software handles discontiguous spectral intervals and complex atomic blends. As a demonstration, we fit 26 FeI lines in the NSO Solar Atlas (Kurucz et al. 1984), determining various solar and atomic parameters. Title: The Three-Dimensional Structure of the Local Interstellar Medium Authors: Linsky, J. L.; Piskunov, N.; Wood, B. E. Bibcode: 1996AAS...188.4407L Altcode: 1996BAAS...28..892L We construct the first detailed three-dimensional models of the Local Interstellar Cloud (LIC) and the total amount of warm gas in the local interstellar medium (LISM) within 10 parsecs of the Sun. These models are based on the amount of neutral hydrogen gas deduced (a) from measurements of the deuterium column density toward nearby late-type stars, obtained from the analysis of Hubble Space Telescope spectra, and (b) from the spectra of hot white dwarf stars measured with the Extreme Ultraviolet Explorer satellite. The two methods give consistent results. We find that the LIC is flattened in the Galactic plane and that the hydrogen column densities are very similar for stars located in the sky within 12(deg) , indicating the angular scale of the gas close to the Sun. The direction of minimum hydrogen absorption through the LISM is near Galactic longitude l=262(deg) and latitude b=+22(deg) . This work is supported by NASA Grant S-56460-D. Title: M-Dwarfs: Molecules and Magnetic Fields Authors: Valenti, J. A.; Johns-Krull, C. M.; Piskunov, N. Bibcode: 1996AAS...188.3206V Altcode: 1996BAAS...28..867V At McDonald Observatory, we recently obtained echelle spectra (R=120,000; S/N>100) of several M0V to M5V stars. Interpreting these spectra in detail has been challenging, but also quite fascinating. From an analysis standpoint, the largest perturbation from a solar analogy arises because of the prevalence of molecules in the atmosphere. Fortunately, Allard & Hauschildt (1995) have constructed and continue to refine theoretical atmospheres, which include the effects of molecules. Meanwhile, Jorgensen (1994) has recently compiled extensive lists of molecular line data. These important contributions, available in an electronic format, allowed us to synthesize spectra using standard LTE radiative transfer techniques. By comparing these synthetic spectra with selected wavelength regions in our observed spectra, we were able to correct the electronic oscillator strength for the epsilon band of TiO, and also to refine the molecular constants for the gamma band. In addition, we hope to assess how well the theoretical atmospheres for various effective temperatures are able to reproduce observed depths of TiO lines. Active M dwarfs have relatively large flare luminosities and X-ray surface fluxes, implying magnetic fields and/or filling factors well above solar. Saar & Linsky (1985) provided the first direct evidence for 4 kG fields covering the surface of an M dwarf. We recently confirmed this result by detecting Zeeman split sigma --components in the FeI line at 8468.40 Angstroms (Johns--Krull & Valenti 1996). This demonstration was primarily empirical: the extended wings seen in the FeI line are not seen in spectra of inactive M dwarfs, whereas the neighboring TiO lines are all well matched, ruling out most nonmagnetic explanations. We also determined magnetic field strength and filling factor by modeling the ratio of active and inactive spectra, which is less sensitive to model uncertainties and molecular blends. We are implementing a Feautrier scheme to accurately synthesize spectra when both molecules and magnetic fields are important. We hope to have available for discussion initial results from a new analysis of active M dwarfs. Title: Introduction Authors: Lester, J. B.; Piskunov, N. E. Bibcode: 1996ASPC..108..159L Altcode: 1996mass.conf..159L No abstract at ADS Title: Spectroscopy Made Easy Authors: Valenti, J. A.; Piskunov, N. E. Bibcode: 1996ASPC..108..175V Altcode: 1996mass.conf..175V No abstract at ADS Title: Doppler imaging of eclipsing binaries Authors: Piskunov, N. Bibcode: 1996IAUS..176...45P Altcode: No abstract at ADS Title: The Structure of VALD Authors: Piskunov, N. E. Bibcode: 1996ASPC..108..307P Altcode: 1996mass.conf..307P No abstract at ADS Title: The Chromosphere and Wind of zeta Aurigae Authors: Bennett, P. D.; Brown, A.; Harper, G. M.; Piskunov, N.; Griffin, R. E. M. Bibcode: 1995AAS...18710304B Altcode: 1995BAAS...27.1431B The zeta Aurigae binary systems consist of evolved supergiants which eclipse their early-type main sequence companions. These binaries have been extensively studied because of their potential for probing the outer atmospheric structure of the evolved late-type primary. This technique is extremely advantageous in the ultraviolet where the cool primary contributes little flux. To this end, we have undertaken an analysis of the chromosphere and wind of the prototype system, zeta Aurigae, and we graphically demonstrate the resulting model by means of a video presentation. Our atmospheric model of the chromosphere and wind of the primary star of zeta Aurigae (K4 Ib + B5 V) is based on Cycle 2 and recent Cycle 5 observations obtained with the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope, and on archival IUE and optical spectra. The models were iterated to reproduce the observed circumstellar absorption line curves of growth, and individual absorption profiles, for various projected heights above the limb of the K supergiant. To conveniently show the variation of typical line profiles computed with this model, we have prepared a video that follows the zeta Aurigae binary system through a complete orbit. We display several windows showing a perspective view of the system from a vantage point above the orbital plane, the view as seen from earth (nearly edge-on, i=87.3(deg) ), and the behavior of absorption lines formed in the chromosphere and wind of zeta Aurigae as a function of orbital phase. Support for this work was provided by NASA through grants GO-3626-91A and GO-06069.01-94A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Title: VALD: The Vienna Atomic Line Data Base. Authors: Piskunov, N. E.; Kupka, F.; Ryabchikova, T. A.; Weiss, W. W.; Jeffery, C. S. Bibcode: 1995A&AS..112..525P Altcode: The "Vienna Atomic Line Data Base" (VALD) consists of a set of critically evaluated lists of astrophysically important atomic transition parameters and supporting extraction software. VALD contains about 600000 entries and is one of the largest collections of accurate and homogeneous data for atomic transitions presently available. It also includes specific tools for extracting data for spectrum synthesis and model atmosphere calculations. The different accuracies of data available in the literature made it necessary to introduce a ranking system and to provide a flexible method for extracting the best possible set of atomic line parameters for a given transition from all the available sources. The data base is presently restricted to spectral lines which are relevant for stars in which the LTE approximation is sufficient and molecular lines do not have to be taken into account. The provision was made that these requirements should not restrict the general design of VALD and the possibility of future expansion. In this paper we describe the structure of VALD, the available data sets and specific retrieval tools. The electronic-mail interface (VALD-EMS) created to allow remote access to VALD is also described. Both users and producers of atomic data are invited to explore the database, and to collaborate in improving and extending its contents. Title: The HeI surface distribution of the CP2 star CU Virginis. Authors: Hiesberger, F.; Piskunov, N.; Bonsack, W. K.; Weiss, W. W.; Ryabchikova, T. A.; Kuschnig, R. Bibcode: 1995A&A...296..473H Altcode: Based on Coude spectra obtained with the 2.24-m telescope at MKO, we derive a map of the surface distribution of helium for the B9pSi star CU Vir. The helium abundance varies by more than one order of magnitude over the surface of this star and is concentrated in one large spot and a second, less pronounced, spot. This pattern is in anti-phase to the silicon surface distribution and is similar to what we have found for ET And, which is another Si-star. We compare our observed equivalent width measurements and synthetic ones, which we have derived from our map, with previously published data and can corroborate the long-term stability of the spots. CU Vir is the second CP2 star, for which a helium surface map is available. Title: The atmosphere of the peculiar binary system ET Andromedae. Authors: Kuschnig, R.; Ryabchikova, T.; Piskunov, N.; Weiss, W. W.; Lecontel, J. M. Bibcode: 1995A&A...294..757K Altcode: High spectral resolution, high signal-to-noise OHP spectra which cover the range from 4000A to 7500A were used to derive abundances for ET And. An extreme overabundance of silicon by nearly 100 times of the solar value corroborates the Si-star classification. We find also enhanced abundances for iron-peak and rare-earths elements, which is typical for this group of CP stars. The deficiency of He (1/30 of the solar value), and to a lesser extent of Mg and C, is remarkable. Based on an estimate for R/Rsun_, derived from geometric arguments, and the measured interstellar Nai lines we conclude that ET And probably still has not evolved significantly from the main sequence. We present arguments, why some earlier luminosity determinations seem to be incorrect. Title: The Vienna Atomic Line Data-Base Authors: Piskunov, N. E.; Kupka, F.; Ryabchikova, T. A.; Weiss, W. W.; Jeffery, C. S. Bibcode: 1995ASPC...81..610P Altcode: 1995lahr.conf..610P No abstract at ADS Title: Ap-star mapping: He, Mg, Si, and Fe surface distributions on the CP2 star CU Virginis Authors: Kuschnig, R.; Ryabchikova, T.; Piskunov, N. E.; Weiss, W. W. Bibcode: 1995IAUS..176P.135K Altcode: No abstract at ADS Title: Progress in surface imaging Authors: Piskunov, N. E.; Rice, J. B. Bibcode: 1995BCrAO..91..176P Altcode: No abstract at ADS Title: Ap-star mapping: Fe and Cr abundance distribution on the surface of HD 153882 Authors: Ryabchikova, T.; Kuschnig, R.; Piskunov, N. E.; Pavlova, V. Bibcode: 1995IAUS..176P.132R Altcode: No abstract at ADS Title: Providing a Common GUI to Image Processing Tasks under pcIPS Authors: Smirnov, O. M.; Piskunov, N. E. Bibcode: 1995ASPC...77..133S Altcode: 1995adass...4..133S No abstract at ADS Title: Spectrum variability of ET Andromedae: SI and He surface mapping. Authors: Piskunov, N.; Ryabchikova, T. A.; Kuschnig, R.; Weiss, W. W. Bibcode: 1994A&A...291..910P Altcode: ETAnd is a silicon star with a rotation period of 1.62d and the visible component of a binary system with an orbital period of 48.3d. We present abundance maps for silicon and helium, based on OHP-AURELIE spectra, and demonstrate that silicon and helium are concentrated in a belt-like structure along the magnetic equator. Surface regions with a silicon overabundance are correlated with helium underabundance. In the framework of diffusion theory, this pattern implies that a magnetic field configuration of ETAnd which favours the elevation of Si, simultaneously causes He to sink. In addition, we comment on the significance of Doppler mapping of CP stars for a correct abundance determination and on implications to pulsation mode identifications. We discuss our upper limit for short time-scale radial velocity variations of 1.4km/s, which contrasts to 4km/s, as was claimed in the literature with a period of 4.8^h^. Title: The detectability of cool polar caps on late type stars. Authors: Piskunov, N.; Wehlau, W. H. Bibcode: 1994A&A...289..868P Altcode: From spectral line profiles the presence of a cool polar cap has been inferred for several late-type stars; for some other similar stars the absence of a cool polar cap has been suggested. In addition, it would be surprising if a star with a cool region at one rotational pole did not have a similar cool region at the other pole. To test the detectability of cool polar caps on late type stars we have computed the effect such cool spots would have on the profile of the Ca I 6439 A. While a cool cap at the visible pole may be detected, the presence of another equivalent cap at the other pole cannot be detected with current techniques. Title: Surface imaging of stars. Authors: Piskunov, N. Bibcode: 1994JRASC..88..254P Altcode: No abstract at ADS Title: Astrophysical determination of optical oscillator strengths for TI II. Authors: Ryabchikova, T. A.; Hill, G. M.; Landstreet, J. D.; Piskunov, N.; Sigut, T. A. A. Bibcode: 1994MNRAS.267..697R Altcode: An internally consistent set of relative oscillator strengths for 109 spectral lines of Ti II in the range 3800-5500 Å has been derived. These oscillator strengths have been obtained by combining available laboratory data and theoretical calculations with new astrophysical oscillator strengths determined from both published photographic equivalent width lists and spectral synthesis of a number of available Reticon spectra of several sharp-lined stars. The accuracy of our astrophysical oscillator strengths has been tested by determining astrophysical gf-values for a number of lines of Fe II by the same methods. The Ti II data have been normalized to the astrophysical oscillator strengths of Kostyk & Orlova, which also places them essentially on the scale of Danzmann & Kock, one of the most recent and extensive experimental data sets. It appears that the accuracy of the relative gf-values in our final mean list for Ti II is typically about 0.08 dex. The absolute normalization is believed to be secure to within about 0.15 dex. Title: Simultaneous SPOT and Chromosphere Maps of FK Comae Authors: Piskunov, N. E.; Huenemoerder, D.; Saar, S. H. Bibcode: 1994ASPC...64..658P Altcode: 1994csss....8..658P Maps of the local T_eff and chromospheric intensity (from He I D3) from a surface imaging analysis of 51 echelle spectra of FK Comae show a complex relationship between spots and activity. Title: Surface Imaging of Spotted Stars Authors: Piskunov, N. Bibcode: 1994cpms.conf...53P Altcode: No abstract at ADS Title: PC-based Astronomical Image Processing with pcIPS Authors: Smirnov, O. M.; Piskunov, N. E. Bibcode: 1994ASPC...61..245S Altcode: 1994adass...3..245S Modern 486-based PCs are fast enough for many serious image processing applications, and inexpensive enough even for amateur astronomers. Our pcIPS image processing system runs on these platforms and satisfies a broad range of data analysis needs, while providing maximum expandability. It supports large format 1D and 2D images in any numeric type, from 8-bit integer to 64-bit floating point. pcIPS includes a set of visualization tools as part of an intuitive graphical user interface that employs buttons, pop-up menus, and a mouse. It is extremely expandable, because all of the image processing functionality is provided by external modules ( applications ), with new ones constantly being developed. The basic application package includes ones for elementary arithmetics and statistics, geometric transformations, and import/export of various data formats (FITS, plain ASCII, Photometrics, binary, GIF, etc.); specialized astronomy-oriented packages will be demonstrated. An API lets the user create his own applications in C and FORTRAN. The demo will show the latest version of the system, as well as some of its recently-created applications. The newest of them is a port of the DAOPHOTII stellar photometry program, and a Fourier analysis package. A CCD/Echelle processing package (location of echelle orders, geometric correction and extraction of orders, flat field correction, etc.) and a Spectral package (generation of dispersion curve, continuum fitting, wavelength calibration, multiple simultaneous line profile fits) will also be shown. Title: Progress in surface imaging. Authors: Piskunov, N. E.; Rice, J. B. Bibcode: 1994IzKry..91..208P Altcode: Surface imaging of stars from the profiles of spectral line became an important tool in modern astrophysics. It is applied for mapping the distribution of chemical elements on Ap stars and temperature on late-type stars. Magnetic field maps appear as well as high quality polarization observations will be available. The authors review the latest achievements in all components of surface imaging which resulted in more reliable and detailed maps. Title: Multiepoch Magnetic Surface Images of LQ Hya Authors: Saar, S. H.; Piskunov, N. E.; Tuominen, I. Bibcode: 1994ASPC...64..661S Altcode: 1994csss....8..661S We study several epochs of magnetic surface images of the active single dwarf LQ Hya to explore the surface differential rotation (SDR) rate and the correlation between magnetic flux Phi_B and T_eff. Title: Techniques for Surface Imaging of Stars Authors: Piskunov, N. E.; Rice, J. B. Bibcode: 1993PASP..105.1415P Altcode: Surface imaging of stars from the profiles of spectral lines, has become an important tool in modern astrophysics. It is presently used for mapping the distribution of chemical elements on Ap stars and the variation in temperature over the surface of late-type stars. Magnetic field maps will be produced as soon as high quality polarization observations are available. Recently imaging techniques have been developed for application to eclipsing binary stars. In this paper we review the improvements we have found to result in more reliable and detailed maps in all aspects of surface imaging. (SECTION: Stars) Title: Surface imaging of eclipsing binary stars. I. Techniques. Authors: Vincent, A.; Piskunov, N. E.; Tuominen, I. Bibcode: 1993A&A...278..523V Altcode: Surface (Doppler) imaging techniques for mapping the temperature distribution of a single star are generalized to the case of an eclipsing spectroscopic binary. In this paper we study three main questions, crucial for further application of the techniques. We found that the method described in this paper can be successfully used for imaging eclipsing binary systems. The resulting map is more sensitive to the errors in the parameters of the system than is the case of a single star. Characteristic distortions of the map can be used as indicators for fine tuning of some of the parameters. We also found that a good phase coverage of the observations is most important for reducing the artificial equatorial symmetry, typical for the line profile inversion when used for high inclination binary systems. Title: Image Processing on Your Desktop with pcIPS Authors: Smirnov, O. M.; Piskunov, N. E. Bibcode: 1993IAPPP..53...16S Altcode: No abstract at ADS Title: PcIPS 2.0: Powerful Multiprofile Image Processing Implemented On PCs Authors: Smirnov, O. M.; Piskunov, N. E. Bibcode: 1993ASPC...52..259S Altcode: 1993adass...2..259S No abstract at ADS Title: A New Programming Metaphor For Image Processing Procedures Authors: Smirnov, O. M.; Piskunov, N. E. Bibcode: 1993ASPC...52..208S Altcode: 1993adass...2..208S No abstract at ADS Title: Magnetic Surface Images of the BY DRA Star HD 82558 Authors: Saar, S. H.; Piskunov, N. E.; Tuominen, I. Bibcode: 1992ASPC...26..255S Altcode: 1992csss....7..255S We present preliminary results of a new analysis method applied to spectra of the BY Dra star HD 82558. We invert a time series of unpolarized line profiles with different Lande g_eff values to derive both temperature and magnetic field maps of the star. We find strong fields (B > 2 kG) near cool spots and weaker fields elsewhere, with <B> ~ 1 kG. Title: PC-IPS: Interactive System For Astronomical Image Processing Authors: Smirnov, O. M.; Piskunov, N. E.; Afanasyev, V. P.; Morozov, A. I. Bibcode: 1992ASPC...25..344S Altcode: 1992adass...1..344S No abstract at ADS Title: SYNTH - a code for rapid spectral synthesis Authors: Piskunov, N. E. Bibcode: 1992pess.conf...92P Altcode: 1992stma.conf...92P No abstract at ADS Title: Doppler imaging of hig-latitude SPOT activity on HD 26337. Authors: Strassmeier, K. G.; Rice, J. B.; Wehlau, W. H.; Vogt, S. S.; Hatzes, A. P.; Tuominen, I.; Piskunov, N. E.; Hackman, T.; Poutanen, M. Bibcode: 1991A&A...247..130S Altcode: Three different versions of the Doppler-imaging technique are applied to the spotted RS CVn-type binary HD 26337 = Ei Eri. New high-resolution high-S/N spectroscopy was obtained along with simultaneous BV photometry during 1988. Images were generated independently by three separate groups using different versions of the Doppler-imaging technique but the same data. All maps from Ca I 6439 A showed a cool asymmetric spot at the pole or at high latitudes generally surrounding the rotation pole and also some smaller equatorial spots. The maps from Fe I exhibit detailed differences to the maps from Ca I. The equatorial features were found to change on short time-scales (weeks). It is inferred that the polar spot is short-lived (years) but changes its appearance on the same several-week time-scale. Simultaneous and contemporary broad-band photometry was found to be crucial as additional data in the mapping procedure and as a reliability test of the Doppler-imaging solution. Title: The second generation automated system for spectrum processing in the Astronomical council of the Academy of sciences of USSR Authors: Kulkova, L. I.; Piskunov, N. E.; Svyatoslavskij, N. L. Bibcode: 1991NInfo..70...56K Altcode: No abstract at ADS Title: The Art of Surface Imaging Authors: Piskunov, N. E. Bibcode: 1991LNP...380..309P Altcode: 1991sacs.coll..309P; 1991IAUCo.130..309P We intend to analyze the reliability of surface imaging of stars based on high resolution spectroscopy and the technique of inverse problem solution. Both astrophysical and mathematical aspects including different regularization methods are reviewed. The influence of the different factors on the resulting map is discussed and it is shown that the simultaneous use of different kinds of observational data (spectroscopy, photometry, polarimetry etc.) is very useful in providing additional constraints for the solution. The recent results in the surface imaging of Cp- and late-type stars show the way for further progress: the use of more adequate mathematical description of the stellar atmosphere and the simultaneous consideration of various surface inhomogeneities. Title: Surface Imaging of Ei-Eridani Authors: Hackman, T.; Piskunov, N. E.; Poutanen, M.; Strassmeier, K. G.; Tuominen, I. Bibcode: 1991LNP...380..321H Altcode: 1991IAUCo.130..321H; 1991sacs.coll..321H We present maps of the temperature distribution on the spotted RS CVn-type binary EI Eri (HD 26337), obtained by means of the surface imaging technique described in the Colloquium (Piskunov, 1991). Images were calculated for two separate lines for two epochs of observation. For one epoch we also calculated an image using a blend of several lines. The reliability of the maps is confirmed by comparing the simultaneous photometric observations with the light curves calculated from the temperature maps. Title: Proton and triton momentum distributions from4He fragmentation at relativistic energies Authors: Ableev, V. G.; Dshemuchadse, S. V.; Dimitrov, C.; Kobushkin, A. P.; Naumann, B.; Naumann, L.; Nomofilov, A. A.; Penchev, L.; Piskunov, N. M.; Sharov, V. I.; Sitnik, I. M.; Strokovsky, E. A.; Strunov, L. N.; Tesch, S.; Zaporozhets, S. A. Bibcode: 1990FBS.....8..137A Altcode: The 0° differential cross sections of the12C(4He, p) and12C(4He, t) reactions have been measured at beam momenta of 4.52 and 2.69 GeV/ c/nucleon, respectively. The proton and triton momentum distributions in4He are extracted from the cross sections using a relativistic impulse approximation. Some theoretical models based on realistic N-N potentials are examined for our data. Title: Mapping stellar surfaces from spectra of medium resolution Authors: Piskunov, N. E.; Wehlau, W. H. Bibcode: 1990A&A...233..497P Altcode: The use of spectra with resolutions of 6, 9, 12, and 15 km/s to produce maps of abundance inhomogeneities on the surfaces of stars is studied. It is assumed that the spectra have a high SNR, are free from blends, and that the inclination of the axis of rotation and the locations of surface features are favorable. Numerical studies of the Fe II 4923 A line showed that, for v sin i greater than about 30 km/s, good maps of surface features can be expected from spectra with resolutions of 6 km/s or better. Title: Surface imaging of late-type stars. Authors: Piskunov, N. E.; Tuominen, I.; Vilhu, O. Bibcode: 1990A&A...230..363P Altcode: The basic principles of stellar surface imaging techniques are discussed, and two ways of regularizing this ill-posed inverse problem are compared. Maximizing the information entropy means that minimum correlation between different points at the stellar surface should be expected, while the use of a Tikhonov regularization functional leads to the smoothest possible solution. Physical conditions in the stellar surface layers may favor the latter method, and the present simulation experiment shows that it does not produce small size, high contrast features below the spatial and temporal resolution of the data, which is typical of maximum entropy images. The technique is also illustrated by applying it to the FK Comae-type star HD 32918. Title: The surface imaging of the stars. Authors: Piskunov, N. E. Bibcode: 1990MmSAI..61..577P Altcode: A general approach to the surface imaging of stars based on high resolution spectroscopy and the technique of inverse problem solution are formulated. Both astrophysical and mathematical aspects including different regularization methods are reviewed. The influence of the different factors on the reliability of the resulting map is discussed. It is shown that the simultaneous use of different kinds of observational data (spectroscopy, photometry, and polarimetry) might be very useful in providing additional constraints for the solution. The recent results in the surface imaging of Cp- and late-type stars show the way for further progress: the use of a more adequate mathematical description of stellar atmospheres and the simultaneous consideration of various surface inhomogeneities. Title: Surface Imaging of Giant Stars and Nonlinear Dynamos Authors: Tuominen, I.; Piskunov, N. E.; Moss, D.; Brandenburg, A. Bibcode: 1990ASPC....9...73T Altcode: 1990csss....6...73T Recent results of photometric cycles and surface images of active giants are discussed in terms of nonlinear 3D mean-field dynamos. The existence of mixed parity solutions with periodic and quasi-periodic time dependence is suggestive for explaining the nonaxisymmetric surface patterns observed on active giant stars. Title: Preliminary results of new observations of NGC 6888. Authors: Bochkarev, N. G.; Lozinskaya, T. A.; Pravdikova, V. V.; Sitnik, T. G.; Piskunov, N. N. Bibcode: 1988TarOT..89..168B Altcode: Einstein Observatory X-ray data and new monochromatic Fabry-Perot interferometric observations are presented for nebula NGC 6888 around the WN6 star HD 192163. Temperature and density stratification and large-scale asymmetry of the nebula are discussed. Title: Abundance analysis of Hg-Mn star ϕ Herculis Authors: Ryabchikova, T. A.; Piskunov, N. E. Bibcode: 1988mast.conf..124R Altcode: Method and main results of abundance analysis of φ Her are presented. Title: Abundance Analysis of the Mercury-Manganese Star Phi Herculis Authors: Ryabchikova, T. A.; Piskunov, N. E. Bibcode: 1988eaa..conf...93R Altcode: Contents: 1. Introduction. 2. Spectra reductions. 3. Stellar radial velocity and line identifications. 4. Model atmosphere parameters. 5. Computer code for line profiles calculation. 6. The determination of metal abundances and microturbulent velocity. 7. Conclusions. Title: The estimation of 53 Cam magnetic field value by means of spectral line width analysis Authors: Glagolevskij, Yu. V.; El'Kin, V. G.; Romanyuk, I. I.; Piskunov, N. E. Bibcode: 1988mast.conf...32G Altcode: Systematical studies of 53 Cam spectral lines widening were carried out in order to find the possible structural features and the mean value of the surface magnetic field. Title: Service programmes expanding possibilities of programming in FORTRAN language in OS ES Authors: Lukin, V. Yu.; Piskunov, N. E. Bibcode: 1986NInfo..59...89L Altcode: No abstract at ADS Title: General principles of computer image processing Authors: Lukin, V. Yu.; Mit'kin, K. N.; Piskunov, N. E. Bibcode: 1986NInfo..59...99L Altcode: No abstract at ADS Title: Estimation of Stellar Surface Magnetic Fields by the Curve-Of Method Authors: Riabchikova, T. A.; Piskunov, N. E. Bibcode: 1986ASSL..125...45R Altcode: 1986umss.conf...45R; 1986umss.proc...45R; 1986IAUCo..90...45R The curve-of-growth method of estimating the stellar surface magnetic fields is applied to six Ap stars of different temperatures and one normal (or metallic-line) star, Sigma Aqr. The values of H(s) determined by the curve-of-growth technique are in good agreement with those obtained by the photometric method. Title: An automated astronomical image processor Authors: Grishin, M. P.; Kurbanov, S. M.; Pakhomov, S. V.; Piskunov, N. E.; Sviatoslavskii, N. L. Bibcode: 1985SvAL...11..335G Altcode: The design of an automatic image processing system which is based on an AMD-1 microdensitometer is described. The system contains an optical section with a dual-beam design, a measurement unit, and a calibration unit. The measurement unit is composed of illuminating and projection microscopes, illumination and measurement diaphragms, and a photodetector, and the calibration unit has a light guide and a reference photodetector. The image scanning, which is conducted with a two-coordinate mechanically controlled sweep, is examined. The system is also capable of reproducing extracted halftone information on photographic film. The system has a photometric accuracy of 1-2 percent, positional accuracy of 5 microns, and an optical density range of 0-4 D. The potential error factors which include scattering with the optics, nonlinearity, drift, and the operation speed of the electronic photometry channel are analyzed. The image processing system is applied to stellar spectra and the optical identification of radio sources. Title: Investigation of the AP star alpha2 CVn magnetic field geometry from circular polarization profiles of metallic lines. Authors: Glagolevskij, Yu. V.; Piskunov, N. E.; Khokhlova, V. L. Bibcode: 1985PAZh...11..371G Altcode: Circular-polarization profiles of Fe II, Ti II lines are processed by solving the inverse problem to yield a model for the magnetic field geometry of the Ap star Alpha(2) CVn, allowing for the nonuniform distribution of elements over the stellar surface. The results are compared with other authors' models deduced by interpretation of effective-field curves. Title: Magnetic Field Geometry of ALPHA-2-CANUM-VENATICORUM Derived from Circular Polarization Profiles of Metal Lines Authors: Glagolevskii, Y. V.; Piskunov, N. E.; Khokhlova, V. L. Bibcode: 1985SvAL...11..154G Altcode: No abstract at ADS Title: The magnetic field geometry of AP stars - A solution algorithm Authors: Piskunov, N. E. Bibcode: 1985PAZh...11...44P Altcode: A solution algorithm is obtained for calculating the magnetic field geometry of an Ap star based on the circular and linear polarization of its spectral lines. The algorithm is based on the conjugate gradient of Fletcher and Reeves (1964). The magnetic field geometry of an Ap star with magnetic field strength in the range 2500-5000 gauss was calculated numerically, in order to assess the efficiency of the algorithm. It is shown that the computed parameters were free from error due to variations in rotational velocity. Some advantages of the present method are discussed in comparison with the conventional practice of interpreting effective-field curves for Ap stars. Title: The Magnetic Field Geometry of Ap-Stars - a Solution Algorithm Authors: Piskunov, N. E. Bibcode: 1985SvAL...11...18P Altcode: No abstract at ADS Title: Automated System for Astronomical Image Processing Authors: Grishin, M. P.; Kurbanov, S. M.; Pakhomov, S. V.; Piskunov, N. E.; Svyatoslavskij, N. L. Bibcode: 1985PAZh...11..793G Altcode: A system for astronomical image processing based on the microdensitometer AMD-1BC is described. Its general technical characteristics are given in comparison with other similar systems. The distortions due to the image reading device are described. Results of the experimental studying of the system are given. The application fields for the system are specified. Title: Linear-polarization line profiles as an indicator of the magnetic field geometry of AP stars Authors: Piskunov, N. E.; Khokhlova, V. L. Bibcode: 1984PAZh...10..449P Altcode: Linear polarization profiles for normal Zeeman triplet structure of spectral lines where calculated in the framework of the oblique rotator model. It is shown that the orientation of magnetic and rotation axes can be uniquely derived from the observed phase variation of linear polarization profiles. Title: Linear Polarization Line Profiles as an Indicator of the Magnetic Field Geometry of Ap-Stars Authors: Piskunov, N. E.; Khokhlova, V. L. Bibcode: 1984SvAL...10..187P Altcode: No abstract at ADS Title: Estimate of stellar surface magnetic fields by the curve-of-growth method. Authors: Ryabchikova, T. A.; Piskunov, N. E. Bibcode: 1984mast.conf...27R Altcode: No abstract at ADS Title: The study of magnetic field geometry of Ap stars by spectral line polarization profiles. Authors: Piskunov, N. E.; Khokhlova, V. L. Bibcode: 1984mast.conf...20P Altcode: No abstract at ADS Title: Numerical modeling of circular-polarization profiles for magnetic AP stars Authors: Piskunov, N. E.; Khokhlova, V. L. Bibcode: 1983PAZh....9..665P Altcode: A numerical model is developed to relate an Ap star's circular polarization profile to its geometrical parameters at a given phase. The profiles are integrated over the visible surface of the star as Doppler shifted by the rotation of the star to obtain an approximation of the magnetic field structure. When the profiles of a specific spectral line are calculated according to a centered dipole model, the Ap star's rotation and nonuniformity of surface element abundances are found to have a significant effect on the observed field strength. Therefore, intensity profiles must be used with polarization profiles to define the star geometry and magnetic field intensity. Title: Numerical Modeling of Circular Polarization Profiles for Magnetic Ap-Stars Authors: Piskunov, N. E.; Khokhlova, V. L. Bibcode: 1983SvAL....9..346P Altcode: No abstract at ADS Title: A Spectrogram Reducing System Based on the Microdensitometer MDM-6 Joyce Loebl Coupled with the Minicomputer NOVA3/12 Authors: Piskunov, N. E.; Ptitsyn, D. A.; Ryabchikova, T. A.; Khoklova, V. L. Bibcode: 1983NInfo..54...45P Altcode: No abstract at ADS Title: Mapping of iron and chromium on the surface of the AP star Epsilon Ursae Majoris Authors: Wehlau, W.; Rice, J.; Piskunov, N. E.; Khokhlova, V. L. Bibcode: 1982SvAL....8...15W Altcode: 1982PAZh....8...30W Epsilon Ursae Majoris (HD 112185) is one of the brightest peculiar A stars, and it has long been classified as Ap. In connection with an investigation of the surface of Epsilon UMa, high-precision profiles of the Fe I, Fe II, Cr I, Cr II lines in the stellar spectrum have been obtained with the aid of a reticon on a 1.2-m telescope. The obtained profiles have been employed to solve the inverse problem numerically by means of a method described by Goncharskii et al. (1977). The line profiles were recorded between March and August 1980 at 2.4-A dispersion with the coude spectrograph of a 1.2-A reflector. The profiles were recorded to better than 1 percent photometric accuracy. Title: The procedure system for files management in OS ES Authors: Piskunov, N. E. Bibcode: 1982NInfo..51..111P Altcode: No abstract at ADS Title: The procedure system for files menagement in OS ES Authors: Piskunov, N. E. Bibcode: 1982NInfo..31..111P Altcode: No abstract at ADS Title: The distribution of iron and chromium over the surface of Epsilon UMa Authors: Rice, J.; Wehlau, W.; Khokhlova, V. L.; Piskunov, N. E. Bibcode: 1981LIACo..23..265R Altcode: 1981cpsu.conf..265R The distribution of Fe and Cr on the surface of Epsilon UMa has been determined using high precision profiles of FeI, FeII, CrI and CrII lines obtained with a Reticon. The mathematical methods previously described by Goncharski et al. (1977, 1981) have been used to derive maps of local equivalent width from the observational data. Both elements are concentrated in two large regions situated near the rotational equator. There is an indication that the spots for the neutral states are displaced in longitude from the spots for the singly ionized states.