Shulyak, Denis V.

[["dc.bibliographiccitation.firstpage","4094"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","4104"],["dc.bibliographiccitation.volume","445"],["dc.contributor.author","Fossati, Luca"],["dc.contributor.author","Kolenberg, Katrien"],["dc.contributor.author","Shulyak, Denis V."],["dc.contributor.author","Elmasli, A."],["dc.contributor.author","Tsymbal, V."],["dc.contributor.author","Barnes, T. G."],["dc.contributor.author","Guggenberger, Elisabeth"],["dc.contributor.author","Kochukhov, Oleg"],["dc.date.accessioned","2018-11-07T09:31:09Z"],["dc.date.available","2018-11-07T09:31:09Z"],["dc.date.issued","2014"],["dc.description.abstract","The stellar parameters of RR Lyrae stars vary considerably over a pulsation cycle, and their determination is crucial for stellar modelling. We present a detailed spectroscopic analysis of the pulsating star RR Lyr, the prototype of its class, over a complete pulsation cycle, based on high-resolution spectra collected at the 2.7-m telescope of McDonald Observatory. We used simultaneous photometry to determine the accurate pulsation phase of each spectrum and determined the effective temperature, the shape of the depth-dependent microturbulent velocity, and the abundance of several elements, for each phase. The surface gravity was fixed to 2.4. Element abundances resulting from our analysis are stable over the pulsation cycle. However, a variation in ionization equilibrium is observed around minimum radius. We attribute this mostly to a dynamical acceleration contributing to the surface gravity. Variable turbulent convection on time-scales longer than the pulsation cycle has been proposed as a cause for the Blazhko effect. We test this hypothesis to some extent by using the derived variable depth-dependent microturbulent velocity profiles to estimate their effect on the stellar magnitude. These effects turn out to be wavelength dependent and much smaller than the observed light variations over the Blazhko cycle: if variations in the turbulent motions are entirely responsible for the Blazhko effect, they must surpass the scales covered by the microturbulent velocity. This work demonstrates the possibility of a self-consistent spectroscopic analysis over an entire pulsation cycle using static atmosphere models, provided one takes into account certain features of a rapidly pulsating atmosphere."],["dc.identifier.doi","10.1093/mnras/stu2044"],["dc.identifier.isi","000346963300058"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/31475"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","1365-2966"],["dc.relation.issn","0035-8711"],["dc.title","An in-depth spectroscopic analysis of RR Lyr Variations over the pulsation cycle"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2548"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","2557"],["dc.bibliographiccitation.volume","418"],["dc.contributor.author","Shulyak, D."],["dc.contributor.author","Seifahrt, Andreas"],["dc.contributor.author","Reiners, Ansgar"],["dc.contributor.author","Kochukhov, Oleg"],["dc.contributor.author","Piskunov, Nikolai E."],["dc.date.accessioned","2018-11-07T08:49:03Z"],["dc.date.available","2018-11-07T08:49:03Z"],["dc.date.issued","2011"],["dc.description.abstract","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 mu m 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 Landeg-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 nu 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 nu sin i which is consistent with other results from studying field stars."],["dc.identifier.doi","10.1111/j.1365-2966.2011.19644.x"],["dc.identifier.isi","000298088100036"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/21363"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-blackwell"],["dc.relation.issn","0035-8711"],["dc.title","Rotation, magnetism and metallicity of M dwarf systems"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","428"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Astronomische Nachrichten"],["dc.bibliographiccitation.lastpage","441"],["dc.bibliographiccitation.volume","338"],["dc.contributor.author","Kochukhov, Oleg"],["dc.contributor.author","Petit, P."],["dc.contributor.author","Strassmeier, K. G."],["dc.contributor.author","Carroll, T. A."],["dc.contributor.author","Fares, R."],["dc.contributor.author","Folsom, C. P."],["dc.contributor.author","Jeffers, Sandra V."],["dc.contributor.author","Korhonen, H."],["dc.contributor.author","Monnier, J. D."],["dc.contributor.author","Morin, Julien"],["dc.contributor.author","Rosen, L."],["dc.contributor.author","Roettenbacher, R. M."],["dc.contributor.author","Shulyak, D."],["dc.date.accessioned","2018-11-07T10:24:19Z"],["dc.date.available","2018-11-07T10:24:19Z"],["dc.date.issued","2017"],["dc.description.abstract","Magnetic fields are essential ingredients of many physical processes in the interiors and envelopes of cool stars. Yet their direct detection and characterization is notoriously difficult, requiring high-quality observations and advanced analysis techniques. Significant progress has been recently achieved by several types of direct magnetic field studies on the surfaces of cool, active stars. In particular, complementary techniques of field topology mapping with polarization data and total magnetic flux measurements from intensity spectra have been systematically applied to different classes of active stars, leading to interesting and occasionally controversial results. In this paper, we summarize the current status of direct magnetic field studies of cool stars and investigations of surface inhomogeneities caused by the field, based on the material presented at the Cool Stars 19 splinter session."],["dc.identifier.doi","10.1002/asna.201713310"],["dc.identifier.isi","000400944700007"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/42634"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","PUB_WoS_Import"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.relation.issn","1521-3994"],["dc.relation.issn","0004-6337"],["dc.title","Surface magnetism of cool stars"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","48"],["dc.bibliographiccitation.issue","1-2"],["dc.bibliographiccitation.journal","Astronomische Nachrichten"],["dc.bibliographiccitation.lastpage","52"],["dc.bibliographiccitation.volume","334"],["dc.contributor.author","Morin, Julien"],["dc.contributor.author","Jardine, M."],["dc.contributor.author","Reiners, Ansgar"],["dc.contributor.author","Shulyak, D."],["dc.contributor.author","Beeck, Benjamin"],["dc.contributor.author","Hallinan, G."],["dc.contributor.author","Hebb, L."],["dc.contributor.author","Hussain, G. A. J."],["dc.contributor.author","Jeffers, Sandra V."],["dc.contributor.author","Kochukhov, Oleg"],["dc.contributor.author","Vidotto, A."],["dc.contributor.author","Walkowicz, Lucianne M."],["dc.date.accessioned","2018-11-07T09:28:17Z"],["dc.date.available","2018-11-07T09:28:17Z"],["dc.date.issued","2013"],["dc.description.abstract","Magnetic fields are regarded as a crucial element for our understanding of stellar physics. They can be studied with a variety of methods which provide complementary - and sometimes contradictory - information about the structure, strength and dynamics of the magnetic field and its role in the evolution of stars. Stellar magnetic fields can be investigated either with direct methods based on the Zeeman effect or through the observation of activity phenomena resulting from the interaction of the field with the stellar atmosphere. In this Cool Stars 17 Splinter Session we discussed the results obtained by the many ongoing studies of stellar activity and direct studies of surface magnetic fields, as well as the state-of-the-art techniques on which they are based. We show the strengths and limitations of the various approaches currently used and point out their evolution as well as the interest of coupling various magnetism and activity proxies. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim"],["dc.description.sponsorship","Alexander von Humboldt foundation"],["dc.identifier.doi","10.1002/asna.201211771"],["dc.identifier.isi","000325859900012"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/30735"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.relation.issn","1521-3994"],["dc.relation.issn","0004-6337"],["dc.title","Multiple views of magnetism in cool stars"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1629"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","1642"],["dc.bibliographiccitation.volume","443"],["dc.contributor.author","Shulyak, D."],["dc.contributor.author","Paladini, C."],["dc.contributor.author","Li Causi, G."],["dc.contributor.author","Perraut, K."],["dc.contributor.author","Kochukhov, Oleg"],["dc.date.accessioned","2018-11-07T09:35:19Z"],["dc.date.available","2018-11-07T09:35:19Z"],["dc.date.issued","2014"],["dc.description.abstract","By means of numerical experiments we explore the application of interferometry to the detection and characterization of abundance spots in chemically peculiar (CP) stars using the brightest star epsilon UMa as a case study. We find that the best spectral regions to search for spots and stellar rotation signatures are in the visual domain. The spots can clearly be detected already at a first visibility lobe and their signatures can be uniquely disentangled from that of rotation. The spots and rotation signatures can also be detected in near-infrared at low spectral resolution but baselines longer than 180 m are needed for all potential CP candidates. According to our simulations, an instrument like VEGA (or its successor e. g. Fibered and spectrally Resolved Interferometric Equipment New Design) should be able to detect, in the visual, the effect of spots and spots+rotation, provided that the instrument is able to measure V-2 approximate to 10(-3), and/or closure phase. In infrared, an instrument like AMBER but with longer baselines than the ones available so far would be able to measure rotation and spots. Our study provides necessary details about strategies of spot detections and the requirements for modern and planned interferometric facilities essential for CP star research."],["dc.identifier.doi","10.1093/mnras/stu1259"],["dc.identifier.isi","000340436800054"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/32358"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","1365-2966"],["dc.relation.issn","0035-8711"],["dc.title","Interferometry of chemically peculiar stars: theoretical predictions versus modern observing facilities"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3004"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","3018"],["dc.bibliographiccitation.volume","421"],["dc.contributor.author","Kochukhov, Oleg"],["dc.contributor.author","Wade, G. A."],["dc.contributor.author","Shulyak, D."],["dc.date.accessioned","2018-11-07T09:11:36Z"],["dc.date.available","2018-11-07T09:11:36Z"],["dc.date.issued","2012"],["dc.description.abstract","Magnetic Doppler imaging is currently the most powerful method of interpreting high-resolution spectropolarimetric observations of stars. This technique has provided the very first maps of stellar magnetic field topologies reconstructed from time series of full Stokes vector spectra, revealing the presence of small-scale magnetic fields on the surfaces of Ap stars. These studies were recently criticised by Stift et al., who claimed that magnetic inversions are not robust and are seriously undermined by neglecting a feedback on the Stokes line profiles from the local atmospheric structure in the regions of enhanced metal abundance. We show that Stift et al. misinterpreted published magnetic Doppler imaging results and consistently neglected some of the most fundamental principles behind magnetic mapping. Using state-of-the-art opacity sampling model atmosphere and polarized radiative transfer codes, we demonstrate that the variation of atmospheric structure across the surface of a star with chemical spots affects the local continuum intensity but is negligible for the normalized local Stokes profiles except for the rare situation of a very strong line in an extremely Fe-rich atmosphere. For the disc-integrated spectra of an Ap star with extreme abundance variations, we find that the assumption of a mean model atmosphere leads to moderate errors in Stokes I but is negligible for the circular and linear polarization spectra. Employing a new magnetic inversion code, which incorporates the horizontal variation of atmospheric structure induced by chemical spots, we reconstructed new maps of magnetic field and Fe abundance for the bright Ap star a2 CVn. The resulting distribution of chemical spots changes insignificantly compared to the previous modelling based on a single model atmosphere, while the magnetic field geometry does not change at all. This shows that the assertions by Stift et al. are exaggerated as a consequence of unreasonable assumptions and extrapolations, as well as methodological flaws and inconsistencies of their analysis. Our discussion proves that published magnetic inversions based on a mean stellar atmosphere are highly robust and reliable, and that the presence of small-scale magnetic field structures on the surfaces of Ap stars is indeed real. Incorporating horizontal variations of atmospheric structure in Doppler imaging can marginally improve reconstruction of abundance distributions for stars showing very large iron overabundances. But this costly technique is unnecessary for magnetic mapping with high-resolution polarization spectra."],["dc.identifier.doi","10.1111/j.1365-2966.2012.20526.x"],["dc.identifier.isi","000302620700025"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/26759"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-blackwell"],["dc.relation.issn","0035-8711"],["dc.title","Magnetic Doppler imaging considering atmospheric structure modifications due to local abundances: a luxury or a necessity?"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1513"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","1527"],["dc.bibliographiccitation.volume","431"],["dc.contributor.author","Folsom, C. P."],["dc.contributor.author","Likuski, K."],["dc.contributor.author","Wade, G. A."],["dc.contributor.author","Kochukhov, Oleg"],["dc.contributor.author","Alecian, E."],["dc.contributor.author","Shulyak, D."],["dc.date.accessioned","2018-11-07T09:25:14Z"],["dc.date.available","2018-11-07T09:25:14Z"],["dc.date.issued","2013"],["dc.description.abstract","HD 98088 is a synchronized, double-lined spectroscopic binary system with a magnetic Ap primary component and an Am secondary component. We study this rare system using high-resolution Multi-Site Continuous Spectroscopy spectropolarimetric data, to gain insight into the effect of binarity on the origin of stellar magnetism and the formation of chemical peculiarities in A-type stars. Using a new collection of 29 high-resolution Stokes VQU spectra we re-derive the orbital and stellar physical parameters and conduct the first disentangling of spectroscopic observations of the system to conduct spectral analysis of the individual stellar components. From this analysis we determine the projected rotational velocities of the stars and conduct a detailed chemical abundance analysis of each component using both the SYNTH3 and ZEEMAN spectrum synthesis codes. The surface abundances of the primary component are typical of a cool Ap star, while those of the secondary component are typical of an Am star. We present the first magnetic analysis of both components using modern data. Using least-squares deconvolution, we extract the longitudinal magnetic field strength of the primary component, which is observed to vary between +1170 and -920 G with a period consistent with the orbital period. There is no field detected in the secondary component. The magnetic field in the primary is predominantly dipolar, with the positive pole oriented approximately towards the secondary."],["dc.identifier.doi","10.1093/mnras/stt269"],["dc.identifier.isi","000318345200041"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/30017"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","0035-8711"],["dc.title","Orbital parameters, chemical composition and magnetic field of the Ap binary HD 98088"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2669"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","2677"],["dc.bibliographiccitation.volume","416"],["dc.contributor.author","Sachkov, M. E."],["dc.contributor.author","Hareter, M."],["dc.contributor.author","Ryabchikova, Tanya"],["dc.contributor.author","Wade, G."],["dc.contributor.author","Kochukhov, Oleg"],["dc.contributor.author","Shulyak, D."],["dc.contributor.author","Weiss, W. W."],["dc.date.accessioned","2018-11-07T08:51:07Z"],["dc.date.available","2018-11-07T08:51:07Z"],["dc.date.issued","2011"],["dc.description.abstract","In 2009, the rapidly oscillating peculiar A-type (roAp) star 33 Lib was the target of an intense observing campaign, combining ground-based spectroscopy with space photometry obtained with the Microvariability and Oscillation of STars (MOST) satellite. We collected 780 spectra using the Echelle Spectro Polarimetric Device for the Observation of Stars (ESPaDOnS) spectrograph attached at the 3.6-m Canada-France-Hawaii Telescope and 374 spectra with the Fibre-fed Echelle Spectrograph attached at the 2.56-m Nordic Optical Telescope to perform time-resolved spectroscopy of 33 Lib. In addition, we used 111 Ultraviolet and Visual Echelle Spectrograph (UVES) spectra (2004) from the European Southern Observatory archive to check mode stability. Frequency analysis of the new radial velocity (RV) measurements confirms the previously reported frequency pattern (two frequencies and the first harmonic of the main one) and reveals an additional frequency at 1.991 mHz. The new frequency solution perfectly reproduces the RV variations from the 2004 and 2009 observational sets, providing strong support for p mode stability in this roAp star over at least 5 years."],["dc.identifier.doi","10.1111/j.1365-2966.2011.19219.x"],["dc.identifier.isi","000295592600021"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/21857"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","1365-2966"],["dc.relation.issn","0035-8711"],["dc.title","Pulsations in the atmosphere of the rapidly oscillating star 33 Lib"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","444"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","452"],["dc.bibliographiccitation.volume","417"],["dc.contributor.author","Pandey, Chhavi P."],["dc.contributor.author","Shulyak, Denis V."],["dc.contributor.author","Ryabchikova, Tanya"],["dc.contributor.author","Kochukhov, Oleg"],["dc.date.accessioned","2018-11-07T08:51:03Z"],["dc.date.available","2018-11-07T08:51:03Z"],["dc.date.issued","2011"],["dc.description.abstract","The slow rotation and the absence of strong mixing processes in the atmospheres of chemically peculiar stars develop the ideal conditions for the appearance of abundance anomalies through the mechanism of microscopic particle diffusion. This makes these objects look spectroscopically and photometrically different from their 'normal' analogues. As a result, it is often difficult to accurately determine the atmospheric parameters of these stars, and special methods are needed for a consistent analysis of their atmospheres. The main aim of the present paper is to analyse atmospheric abundance and stratification of chemical elements in the atmosphere of the chemically peculiar star HD 103498. We find that there are two model atmospheres, computed with individual and stratified abundances, that provide a reasonable fit to the observed spectroscopic and photometric indicators: T(eff) = 9300 K, log g = 3.5 and T(eff) = 9500 K, log g = 3.6. It is shown that Mg has a large abundance gradient in the star's atmosphere with accumulation of Mg ions in the uppermost atmospheric layers, whereas Si demonstrates the opposite behaviour with accumulation in deep layers. In addition, a detailed non-local thermodynamic equilibrium (non-LTE) analysis showed that none of the Mg transitions under consideration is a subject of noticeable non-LTE effects. By comparing the photometry observations after transforming them to physical units, we estimated the radius of HD103498 to be between R = (4.56 +/- 0.77) R(circle dot) for T(eff) = 9300 K, log g = 3.5, and R = (4.39 +/- 0.75) R(circle dot) for T(eff) = 9500 K, log g = 3.6 models, respectively. We note that the lack of suitable observations in absolute units prevents us from uniquely determining the T(eff) of the star at the current stage of analysis."],["dc.identifier.doi","10.1111/j.1365-2966.2011.19281.x"],["dc.identifier.isi","000296276300052"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/21842"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-blackwell"],["dc.relation.issn","0035-8711"],["dc.title","Abundance and stratification analysis of the chemically peculiar star HD 103498"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","872"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","The Astrophysical Journal"],["dc.bibliographiccitation.lastpage","886"],["dc.bibliographiccitation.volume","720"],["dc.contributor.author","Fossati, Luca"],["dc.contributor.author","Bagnulo, S."],["dc.contributor.author","Elmasli, A."],["dc.contributor.author","Haswell, C. A."],["dc.contributor.author","Holmes, S."],["dc.contributor.author","Kochukhov, Oleg"],["dc.contributor.author","Shkolnik, Evgenya L."],["dc.contributor.author","Shulyak, Denis V."],["dc.contributor.author","Bohlender, D."],["dc.contributor.author","Albayrak, B."],["dc.contributor.author","Froning, C."],["dc.contributor.author","Hebb, L."],["dc.date.accessioned","2018-11-07T08:39:30Z"],["dc.date.available","2018-11-07T08:39:30Z"],["dc.date.issued","2010"],["dc.description.abstract","The knowledge of accurate stellar parameters is paramount in several fields of stellar astrophysics, particularly in the study of extrasolar planets, where often the star is the only visible component and therefore used to infer the planet's fundamental parameters. Another important aspect of the analysis of planetary systems is the stellar activity and the possible star planet interaction. Here, we present a self-consistent abundance analysis of the planet-hosting star WASP-12 and a high-precision search for a structured stellar magnetic field on the basis of spectropolarimetric observations obtained with the ESPaDOnS spectropolarimeter. Our results show that the star does not have a structured magnetic field, and that the obtained fundamental parameters are in good agreement with what was previously published. In addition, we derive improved constraints on the stellar age (1.0-2.65 Gyr), mass (1.23-1.49 M/M(circle dot)), and distance (295-465 pc). WASP-12 is an ideal object in which to look for pollution signatures in the stellar atmosphere. We analyze the WASP-12 abundances as a function of the condensation temperature and compare them with those published by several other authors on planet-hosting and non-planet-hosting stars. We find hints of atmospheric pollution in WASP-12's photosphere but are unable to reach firm conclusions with our present data. We conclude that a differential analysis based on WASP-12 twins will probably clarify whether an atmospheric pollution is present as well as the nature of this pollution and its implications in planet formation and evolution. We also attempt the direct detection of the circumstellar disk through infrared excess, but without success."],["dc.identifier.isi","000281596000074"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/19010"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Iop Publishing Ltd"],["dc.relation.issn","0004-637X"],["dc.title","A DETAILED SPECTROPOLARIMETRIC ANALYSIS OF THE PLANET-HOSTING STAR WASP-12"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]