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200 papers

Planetary atmospheres, and models of them, are discussed from the viewpoint of condensed matter physics. Atmospheres are a form of condensed matter, and many interesting phenomena of condensed matter systems are realized by them. The…

Statistical Mechanics · Physics 2012-02-27 J. B. Marston

$Aims.$ We present a database of 43,340 atmospheric models ($\sim$80,000 models at the conclusion of the project) for stars with stellar masses between 9 and 120 $M_{\odot}$, covering the region of the OB main-sequence and Wolf-Rayet (W-R)…

Solar and Stellar Astrophysics · Physics 2020-11-18 J. Zsargo , C. R. Fierro-Santillan , J. Klapp , A. Arrieta , L. Arias , J. M. Valencia , L. Di G. Sigalotti , M. Hareter , R. E. Puebla

The formation of lithium lines in the atmosphere of C-rich giants is discussed. LTE and NLTE approximations are used to model lithium lines in the spectra of super Li-rich AGB stars. The system of equations of the statistical balance of…

Astrophysics · Physics 2011-05-23 Carlos Abia , Yakiv Pavlenko , Patrick de Laverny

Based on detailed 2D and 3D numerical radiation-hydrodynamics (RHD) simulations of time-dependent compressible convection, we have studied the dynamics and thermal structure of the convective surface layers of a prototypical late-type…

Astrophysics · Physics 2009-11-07 H. -G. Ludwig , F. Allard , P. H. Hauschildt

Radiation-hydrodynamical simulations of surface convection in low-mass stars can be exploited to derive estimates of i) the efficiency of the convective energy transport in the stellar surface layers; ii) the convection-related photometric…

Astrophysics · Physics 2009-11-13 Hans-G. Ludwig , Elisabetta Caffau , Arunas Kucinskas

We compare current 1D and multi-dimensional atmosphere modelling approaches for massive stars to understand their strengths and shortcomings. We calculate averaged stratifications from selected 2D calculations for O stars -- corresponding…

Standard 1D stellar evolution model has poor descriptions of the near-surface layers of stars, and this can be improved by using the atmosphere model computed from 3D hydrodynamical simulations. In this work, we validated the model…

Solar and Stellar Astrophysics · Physics 2025-12-02 Zhikai Li , Tanda Li , Yixiao Zhou , Shaolan Bi

Methods to determine abundances of the elements in the atmospheres of F, G, and K stars with precisions of 0.01-0.03 dex are reviewed. Such high-precision stellar abundances have led to the discovery of unexpected phenomena and relations…

Solar and Stellar Astrophysics · Physics 2018-11-06 Poul Erik Nissen , Bengt Gustafsson

We investigate the synthesis of the Balmer and Paschen lines of the quiet Sun, using both classical semi-empirical and theoretical model atmospheres, modern line broadening theory and non-LTE line-formation. The computations alleviate…

Astrophysics · Physics 2009-11-10 Norbert Przybilla , Keith Butler

Understanding the atmospheric parameters of stars on the top of the RGB is essential to reveal the chemical composition of the Milky Way, as they can be used to probe the farthest parts of our Galaxy. Our goal is to determine the chemical…

Solar and Stellar Astrophysics · Physics 2024-04-23 Z. Dencs , A. Derekas , T. Mitnyan , M. F. Andersen , B. Cseh , F. Grundahl , V. Hegedűs , J. Kovács , L. Kriskovics , P. L. Palle , A. Pál , L. Szigeti , Sz. Mészáros

The M-type star Gliese 581 is orbited by at least one terrestrial planet candidate in the habitable zone, i.e. GL 581 d. Orbital simulations have shown that additional planets inside the habitable zone of GL 581 would be dynamically stable.…

Earth and Planetary Astrophysics · Physics 2015-05-27 P. von Paris , S. Gebauer , M. Godolt , H. Rauer , B. Stracke

On the basis of geological evidence, it is often stated that the early martian climate was warm enough for liquid water to flow on the surface thanks to the greenhouse effect of a thick atmosphere. We present 3D global climate simulations…

We investigate departures from LTE in the line formation of Fe for a number of well-studied late-type stars in different evolutionary stages. A new model of Fe atom was constructed from the most up-to-date theoretical and experimental…

Solar and Stellar Astrophysics · Physics 2015-06-05 Maria Bergemann , Karin Lind , Remo Collet , Zazralt Magic , Martin Asplund

Evolved stars are among the largest and brightest stars and they are ideal targets for the new generation of sensitive, high resolution instrumentation that provides spectrophotometric, interferometric, astrometric, and imaging observables.…

Solar and Stellar Astrophysics · Physics 2015-12-16 A. Chiavassa , B. Freytag

We investigate the role of convection in the formation of atomic and molecular lines in the atmosphere of a red giant star. For this purpose we study the formation properties of spectral lines that belong to a number of astrophysically…

Solar and Stellar Astrophysics · Physics 2013-05-16 A. Kucinskas , M. Steffen , H. -G. Ludwig , V. Dobrovolskas , A. Ivanauskas , J. Klevas , D. Prakapavicius , E. Caffau , P. Bonifacio

As one of the most important elements in astronomy, iron abundance determinations need to be as accurate as possible. We investigate the accuracy of spectroscopic iron abundance analyses using archetypal metal-poor stars. We perform…

Solar and Stellar Astrophysics · Physics 2016-09-15 A. M. Amarsi , K. Lind , M. Asplund , P. S. Barklem , R. Collet

We present a homogeneous set of stellar atmospheric parameters Teff, log g, [Fe/H] for MILES, a new spectral stellar library covering the range 3525 - 7500 angstrom at 2.3 angstrom (FWHM) spectral resolution. The library consists of 985…

The fitting atmosphere parameters (Teff, g, and [Fe/H]) for over 300 stars in the Gunn & Striker and Jacoby et al. catalogs have been obtained relying on the Kurucz (1992) ATLAS9 and Hauschildt et al (1999) NextGen5 synthesis models. The…

Astrophysics · Physics 2016-01-27 E. Bertone , A. Buzzoni , M. Chavez , L. H. Rodriguez

Late type giants (RGB/AGB stars) will be important tracers of the Galactic morphology and evolution in the framework of Gaia, as they are intrinsically bright and thus can probe distant stellar populations or those obscured by interstellar…

The accuracy of measuring the basic parameters of neutron stars is limited in particular by uncertainties in chemical composition of their atmospheres. For example, atmospheres of thermally - emitting neutron stars in supernova remnants…

High Energy Astrophysical Phenomena · Physics 2015-06-18 V. F. Suleimanov , D. Klochkov , G. G. Pavlov , K. Werner