Journal Article

A grid of non-local thermodynamic equilibrium corrections for magnesium and calcium in late-type giant and supergiant stars: application to <i>Gaia</i>

T. Merle, F. Thévenin, B. Pichon and L. Bigot

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 418, issue 2, pages 863-887
Published in print December 2011 | ISSN: 0035-8711
Published online November 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.19540.x
A grid of non-local thermodynamic equilibrium corrections for magnesium and calcium in late-type giant and supergiant stars: application to Gaia

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We investigate non-local thermodynamic equilibrium (NLTE) effects for magnesium and calcium in the atmospheres of late-type giant and supergiant stars. The aim of this paper is to provide a grid of NLTE/LTE equivalent width ratios W/W* of Mg and Ca lines for the following range of stellar parameters: Teff∈ [3500, 5250] K, log g∈ [0.5, 2.0] dex and [Fe/H] ∈ [− 4.0, 0.5] dex. We use realistic model atoms with the best physics available and taking into account the fine structure. The Mg and Ca lines of interest are in optical and near-IR ranges. A special interest concerns the lines in the Gaia spectrograph [Radial Velocity Spectrometer (RVS)] wavelength domain [8470, 8740] Å. The NLTE corrections are provided as a function of stellar parameters in an electronic table as well as in a polynomial form for the Gaia/RVS lines.

Keywords: line: formation; radiative transfer; stars: abundances; stars: atmospheres; stars: late-type

Journal Article.  14775 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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