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arXiv · 1011.2092

A grid of MARCS model atmospheres for S stars

Sophie Van Eck·Pieter Neyskens·Bertrand Plez·Alain Jorissen·Bengt Edvardsson·Kjell Eriksson·Bengt Gustafsson·Uffe-Grae Jorgensen·Ake Nordlund
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Abstract

S-type stars are late-type giants whose atmosphere is enriched in carbon and s-process elements because of either extrinsic pollution by a binary companion or intrinsic nucleosynthesis and dredge-up on the thermally-pulsing AGB. A large grid of S-star model atmospheres has been computed covering the range 2700 < Teff < 4000 K with 0.5 < C/O < 0.99. ZrO and TiO band strength indices as well as VJHKL photometry are needed to disentangle Teff, C/O and [s/Fe]. A "best-model finding tool" was developed using a set of well-chosen indices and checked against photometry as well as low- and high-resolution spectroscopy. It is found that applying M-star model atmospheres (i.e., with a solar C/O ratio) to S stars can lead to errors on Teff up to 400K. We constrain the parameter space occupied by S stars of the vast sample of Henize stars in terms of Teff, [C/O] and [s/Fe].

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Sophie Van Eck, Pieter Neyskens, Bertrand Plez, Alain Jorissen, Bengt Edvardsson, Kjell Eriksson, Bengt Gustafsson, Uffe-Grae Jorgensen, Ake Nordlund. 2010-11-09. A grid of MARCS model atmospheres for S stars. https://arxiv.org/abs/1011.2092

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