%0 Journal Article
%T Red Supergiant Stars as Cosmic Abundance Probes: II. NLTE Effects in J-band Silicon Lines
%A Maria Bergemann
%A Rolf-Peter Kudritzki
%A Matthias Wueurl
%A Bertrand Plez
%A Ben Davies
%A Zach Gazak
%J Physics
%D 2012
%I arXiv
%R 10.1088/0004-637X/764/2/115
%X Medium resolution J-band spectroscopy of individual red supergiant stars is a promising tool to investigate the chemical composition of the young stellar population in star forming galaxies. As a continuation of recent work on iron and titanium, detailed non-LTE calculations are presented to investigate the influence of NLTE on the formation of silicon lines in the J-band spectra of red supergiants. Substantial effects are found resulting in significantly stronger absorption lines of neutral silicon in non-LTE. As a consequence, silicon abundances determined in non-LTE are significantly smaller than in LTE with the non-LTE abundance corrections varying smoothly between -0.4 dex to -0.1 dex for effective temperatures between 3400K to 4400K. The effects are largest at low metallicity. The physical reasons behind the non-LTE effects and the consequences for extragalactic J-band abundance studies are discussed.
%U http://arxiv.org/abs/1212.2649v1