NLTE analyses of sdB stars: progress and prospects
Abstract
We report on preliminary results of a hybrid non-LTE analysis of high-resolution, high-S/N spectra of the helium-rich subdwarf B star Feige49 and the helium-poor sdB HD205805. Non-LTE effects are found to have a notable impact on the stellar parameter and abundance determination. In particular the HeI lines show significant deviations from detailed balance, with the computed equivalent widths strengthened by up to ~35%. Non-LTE abundance corrections for the metals (C, N, O, Mg, S) are of the order ~0.05-0.25 dex on the mean, while corrections of up to ~0.7 dex are derived for individual transitions. The non-LTE approach reduces systematic trends and the statistical uncertainties in the abundance determination. Consequently, non-LTE analyses of a larger sample of objects have the potential to put much tighter constraints on the formation history of the different sdB populations than currently discussed.
Keywords
Cite
@article{arxiv.astro-ph/0512151,
title = {NLTE analyses of sdB stars: progress and prospects},
author = {N. Przybilla and M. F. Nieva and H. Edelmann},
journal= {arXiv preprint arXiv:astro-ph/0512151},
year = {2007}
}
Comments
8 pages, 5 figures; to appear in: Baltic Astronomy, Proceedings of the Second Meeting on Hot Subdwarf Stars an Related Objects, La Palma, June 2005