| Issue |
A&A
Volume 402, Number 1, April IV 2003
|
|
|---|---|---|
| Page(s) | 335 - 342 | |
| Section | Stellar atmospheres | |
| DOI | https://doi.org/10.1051/0004-6361:20030233 | |
| Published online | 07 April 2003 | |
Physical parameters of helium-rich subdwarf B stars from medium resolution optical spectroscopy*
Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland, UK
Corresponding author: A. Ahmad, amir@star.arm.ac.uk
Received:
24
December
2002
Accepted:
13
February
2003
Most subdwarf B (sdB) stars have spectra that show helium (He) abundances depleted to a lesser or greater extent. This has been attributed to diffusion and gravitational settling. However a small but significant number of stars with similar temperatures and gravities show relatively strong helium spectra. The question is how these helium-rich sdB (He-sdB) stars are related to their He-deficient counterparts. We present physical parameters for sample of He-sdB stars using line-blanketed LTE models. From the analysis we show that the He-sdB stars are quite distinct from the He-poor sdB. We also explore the idea of a possible link between some extreme helium (EHe) stars and He-rich subdwarf O (He-sdO) stars.
Key words: stars: chemically peculiar / stars: early-type / subdwarfs / stars: atmospheres / stars: fundamental parameters
© ESO, 2003
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