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- Title
Oxygen abundance determination of B-type stars with the O ı 7771-5 Å lines.
- Authors
Yoichi TAKEDA; Satoshi HONDA
- Abstract
Oxygen abundances of 34 B-type stars in the effective temperature range of Teff ~ 10000-28000 K with diversified rotational velocities (vesin i ~ 0-250 kms-1) were determined from the O ı triplet lines at 7771-5 Å, with an aim of examining whether this O ı feature can be a reliable abundance indicator for such high-temperature stars including rapid rotators. It revealed that the required non-local thermodynamic equilibrium (LTE) abundance correction is distinctly large (ranging from ~-0.6 dex to ~-1.7 dex) and its consideration is indispensable. On the condition that the non-LTE effect is taken into account, this triplet is a useful O abundance indicator (with a precision of ≲0.2 dex) up to Teff ≲ 25000 K, since its total equivalent width is sufficiently large (≲200 mÅ). In contrast, it is not adequate for abundance derivation for stars at Teff ≲ 25000 K, where its strength rapidly drops down toward a hardly detectable level (except for sharp-lined stars) and its sensitivity to Teff or log g becomes considerably large. The resulting non-LTE oxygen abundances turned out to be almost normal (i.e., near-solar around ~8.7-8.8 within ~±0.2 dex) for most stars without any dependence upon projected rotational velocity as well as luminosity (or mass), which is consistent with the prediction of recent stellar evolution calculations.
- Subjects
STELLAR atmospheres; STELLAR rotation; STELLAR dynamics; OXYGEN; STARS
- Publication
Publications of the Astronomical Society of Japan, 2016, Vol 68, Issue 3, p1
- ISSN
0004-6264
- Publication type
Article
- DOI
10.1093/pasj/psw021