Spectroscopic studies of DB white dwarfs: The instability strip of the pulsating DB (V777 HER) stars

被引：124

作者：

Beauchamp, A

Wesemael, F

Bergeron, P

Fontaine, G

Saffer, RA

Liebert, J

Brassard, P

机构：

[1] CAE Elect Ltee, St Laurent, PQ H4L 4X4, Canada

[2] Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada

[3] Lockheed Martin Canada, Montreal, PQ H4P 1K6, Canada

[4] Villanova Univ, Dept Astron & Astrophys, Villanova, PA 19085 USA

[5] Univ Arizona, Steward Observ, Tucson, AZ 85721 USA

来源：

ASTROPHYSICAL JOURNAL | 1999年 / 516卷 / 02期

关键词：

stars : atmospheres; stars : oscillations; white dwarfs;

D O I：

10.1086/307148

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We have secured optical spectra for the eight currently known variable DB, or V777 Her, stars. With the help of a new generation of synthetic spectra, spectroscopic effective temperatures are derived for these objects, as well as for 15 other DB or DBA stars above 20,000 K. We find that the location of the boundaries of the instability strip is sensitive to the atmospheric hydrogen abundance assumed for DB stars: the strip covers the range 22,400-27,800 K if atmospheres of pure helium are used and the range 21,800-24,700 K if undetectable traces of hydrogen are allowed for in the DB models. These determinations provide independent constraints for current seismological analyses of the V777 Her stars. More sensitive searches for weak hydrogen features in hot DB stars should help decide between the two temperature scales.

引用

页码：887 / 891

页数：5