On the Empirical Instability Domains for Pulsating Subdwarf B Stars
Résumé
We present some of the results of an ongoing spectroscopic survey to derive reliable atmospheric parameters for the known pulsating sdB stars as well as several known constant stars. This survey involves high S/N ratio optical observations in conjunction with detailed NLTE model atmospheres. The homogeneity of our approach allows us, for the first time, to discuss with some confidence the locations of the empirical instability regions for the short-period pulsating EC 14026 stars and for the long-period PG 1716 stars in the surface gravity-effective temperature plane. We also briefly address the question of the influence of a weak stellar wind on these pulsators.