Study of a sample of periodically variable B-type supergiants

Contains fulltext : 35372.pdf (publisher's version ) (Closed access)One of the pleasing results obtained from the ESA HIPPARCOS space mission was the discovery of a large number of new B-type variables. We were involved in their classification and found some 30 new B-type supergiants with alpha Cyg-like behaviour. The most natural way of explaining this kind of variability is oscillations (see \citet{waelkens1998}). As a follow-up project, we have gathered high-resolution spectroscopic data including the H, He and Si lines for most of these targets. Our aim was to determine from these lines their basic stellar parameters, such as effective temperature, gravity, luminosity, helium abundance and wind characteristics with unprecedented accuracy. For this purpose we use the method of line profile fitting based on the NLTE atmosphere and line formation code FASTWIND (see \citet{puls2005}). Once the parameters are fixed, we will search for correlations among them to help reveal more about the variability mechanism and we will deduce a new calibration for the stellar parameters of galactic B-type supergiants