Characterization of variability to unveil the link between pulsations and stellar mass-loss in B-Supergiants

Abstract

B-Supergiants are famous for their spectroscopic variability that has been assigned to pulsations and related changes in their stellar wind properties (Kraus et al. 2015). In particular, these objects that have passed through a red supergiant stage are known to present many pulsation modes including radial strange modes (Saio et al. 2013).

The latter have been proposed to facilitate mass-loss. For a proper identification and classification of the pulsations of B-supergiants along with a proper determination of the stellar and wind parameters, simultaneous photometric and spectroscopic observations are indispensable.

TESS revealed that many B-supergiants display a rather irregular behaviour of their light curves. From the TESS mission we have selected northern B-supergiants that have already or will be observed (respectively re-observed) in the upcoming cycles.

From this sample, we selected those objects which display irregular variability, a likely indicator of radial strange mode pulsations. Many of those objects lack spectroscopic data, therefore we have initiated a spectroscopic monitoring campaign carried out with the PEREK 2m telescope.

The spectra will be used to search for variations in temperature and radius using strategic line ratios. Any detected variability can be directly linked with radial pulsations.

Moreover changes in the strength and profile of the Hɑ line provide complementary information about wind variability. In this poster we present first results on 3 selected B-Supergiants: Rho Leo, HD 21291, and HD 205196.