Würzburg 2018 – scientific programme
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EP: Fachverband Extraterrestrische Physik
EP 13: Astrophysics II - Massive stars: Evolution, Winds and Pulsation
EP 13.3: Talk
Friday, March 23, 2018, 10:00–10:15, BSZ - Pabel HS
Pulsations as a mass-loss trigger in B-type supergiants — •Michaela Kraus1, Lydia Cidale2, Maximiliano Haucke2, Anna Aret1,3, Indrek Kolka3, Dieter Nickeler1, and Sanja Tomić1 — 1Astronomical Institute, Czech Academy of Sciences, Ondřejov, Czech Republic — 2National University of La Plata, La Plata, Argentina — 3Tartu Observatory, Tõravere, Estonia
The evolutionary path of massive stars from the main-sequence to their deaths as supernovae is still most uncertain. It comprises various extreme transition phases, in which the stars shed huge amounts of material into their environments, typically via episodic, sometimes even eruptive events. These objects are luminous super- or hypergiants populating the upper, luminous part of the HR diagram and spreading from spectral type O to F or even later. As mass-loss is crucial for the fate of a star, understanding the mechanisms behind mass ejection phases and exploring the mass lost during such events is essential.
We focus on B supergiants which are known to display photometric and spectroscopic variability which has been suggested to be linked to pulsations. To elucidate the influence of pulsations on their mass-loss behavior we initiated a spectroscopic monitoring campaign. Our analysis reveals that B supergiants on a blue-loop evolution tend to pulsate in multiple modes, including radial strange-modes which are known to facilitate mass-loss. Moreover, we find that these stars display variable mass-loss on time-scales that correlate with the suspected period of strange mode pulsation, suggesting a tight relation between strange modes and phases of enhanced mass loss in these objects.