Seminario FCAG: “Variability of Galactic blue supergiants observed with TESS”

Lunes 22 de abril – 14:00 hs – Salón Meridiano

Dr. Michalis Kourniotis (Astronomical Institute, Czech Academy of Sciences)

Resumen: Blue supergiants (BSGs) are core-helium or shell-hydrogen burning stars of OB type that evolve redwards, bringing so the poorly explored gap between the hot early phases of massive stars and their late stages prior to their supernova explosion. As a result, they mediate between stellar types with divergent properties with respect to atmospheric stability, mass loss, and interior structure. Therefore, their study offers a unique opportunity to capture deterministic for the post-main sequence evolution mechanisms, which drive evolutionary channels to the occurrence of rare exotic stars such as the luminous blue variables, and lead to the diverse types of supernovae. The current study focuses on a compilation of 64 Galactic southern BSGs, significant fraction of which have been observed with CASLEO 2.15 JS m telescope. In collaboration with the massive star group of University of La Plata, we systematically explore the TESS light curves of the studied sample in order to characterize the stellar variability with timescales up to 80 d, periodicity up to 14 d that is attributed to gravity-mode oscillations or to rotational modulation, as well as stochastic low-frequency variability that is generated by the turbulent convective core and/or to sub-surface convection. We present correlations between the stellar parameters and the manifestations of the individual physical mechanisms on the time-series data, further extending our discussion to diagnostics of the evolutionary stage of BSGs and of their binarity.

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ID de reunión: 896 4268 7970

Código de acceso: 526656