Piotr Kołaczek-Szymański

Instytut Astronomiczny, Uniwersytet Wrocławski

Sesja VI: Gwiazdy, układy gwiazd oraz materia międzygwiazdowa

Czwartek 14.09.2023 10:24 – 10:37

abstrakt:
Eccentric ellipsoidal variables (EEVs, also dubbed as heartbeat stars) provide an excellent laboratory for studying the strong tidal interactions between components in binary systems. The record holder in terms of the range of brightness variations (~0.4 mag in V passband) is the `extreme’ and massive EEV, MACHO80.7443.1718, whose primary component is a B0.5 Iae blue supergiant orbited by a late-O type dwarf in a highly eccentric orbit. However, the problem is that even combined proximity effects fail to explain such significant changes in brightness. The time-series spectra of this object and the light curves obtained by us in the U and B passbands come to the rescue, showing that MACHO80.7443.1718 is probably a very rare example of a massive star that entered the Hertzsprung gap quite recently and undergoes envelope stripping due to the extreme stellar wind, enhanced by the close stellar companion.