Contributed Talk - Splinter Stellar

Thursday, 24 September 2020, 15:17   (virtual room M)

Kinematic and cosmetic consequences of (massive) binary interactions

Mathieu Renzo
CCA, Flatiron Institute

Massive OB-type stars are predominantly members of binary systems close enough to experience mass transfer during their lifetime. Even in the most gentle case of a stable Roche-lobe overflow, both stars and their orbit will be affected. In ~80% of the cases, when one star (typically the donor) goes supernova, the companion is ejected and becomes a slow-moving "walkaway". Even in the Gaia era, kinematics alone might not be sufficient to find these abundant and yet elusive binary products. In this talk, I will present detailed stellar evolution models of both stars in a binary, focusing in particular on the accretor star. Modeling the detailed internal structure of the accretor is crucial to find them in observed sample, especially at the high mass end where the stellar lifetimes of donors and accretors become comparable, and thus the accretor is significantly evolved when mass transfer starts. In particular, accreting models will have a different core-envelope boundary layer due to the "rejuvenation" and fast surface rotation, which could lead to peculiar asteroseismology and/or time variability. Although systematic uncertainties in the models are large and difficult to quantify, significant pollution of the surface by CNO processed material might be limited by the early onset of fast rotation in the accretor.