Abstract

Properties of Young Massive Stars and the role of Rotation, Binary Interaction and Stellar Mergers

Selma de Mink (Space Telescope Science Institute)

N. Langer, Argelander Institute Bonn R. Izzard, Argelander Institute Bonn

Rotation can have severe consequences for the evolution of massive stars and is now considered as one of the main parameters (alongside mass and metallicity) determining the final fate of single stars. Especially in binaries high stellar rotation rates can be readily achieved as a result of (I) tides in close binaries, (II) mass transfer, which can drive the accreting star towards critical rotation probably resulting in severe mass loss from the system, and (III) mergers. I will discuss new evolutionary models and population synthesis simulations that are performed in the context of the VLT-FLAMES Tarantula survey (Evans et al 2011). In particular, I will discuss the effect of binary interaction on the distribution of rotation rates of hot massive stars and the role of stellar mergers in close binaries. A somewhat surprising outcome is the very significant fraction of stellar mergers predicted to be present among the most massive stars in young clusters. This raises various questions, for example, whether "apparent single stars" are indeed suitable to test evolutionary models of single stars (as for example in Hunter et al. 2008).