Simulating young star clusters with different metallicity: impact on structural evolution and stellar exotica

by Michela Mapelli (INAF - Osservatorio Astronomico di Padova)

Monday 6 May 2013, 16:00 → 18:00 Europe/Rome

Aula Conversi (Dip. di Fisica - Edificio G. Marconi)

In this talk, I present an upgraded version of the public code STARLAB, in which we implemented metal-dependent stellar evolution, stellar winds from Wolf-Rayet and luminous blue variable stars, and new recipes for the formation of stellar remnants. This code is suitable for simulating young dense star clusters (SCs) with different metallicity. I discuss the results of a set of simulations of young dense SCs, with metallicity ranging from 0.01 solar up to solar. The metallicity plays a crucial role for both the structural e! volution of the SC and the formation of stellar exotica. As for the structural evolution, I show that mass-loss by stellar winds influences the reversal of core collapse and the expansion of the half-mass radius. In particular, the post-collapse re-expansion of the core is weaker for metal-poor SCs than for metal-rich SCs, because the former lose less mass (through stellar winds) than the latter. As a consequence, the half-mass radius expands faster in metal-poor SCs. The difference in the half-light radius between metal-poor SCs and metal-rich SCs is larger than the difference in the half-mass radius. As for the stellar exotica, I discuss the formation and the dynamical evolution of massive (>25 Msun) stellar black holes (MSBHs) in metal-poor SCs. I show that they can contribute significantly to the population of X-ray binaries and of double-degenerate binaries.