Impact of metallicity on the evolution of young star clusters

Abstract

We discuss the results of N-body simulations of intermediate-mass young star clusters (SCs) with three different metallicities (Z=0.01, 0.1 and 1 Zsun), including metallicity-dependent stellar evolution recipes and metallicity-dependent prescriptions for stellar winds and remnant formation. The initial half-mass relaxation time of the simulated young SCs (~10 Myr) is comparable to the lifetime of massive stars. We 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 (up to a factor of two) larger than the difference in the half-mass radius.