Mass loss of stars in star clusters: an energy source for dynamical evolution

Abstract: Dense star clusters expand until their sizes are limited by the tidal field of their host galaxy. During this expansion phase the member stars evolve and lose mass. We show that for clusters with short initial relaxation time scales (<~100 Myr) the dynamical expansion is largely powered by mass loss from stars in the core, but happens on a relaxation time scale. That is, the energy release following stellar mass loss is in balance with the amount of energy that is transported outward by two-body relaxation.