Monte Carlo simulations of globular cluster evolution

We study the dynamical evolution of globular clusters using our new two-dimensional Monte Carlo code, and we calculate the lifetimes of clusters in the Galactic environment. We include the eects of a mass spectrum, mass loss in the Galactic tidal Ðeld, and stellar evolution. We consider initial King models containing N \ 105È3] 105 stars, with the dimensionless central potential 3, and 7, andW0 \ 1,with power-law mass functions m~a, with a \ 1.5, 2.5, and 3.5. The evolution is followed up to core collapse or disruption, whichever occurs Ðrst. We compare our results with those from similar calcu-lations using Fokker-Planck methods. The disruption and core collapse times of our models are signiÐ-cantly longer than those of one-dimensional Fokker-Planck models. This is consistent with recent comparisons with direct N-body simulations, which have also shown that the one-dimensional Fokker-Planck models can signiÐcantly overestimate the escape rate from tidally truncated clusters. However, we Ðnd that our results are in very good agreement with recent two-dimensional Fokker-Planck calcu-lations, for a wide range of initial conditions, although our Monte Carlo models have a slightly lower mass-loss rate. We Ðnd even closer agreement of our results with modiÐed Fokker-Planck calculations that take into account the Ðnite nature of the system. In agreement with previous studies, our results show that the direct mass loss due to stellar evolution can signiÐcantly accelerate the mass-loss rat