Evolution of star clusters on eccentric orbits: semi-analytical approach

We study the dynamical evolution of star clusters on eccentric orbits using a semi-analytical approach. In particular we adapt and extend the equations of the EMACSS code, introduced by Gieles et al., to work with eccentric orbits. We follow the evolution of star clusters in terms of mass, half-mass radius, core radius, Jacobi radius, and the total energy over their dissolution time. Moreover, we compare the results of our semi-analytical models against N-body computations of clusters with various initial half-mass radii, numbers of stars, and orbital eccentricities to cover both tidally filling and underfilling systems. The evolution profiles of clusters obtained by our semi-analytical approach closely follow those of N-body simulations in different evolutionary phases of star clusters, from pre-collapse to post-collapse. Given that the average runtime of our semi-analytical models is significantly less than that of N-body models, our approach makes it feasible to study the evolution of large samples of globular clusters on eccentric orbits.