paper

A comprehensive Nbody study of mass segregation in star clusters: Energy equipartition and escape

arXiv:astro-ph/0602570 · doi:10.1111/j.1365-2966.2006.11184.x

Abstract

We address the dynamical evolution of an isolated self--gravitating system with two stellar mass groups. We vary the individual ratio of the heavy to light bodies, from 1.25 to 50 and alter also the fraction of the total heavy mass $\MH$ from 5% to 40% of the whole cluster mass. Clean-cut properties of the cluster dynamics are examined, like core collapse, the evolution of the central potential, as well as escapers. We present in this work collisional -body simulations, using the high--order integrator NBODY6++ with up to particles improving the statistical significancy of the lower-- simulations by ensemble averages. Equipartition slows down the gravothermal contraction of the core slightly. Beyond a critical value of , no equipartition can be achieved between the different masses; the heavy component decouples and collapses. For the first time the critical boundary between Spitzer--stable and --unstable systems is demonstrated in direct -body models.

21 pages, minor changes, accepted for publication MNRAS, needs mn2e.bst and mn2e.cls (included)

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