N ‐body models of rotating globular clusters

In this paper we examine the dynamical evolution of rotating globular clusters with direct N ‐body models. Our initial models are rotating King models, and we obtain results both for equal‐mass systems and for systems composed of two mass components. Previous investigations using a Fokker–Planck solver have shown that rotation has a noticeable influence on stellar systems such as globular clusters that evolve by two‐body relaxation. In particular, it accelerates their dynamical evolution through the gravogyro instability. We have validated the occurrence of the gravogyro instability with direct N ‐body models. In the case of systems composed of two mass components, mass segregation takes place, a process that competes with the rotation in the acceleration of the core collapse. The ‘accelerating’ effect of rotation was detected in our isolated two‐mass N ‐body models. Finally, we look at rotating N ‐body models in a tidal field within the tidal approximation. It turns out that rotation increases the escape rate significantly. A difference between retrograde‐ and prograde‐rotating stellar clusters, with respect to the orbit of the cluster around the Galaxy, occurs. This difference is the result of the presence of a ‘third integral’ and chaotic scattering, respectively.