Large scale calculations of core oscillations in globular clusters

Fokker-Planck simulations of the evolution of globular clusters containing binaries produced by two-body tidal captures and three-body interactions have been separately carried out. In both cases, the expansion phase following the first core collapse is found to be unstable when the codes are run with small time steps (of order the central relaxation time t/sub ro/). Large amplitude highly nonlinear oscillations develop in the core structure parameters such as central density. The instability observed for the case of three-body binaries is quite similar to that found by Bettwiser and Sugimoto in several studies based on the fluid dynamical model for star clusters. It is shown for the case of three-body binaries that the instability is intrinsic to the model rather than numerical in origin. A large-scale study of core oscillations is planned using the Cray X-MP at the National Center for Supercomputing Applications