Late core collapse in star clusters and the gravothermal instability

The numerical Fokker-Planck determinations of core collapse in a one-component star cluster shows that a nonisothermal self-similar structure develops in the region between the shrinking isothermal core and the halo during the late stages of the core collapse. The region is characterized by the radial profiles of the stellar density, the gravitational potential, and velocity dispersion following the power laws; the central velocity dispersion increases with the central density. The data provide new evidence for the identification of the late stage of core collapse with the gravothermal instability of Lynden-Bell and Wood (1968).