Monte Carlo calculations for the evolution of spherical stellar systems are extended to Plummer's (1915) model, a system whose initial state is an n = 5 polytrope. The evolution of this model is shown to be entirely consistent with that of previous one-component models. It is found that the initial halo is intermediate between those of Spitzer and Thuan's (1972) models D and F. The time to collapse as well as the growth rate of the escape rate are consequently intermediate between the corresponding values of those previous models. It is also found that the collapse rate for the present model is the same as that for the previous one-component models and that the velocity anisotropy in the transition region between the isothermal core and the halo increases quickly as the collapse accelerates. The latter effect is shown to be qualitatively consistent with a gravitational instability in a system with long mean free paths.
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L. et al. (1975) studied this question.