The initial mass function and the dynamical evolution of open clusters .3. With primordial binaries

This paper presents the results of several direct N-body calculations of star cluster models, containing a fraction of initial binary population, without mass loss due to stellar evolution. These primordial binaries are generated with several initial mass functions for checking their influence on the dynamical evolution of clusters. Our results show that primordial binaries dominate completely the evolution of poor clusters and control it until they are ejected or disrupted; their effect is smaller for rich clusters. The quantitative behaviour seems to be dependent on the mass spectrum. Evolution of primordial binaries is examined in detail. The binary escape rate is studied and some conclusions are presented. The final product of cluster evolution, the star cluster remnant, is also discussed.