Dissolution of Globular Clusters

Globular clusters are among the oldest objects in galaxies, and understanding the details of their formation and evolution can bring valuable insight into the early history of galaxies. Until the late 1970s, globular clusters were thought of to be relatively static stellar systems, a view which was supported by the fact that most observed density profiles of globular clusters can be fitted with equilibrium models like e.g. King (1966) profiles. This view has changed significantly over the last twenty years. On the observational side, the evidence for differences in the stellar mass-functions of globular clusters (Piotto, Cool & King 1997, de Marchi et al. 1999), which are believed to be at least partly the result of their dynamical evolution, and the discovery of extratidal stars surrounding globular clusters (Grillmair et al. 1995, Odenkirchen et al. 2003) are strong indications for the ongoing dynamical evolution and dissolution of globular clusters. On the theoretical side, N -body simulations of star cluster evolution have become increasingly sophisticated, due to both progresses in simulation techniques (e.g. Mikkola & Aarseth 1993, Aarseth 1999) and the development of the GRAPE series of special purpose computers (Sugimoto et al. 1990, Makino et al. 2003), which allows to simulate the evolution of star clusters with increasingly larger particle numbers. This review summarises the current knowledge about the dissolution of star clusters and discusses the implications of star cluster dissolution for the evolution of the mass function of star cluster systems in galaxies.