Star Clusters as Touchstones for Theories of Galactic Evolution — A Few Examples

Abstract

Observations of NGC 5128 (Cen A) show that this giant elliptical galaxy contains few globular clusters. The fact that the number of globular clusters per unit luminosity in E galaxies has a range of ∼ 102 indicates that different ellipticals were formed in differing physical environments. It is pointed out that more data on the frequency with which globular clusters occur in elliptical galaxies might place interesting constraints on theories of galaxy clustering.Intercomparison of the Local Group galaxies IC 1613 and the SMC shows that differences in the frequency of cluster formation also occur among Irregular galaxies.It is pointed out that globular clusters associated with distant galaxies probably start to outnumber galactic stars for B > 31.The discovery that the LMC supernova remnant N63A is situated in the small association N2030 shows that this object must have been formed from a star with a main sequence mass > 30 M⊙.Finally we show that E3, which is one of the faintest known galactic globular cluster, was decimated by tidal forces. Due to the interplay of equipartition and tidal effects this cluster has been severely depleted in single stars while retaining many (presumably binary) blue stragglers.