Multiple stellar generations in globular clusters

Abstract

Globular clusters are spherical shaped objects which consist of a dense distribution of thousands of stars and which orbit the centers of galaxies. Unlike the stars in the disk of a galaxy, globular clusters are found in the halos around galaxies. The MilkyWay hosts approximately 200 globular clusters, from which ! Centauri is the brigthest and largest. It is commonly believed that most globular clusters consist of a single generation of stars, which are mostly very old and have low metallicity (these stars are called population II stars).