Multiple stellar generations in globular clusters
Summary
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).