Clusters

Why do stars form in groups? What is the difference between an open star cluster and a globular star cluster? Stars are the ultimate result of interstellar cloud collapse; so many stars are born from the same parent cloud. The stars from the same parent clouds lay in the same region in the space. The fragmented pieces of cloud, which later are converted to stars, are not ejected far in during collision. When the fragments become star clusters or star groups are created. The difference between Open cluster and Globular clusters are: An open cluster is normally a loose, irregular grouping where as Globular clusters is tightly bound. Open clusters usually contains somewhere between a dozen to thousand stars where as Globular clusters contain ten thousand to a million stars. The stars in open clusters are much younger then the stars in Globular clusters. The stars in open clusters are held together by mutual gravitational attraction and have a common center mass, where as stars in Globular clusters are gravitationally bound in a tight concentration.