where N is the number of stars in the cluster and t c r o s s is the typical time it takes for a star to cross the cluster. This is on the order of 100 million years for a typical globular cluster with radius 10 parsecs consisting of 100 thousand stars. The most massive stars in a cluster can segregate more rapidly than the less massive stars. This time-scale can be approximated using a toy model developed by Lyman Spitzer of a cluster where stars only have two possible masses ( m 1 and m 2 ). In this case, the more massive stars (mass m 1 ) will segregate in the time