Star clusters are ideal natural laboratories to study stars and our models of stellar evolution. Higher mass stars leave the main sequence faster than lower mass stars. For a star cluster, where all the stars are the same age, this creates the astronomers use to determine the age of the cluster. on the HR diagram of the cluster, which Electron Degeneracy Region Roche Limit Chandrasekhar Limit Main-sequence Turnoff Globular Cluster Conundrum