Abstract:
Stars spend most of their lifetimes on the main sequence. Extended main-sequence turnoffs and split main sequences seen in the colour-magnitude diagrams of star clusters pose a fundamental challenge to our traditional understanding of star clusters as “single stellar populations.” These features of early-type stars with masses greater than ∼1.6 solar mass is thought to result from a range in the stellar rotation rates. Here we summarize our current understanding of the role of stellar rotation in defining the morphology of the cluster’s CMD. I will also discuss the origin of the observed rotational distribution of stars in young and intermediate-age stellar clusters.
