Stellar populations in globular cluster cores: evidence for a peculiar trend among red giant branch stars

Abstract We investigate the relationship between the mass of a globular cluster core and the sizes of its various stellar populations in a sample of 56 globular clusters. The number of core red giant branch stars is found to scale sub-linearly with core mass at the 3σ confidence level, whereas the relation is linear to within one standard deviation for main-sequence turn-off (MSTO) and sub-giant branch stars. We interpret our results as evidence for a surplus of red giant branch stars in the least massive cluster cores which is not seen for MSTO and sub-giant branch stars. We explore various possibilities for the source of this discrepancy, discussing our results primarily in terms of the interplay between the cluster dynamics and stellar evolution.

Stellar populations in globular cluster cores: evidence for a peculiar trend among red giant branch stars Journal Articles