The Star Clusters of the Small Magellanic Cloud: Age Distribution

TL;DR

This study measures ages of 195 star clusters in the Small Magellanic Cloud, revealing a smooth decline in cluster numbers with age, insights into cluster disruption, and spatial distribution differences across ages.

Contribution

It provides a comprehensive age catalog for SMC clusters using integrated colors and models, highlighting the importance of color evolution and spatial distribution in understanding cluster formation and disruption.

Findings

Cluster age distribution declines as t^{-2.1}

Disruption time scales with mass as M^{0.48}

Initial cluster formation was the dominant epoch

Abstract

We present age measurements for 195 star clusters in the Small Magellanic Cloud based on comparison of integrated colors measured from the Magellanic Clouds Photometric Survey with models of simple stellar populations. We find that the modeled nonuniform changes of cluster colors with age can lead to spurious age peaks in the cluster age distribution, that the observed numbers of clusters with age, t, declines smoothly as t^{-2.1}, that for an assumed initial cluster mass function scaling as M^{-2} the dependence of the cluster disruption time on mass is proportional to M^{0.48}, that despite the apparent abundance of young clusters the dominant epoch of cluster formation was the initial one, and that there are significant differences in the spatial distribution of clusters of different ages. Because of limited precision in our age measurements, we cannot address the question of detailed correspondence between the cluster age function and the field star formation history. However, this sample provides an initial guide for which clusters to target in more detailed studies of specific age intervals.