No evidence for younger stellar generations within the intermediate age massive clusters NGC 1783, NGC 1696 and NGC 411

TL;DR

This study challenges previous claims of multiple stellar generations within certain intermediate age clusters, demonstrating that the supposed young populations are likely field stars and not cluster members.

Contribution

The paper refutes prior evidence for multiple stellar generations in specific clusters by analyzing background contamination and field star presence.

Findings

Young stellar populations are from surrounding fields, not the clusters.

Background subtraction methods used previously are inadequate.

No evidence supports multiple generations within the clusters.

Abstract

Recently, Li et al. (2016) claimed to have found evidence for multiple generations of stars in the intermediate age clusters NGC 1783, NGC 1696 and NGC 411 in the Large and Small Magellanic Clouds (LMC/SMC). Here we show that these young stellar populations are present in the field regions around these clusters and are not likely associated with the clusters themselves. Using the same datasets, we find that the background subtraction method adopted by the authors does not adequately remove contaminating stars in the small number Poisson limit. Hence, we conclude that their results do not provide evidence of young generations of stars within these clusters.