Origin of Extended Star Clusters

TL;DR

This paper reports the discovery of nearby extended star clusters in galaxy NGC 6822, highlighting their large size compared to globular clusters and discussing potential formation scenarios and the need for further research.

Contribution

First identification of nearby extended star clusters in NGC 6822, providing new data for understanding their properties and origins.

Findings

ESCs are larger than typical globular clusters

ESCs share similar color and luminosity with globular clusters

Sample of ESCs is the nearest available to date

Abstract

We have discovered new extended star clusters (ESCs) in a nearby dIrr galaxy NGC 6822. These clusters are the nearest sample of ESCs available to date. The key characteristic of ESCs is their large size compared to typical globular clusters even though the two cluster populations are rather similar in terms of other parameters, i.e., color and luminosity. Several scenarios have been suggested to explain the formation of ESCs. However, the currently known ESCs may be a mixture of populations with heterogeneous formation histories. Future observational and theoretical studies are expected to better constrain the origins of ESCs as well as to increase their sample size.