Resolving Extragalactic Star Clusters with HST/ACS

TL;DR

This paper uses HST/ACS to obtain detailed color-magnitude diagrams of extragalactic star clusters, aiding in understanding their properties and testing stellar evolution models.

Contribution

It presents CMDs for two massive extragalactic clusters and compares them with theoretical isochrones, addressing the blue to red supergiant ratio.

Findings

CMDs for two massive clusters are successfully obtained.

Comparison with isochrones provides insights into cluster ages and metallicities.

The blue to red supergiant ratio is analyzed.

Abstract

With HST, colour-magnitude diagrams (CMDs) can be obtained for young star clusters well beyond the Local Group. Such data can help constrain cluster ages and metallicities, and also provide a reference against which intermediate- and high mass stellar models can be compared. Here, CMDs are presented for two massive (>10^5 Msun) clusters and compared with Padua and Geneva isochrones. The problem of the ratio of blue to red supergiants is also addressed.