Cataloging Variable Stars in Andromeda's Stellar Clusters

Recent research has cataloged 86 luminous variable stars within stellar clusters of the Andromeda galaxy (M31), utilizing data from the Panchromatic Hubble Andromeda Treasury (PHAT) survey. This study, titled "Variable Stars in M31 Stellar Clusters from the Panchromatic Hubble Andromeda Treasury," presents a detailed analysis of these stars, which have initial masses ranging from 0.8 to 67 solar masses. The findings indicate that these stars are in various evolutionary phases, including the main sequence and more evolved stages such as hydrogen- and helium-burning phases, as well as the post-asymptotic giant branch.

The researchers employed statistical analysis of light curves and difference imaging techniques to identify the variable stars. They also assessed the likelihood of photometric blending due to the crowded environments of the clusters, which informed their confidence in the derived properties of each star. Among the identified variable star types are RV Tauri variables, red supergiants, and slowly pulsating B-type supergiants, along with Wolf-Rayet stars and classical Cepheids.

This study is significant as it is the first systematic investigation of variable stars in extragalactic stellar clusters, leveraging the high-resolution capabilities of the Hubble Space Telescope. The results contribute to a better understanding of stellar evolution and the physical parameters of variable stars, which can have broader implications for astrophysics and our comprehension of stellar populations in other galaxies. The complete findings are documented in the paper, which is accessible via arXiv: arXiv:2408.12765.