Mass loss of different stellar populations in globular clusters

TL;DR

This paper aims to disentangle the effects of helium abundance and mass loss on the horizontal branch stars in globular clusters by combining advanced photometric analysis with stellar evolution models.

Contribution

It introduces a novel approach using chromosome maps and multi-band photometry to estimate helium abundance and break parameter degeneracies in globular cluster studies.

Findings

First estimates of helium abundance for multiple populations in GCs.

Insights into the role of mass loss during pre-HB stages.

Foundation for understanding multiple stellar populations.

Abstract

Once fixed the age and metallicity; the colour distribution of horizontal branch stars in a globular cluster depends on few parameters: the helium abundance of the population and the mass lost during the pre-HB stages. These parameters are usually derived from the HB itself, hence they are degenerate. Breaking this degeneracy and understanding their role is a tricky and challenging problem that no study has tried to solve yet. Combining the information obtained from the chromosome maps and the analysis of multi-band photometry with state of the art stellar evolution models, we can obtain a solid estimate of Y for the various stellar populations in a GC. We will then have, for the first time, the possibility to break the parameters degeneracy on the HB, understand the role of the mass loss, and lay the foundation to build another piece of the multiple populations mosaic.