Evolution of Binary Stars in Multiple-Population Globular Clusters

TL;DR

This study uses N-body simulations to analyze how initial spatial differences between multiple stellar populations in globular clusters influence the evolution, survival, and properties of binary stars within these systems.

Contribution

It reveals how initial spatial distributions affect binary star survival and properties, highlighting differences between first- and second-generation stars in globular clusters.

Findings

SG binaries are disrupted more efficiently than FG binaries.

SG binary fraction is smaller than FG binary fraction.

Inner regions may still be dominated by SG binaries despite global trends.

Abstract

The discovery of multiple stellar populations in globular clusters has implications for all the aspects of the study of these stellar systems. In this paper, by means of N-body simulations, we study the evolution of binary stars in multiple-population clusters and explore the implications of the initial differences in the spatial distribution of different stellar populations for the evolution and survival of their binary stars. Our simulations show that initial differences between the spatial distribution of first-generation (FG) and second-generation (SG) stars can leave a fingerprint in the current properties of the binary population. SG binaries are disrupted more efficiently than those of the FG population resulting in a global SG binary fraction smaller than that of the FG. As for surviving binaries, dynamical evolution produces a difference between the SG and the FG binary binding energy distribution with the SG population characterized by a larger fraction of high binding energy (more bound) binaries. We have also studied the dependence of the binary properties on the distance from the cluster centre. Although the global binary fraction decreases more rapidly for the SG population, the local binary fraction measured in the cluster inner regions may still be dominated by SG binaries. The extent of the differences between the surviving FG and SG binary binding energy distribution also varies radially within the cluster and is larger in the cluster inner regions.