Blue Straggler Stars in Globular Clusters: a powerful tool to probe the internal dynamical evolution of stellar systems

TL;DR

This paper reviews how Blue Straggler Stars in globular clusters serve as effective indicators of the clusters' internal dynamical evolution, especially through their radial distribution which acts as a 'dynamical clock'.

Contribution

It introduces the concept of using BSS radial distribution as an empirical tool to measure the dynamical age of globular clusters.

Findings

BSS specific frequency varies with cluster properties

Radial distribution of BSS traces dynamical evolution

Defined the first empirical 'dynamical clock' for clusters

Abstract

This chapter presents an overview of the main observational results obtained to date about Blue Straggler Stars (BSSs) in Galactic Globular Clusters (GCs). The BSS specific frequency, radial distribution, chemical composition and rotational properties are presented and discussed in the framework of using this stellar population as probe of GC internal dynamics. In particular, the shape of the BSS radial distribution has been found to be a powerful tracer of the dynamical age of stellar systems, thus allowing the definition of the first empirical "dynamical clock".