Exotic populations in Globular Clusters: Blue Stragglers as tracers of the internal dynamical evolution of stellar systems

TL;DR

This paper reviews Blue Straggler Stars in globular clusters, highlighting their potential as observational probes for understanding the clusters' internal dynamical evolution and providing an empirical method to estimate their dynamical age.

Contribution

It introduces the use of BSS radial distribution as a new empirical clock to measure the dynamical age of globular clusters based on observational properties.

Findings

BSS specific frequency varies with cluster properties

Radial distribution of BSS is a powerful dynamical evolution indicator

An empirical 'clock' for cluster dynamical age is proposed

Abstract

In this paper I present an overview of the main observational properties of a special class of exotic objects (the so-called Blue Straggler Stars, BSSs) in Galactic Globular Clusters (GCs). The BSS specific frequency and their radial distribution are 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 evolution of stellar systems, thus allowing the definition of an empirical "clock" able to measure the dynamical age of stellar aggregates from pure observational properties.