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

摘要

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