The fraction of globular cluster second-generation stars in the Galactic halo

TL;DR

This study uses hydrodynamical simulations to estimate the contribution of second-generation stars from globular clusters to the Galactic halo, finding it to be less than 10% depending on the initial mass function.

Contribution

It provides the first quantitative estimate of the fraction of the Galactic halo composed of second-generation globular cluster stars based on simulation results.

Findings

Second-generation stars constitute less than 4-6% of the Galactic halo mass with a Kroupa-1993 IMF.

The fraction increases to less than 7-9% with a Kroupa-2001 IMF.

Simulations show the halo contribution is small across a range of initial conditions.

Abstract

Many observational studies have revealed the presence of multiple stellar generations in Galactic globular clusters. These studies suggest that second-generation stars make up a significant fraction of the current mass of globular clusters, with the second-generation mass fraction ranging from ~50 to 80 per cent in individual clusters. In this Letter we carry out hydrodynamical simulations to explore the dependence of the mass of second-generation stars on the initial mass and structural parameters and stellar initial mass function (IMF) of the parent cluster. We then use the results of these simulations to estimate the fraction, f_{SG,H}, of the mass of the Galactic stellar halo composed of second-generation stars that originated in globular clusters. We study the dependence of f_{SG,H} on the parameters of the initial mass function of the Galactic globular cluster system. For a broad range of initial conditions, we find that the fraction of mass of the Galactic stellar halo in second-generation stars is always small, f_{SG,H}<4-6 per cent for a Kroupa-1993 IMF and f_{SG,H}<7-9 per cent for a Kroupa-2001 IMF.