Two views of globular cluster stars in the Galactic halo

TL;DR

This paper investigates the presence of globular cluster-like chemical signatures in halo stars, providing insights into the formation and assembly history of the Galactic halo through spectroscopic analysis.

Contribution

It presents two new efforts to expand the detection of globular cluster-like stars in the Galactic halo using spectroscopic data.

Findings

Detection of globular cluster-like stars in the halo supports hierarchical galaxy formation models.

Approximately 2.5% of halo red giants show globular cluster chemical signatures.

Results imply a significant contribution of disrupted globular clusters to the halo population.

Abstract

In Martell & Grebel (2010) we reported the discovery in the Sloan Digital Sky Survey-II/SEGUE spectroscopic database of a small subset of halo red giants, 2.5%, with CN and CH band strengths indicative of globular-cluster-like carbon and nitrogen abundances. Because the formation of stars with unusual light-element abundances is thought to be restricted to high-density environments like globular clusters, this result has strong implications for both cluster formation processes and the assembly history of the Galactic halo. Here we discuss two efforts to expand upon that work.