APOGEE-2 Discovery of a Large Population of Relatively High-Metallicity Globular Cluster Debris

TL;DR

This paper reports the discovery of a new population of high-metallicity, nitrogen-rich stars in the Milky Way, likely originating from disrupted globular clusters, based on APOGEE-2 spectroscopic data.

Contribution

It identifies a chemically distinct population of stars as debris from disrupted metal-rich globular clusters using APOGEE-2 data.

Findings

Discovery of high-metallicity, nitrogen-rich stars across the Milky Way.

Evidence linking some stars to the Gaia-Enceladus-Sausage accretion event.

Identification of stars likely originating from destroyed globular clusters.

Abstract

We report the discovery of a new, chemically distinct population of relatively high-metallicity ([Fe/H] $> -0.7$) red giant stars with super-solar [N/Fe] ($\gtrsim +0.75$) identified within the bulge, disk, and halo of the Milky Way. This sample of stars was observed during the second phase of the Apache Point Observatory Galactic Evolution Experiment (APOGEE-2); the spectra of these stars are part of the seventeenth Data Release (DR 17) of the Sloan Digital Sky Survey. We hypothesize that this newly identified population was formed in a variety of progenitors, and are likely made up of either fully or partially destroyed metal-rich globular clusters, which we refer to as Globular Cluster Debris (GCD), identified by their unusual photospheric nitrogen abundances. It is likely that some of the GCD stars were probable members of the Gaia-Enceladus-Sausage accretion event, along with clusters formed in situ.