The Detailed Chemical Abundance Patterns of M31 Globular Clusters

TL;DR

This study provides detailed chemical abundance patterns for over 20 elements in approximately 30 globular clusters in M31, revealing insights into galaxy formation and chemical evolution across different galactic regions.

Contribution

It introduces a novel high-resolution spectral analysis method to determine detailed chemical abundances in M31 globular clusters, covering a wide galactocentric radius.

Findings

Inner halo clusters show a wide metallicity range.

Outer halo clusters have a narrow metallicity distribution.

First detailed abundance patterns for M31's old populations comparable to the Milky Way.

Abstract

We present detailed chemical abundances for $>$20 elements in $\sim$30 globular clusters in M31. These results have been obtained using high resolution ($\lambda/\Delta\lambda\sim$24,000) spectra of their integrated light and analyzed using our original method. The globular clusters have galactocentric radii between 2.5 kpc and 117 kpc, and therefore provide abundance patterns for different phases of galaxy formation recorded in the inner and outer halo of M31. We find that the clusters in our survey have a range in metallicity of $-2.2<$[Fe/H]$<-0.11$. The inner halo clusters cover this full range, while the outer halo globular clusters at R$>$20 kpc have a small range in abundance of [Fe/H]$=-1.6 \pm 0.10$. We also measure abundances of alpha, r- and s-process elements. These results constitute the first abundance pattern constraints for old populations in M31 that are comparable to those known for the Milky Way halo.