Metallicities of Outer Halo M31 Globular Clusters from Integrated Light Calcium-II Triplet Spectroscopy

Abstract

This paper presents [Fe/H] ratios for GCs in the outer halo of the Andromeda Galaxy, M31, based on moderate-resolution, integrated light (IL) spectroscopy of the calcium-II triplet (CaT) lines. The CaT strengths are measured by fitting Voigt profiles to the lines and integrating those profiles; integrations of defined bandpasses are also considered. The [Fe/H] ratios are determined using an empirical calibration with CaT line strength, as derived from another sample of M31 GCs that were previously studied at high-resolution. The [Fe/H] ratios for the new GCs reveal that the outer halo GCs are indeed generally more metal-poor than typical inner halo GCs, though there are several more metal-rich GCs that look to have been accreted from dwarf satellites. The metallicities of these GCs also place important constraints on the nature of the substructure in the outer halo and the dwarf satellites that created this substructure.

Accepted for publication in MNRAS

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Cited by in corpus (5)

• Elemental abundances in M31: Individual and Coadded Spectroscopic [Fe/H] and [α/Fe] throughout the M31 Halo with SPLASH
• Revisiting the near infrared Calcium triplet as metallicity indicator
• On the Use of Field RR Lyrae as Galactic Probes -- VIII. Early Formation of the Galactic Spheroid
• Synthetic stellar spectra to study multiple populations in globular clusters: an extended grid and the effects on the integrated light
• Properties of the Lower Segment of M31's North West Stream