Keck/KCWI Spectroscopy of Globular Clusters in Local Volume Dwarf Galaxies

TL;DR

This study uses Keck/KCWI spectroscopy to confirm the nature and origins of globular clusters in nearby dwarf galaxies and the M31 halo, revealing their ages, metallicities, and potential accretion history.

Contribution

First spectroscopic confirmation of globular cluster candidates in several dwarf galaxies and the M31 halo, providing insights into their ages, metallicities, and origins.

Findings

Confirmed 6 GCs in NGC 247 as associated with the galaxy.

Identified young star clusters in F8D1 and DDO190.

Discovered 3 M31 halo GCs likely from accreted dwarf galaxy.

Abstract

A number of nearby dwarf galaxies have globular cluster (GC) candidates that require spectroscopic confirmation. Here we present Keck telescope spectra for 15 known GCs and GC candidates that may be associated with a host dwarf galaxy, and an additional 3 GCs in the halo of M31 that are candidates for accretion from a now disrupted dwarf galaxy. We confirm 6 star clusters (of intermediate-to-old age) to be associated with NGC~247. The vast bulk of its GC system remains to be studied spectroscopically. We also confirm the GC candidates in F8D1 and DDO190, finding both to be young star clusters. The 3 M31 halo GCs all have radial velocities consistent with M31, are old and very metal-poor. Their ages and metallicities are consistent with accretion from a low mass satellite galaxy. Finally, three objects are found to be background galaxies -- two are projected near NGC~247 and one (candidate GCC7) is near the IKN dwarf. The IKN dwarf thus has only 5 confirmed GCs but still a remarkable specific frequency of 124.