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Keck Spectroscopy of Red Giant Stars in the Vicinity of M31's Massive Globular Cluster G1

David B. Reitzel·Puragra Guhathakurta·R. Michael Rich
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Abstract

We present results from a Keck spectroscopic survey of red giants in a field near M31's major axis, ~34kpc in projection from the nucleus, near the globular cluster G1. We use multislit LRIS spectroscopy to measure the CaII triplet in 41 stars with apparent mags 20 =-0.8 for these potential M31 outer disk stars. Six of the 23 M31 members v and [Fe/H] values consistent with those of G1 (after accounting forits intrinsic spread in both): one of these stars lies within G1's projected tidal radius and is a likely member; the remaining 5 stars are not physically close to G1 but may represent its tidal debris. More data are needed to confirm the nature of these 5 stars as it is likely that they represent M31's smooth halo population. We might have expected to detect tidal debris if G1 were the remnant core of a dwarf galaxy being accreted by M31; instead, the majority of M31 giants in this field are metal-rich and belong to what is evidently the outer disk of M31, and only a small fraction (<~20%) could possibly have originated in G1.

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David B. Reitzel, Puragra Guhathakurta, R. Michael Rich. 2004-01-06. Keck Spectroscopy of Red Giant Stars in the Vicinity of M31's Massive Globular Cluster G1. https://doi.org/10.1086/382517

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