Unearthing the fossilized Andromeda galaxy: a spectroscopic pilot survey of M31 giants

Mackereth, John Edward; Allende-Prieto, Carlos; Nataf, David Moise; Schiavon, Ricardo
Bibliographical reference

JWST Proposal. Cycle 1

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Galaxy evolution models are strongly underpinned by anchoring constraints made locally in the Milky Way. In this proposal, we aim to perform a pilot study toward providing a secondary local anchor in the form of a detailed mapping in element abundances of the stellar populations of the Andromeda galaxy, M31. Primarily, we will use NIRSpec spectroscopy of giant stars to study element abundances in the old disk of M31, establishing whether it plays host to a dichotomy in the ratio of its alpha-element abundances relative to Iron. Such a feature is readily observed in the Milky Way, and thought to be indicative of an early and rapid assembly of its mass. These pilot observations towards larger spectroscopic surveys of the M31 disk will allow us to discriminate between the myriad models which are now proposed for the origin of this feature in the Milky Way. This will place the first stake of true galactic archaeology in Andromeda, opening the door to more detailed future studies which will attempt to reconstruct the star formation history and more fully constrain the history of mass assembly in our nearest giant disk.