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Title: Elemental Abundances in And XIX from Coadded Spectra
Abstract With a luminosity similar to that of Milky Way dwarf spheroidal systems like Sextans, but a spatial extent similar to that of ultra-diffuse galaxies, Andromeda (And) XIX is an unusual satellite of M31. To investigate the origin of this galaxy, we measure chemical abundances for And XIX derived from medium-resolution (R∼ 6000) spectra from the Deep Extragalactic Imaging Multi-Object Spectrograph on the Keck II telescope. We coadd 79 red giant branch stars, grouped by photometric metallicity, in order to obtain a sufficiently high signal-to-noise ratio to measure 20 [Fe/H] and [α/Fe] abundances via spectral synthesis. The latter are the first such measurements for And XIX. The mean metallicity we derive for And XIX places it ∼2σhigher than the present-day stellar mass–metallicity relation for Local Group dwarf galaxies, potentially indicating it has experienced tidal stripping. A loss of gas and associated quenching during such a process, which prevents the extended star formation necessary to produce shallow [α/Fe]–[Fe/H] gradients in massive systems, is also consistent with the steeply decreasing [α/Fe]–[Fe/H] trend we observe. In combination with the diffuse structure and disturbed kinematic properties of And XIX, this suggests tidal interactions, rather than galaxy mergers, are strong contenders for its formation.  more » « less
Award ID(s):
2233781
PAR ID:
10543332
Author(s) / Creator(s):
; ; ; ; ; ; ; ;
Publisher / Repository:
NASA ADS
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
972
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
133
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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