Elemental Abundances in And XIX from Coadded Spectra

L. R. Cullinane; Karoline M. Gilbert; Ivanna Escala; J. Leigh Wojno; Evan N. Kirby; Kateryna A. Kvasova; Erik Tollerud; Michelle L. M. Collins; R. Michael Rich

doi:10.3847/1538-4357/ad5f2e

The Astrophysical Journal (Jan 2024)

Elemental Abundances in And XIX from Coadded Spectra

L. R. Cullinane,
Karoline M. Gilbert,
Ivanna Escala,
J. Leigh Wojno,
Evan N. Kirby,
Kateryna A. Kvasova,
Erik Tollerud,
Michelle L. M. Collins,
R. Michael Rich

Affiliations

L. R. Cullinane: ORCiD; Leibniz-Institut für Astrophysik (AIP) , An der Sternwarte 16, D-14482 Potsdam, Germany ; [email protected]; The William H. Miller III Department of Physics & Astronomy, Bloomberg Center for Physics and Astronomy, Johns Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA
Karoline M. Gilbert: ORCiD; The William H. Miller III Department of Physics & Astronomy, Bloomberg Center for Physics and Astronomy, Johns Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Ivanna Escala: ORCiD; Department of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA; The Observatories of the Carnegie Institution for Science , 813 Santa Barbara Street, Pasadena, CA 91101, USA
J. Leigh Wojno: ORCiD; Max-Planck Institute for Astronomy , Königstuhl 17, D-69117 Heidelberg, Germany
Evan N. Kirby: ORCiD; Department of Physics and Astronomy, University of Notre Dame , 225 Nieuwland Science Hall, Notre Dame, IN 46556, USA
Kateryna A. Kvasova: ORCiD; Department of Physics and Astronomy, University of Notre Dame , 225 Nieuwland Science Hall, Notre Dame, IN 46556, USA
Erik Tollerud: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Michelle L. M. Collins: ORCiD; Physics Department, University of Surrey , Guildford, GU2 7XH, UK
R. Michael Rich: ORCiD; Department of Physics and Astronomy, UCLA , Los Angeles, CA 90095, USA

DOI: https://doi.org/10.3847/1538-4357/ad5f2e
Journal volume & issue: Vol. 972, no. 2
p. 133

Abstract

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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 ∼2 σ higher 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.

Published in The Astrophysical Journal

ISSN: 1538-4357 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/0004-637X

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