The Apache Point Observatory Extra-galactic Evolution Experiment (APOeGEE): Chemical Abundance Trends for Seven Dwarf Spheroidal Galaxies in the APOGEE Survey

Shetrone, M, Beaton, RL, Hayes, CR, Hasselquist, S, Simon, JD, Holtzman, JA, Cunha, K, Majewski, SR, Sobeck, J, Schiavon, R ORCID: 0000-0002-2244-0897, Masseron, T, Smith, VV and Nidever, DL (2026) The Apache Point Observatory Extra-galactic Evolution Experiment (APOeGEE): Chemical Abundance Trends for Seven Dwarf Spheroidal Galaxies in the APOGEE Survey. The Astrophysical Journal, 998 (1). ISSN 1538-4357

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Abstract

In addition to comprehensive surveys of the Milky Way (MW) bulge, disk, and halo, the Apache Point Galactic Evolution Experiment (APOGEE) project observed seven dwarf spheroidal satellites (dSphs) of the MW: Carina, Sextans, Sculptor, Draco, Ursa Minor, Bootes 1, and Fornax. APOGEE radial velocities, stellar parameters, and Gaia EDR3 proper motions are used to identify member stars from the targets in the vicinity of each dwarf; for seven dwarfs, new member stars are identified. To properly analyze the abundance patterns of these galaxies, a novel procedure was developed to determine the measurable upper limits of the APOGEE chemical abundances as a function of the effective temperature and the spectral signal-to-noise ratio. In general, the APOGEE abundance patterns of these galaxies (limited to [Fe/H] > −2.5) agree with those found in high-resolution optical studies in the literature after abundance offsets are applied. Most of the galaxies studied here have abundance patterns that are distinctly different from the majority of stars found in the MW halo, suggesting that these galaxies contributed little to the MW halo above [Fe/H] > −2.0. From these abundance patterns, we also find that these dSphs tend to follow two types of chemical evolution paths: episodic and continuous star formation, a result that is broadly consistent with previous photometric studies of the star formation histories (SFHs) of these galaxies. We explore whether mass and/or environment have an impact on whether a galaxy has an episodic or continuous SFH, finding tentative evidence that, in addition to the galaxy’s mass, proximity to a larger galaxy and the cessation of star formation may drive the overall shape of the chemical evolution.

Item Type:	Article
Uncontrolled Keywords:	5101 Astronomical Sciences; 51 Physical Sciences; 0201 Astronomical and Space Sciences; 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics; 0306 Physical Chemistry (incl. Structural); Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences
Subjects:	Q Science > QB Astronomy
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society
Date of acceptance:	5 November 2025
Date of first compliant Open Access:	12 June 2026
Date Deposited:	12 Jun 2026 14:54
Last Modified:	12 Jun 2026 14:54
DOI or ID number:	10.3847/1538-4357/ae27c5
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28837

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