The Chemodynamics of the Stellar Populations in M31 from APOGEE Integrated-light Spectroscopy

Journal Article · Fri Jul 14 00:00:00 EDT 2023 · The Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/acd9a9· OSTI ID:2425316

Gibson, Benjamin J. ^[1]; Zasowski, Gail ^[1]; Seth, Anil ^[1]; Ashok, Aishwarya ^[1]; Goold, Kameron ^[1]; Wainer, Tobin ^[2]; Hasselquist, Sten ^[3]; Holtzman, Jon ^[4]; Imig, Julie ^[4]; Bizyaev, Dmitry ^[5]; Majewski, Steven R. ^[6]

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1. Univ. of Utah, Salt Lake City, UT (United States)
2. Univ. of Utah, Salt Lake City, UT (United States); Univ. of Washington, Seattle, WA (United States)
3. Space Telescope Science Institute, Baltimore, MD (United States)
4. New Mexico State Univ., Las Cruces, NM (United States)
5. New Mexico State Univ., Las Cruces, NM (United States); Moscow State Univ., Moscow (Russian Federation)
6. Univ. of Virginia, Charlottesville, VA (United States)

We present an analysis of nearly 1000 near-infrared, integrated-light spectra from APOGEE in the inner ~7 kpc of M31. We utilize full-spectrum fitting with A-LIST simple stellar population spectral templates that represent a population of stars with the same age, [M/H], and [α/M]. With this, we determine the mean kinematics, metallicities, α abundances, and ages of the stellar populations of M31's bar, bulge, and inner disk (~4–7 kpc). We find a nonaxisymmetric velocity field in M31 resulting from the presence of a bar. The bulge of M31 is less metal-rich (mean [M/H] = $0.149$$$$^{+0.067}_{-0.081}$$ dex) than the disk, features minima in metallicity on either side of the bar ([M/H] ~ -0.2), and is enhanced in α abundance (mean [α/M] = $0.281$$$$^{+0.035}_{-0.038}$$). The disk of M31 within ~7 kpc is enhanced in both metallicity ([M/H] = $-0.023$$$$^{+0.050}_{-0.052}$$) and α abundance ([α/M] = $0.274$$$$^{+0.020}_{-0.025}$$). Both of these structural components are uniformly old at ≃12 Gyr. We find the mean metallicity increases with distance from the center of M31, with the steepest gradient along the disk major axis (0.043 ± 0.021 dex kpc^-1). This gradient is the result of changing light contributions from the bulge and disk. The chemodynamics of stellar populations encodes information about a galaxy's chemical enrichment, star formation history, and merger history, allowing us to discuss new constraints on M31's formation. Our results provide a stepping stone between our understanding of the Milky Way and other external galaxies.

• Research Organization: US Department of Energy (USDOE), Washington, DC (United States). Office of Science, Sloan Digital Sky Survey (SDSS)
• Sponsoring Organization: USDOE Office of Science (SC)
• OSTI ID: 2425316
• Journal Information: The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 1 Vol. 952; ISSN 0004-637X
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS