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We measured [Fe/H] and [$alpha$/Fe] using spectral synthesis of low-resolution stellar spectroscopy for 70 individual red giant branch stars across four fields spanning the outer disk, Giant Stellar Stream (GSS), and inner halo of M31. Fields at M31-centric projected distances of 23 kpc in the halo, 12 kpc in the halo, 22 kpc in the GSS, and 26 kpc in the outer disk are $alpha$-enhanced, with $langle$[$alpha$/Fe]$rangle$ = 0.43, 0.50, 0.41, and 0.58, respectively. The 23 kpc and 12 kpc halo fields are relatively metal-poor, with $langle$[Fe/H]$rangle$ = $-$1.54 and $-$1.30, whereas the 22 kpc GSS and 26 kpc outer disk fields are relatively metal-rich with $langle$[Fe/H]$rangle$ = $-$0.84 and $-$0.92, respectively. For fields with substructure, we separated the stellar populations into kinematically hot stellar halo components and kinematically cold components. We did not find any evidence of an [$alpha$/Fe] gradient along the high surface brightness core of the GSS between $sim$17$-$22 kpc. However, we found tentative suggestions of a negative [$alpha$/Fe] gradient in the stellar halo, which may indicate that different progenitor(s) or formation mechanisms contributed to the build up of the inner versus outer halo. Additionally, the [$alpha$/Fe] distribution of the metal-rich ([Fe/H] $>$ $-$1.5), smooth inner stellar halo (r$_{rm{proj}}$ $lesssim$ 26 kpc) is inconsistent with having formed from the disruption of progenitor(s) similar to present-day M31 satellite galaxies. The 26 kpc outer disk is most likely associated with the extended disk of M31, where its high $alpha$-enhancement provides support for an episode of rapid star formation in M31s disk, possibly induced by a major merger.
We present [Fe/H] and [$alpha$/Fe] abundances, derived using spectral synthesis techniques, for stars in M31s outer stellar halo. The 21 [Fe/H] measurements and 7 [$alpha$/Fe] measurements are drawn from fields ranging from 43 to 165 kpc in projected
Measurements of [Fe/H] and [$alpha$/Fe] can probe the minor merging history of a galaxy, providing a direct way to test the hierarchical assembly paradigm. While measurements of [$alpha$/Fe] have been made in the stellar halo of the Milky Way, little
We present the first measurements of [Fe/H] and [$alpha$/Fe] abundances, obtained using spectral synthesis modeling, for red giant branch stars in M31s giant stellar stream. The spectroscopic observations, obtained at a projected distance of 17 kpc f
We present measurements of [Fe/H] and [$alpha$/Fe] for 128 individual red giant branch stars (RGB) in the stellar halo of M31, including its Giant Stellar Stream (GSS), obtained using spectral synthesis of low- and medium-resolution Keck/DEIMOS spect
We analyze existing measurements of [Fe/H] and [$alpha$/Fe] for individual red giant branch (RGB) stars in the Giant Stellar Stream (GSS) of M31 to determine whether spatial abundance gradients are present. These measurements were obtained from low-