The Distribution of Alpha Elements in Andromeda Dwarf Galaxies
Luis C. Vargas, Marla C. Geha, Erik J. Tollerud (Yale University)

TL;DR
This study measures alpha to iron abundance ratios in 226 stars across nine Andromeda dwarf galaxies, revealing diverse chemical patterns and radial gradients, and compares these to the Milky Way's dwarf satellites and stellar halo.
Contribution
First large sample of alpha abundance ratios in M 31 satellites, providing new insights into their chemical diversity and gradients compared to the Milky Way.
Findings
Dwarf galaxies show a range of alpha/Fe ratios from solar to +0.5.
Radial iron abundance gradients are confirmed in two galaxies.
M 31 satellites' chemical patterns are more diverse than those of the Milky Way.
Abstract
We present alpha to iron abundance ratios for 226 individual red giant branch stars in nine dwarf galaxies of the Andromeda (M 31) satellite system. The abundances are measured from the combined signal of Mg, Si, Ca, and Ti lines in Keck/DEIMOS medium-resolution spectra. This constitutes the first large sample of alpha abundance ratios measured in the M 31 satellite system. The dwarf galaxies in our sample exhibit a variety of alpha abundance ratios, with the average values in each galaxy ranging from approximately solar ([alpha/Fe] ~ +0.0) to alpha-enhanced ([alpha/Fe] ~ +0.5). These variations do not show a correlation with internal kinematics, environment, or stellar density. We confirm radial gradients in the iron abundance of two galaxies out of the five with sufficient data (NGC 185 and And II). There is only tentative evidence for an alpha abundance radial gradient in NGC 185. We…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
