M31 Globular Cluster Abundances from High-Resolution, Integrated-Light
  Spectroscopy
  We report the first detailed chemical abundances for 5 globular clusters
(GCs) in M31 from high-resolution (R ~ 25,000) spectroscopy of their integrated
light. These GCs are the first in a larger set of clusters observed as part of
an ongoing project to study the formation history of M31 and its globular
cluster population. The data presented here were obtained with the HIRES
echelle spectrograph on the Keck I telescope, and are analyzed using a new
integrated light spectra analysis method that we have developed. In these
clusters, we measure abundances for Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co,
Ni, Y, and Ba, ages >10 Gyrs, and a range in [Fe/H] of -0.9 to -2.2. As is
typical of Milky Way GCs, we find these M31 GCs to be enhanced in the
alpha-elements Ca, Si, and Ti relative to Fe. We also find [Mg/Fe] to be low
relative to other [alpha/Fe], and [Al/Fe] to be enhanced in the integrated
light abundances. These results imply that abundances of Mg, Al (and likely O,
Na) recovered from integrated light do display the inter- and intra-cluster
abundance variations seen in individual Milky Way GC stars, and that special
care should be taken in the future in interpreting low or high resolution
integrated light abundances of globular clusters that are based on Mg-dominated
absorption features. Fe-peak and the neutron-capture elements Ba and Y also
follow Milky Way abundance trends. We also present high-precision velocity
dispersion measurements for all 5 M31 GCs, as well as independent constraints
on the reddening toward the clusters from our analysis.
