The Outer Halo Globular Clusters of M31
  We present Keck/HIRES spectra of 3 globular clusters in the outer halo of
M31, at projected distances beyond ~80 kpc from M31. The measured recession
velocities for all 3 globular clusters confirm their association with the
globular cluster system of M31. We find evidence for a declining velocity
dispersion with radius for the globular cluster system. Their measured internal
velocity dispersions, derived virial masses and mass-to-light ratios are
consistent with those for the bulk of the M31 globular cluster system. We
derive old ages and metallicities which indicate that all 3 belong to the
metal-poor halo globular cluster subpopulation. We find indications that the
radial gradient of the mean metallicity of the globular cluster system interior
to 50 kpc flattens in the outer regions, however it is still more metal-poor
than the corresponding field stars at the same (projected) radius.
