The Metal-poor Halo of the Andromeda Spiral Galaxy (m31)

  title={The Metal-poor Halo of the Andromeda Spiral Galaxy (m31)},
  author={Jasonjot Singh Kalirai and Karoline M. Gilbert and Puragra Guhathakurta and Steven R. Majewski and James C. Ostheimer and R. Michael Rich and Michael C. Cooper and David B. Reitzel and Richard J. Patterson},
We present spectroscopic observations of red giant branch (RGB) stars over a large expanse in the halo of the Andromeda spiral galaxy (M31), acquired with the DEIMOS instrument on the Keck II 10-m telescope. Using a combination of five photometric/spectroscopic diagnostics — (1) radial velocity, (2) intermediate-width DDO51 photometry, (3) Na i equivalent width (surface gravity sensitive), (4) position in the color-magnitude diagram, and (5) comparison between photometric and spectroscopic [Fe… CONTINUE READING