Carbon Stars in the Satellites and Halo of M31
  We spectroscopically identify a sample of carbon stars in the satellites and
halo of M31 using moderate-resolution optical spectroscopy from the
Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey. We
present the photometric properties of our sample of 41 stars, including their
brightness with respect to the tip of the red giant branch (TRGB) and their
distributions in various color-color spaces. This analysis reveals a bluer
population of carbon stars fainter than the TRGB and a redder population of
carbon stars brighter than the TRGB. We then apply principal component analysis
to determine the sample's eigenspectra and eigencoefficients. Correlating the
eigencoefficients with various observable properties reveals the spectral
features that trace effective temperature and metallicity. Putting the
spectroscopic and photometric information together, we find the carbon stars in
the satellites and halo of M31 to be minimally impacted by dust and internal
dynamics. We also find that while there is evidence to suggest that the
sub-TRGB stars are extrinsic in origin, it is also possible that they are are
particularly faint members of the asymptotic giant branch.
