Our recent discovery of an extended stellar halo in M31 (R > 150 kpc) shows
that most previous studies of its spheroid have been sampling its bulge, not
its halo. Our studies of M31's stellar populations use three methods:
(1) Spectroscopy of individual luminous red giant branch stars with Keck
and DEIMOS
(2) Ground-based wide-field imaging and photometry, most recently with
KPNO/Mosaic, CFHT/MegaCam, and Subaru/Suprime-Cam
(3) Deep Hubble Space Telescope imaging, including ultradeep imaging
reaching below the main-sequence turnoff
In my talk I will focus on the first two categories of studies touching upon
subjects such as: halo dynamics, structure/substructure, chemical abundance
constraints, bulge versus halo, orbit and progenitor of the giant southern
stream, outer disk-halo interface, and tidal disruption of dwarf satellites.
The seminar will be held in 544 Campbell Hall.