Abstract:

Detailed studies of nearby galaxies provide vital clues about their formation and evolutionary history. This "fossil record" approach is complementary to direct look-back studies of distant galaxies. Our Galaxy and the Andromeda spiral galaxy (M31) have long been cornerstones in the former category. M31 provides an external perspective on a large galaxy similar to our own and yet is close enough to allow detailed studies of individual stars. I will present results from the SPLASH collaboration: Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo. The survey data set includes spectra and brightness measurements of individual luminous, evolved red giant stars and ultra-deep studies with the Hubble Space Telescope of Sun-like (and 10x less luminous) stars. Recent survey highlights include: - Discovery of an extended population of stars in M31 (halo) - Detailed characterization of a recent cannibalism event involving a merger of a dwarf satellite galaxy with the parent - Chemical abundance patterns in red giant stars - Insight into the formation of a large galaxy like M31 from dwarf galaxy building blocks - Constraints on the motion of M31 in the plane of the sky and implications for the dynamics of the Local Group of galaxies