Prof. Puragra GuhaThakurta

The resolved stellar populations of Local Group galaxies, and the partially resolved stellar populations of galaxies in the immediate vicinity of the Local Group (out to a few Mpc), serve as excellent tracers of the dark matter content, accretion/interaction history, and chemical enrichment history of their host galaxies. I will present results from a few different Keck/DEIMOS spectroscopic campaigns and photometric (including time-domain) surveys of these stellar populations in the remote halo of the Milky Way (HALO7D, NGVS), disk and halo of M31 and M33 (PHAT, SPLASH), and halo and dwarf satellites of Milky-Way mass galaxies in nearby groups (PISCeS). Using the M31 and M33 galaxies as stellar evolution testbeds, I will report on the discovery of a rare population of massive evolved stars with a hitherto undetected weak CN spectral absorption feature.