Astronomy Colloquium

Observations of resolved stars in nearby galaxies anchor our knowledge of the distant Universe (e.g., stellar evolution, the distance scale, initial mass function) and encode the formation history of the local Universe. In this talk, I will highlight some of the broad science enabled by resolved star studies, with a particular emphasis on new insights into the formation histories of the lowest-mass, lowest-metallicity galaxies in the Universe. I will present results from my 1000+ orbit Hubble Space Telescope Treasury survey of M31 satellite galaxies, which has revealed a previously unknown channel for low-mass galaxy growth. I will describe my team's work on expanding resolved star "galaxy archaeology" science from dozens of galaxies in the Local Group (D~1 Mpc) to thousands of galaxies at much larger distances (D~50 Mpc) using facilities such as the James Webb Space Telescope (JWST), Euclid, and Roman. Finally, I will preview "J-Virgo", my team's new JWST Treasury program that is undertaking the first systematic study of galaxy evolution in a massive galaxy cluster, Virgo, using resolved stellar populations.