Speaker: David Nataf

Host: Steve Kawaler

Title: On the Star-Formation History of the Large disk galaxies of the Local Group

Abstract: Precision age determinations are a holy grail of Galactic astronomy. Here, I discuss the successful use of astrophotometric age-metallicity determinations of 400,000 solar neighbourhood subgiant stars, to a precision of 9% in age and 0.12 dex in metallicity, where we thus not only match but define the state-of-the-art. We resolve the star formation history of the solar neighbourhood as never done before, and show that contrary to expectations from cosmological models of galaxy formation, the oldest and most metal-poor stellar populations include not only Halo stars but also Disk stars. I conclude my talk by discussing by discussing early analysis of two observed JWST programs, aiming the infer star-by-star abundance distributions for Andromeda (M31) and Triangulum (M33) disk galaxies. Andromeda’s Disk is found to be surprisingly older, much older, than that of the Milky Way.

Bio: