7) Star formation history across the Milky Way from age-chemical abundance structure

Abstract: Our picture of how galaxies evolve and enrich the Universe relies directly on our understanding of when, where, and how our own Galaxy’s stars evolved and died, but until recently, our measurements of the Milky Way’s enrichment history were largely limited to the solar neighborhood. Now, massive stellar surveys are yielding spectroscopic datasets of unprecedented quantity and quality for stars through out the Galactic disk. These measurements reveal complex, position-dependent patterns of age and abundance that comprise the most rigorous observational constraints to date for models of Galactic star formation. I will give a talk to introduce our recent works on revealing the Milky Way’s star formation and chemical enrichment history, from the Galactic bulge to the outskirts of the disk, by applying a novel star formation model to age and chemical information of 10^5 stars from the APOGEE survey. We conduct the first systematic fitting of a multi-phase accretion and star formation numerical framework to the multi-dimensional constraints of ages and abundances. One of the most interesting finding is that the observed chemical bimodal distribution originates from an early star formation quenching episode. The similarity to the quenching-induced galaxy bimodal distribution in the color-magnitude diagram suggests an intriguing link between the evolutionary path of our Galaxy and the general galaxy population, and that the quenching process has been playing a critical role in shaping galaxies observed today, including our Galaxy.

Bio: My name is Jianhui Lian, and I'm a postdoc at University of Utah working with Gail Zasowski on stellar abundances and Galaxy formation history using APOGEE data. My research interests cover both Galactic and extragalactic studies with an emphasis on their stellar population and ISM chemistry properties and their chemical evolution history.