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Physics & Astronomy Colloquium – Spring 2022 – David Nataf
February 28 @ 3:30 pm - 5:00 pm
Speaker: David Nataf (Johns Hopkins University)
Title: On the Milky Way’s Extinction Curve and Oldest Stellar Populations
Abstract: The study of Galactic astronomy is being revolutionized by the plethora of incredible data from various new surveys, facilities, and the use of modern probabilistic methods. In this talk of two parts, I first describe efforts to characterize the nature of the interstellar extinction curve, which dims and reddens the light of all distant stars and galaxies. I discuss applications for the study of extrasolar planets in the inner Milky Way, in the context of NASA’s upcoming Nancy Grace Roman Space Telescope, and for the extragalactic distance scale, where the uncertainty in the extinction toward the Large Magellanic Cloud is equivalent to an uncertainty in Hubble’s Constant of 3 kilometers per second per megaparsec. In the second part, I pivot to the study of the Milky Way’s (and Local Group’s) oldest stellar populations, specifically RR Lyrae stars and globular cluster stars. I discuss our ongoing efforts to better characterize RR Lyrae stars, and to study the contribution of globular cluster stars to the earliest epochs of star formation in the Milky Way. I conclude with a preview of an upcoming James Webb Space Telescope study of the Andromeda Galaxy, to compare its star formation history and chemical evolution to that of the Milky Way.