31) The disc of the Milky Way: Clues to its origin and evolution from large spectroscopic surveys

Abstract: Large observational surveys of the Milky Way are now providing detailed ages, kinematics and abundances for close to a million stars in the Milky Way, which is having a transformational effect on our understanding of the formation and evolution of the Milky Way. We present a chemo dynamical model to make sense of the vast amount of information that is available to us. The model sheds new light on the various physical processes that shape the Milky Way and provides answers to some of the peculiar patterns in kinematics and abundances seen in the Milky Way. First we explore the fundamental relations governing the radial and vertical velocity dispersions of stars in the Milky Way. We find that different surveys, even though they target different tracer populations and employ a variety of age estimation techniques, follow the same set of fundamental relations. We discuss the physical implications of these fundamental relations. Next we explore the ([alpha/Fe],[Fe/H]) distribution of Milky Way stars, which shows at least two distinct sequences and have traditionally been associated with the thin and thick disc components. Using an analytical chemodynamical model that includes the effects of radial migration and fundamental velocity dispersion relations, we show that it is possible to reproduce the observed abundance distribution at different locations. Unlike some earlier models, our scheme does not require a distinct thick disc component emerging from a separate evolutionary path. The proposed model has a continuous star formation history and a continuous age velocity dispersion relation.

Bio: PhD, University of Arizona. Research Fellow, University of Sydney. My primary research interest in astronomy is to understand the formation and evolution of the Milky Way. My other interests include Bayesian statistics, computational methods and algorithms. My current focus has been to make use of data from large spectrocopic surveys like GALAH, APOGEE, and asteroseismic data from mission like Kepler and K2 to understand the Milky Way. I am very keen on exploring new data analysis techniques.