Exploring the Local Milky Way: M Dwarfs as Tracers of Galactic Populations

Abstract

We have assembled a spectroscopic sample of low-mass dwarfs observed as part of the Sloan Digital Sky Survey along one Galactic sight line, designed to investigate the observable properties of the thin and thick disks. This sample of ~7400 K and M stars also has measured ugriz photometry, proper motions, and radial velocities. We compute UVW space-motion distributions, and investigate their structure with respect to vertical distance from the Galactic plane. We place constraints on the velocity dispersions of the thin and thick disks, using two-component Gaussian fits. We also compare these kinematic distributions to a leading Galactic model. Finally, we investigate other possible observable differences between the thin and thick disks, such as color, active fraction, and metallicity.