“Big Science from Little Stars: The Activity and Kinematics of Low-Mass Stars "

I will present the results from a study of the dynamics and magnetic activity of M dwarfs using the largest spectroscopic sample of low-mass stars ever assembled. The age at which strong surface magnetic activity ceases in M dwarfs has been inferred to have a strong dependence on mass (spectral type, surface temperature) to explain previous results showing a large increase in the fraction of active stars at later spectral types. Using spectral observations of more than 40,000 M dwarfs from the SDSS, I show that the fraction of active stars decreases as a function of vertical distance from the Galactic plane, and that the magnitude of this decrease changes significantly for different M spectral types. Adopting a simple dynamical model for thin disk vertical heating, I assign an age for the activity decline at each spectral type, and thus determine an activity-age relation for M dwarfs. These results provide constraints for dynamo models that seek to describe the production of surface magnetic fields in low mass stars. In addition, I will show how M dwarfs can be used to probe both the metallicity evolution as well as the dynamical heating and structure of the Milky Way thin disk.