Using the Galactic Dynamics of Cool Stars
to Infer the Evolution of their Magnetic Activity

I will present results from a spectroscopic study and dynamical analysis of almost 50000 M and L-type dwarfs from the SDSS Data Release 5. I find that the fraction of magnetically active stars (as traced by H-alpha) decreases as a function of vertical distance from the Galactic Plane. The magnitude and slope of this effect varies as a function of spectral type. Using space motions for ~29000 of the stars and a simple dynamical model, I demonstrate that the observed drop in activity fraction can be explained by thin disk dynamical heating and a rapid decrease in magnetic activity with a timescale that changes according to spectral type. By comparing the data to the simulations, I calibrate the age-activity relation at each spectral type. In addition, using metal sensitive molecular bands, I show that metallicity also decreases as a function of Galactic height and that these data can be used to derive the metallicity evolution of the Galaxy.