Princeton University Thunch Talk

Ages of low mass stars, particularly for M dwarfs, cannot be obtained with the same methods used for solar type stars because stellar evolution models break down for fully convective stars. Therefore, empirical and statistical methods are required to constrain the ages of M dwarfs. We have started a project called “Gaia-Cupid”, with the goal of building a robust bayesian inference model for the ages of ultracool dwarfs. We began by collecting a significant sample of age indicators for M and L dwarfs, including magnetic activity and full kinematics that will be complemented with rotation periods. We compiled a sample of over 70,000 M and L-dwarfs based on SDSS spectroscopy that contains spectral type, H???? strength, and radial velocities, and is cross-matched to Gaia DR2 for high quality proper motions and parallaxes. In this talk, I will describe the sample and show how we used it to study the relationships between age indicators and to explain the scatter on a “clean” color-magnitude diagram, whose width nearly doubles from FGK stars into the M dwarf regime. Our analysis suggests that the scatter is a consequence of a combination of magnetic properties, metallicity, and age diversity. I will conclude showing our progress towards achieving a functional form for the age-activity relation for M dwarfs.