Characterizing the Evolved Stellar Population in the Galactic Foreground. I. Bolometric Magnitudes, Spatial Distribution and Period-Luminosity Relations

Radio campaigns using maser stellar beacons have provided crucial information to characterize Galactic stellar populations. Currently, the Bulge Asymmetries and Dynamical Evolution (BAaDE) project is surveying infrared (IR) color-selected targets for SiO masers. This provides a sample of evolved stars that can be used to study the inner, optically obscured Galaxy using line-of-sight velocities and possibly very long baseline interferometry proper motions. In order to use the BAaDE sample for kinematic studies, the stellar population should be characterized. In this study, the BAaDE targets have been cross-matched with IR (2MASS) and optical (Gaia) samples. By exploring the synergies of this cross-match together with Gaia parallaxes and extinction maps, the local (d < 2 kpc) asymptotic giant branch (AGB) stars can be characterized. We have defined a BAaDE-Gaia sample of 20,111 sources resulting from cross-matching BAaDE targets with IR and optical surveys. From this sample, a local sample of 1812 evolved stars with accurate parallax measurements, confirmed evolved stellar evolution stage, and within 2 kpc distance around the Sun was selected, for which absolute (bolometric) magnitudes are estimated. The evolved stellar population with Gaia counterparts that are variable seems to be predominantly associated with AGB stars with moderate luminosity ( ${1500}_{-500}^{+3000}\ {L}_{\odot }$ ) and periods between 250 and 1250 days.