Characterizing evolved stars in the inner Galaxy using VLBI and Gaia

Abstract:
The Bulge Asymmetries and Dynamical Evolution (BAaDE) survey targets circumstellar SiO masers in the Galactic plane and especially the bulge. Follow-up radio-astrometric measurements will be complementary to Gaia results, since the inner plane of the Galaxy will be obscured at optical wavelengths. We are cross-matching Gaia sources and BAaDE targets using a combination of different criteria. The resulting sample will provide important clues on the intrinsic properties and population distribution of evolved stars in the Galactic bulge. We will also discuss the progress with VLBI observations of a pilot sample in order to directly compare the parallax accuracy at radio and optical wavelengths.