Characterizing the Evolved Stellar Population in the Galactic Foreground I: Bolometric Magnitudes, Spatial Distribution and P-L Relations

TL;DR

This study characterizes evolved stellar populations in the Galactic foreground using cross-matched IR and optical data, focusing on bolometric magnitudes, spatial distribution, and period-luminosity relations of AGB stars within 2 kpc.

Contribution

It introduces the BAaDE-Gaia sample of over 20,000 sources and provides detailed characterization of local evolved stars, including bolometric magnitudes and variability properties.

Findings

Identified 1,812 evolved stars within 2 kpc with accurate parallaxes.

Most variable Gaia counterparts are AGB stars with moderate luminosity.

Derived period-luminosity relations for the local AGB population.

Abstract

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 VLBI 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) AGB stars can be characterized. We have defined a \textit{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 1,812 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 ($1,500^{+3,000}_{-500} \ L_\odot$) and periods between 250 and 1,250 days.