© Megan Lewis

During the asymptotic giant branch (AGB) phase, evolved stars are shrouded in the gas and dust associated with their own mass loss. The circumstellar envelopes that form via this process are molecularly rich environments, many of which host SiO masers. As SiO maser pumping mechanisms are not fully understood, there are many challenges in relating maser activity to physical (circum-)stellar properties.

I will share results from the largest SiO maser survey, BAaDE, which detected over 15000 SiO masers in the Milky Way plane. The BAaDE database contributes to statistical studies of maser properties, AGB properties, and even Galactic dynamics. Beyond these statistical studies, we also have a huge sample from which to draw exceptional maser sources.