Ground Vibrational State SiO Emission in the VLA BAaDE Survey
  Using a subsample of the Bulge Asymmetries and Dynamical Evolution (BAaDE)
survey of stellar SiO masers, we explore the prevalence and characteristics of
$^{28}$SiO $J=1-0, v=0$ emission. We identify 90 detections of maser, thermal,
or composite $^{28}$SiO $J=1-0, v=0$ emission out of approximately 13,000
candidate spectra from the NSF's Karl G. Jansky Very Large Array (VLA). We find
that the detected sources are likely asymptotic giant branch (AGB) stars
belonging to a bright, foreground Milky Way stellar disk population. For the 32
sources showing thermal components, we extract values for outflow velocity by
fitting thermal line profiles. We find a range of circumstellar envelope
expansion velocities, and compare to previously recorded OH and CO expansion
velocities. This preliminary survey is already the largest study of stellar
ground-vibrational-state SiO masers to date, and will be expanded to include
the entire VLA BAaDE dataset when data reduction for the 18,988 target sources
is completed.
