Ground Vibrational State SiO Emission in the VLA BAaDE Survey

TL;DR

This study analyzes ground vibrational state SiO emission in a large stellar survey, identifying 90 sources and measuring outflow velocities, providing new insights into AGB star envelopes in the Milky Way.

Contribution

It is the largest survey of ground-vibrational-state SiO masers, offering new data on stellar outflows and expanding understanding of AGB stars in our galaxy.

Findings

Identified 90 SiO emission sources in the BAaDE survey.

Measured outflow velocities of AGB star envelopes.

Compared SiO velocities with OH and CO data.

Abstract

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.