Center for Astrophysics Research and Technologies Seminar Series
Stellar populations in BAaDE
Presented by Megan Lewis (UNM)
The Bulge Asymmetries and Dynamical Evolution (BAaDE) survey is the largest ever SiO maser survey, covering sources throughout the Galactic Plane. About 21,000 sources have been observed so far for maser emission and data reduction is nearing completion. The name-sake goal of the project is to collect line-of-sight velocities for all the detected masers in the sample to probe Galactic dynamics. However, the survey is also a large sample of infrared (IR) sources with which to explore the different stellar populations within the Milky Way. Specifically, detections of SiO masers from the survey more tightly define the region where Oxygen-rich (O) Asymptotic Giant Branch (AGBs) stars reside in multiple IR color-color diagrams. Using MSX and 2MASS data along with radio spectra from the BAaDE survey we find three main populations were observed in the BAaDE survey: O-rich AGBs of which about 70% host SiO masers, Carbon-rich (C) AGBs which rarely host these masers, and an additional population of possible Young Stellar Objects (YSOs). The distinction between YSOs and AGBs can be drawn using only MSX data, specifically the [D]-[E] color, while the shorter wavelengths provided by 2MASS are necessary to divide C and O-rich AGBs. Divisions similar to these have been seen in multiple IR-studies, but BAaDE far exceeds previous studies in sample size, and therefore, clarity of these divisions. With these IR distinctions in place, we discuss special sources, the abundance and distribution of C-AGBs, and the BAaDE detection rate. Lastly we will briefly discuss line ratios in the BAaDE sample.
2:00 pm, Thursday, September 26, 2019
PAIS-2540, PAIS
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