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Astronomy Colloquium
Galactic HII Regions and Structure in the Milky Way
Date: Thursday, September 29th
Time: 3:30 pm
Place: Sterling Hall 4421; or via Zoom:
Speaker: Trey Wenger, NSF Astronomy & Astrophysics Postdoctoral Fellow
Abstract: Radio recombination lines (RRLs) are an unobscured tracer of ionized gas in both the diffuse interstellar medium (ISM) as well as high-mass star forming regions. The Green Bank Telescope HII Region Discovery Survey (HRDS) and its successors have more than doubled the number of known high-mass star forming regions in the Milky Way by detecting RRL emission toward infrared-identified HII region candidates. HII regions are the classic tracer of structure in galaxies, and their physical conditions (e.g., metallicity, internal kinematics) inform models of high-mass star formation and Galactic chemodynamical evolution. I will give a brief overview of our latest HRDS project, the Southern HII Region Discovery Survey, and some preliminary results with the first Galaxy-wide flux-limited HII region sample, including a novel technique to constrain Milky Way spiral structure. In the SHRDS, we serendipitously discovered a population of HII regions with ionized gas velocity gradients. I will discuss both the origin and implications of this discovery on models of high-mass star formation as well the future of Galactic structure and HII region science (both Galactic and extragalactic) in the era of ALMA and ngVLA.
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