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Proposal Information for 2013A-0482


PI: Jon Mauerhan, University of Arizona, mauerhan@as.arizona.edu
Address: Steward Observatory, 933 N Cherry Ave, Tucosn, AZ 85721, United States

CoI: Hui Dong, NOAO

Title: Continuing Classification of Paschen-(alpha) Excess Sources in the Galactic Center Field with SOAR/OSIRIS

Abstract: The Galactic Center (GC) is a maelstrom of high energy activity, much of which is driven by energetic feedback from massive stars. The hot, turbulent conditions of the GC ISM result in a relatively high rate of massive star production, as evidenced by three extraordinary starburst clusters. Previously, it was thought that starburst clusters were the only important mode of massive star formation in the GC; but recently, we have unveiled a significant population of ``isolated" field Wolf-Rayet stars and OB supergiants that apparently have no spatial association to the known clusters. Statistical analysis has shown that the total massive-star field population in the central ~300 pc is equivalent by number to the three starburst clusters combined. Using HST, we have discovered ~100 sources of Paschen-(alpha) (P(alpha)) emission-line excess scattered throughout the GC field. Preliminary spectroscopy has revealed that most of these objects are massive stars. Their origin is unclear; either they formed \textitin situ, or they have been gravitationally scattered within parent clusters and subsequently stripped from them by the strong GC tidal field. So far, our spectroscopic follow-up program has had a 100% massive-star return rate, targeting the brightest K$<12 mag P(alpha). We now intend to push fainter (K=12.5-13.5 mag). Our program will potentially complete the WR census of the inner ~100 pc of the Galaxy, and, for the first time, potentially identify the OB field giants and early O dwarfs that emit P(alpha) emission. Once classified, their spectral types and demography will elucidate their origins.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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