ISOLATED WOLF-RAYET STARS AND O SUPERGIANTS IN THE GALACTIC CENTER REGION IDENTIFIED VIA PASCHEN-{alpha} EXCESS
- Infrared Processing and Analysis Center, California Institute of Technology, Mail Code 220-6, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
- SETI Institute, 515 North Whisman Road, Mountain View, CA 94043 (United States)
- Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)
- Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52245 (United States)
We report the discovery of 19 hot, evolved, massive stars near the Galactic center region (GCR). These objects were selected for spectroscopy owing to their detection as strong sources of Paschen-{alpha} (P{alpha}) emission-line excess, following a narrowband imaging survey of the central 0.{sup 0}65 x 0.{sup 0}25 (l, b) around Sgr A* with the Hubble Space Telescope. Discoveries include six carbon-type (WC) and five nitrogen-type (WN) Wolf-Rayet stars, six O supergiants, and two B supergiants. Two of the O supergiants have X-ray counterparts having properties consistent with solitary O stars and colliding-wind binaries. The infrared photometry of 17 stars is consistent with the Galactic center distance, but 2 of them are located in the foreground. Several WC stars exhibit a relatively large infrared excess, which is possibly thermal emission from hot dust. Most of the stars appear scattered throughout the GCR, with no relation to the three known massive young clusters; several others lie near the Arches and Quintuplet clusters and may have originated within one of these systems. The results of this work bring the total sample of Wolf-Rayet (WR) stars in the GCR to 88. All sources of strong P{alpha} excess have been identified in the area surveyed with HST, which implies that the sample of WN stars in this region is near completion, and is dominated by late (WNL) types. The current WC sample, although probably not complete, is almost exclusively dominated by late (WCL) types. The observed WR subtype distribution in the GCR is a reflection of the intrinsic rarity of early subtypes (WNE and WCE) in the inner Galaxy, an effect that is driven by metallicity.
- OSTI ID:
- 21565479
- Journal Information:
- Astrophysical Journal, Vol. 725, Issue 1; Other Information: DOI: 10.1088/0004-637X/725/1/188; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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