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Isolated Wolf-Rayet Stars and O Supergiants in the Galactic Center Region Identified Via Paschen-α Excess

Mauerhan, J. C. and Cotera, A. and Dong, H. and Morris, M. R. and Wang, Q. D. and Stolovy, S. R. and Lang, C. (2010) Isolated Wolf-Rayet Stars and O Supergiants in the Galactic Center Region Identified Via Paschen-α Excess. Astrophysical Journal, 725 (1). pp. 188-199. ISSN 0004-637X.

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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-α (Pα) emission-line excess, following a narrowband imaging survey of the central 0°.65 × 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 Pα 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.

Item Type:Article
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URLURL TypeDescription DOIErratum - FEB 20 2011 DOIErratum - OCT 1 2015
Morris, M. R.0000-0002-6753-2066
Additional Information:© 2010 American Astronomical Society. Received 2010 July 27; accepted 2010 September 13; published 2010 November 17. The project is partly supported by NASA through a grant HST-GO-11120 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
Funding AgencyGrant Number
NASANAS 5-26555
Subject Keywords:Galaxy: center; infrared: stars; stars: emission-line, Be; stars: Wolf–Rayet; supergiants; X-rays: stars
Issue or Number:1
Classification Code:PACS: 97.30.Eh; 98.35.Jk; 97.20.Pm; 95.85.Kr; 98.35.Ln
Record Number:CaltechAUTHORS:20110107-141452282
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Official Citation:J. C. Mauerhan et al. 2010 ApJ 725 188 doi: 10.1088/0004-637X/725/1/188
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21648
Deposited By: Jason Perez
Deposited On:11 Jan 2011 19:29
Last Modified:04 Nov 2019 21:48

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