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| Paper: |
Red Eyes on Wolf-Rayet Stars: New Discoveries via Infrared Color Selection |
| Volume: |
465, Four Decades of Massive Star Research - A Scientific Meeting in Honor of Anthony J. Moffat |
| Page: |
472 |
| Authors: |
Mauerhan, J. C.; Van Dyk, S.; Morris, P. |
| Abstract: |
We summarize the latest results form our infrared, color-based survey for Galactic Wolf-Rayet (WR) stars. Using photometry from the Spitzer/GLIMPSE and 2MASS databases, we select WRs via a method that exploits their unique infrared colors, which is mainly the result of excess radiation generated by free-free scattering within their dense ionized winds. The selection criterion results in a WR detection rate of ≈20% in spectroscopic follow-up of candidates that comprise a broad color space defined by the color distribution of all known WRs having B > 14 mag, although there are smaller regions within this color space which yield WRs at a rate of >50%. Cross-correlation with archival X-ray catalogs increases the WR detection rate of the broad color space to ≈40%, although with significant bias toward WN types. Although the majority of the new WRs have no obvious association with stellar clusters, two WC8 stars reside in a previously unknown massive-star cluster, in which five OB supergiants were also identified. In addition, two WC and four WN stars, all but one of which are X-ray sources, were identified in association with the stellar clusters Danks 1 and 2. Our 60 latest WR discoveries (out of nearly 100 to date) include 38 WN types and 22 WC types, bringing the total number of known Galactic WRs close to 500, or ≈8% of the total empirically estimated population. An examination of their Galactic distribution reveals an approximate tracing of spiral arms and an enhanced WR surface density toward several massive-star formation sites. |
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