Searching for hidden Wolf-Rayet stars in the Galactic Plane - 15 new Wolf-Rayet stars
L. J. Hadfield (1), S. D. Van Dyk (2), P. W. Morris (3), J. D. Smith (4), A. P. Marston (5) and D. E. Peterson (6)
(1) University of Sheffield, (2) Spitzer Science Center, (3) NASA Herschel Science Center, (4) Steward Observatory, (5)ESA/ESAC, (6) University of Virginia.
We report the discovery of fifteen previously unknown Wolf-Rayet (WR) stars found as part of an infrared broad-band study of candidate WR stars in the Galaxy. We have derived an empirically-based selection algorithm which has selected ~5000 WR candidate stars located within the Galactic Plane drawn from the GLIMPSE (mid-infrared) and 2MASS (near-infrared) catalogues. Spectroscopic follow-up of 184 of these reveals eleven WN and four WC-type WR stars. Early WC subtypes are absent from our sample and none show evidence for circumstellar dust emission. Of the candidates which are not WR stars, ~120 displayed hydrogen emission line features in their spectra. Spectral features suggest that the majority of these are in fact B supergiants/hypergiants, ~40 of these are identified Be/B[e] candidates.
Here, we present the optical spectra for six of the newly-detected WR stars, and the near-infrared spectra for the remaining nine of our sample. With a WR yield rate of ~7% and a massive star detection rate of ~65%, initial results suggest that this method is one of the most successful means for locating evolved, massive stars in the Galaxy.
Status: Manuscript has been accepted
Comments: Accepted for publication in MNRAS. Full version available by anonymous ftp (ftp:astro1.shef.ac.uk, /pub/lh/hadfield.ps.gz)