NOAO >   Observing Info >   Approved Programs >   2006A-0053

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Proposal Information for 2006A-0053


PI: Schuyler D. Van Dyk, Spitzer Science Center, vandyk@ipac.caltech.edu
Address: Caltech, 220-6, Pasadena, CA 91125, USA

CoI: Lucy Hadfield, U. Sheffield/Spitzer Science Center/Caltech
CoI: Patrick W. Morris, IPAC/Caltech
CoI: J.D.T. Smith, U. of Arizona

Title: Revealing Hidden Wolf-Rayet Stars in the Galaxy with GLIMPSE+2MASS

Abstract: Massive stars strongly influence galaxy evolution, including that of our own. Stars with M\rm init \gtrsim 20 M_\odot evolve to become Wolf-Rayet (WR) stars. WRs are excellent markers and chronometers of very recent star formation and probes of the IMF in galaxies. Galactic optical line surveys for WRs are complete to B \lesssim 14 mag; yet the number is low by 4-10\times relative to Galaxy models: Many WRs must be obscured by the high visual extinction in the Plane. However, in the infrared (IR), extinction is far lower (e.g., A_K/A_V ~ 10%), greatly enhancing our chances of detecting ``hidden'' WRs. We have characterized the known WRs in the near-IR continuum and are currently working to characterize them further in the mid-IR: Using the near-IR all-sky 2MASS in conjunction with the mid-IR \sl Spitzer GLIMPSE Legacy survey of the Plane (which should straightforwardly reveal WRs still associated with their natal molecular clouds), we are selecting candidate WRs across large spans of the Plane. We propose here the natural extension of this work, i.e., spectroscopic candidate confirmation in both the optical and near-IR which are accessible in 2006A from CTIO. Both optical and near-IR spectra are necessary to fully characterize any newly discovered WRs. We therefore hope to facilitate a more complete determination of massive star formation in the Galaxy and more accurate testing of massive stellar evolutionary scenarios.


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