Spitzer Space Telescope - Archive Research Proposal #20574


A GLIMPSE at Hidden Wolf-Rayet Stars in the Galaxy

Principal Investigator: Schuyler Van Dyk
           Institution: Spitzer Science Center

Co-Investigators: 
Anthony Marston, ESTEC/ESA                                            
Patrick Morris, IPAC                                                  
J.D. Smith, University of Arizona                                     

Science Category: massive stars 
Dollars Approved: 66315.0 

Abstract:
Massive stars have an unparalleled effect on galaxy evolution, since
their strong stellar winds and the inevitable supernovae input energy
and chemical elements into the interstellar medium.  O-type stars are
thought to evolve through the red supergiant and luminous blue
variable phases to become H-poor Wolf-Rayet (WR) stars, before
explosion.  Due to their high luminosity, the presence of WR stars can
be detected in the integrated spectra of galaxies, and the short
duration of this phase of massive stellar evolution makes WR stars
excellent probes of very recent star formation, metallicity, and the
initial mass function in the nearby Universe.  Unfortunately, the
number of WR stars in the Milky Way is deficient by factors of 4 to
10, depending on the models, and as a result we know little about the
total massive star formation and the fate of massive stellar evolution
in our own Galaxy.  The culprit is the rapid increase with distance of
the line-of-sight extinction, due to dust in the Galactic Plane, where
most WR stars are located.  Detecting new WR stars is greatly
alleviated in the infrared, where extinction is substantially lower.
For this reason, we will analyze the combination of point source
extractions from the GLIMPSE Legacy and 2MASS surveys, since this
merging of the mid- and near-infrared provides a powerful means of
identifying a significant number of hidden WR stars in the Plane.