A Lifetime of Influence: Abstracts, Talks, and Posters
 

Red Eyes On Wolf-Rayet Stars: Pulling Back the Curtain of Dust on a Hidden Population of Massive Stars

Pat Morris
Caltech

Schuyler van Dyk
Caltech

Lucy Hadfield
Rochester Inst Tech

Tony Marston
ESA

Jon Mauerhan
UCLA/Caltech

JD Smith
U Arizona

Efforts to detect new Wolf-Rayet (WR) stars in relation to massive OB star and Red Supergiant populations in the Milky Way over the last decade have been motivated by testing stellar evolution model predictions on lifetimes in different core burning phases and to better establish their energetic contributions in galaxies. A large number of WR stars, up to 90% of the predicted population, have been suspected to be hidden behind large amounts of extinction, more than 10 magnitues in the K band, especially in dense stellar clusters of Galactic HII regions and especially towards the Galactic Center. Recent near-IR photometric and spectroscopic surveys have in fact revealed several concentrations of WR stars. A near-IR 2MASS-based survey to a completeness of ~12mag in K however is hampered by some degeneracies in colors with transition OB emission line stars and dusty young stars. Yet we recognize that the unique free-free continuum and H/He/C emission line properties which explain their color behavior can also be used to remove this degeneracy to increasing degrees with the inclusion of longer wavelength colors. We demonstrate how combined 2MASS + Spitzer IRAC and MIPS colors set a candidate population of WR stars apart from the OB transition population, empirically understood from the near- and mid-IR spectroscopic properties of known WR stars, and give the status of new discoveries of very reddened stars in the "open" field and in clusters/associations.