NOAO >   Observing Info >   Approved Programs >   2006A-0292

Small NOAO Logo

Proposal Information for 2006A-0292


PI: Mukremin Kilic, University of Texas at Austin, kilic@astro.as.utexas.edu
Address: Department of Astronomy, 1 University Station, C1400, Austin, TX 78712, USA

CoI: Nigel Hambly, The Royal Observatory of Edinburgh
CoI: Ted von Hippel, University of Texas at Austin
CoI: Don Winget, University of Texas at Austin
CoI: Andrew Digby, American Museum of Natural History, NY

Title: CIA vs. Mystery: Understanding the Ultra-Cool White Dwarf Atmospheres

Abstract: Spitzer Space Telescope observations of cool white dwarfs revealed unexpected flux deficits in the mid-infrared spectral energy distributions of these stars. These flux deficits are not predicted by the current white dwarf models, even those including collision induced absorption (CIA) due to molecular hydrogen. The Spitzer observations suggest that the source of this deficit may be some other unknown physical process. Ultra-cool white dwarfs define the faint end of the white dwarf luminosity function, therefore they are crucial in determining the age of the Galaxy. In order to study CIA and the newly discovered flux deficits in cool white dwarf atmospheres, we propose to increase the number of known ultra-cool white dwarfs from a few to tens of objects by obtaining spectrophotometric confirmation of a sample of ultra-cool white dwarf candidates selected on the basis of SuperCOSMOS Sky Survey (SSS) astrometry and photometry. With sky coverage comprising 92% of the southern sky below Dec=+3.0, SSS provides a unique opportunity to find the coolest white dwarfs in the Galactic disk. This new sample of white dwarf stars will also help us resolve the controversy, based for the most part on small number statistics, of the location of the turn down in the white dwarf luminosity function for the Galactic disk.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2006A-0292

noaoprop-help@noao.edu

Small NOAO Logo