NOAO >   Observing Info >   Approved Programs >   2006A-0316

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Proposal Information for 2006A-0316


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: Ted von Hippel, University of Texas
CoI: Sandy Leggett, UKIRT
CoI: Hugh Harris, Jeff Munn, US Naval Observatory
CoI: Jim Liebert, University of Arizona
CoI: Don Winget, University of Texas
CoI: Jay Farihi, Gemini Observatory

Title: New Old White Dwarfs and the Age of the Galaxy

Abstract: We propose to obtain JHK photometry of 50 spectroscopically confirmed new cool white dwarfs, including 5 ultra-cool white dwarf candidates (T_\rm eff<=4000 K), to determine temperatures, bolometric luminosities, and compositions for these stars. Our follow- up spectroscopy of high proper motion objects in the Sloan Digital Sky Survey yielded a large number of new cool white dwarfs which are suitable for constructing an improved white dwarf luminosity function. This luminosity function will ultimately resolve the controversies, based for the most part on small number statistics, of the age of the Galactic disk. The detailed shape of the white dwarf luminosity function will also allow us to constrain the interior physics of cooling white dwarfs and place white dwarf cosmochronometry on a firmer foundation. We have already begun an observing campaign at the IRTF and Gemini-N (2005B). With the Gemini-NIRI, we propose to complete our program by obtaining the infrared photometry of the coolest white dwarfs in the Galactic disk that are intrinsically faint and need 8m class telescope observations. These observations will also improve our understanding of collisionally-induced absorption and other unrecognized opacities in cool white dwarf atmospheres.


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