The Mystery Deepens: Spitzer Observations of Cool White Dwarfs
Abstract
We present 4.5 and 8 μm photometric observations of 18 cool white dwarfs obtained with the Spitzer Space Telescope. Our observations demonstrate that four white dwarfs with T_eff < 6000 K show slightly depressed mid-infrared fluxes relative to white dwarf models. In addition, another white dwarf with a peculiar optical and near-infrared spectral energy distribution (LHS 1126) is found to display significant flux deficits in Spitzer observations. These mid-infrared flux deficits are not predicted by the current white dwarf models including collision-induced absorption due to molecular hydrogen. We postulate that either the collision-induced absorption calculations are incomplete or there are other unrecognized physical processes occurring in cool white dwarf atmospheres. The spectral energy distribution of LHS 1126 surprisingly fits a Rayleigh-Jeans spectrum in the infrared, mimicking a hot white dwarf with effective temperature well in excess of 10^5 K. This implies that the source of this flux deficit is probably not molecular absorption but some other process.
Additional Information
© 2006 American Astronomical Society. Received 2005 October 14; accepted 2006 January 4. We would like to thank Didier Saumon, Lothar Frommhold, Jason Kalirai, Brad Hansen, and Pierre Bergeron for helpful discussions, and our referee, Jay Farihi, for helpful suggestions that greatly improved the article. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory (JPL), California Institute of Technology under NASA contract 1407. Support for this work was provided by NASA through award project NBR: 1269551 issued by JPL/California Institute of Technology to the University of Texas. This publication makes use of data products from the 2MASS, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by NASA and the NSF. This material is based upon work supported by NASA under grant NAG5-13070 issued through the Office of Space Science.Attached Files
Published - KILapj06.pdf
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Additional details
- Eprint ID
- 23681
- Resolver ID
- CaltechAUTHORS:20110516-141034617
- NSF
- NAG5-13070
- NASA
- Created
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2011-05-17Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field