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Spitzer Observations of the Oldest White Dwarfs in the Solar Neighborhood

Kilic, Mukremin and Kowalski, Piotr M. and Reach, William T. and von Hippel, Ted (2009) Spitzer Observations of the Oldest White Dwarfs in the Solar Neighborhood. Astrophysical Journal, 696 (2). pp. 2094-2103. ISSN 0004-637X.

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We present Spitzer 5-15 μm spectroscopy of one cool white dwarf and 3.6-8 μm photometry of 51 cool white dwarfs with T_(eff) < 6000 K. The majority of our targets have accurate BVRIJHK photometry and trigonometric parallax measurements available, which enables us to perform a detailed model atmosphere analysis using their optical, near- and mid-infrared photometry with state-of-the-art model atmospheres. We demonstrate that the optical and infrared spectral energy distributions of cool white dwarfs are well reproduced by our grid of models. Our best-fit models are consistent with the observations within 5% in all filters except the IRAC 8 μm band, which has the lowest signal-to-noise ratio photometry. Excluding the ultracool white dwarfs, none of the stars in our sample show significant mid-infrared flux deficits or excesses. The nondetection of mid-infrared excess flux around our ≈2-9 Gyr old targets constrain the fraction of cool white dwarfs with warm debris disks to 0.8^(+1.5)_(–0.8)%.

Item Type:Article
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Reach, William T.0000-0001-8362-4094
Additional Information:© 2009 The American Astronomical Society. Received 2008 December 10; accepted 2009 February 25; published 2009 April 28. M.K. thanks D. Winget and S. Kenyon for useful discussions. Support for this work was provided by NASA through the Spitzer Space Telescope Fellowship Program, under an award from Caltech, and also award projects NBR 1359963 and 1288635 issued by JPL/Caltech to Ohio State University and the University of Texas. P.M.K. thanks D. Marx and the theoretical chemistry group at Ruhr-Universitat Bochum for their hospitality and support. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407.
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University of TexasUNSPECIFIED
Subject Keywords:infrared: stars; stars: atmospheres; white dwarfs
Issue or Number:2
Record Number:CaltechAUTHORS:20090901-083348740
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Official Citation:Spitzer Observations of the Oldest White Dwarfs in the Solar Neighborhood Mukremin Kilic, Piotr M. Kowalski, William T. Reach, and Ted von Hippel 2009 ApJ 696 2094-2103 doi: 10.1088/0004-637X/696/2/2094.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15507
Deposited By: Tony Diaz
Deposited On:14 Sep 2009 19:12
Last Modified:03 Oct 2019 00:58

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