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The first mid-infrared spectra of cool white dwarfs

Kilic, Mukremin and Kowalski, Piotr M. and Mullally, Fergal and Reach, William T. and von Hippel, Ted (2008) The first mid-infrared spectra of cool white dwarfs. Astrophysical Journal, 678 (2). pp. 1298-1303. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:KILapj08

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Abstract

We present the first mid-infrared spectra of two cool white dwarfs obtained with the Spitzer Space Telescope. We also present 3.5-8 µm photometry for 19 cool white dwarfs with 5000 K ≤ T-eff ≤ 9000 K. We perform a detailed model atmosphere analysis of these white dwarfs by fitting their UBVRIJHK and Spitzer photometry with state-of-the-art model atmospheres, and demonstrate that the optical and infrared spectral energy distributions of cool white dwarfs are well reproduced by our grid of models. Our mid-infrared photometry and 7.5-14.5 µm spectrum of WD0018-267 are consistent with a T-eff 5720 K, pure hydrogen white dwarf model atmosphere. On the other hand, LHS 1126 remains peculiar, with significant mid-infrared flux deficits in all IRAC bands and a featureless spectrum in the 5.2-7.5 µm range. Even though this deficit is attributed to collision-induced absorption (CIA) due to molecular hydrogen, the shape of the deficit cannot be explained with current CIA opacity calculations. The infrared portion of the LHS 1126 spectral energy distribution is best fit with a power-law index of -1.99, identical to a Rayleigh-Jeans spectrum. This argues that the deficit may be due to an unrecognized graylike opacity source in the infrared.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1086/528705DOIArticle
ORCID:
AuthorORCID
Reach, William T.0000-0001-8362-4094
Additional Information:© 2008 American Astronomical Society. Received 2007 October 11; accepted 2007 December 13. P.M.K. acknowledges partial financial support from Ruhr-Universität in Bochum. Support for this work was provided by NASA through awards issued by JPL/Caltech to the University of Texas and The Ohio State University. 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. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.
Funders:
Funding AgencyGrant Number
Ruhr-UniversitätUNSPECIFIED
NASA1407
NSFUNSPECIFIED
Subject Keywords:infrared: stars; stars: individual (WD 0018-267, WD 0038-226, LHS 1126); white dwarfs
Issue or Number:2
Record Number:CaltechAUTHORS:KILapj08
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:KILapj08
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12525
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:23 Dec 2008 22:51
Last Modified:02 Mar 2017 04:44

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