Brinkworth, C. S. and Hoard, D. W. and Wachter, S. and Howell, S. B. and Ciardi, David R. and Szkody, P. and Harrison, T. E. and van Belle, G. T. and Esin, A. A. (2007) Spitzer Space Telescope Observations of Magnetic Cataclysmic Variables: Possibilities for the Presence of Dust in Polars. Astrophysical Journal, 659 (2). pp. 1541-1562. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20091109-133657437
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We present Spitzer photometry of six short-period polars, EF Eri, V347 Pav, VV Pup, V834 Cen, GG Leo, and MR Ser. We have combined the Spitzer IRAC (3.6-8.0 μm) data with the 2MASS JHK_s photometry to construct the SEDs of these systems from the near- to mid-IR (1.235-8 μm). We find that five out of the six polars have flux densities in the mid-IR that are substantially in excess of the values expected from the stellar components alone. We have modeled the observed SEDs with a combination of contributions from the white dwarf, secondary star, and either cyclotron emission or a cool, circumbinary dust disk to fill in the long-wavelength excess. We find that a circumbinary dust disk is the most likely cause of the 8 μm excess in all cases, but we have been unable to rule out the specific (but unlikely) case of completely optically thin cyclotron emission as the source of the observed 8 μm flux density. While both model components can generate enough flux at 8 μm, neither dust nor cyclotron emission alone can match the excess above the stellar components at all wavelengths. A model combining both cyclotron and dust contributions, possibly with some accretion-generated flux in the near-IR, is probably required, but our observed SEDs are not sufficiently well sampled to constrain such a complicated model. If the 8 μm flux density is caused by the presence of a circumbinary dust disk, then our estimates of the masses of these disks are many orders of magnitude below the mass required to affect CV evolution.
|Additional Information:||© 2007 The American Astronomical Society. Received 2006 August 8; accepted 2007 January 10. 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 a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. 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/Caltech, funded by NASA and the National Science Foundation. We acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research. Last, but by no means least, we would like to thank the anonymous referee for the thoughtful and thorough review of our paper.|
|Subject Keywords:||infrared : stars; stars : low-mass, brown dwarfs; stars : magnetic fields|
|Official Citation:||Spitzer Space Telescope Observations of Magnetic Cataclysmic Variables: Possibilities for the Presence of Dust in Polars C. S. Brinkworth, D. W. Hoard, S. Wachter, S. B. Howell, David R. Ciardi, P. Szkody, T. E. Harrison, G. T. van Belle, and A. A. Esin 2007 ApJ 659 1541-1562 doi: 10.1086/512797|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||16 Nov 2009 17:15|
|Last Modified:||26 Dec 2012 11:32|
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