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Herschel Observations of Cataclysmic Variables

Harrison, Thomas E. and Hamilton, Ryan T. and Tappert, Claus and Hoffman, Douglas I. and Campbell, Ryan K. (2013) Herschel Observations of Cataclysmic Variables. Astronomical Journal, 145 (1). Art. No. 19. ISSN 0004-6256. doi:10.1088/0004-6256/145/1/19.

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We have used the PACS instrument on the Herschel Space Observatory to observe eight cataclysmic variables at 70 and 160 μm. Of these eight objects, only AM Her was detected. We have combined the Herschel results with ground-based, Spitzer, and WISE observations to construct spectral energy distributions for all of the targets. For the two dwarf novae in the sample, SS Cyg and U Gem, we find that their infrared luminosities are completely dominated by their secondary stars. For the two highly magnetic "polars" in our survey, AM Her and EF Eri, we find that their mid-infrared excesses, previously attributed to circumbinary dust emission, can be fully explained by cyclotron emission. The WISE light curves for both sources show large, orbitally modulated variations that are identically phased to their near-IR light curves. We propose that significant emission from the lowest cyclotron harmonics (n ≤ 3) is present in EF Eri and AM Her. Previously, such emission would have been presumed to be optically thick, and not provide significant orbitally modulated flux. This suggests that the accretion onto polars is more complicated than assumed in the simple models developed for these two sources. We develop a model for the near-/mid-IR light curves for WZ Sge with an L2 donor star that shows that the ellipsoidal variations from its secondary star are detected. We conclude that none of the targets surveyed have dusty circumbinary disks.

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Hamilton, Ryan T.0000-0001-6350-2209
Additional Information:© 2013 American Astronomical Society. Received 2012 September 10; accepted 2012 November 20; published 2012 December 12. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. This work is based in part on observations made with Herschel, a European Space Agency Cornerstone Mission with significant participation by 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 Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This work is also based in part on observations made with the Spitzer Space Telescope, obtained from the NASA/IPAC Infrared Science Archive, both of which are operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration. We acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research. Finally, we dedicate this paper to the memory of K. M. Merrill, who provided unparalleled support for our extensive use of SQIID over this past decade.
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Subject Keywords:infrared: stars; novae, cataclysmic variables; stars: individual (V592 Cassiopeiae, SS Cygni, EF Eridani, U Geminorum, AM Herculis, EX Hydrae, WZ Sagittae, V1223 Sagittarii)
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Record Number:CaltechAUTHORS:20130115-093506992
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Official Citation:Herschel Observations of Cataclysmic Variables Thomas E. Harrison et al. 2013 The Astronomical Journal 145 19
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36374
Deposited By: Ruth Sustaita
Deposited On:15 Jan 2013 17:57
Last Modified:09 Nov 2021 23:21

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