"Dark matter" in accretion disks
Abstract
Using Spitzer Space Telescope photometric observations of the eclipsing, interacting binary WZ Sge, we have discovered that the accretion disk is far more complex than previously believed. Our 4.5 and 8 µm time series observations reveal that the well-known gaseous accretion disk is surrounded by an asymmetric disk of dusty material with a radius approximately 15 times larger than the gaseous disk. This dust ring contains only a small amount of mass and is completely invisible at optical and near-IR wavelengths, hence consisting of "dark matter." We have produced a model dust ring using 1 µm spherical particles with a density of 3 g cm^(-3) and with a temperature profile ranging from 700 to 1500 K. Our discovery about the accretion disk structure and the presence of a larger, outer dust ring have great relevance for accretion disks in general, including those in other interacting binary systems, pre-main-sequence stars, and active galaxies.
Additional Information
© 2008 The American Astronomical Society. Received 2008 April 23; accepted 2008 May 30. We wish to thank Charles Bailyn for his approval of our SMARTS directors time request to observe WZ Sge with Andicam. We thank the anonymous referee for catching a calculation error that allowed us to improve the model results. 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 the National Aeronautics and Space Administration (NASA). Support for this work was provided by NASA. We thank the Spitzer Science Center (SSC) director for his generous allocation of observing time for the NASA/NOAO/Spitzer Space Telescope Observing Program for Students and Teachers. We especially thank Lynne Zielinski, Jen Tetler, Susan Kelly, and Kareen Borders for their help with the ground-based observations. The National Optical Astronomy Observatory (NOAO), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under cooperative agreement with the National Science Foundation (NSF), has provided many in kind contributions for which S. B. H. is grateful. This work 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 NSF. C. S. B. acknowledges support from the SSC Enhanced Science Fund and NASA's Michelson Science Center.Attached Files
Published - HOWapj08.pdf
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Additional details
- Eprint ID
- 13445
- Resolver ID
- CaltechAUTHORS:HOWapj08
- NASA
- Spitzer Science Center
- Michelson Science Center
- National Optical Astronomy Observatory (NOAO)
- NSF
- Created
-
2009-07-10Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)