NOAO >   Observing Info >   Approved Programs >   2006A-0516

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Proposal Information for 2006A-0516


PI: Carolyn Brinkworth, California Institute of Technology, csb@ipac.caltech.edu
Address: Spitzer Science Center, MC220-6, 1200 E. California Blvd, Pasadena, CA 91125, USA

CoI: Donald Hoard, Caltech / SSC / Pomona College
CoI: Stefanie Wachter, Caltech / SSC

Title: Probing the Paradigm for Cataclysmic Variable Evolution: the Search for Circumbinary Disks

Abstract: The secular evolution of cataclysmic variables (CVs) is driven by the loss of orbital angular momentum. Two mechanisms are usually invoked to account for the dissipation of angular momentum: gravitational radiation and magnetic braking of the secondary star. However, this dual loss-mechanism cannot completely account for the very large mass-transfer rates inferred for some CVs, or for the large spread in mass transfer rates observed at a given orbital period (i.e. evolutionary state). An additional angular momentum loss mechanism is needed; a likely possibility is the presence of a circumbinary disk (CBD) surrounding the CV. The CBD would be large (up to several AU in radius) and cool (a few thousand K at the inner edge to less than 1000 K at the outer edge). Its peak emission therefore occurs in the infrared. We have been awarded Spitzer Space Telescope time to observe 8 CVs in the mid-IR, with the aim of assembling spectral energy distributions for the sample to search for infrared excess indicative of the presence of a CBD. However, due to the highly variable nature of these objects, we are unable to use archival data to extend our SEDs into the near-IR and optical wavebands. We therefore request simultaneous or near- simultaneous ground-based observations of the selected CVs to complement our Spitzer observations.


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