Debris disks in main sequence binary systems

We observed 69 A3-F8 main sequence binary star systems using the Multiband Imaging Photometer for Spitzer onboard the Spitzer Space Telescope. We find emission significantly in excess of predicted photospheric flux levels for 9 −3% and 40 −6% of these systems at 24 and 70 μm, respectively. Twenty two systems total have excess emission, including four systems that show excess emission at both wavelengths. A very large fraction (nearly 60%) of observed binary systems with small (<3 AU) separations have excess thermal emission. We interpret the observed infrared excesses as thermal emission from dust produced by collisions in planetesimal belts. The incidence of debris disks around main sequence A3-F8 binaries is marginally higher than that for single old AFGK stars. Whatever combination of nature (birth conditions of binary systems) and nurture (interactions between the two stars) drives the evolution of debris disks in binary systems, it is clear that planetesimal formation is not inhibited to any great degree. We model these dust disks through fitting the spectral energy distributions and derive typical dust temperatures in the range 100–200 K and typical fractional luminosities around 10, with both parameters similar to other Spitzerdiscovered debris disks. Our calculated dust temperatures suggest that about half the excesses we observe are derived from circumbinary planetesimal belts Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ, 85721 Jet Propulsion Laboratory, MS 183-900, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 Department of Physics and Astronomy, Appalachian State University, Boone, NC 28608 Vatican Observatory Research Group, Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 NOAO, 950 North Cherry Avenue, Tucson, AZ 85719