Planets and infrared excesses:: Preliminary results from a Spitzer MIPS survey of solar-type stars

As part of a large Spitzer MIPS Guaranteed Time Observation program, we have searched for infrared excesses due to debris disks toward 26 FGK field stars known from radial velocity (RV) studies to have one or more planets. While none of these stars show excesses at 24 mu m, we have detected 70 mu m excesses around six stars at the 3 sigma confidence level. The excesses are produced by cool material (<100 K) located beyond 10 AU, well outside the "habitable zones" of these systems and consistent with the presence of Kuiper Belt analogs with similar to 100 times more emitting surface area than in our own planetary system. These planet-bearing stars are, by selection for RV studies, typically older than 1 Gyr, and the stars identified here with excesses have a median age of 4 Gyr. We find a preliminary correlation of both the frequency and the magnitude of dust emission with the presence of known planets. These are the first stars outside the solar system identified as having both well-confirmed planetary systems and well-confirmed IR excesses.