Planets and Debris Disks: Results from a Spitzer/MIPS Search for Infrared Excess

Abstract

Using the MIPS camera on the Spitzer Space Telescope, we have searched for debris disks around 104 stars known from radial velocity studies to have one or more planets. Combining this new data with 42 already published observations of planet-bearing stars, we find that 14 of the 146 systems have IR excess at 24 and/or 70 μm. Only one star, HD 69830, has IR excess exclusively at 24 μm, indicative of warm dust in the inner system analogous to that produced by collisions in the solar system's asteroid belt. For the other 13 stars with IR excess the emission is stronger at 70 μm, consistent with cool dust (<100 K) located beyond 10 AU, well outside of the orbital location of the known planets. Selection effects inhibit detection of faint disks around the planet-bearing stars (e.g., the stars tend to be more distant), resulting in a lower detection rate for IR excess than in a corresponding control sample of nearby stars not known to have planets (9% ± 3% versus 14% ± 3%). Even taking into account the selection bias, we find that the difference between the dust emission around stars with planets and stars without known planets is not statistically significant.

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