Since giant planets scatter planetesimals within a few tidal radii of their orbits , the locations of existing planetesimal belts indicate regions where giant planet formation failed in bygone protostellar disks .
Infrared observations of circumstellar dust produced by colliding planetesimals are therefore powerful probes of the formation histories of known planets .
Here we present new Spitzer IRS spectrophotometry of 111 Solar-type stars , including 105 planet hosts .
Our observations reveal 11 debris disks , including two previously undetected debris disks orbiting HD 108874 and HD 130322 .
Combining our 32 \mu m spectrophotometry with previously published MIPS photometry , we find that the majority of debris disks around solar-type stars have temperatures in the range 60 \lesssim T _ { dust } \lesssim 100 K .

Assuming a dust temperature T _ { dust } = 70 K , which is representative of the nine debris disks detected by both IRS and MIPS , debris rings surrounding Sunlike stars orbit between 15 and 240 AU depending on the mean particle size .
Our observations imply that the planets detected by radial-velocity searches formed within 240 AU of their parent stars .
If any of the debris disks studied here have mostly large , blackbody emitting grains , their companion giant planets must have formed in a narrow region between the ice line and 15 AU .