Characterization of Outer Exoplanetary Systems With Herschel Imaging

Our knowledge of planetary systems outside of ours is confined almostentirely to cases where the planets are close to the star. A criticalstage in the development of the Solar System was the stabilization ofthe orbits of Jupiter and Saturn far from the Sun. What are thecharacteristics of other planetary systems at large radii? Planetarydebris disks provide our best tool to answer this question. However,our interpretation of these systems is currently crippled by the lack,in most cases, of more information beyond a few photometric points ona spectral energy distribution. Such data can be fitted by a broadvariety of quite different disk models. Resolved Herschel images ofdisks can provide much better constraints on models and can lead tosufficient understanding of the general behavior to help interpreteven those systems where resolved images are not possible.We have identified 17 bright disks that show marginally resolvedstructures in Spitzer data, suggesting a radial size of coldplanetesimal belt 3 to 10 times larger than our own Kuiper Belt. Sincethe disk mass is proportional to the disk diameter and covering factorof the dust, these systems are likely to be associated with the mostmassive planetary systems, making them the possible sites where therichest, most massive and extended families of planets will form. Wepropose to image these disks that can be resolved well at PACS 70micron but not in any existing Herschel programs. We will use theresolved images as well as the photometric data obtained with SPIRE toprobe: (1) the properties of cold planetesimal belts as signposts ofice giants at large orbits, and (2) the diversity of outermostplanetesimal zones around other stars and the underlying causes. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]