| Description |
Similar to the Solar system, there are only 18 planetary systems known to harbor planets and planetesimals. This small sample is of unique value to our understanding of the diversity, dynamical history, and formation mechanisms of extra-solar planetary systems. Here we propose to observe seven of these systems, with spectral types F7-K2 and ages from 0.5-6.4 Gyr. They all show excess emission at 70 um but not at 24 um, implying the presence of an inner region depleted of warm dust, resembling the Solar System in its Jovian planets + Kuiper belt configuration. It is possible to characterize their planetesimal belts from the study of their dust disks. However, the disks SEDs are not known beyond 70 um. Long wavelength observations are of fundamental importance to determine the presence of cold grains, the only tracer of the outer edge of the dust-producing planetesimal belts. Because the latter is a critical parameter to understand the dynamical history and formation of these systems, we propose to carry out PACS 70/160 and SPIRE observations with the main goal of constraining the SEDs at long wavelengths. We have selected PACS 70 to take full advantage of the Herschels improved spatial resolution at 70 um compared to Spitzer, opening the opportunity to resolve the cold dust component that traces the planetesimal belt (which extent could be related to the dynamical history of the planetary system), and to detect extended halos (thought to arise from small dust grains on highly eccentric or hyperbolic orbits, that likely relate to the level of dynamical activity in the planetesimal belt). This proposal requires a total of 11.6 hours. The results will increase our understanding of the diversity of planetary systems, helping us place our Solar system into context. Herschel is the only observatory that can carry out the observation required for this study because of its high sensitivity in the wavelength range where the peak of the dust emission may be located. |
