| Description |
Debris disks trace the collisional breakdown of asteroid and comet parent bodies orbiting nearby main sequence stars. They are detectable in virgul16% of FGK stars, nearly twice as often in A stars, and are almost unknown around M stars. The debris disks of sunlike stars are typically cold analogs of our Kuiper belt with emission peaking near 70 microns wavelength. However, a relatively small number of warm disks are known with emission at 24 microns. These systems are especially interesting because they trace dust in the region likely to host terrestrial planets, where the dust has a short dynamical lifetimes. They also tend to be young systems aged < 1 Gyr. This knowledge of warm debris disks - extrasolar analogs to our solar system.s Zodiacal cloud - is based on the 25 year old IRAS survey and observations of selected targets with ISO and Spitzer.
The Wide-Field Infrared Survey Explorer (WISE) has just completed new, sensitive all-sky mapping in the 3.3, 4.6, 12, and 22 micron bands. Association of the WISE sources to Hipparcos and Tycho stars has led to the identification of 99 nearby main sequence stars with robustly detected warm 22 micron excesses not previously known. To determine whether these systems represent outbursts of asteroidal dust production (such as in the HD 69830 system), or simply the Wien side of emission from a cold outer dust belt, photometry at longer wavelengths is needed. We propose Herschel/PACS 70 and 160 micron photometry of this unbiased sample. These data will allow us to fully characterize the dust temperature and infrared luminosity of these systems, allowing them to be understood in the context of other debris disks and disk evolution theory. The sample includes field M stars as close as 12 pc, the first objects of this class seen to have warm dust emission. The results will strongly constrain our picture of the collisional history of inner planetary systems. |
