| Description |
We propose to obtain PACS range spectroscopy to measure the vertical and radial distribution of crystalline silicates in 22 protoplanetary disks around pre-main sequence stars. Dynamical processes, such as nebular shocks and meridional flows, are predicted to generate crystals within the warm, inner-most parts of these disks and transport them further out into the planet-forming regions. Therefore the spatial distribution of crystals, which have broad, mid-infrared spectral features, can be used to trace such mechanisms. Since these processes influence core-building and migration, determining their scope is paramount to our understanding of planet-formation as a whole. Recent studies using Spitzer Space Telescope IRS spectra suggest crystals are distributed farther out in protoplanetary disks than can be accounted for by current theories. Over the Herschel PACS 51-73 micron range, the continuum is extremely sensitive to changes in crystallinity as a function of radius, while the dust emission features over this range and the continuum from 102-146 micron are sensitive to changes in crystallinity in the vertical direction. By using irradiated accretion disk models to do a self-consistent analysis of the combined PACS and Spitzer IRS spectra of our 22 targets, we will unveil the midplanes of these disks and trace the influence of inner disk dynamics on the planet-forming region. |
