Protoplanetary Disks as (Possibly) Viscous Disks

Two-Dimensional Transport of Solids in Viscous Protoplanetary Disks

Large-scale radial transport of solids appears to be a fundamental consequence of protoplanetary disk evolution based on the presence of high temperature minerals in comets and the outer regions of protoplanetary disks around other stars. Further, inward transport of solids from the outer regions of the solar nebula has been postulated to be the manner in which short-lived radionuclides were in...

Silica in Protoplanetary Disks

Mid-infrared spectra of a few T Tauri stars (TTS) taken with the Infrared Spectrograph on board the Spitzer Space Telescope show prominent narrow emission features indicating silica (crystalline silicon dioxide). Silica is not a major constituent of the interstellar medium; therefore, any silica present in the circumstellar protoplanetary disks of TTS must be largely the result of processing of...

Volatiles in Protoplanetary Disks

Chemistry in protoplanetary disks.

3 Material Inventory and Fundamental Chemical Processes in Disks 14 3.1 Inventory of Gas-Phase Molecules . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.1.1 Results from (Sub-)millimeter Spectroscopy . . . . . . . . . . . . . . . . . 15 3.1.2 Results from Far-Infrared Spectroscopy . . . . . . . . . . . . . . . . . . . 17 3.1.3 Results from Midand Near-Infrared Spectroscopy . . . . . . ...

Dust in Protoplanetary Disks

We critically examine the best lines of evidence for grain growth in protoplanetary disks, based on modelling of observed spectral energy distributions and images of T Tauri and Herbig Ae stars. The data are consistent with millimeter-sized grains near disk midplanes, and micron-sized grains near disk surfaces. We review three channels by which grains can grow, including direct condensation fro...