"Illuminating Ideas in Planet Formation: Shadowing and Illumination in Protoplanetary Disks"

Radiative transfer is an important process in protoplanetary disks. Stellar illumination, in particular, is primarily responsible for setting the temperature and density structure of passively accreting protoplanetary disks. Perturbations in the structure of a disk such as clumping, gap-opening, and dust-settling can create shadows and bright spots which in turn further perturb the disk's structure. Density and temperature variations resulting from the dynamical interactions between a planet and a disk can be further enhanced by these cooling and heating effects, leading to alterations in planetary migration rates, planetary growth, and other important planet formation processes. I present radiative transfer calculations on a three-dimensional disk perturbation induced by a protoplanet. These temperature perturbations can affect ice formation vis-à-vis the "snow line" which in turn affects the accumulation of water onto a planet embryo as well as the growth rate of protoplanets. The change in the local pressure gradient caused by these temperature perturbations also changes the migration rate of the planet. Small planets which are insufficiently massive to open a full annular gap in the disk are likely to be out of the range of observability, but gaps with large extent may be detectable in images and SEDs.