  We study the interaction of a low-mass planet with a protoplanetary disk with
a realistic treatment of the energy balance by doing radiation-hydrodynamical
simulations. We look at accretion and migration rates and compare them to
isothermal studies. We used a three-dimensional version of the hydrodynamical
method RODEO, together with radiative transport in the flux-limited diffusion
approach. The accretion rate, as well as the torque on the planet, depend
critically on the ability of the disk to cool efficiently. For densities
appropriate to 5 AU in the solar nebula, the accretion rate drops by more than
an order of magnitude compared to isothermal models, while at the same time the
torque on the planet is positive, indicating outward migration. It is necessary
to lower the density by a factor of 2 to recover inward migration and more than
2 orders of magnitude to recover the usual Type I migration. The torque appears
to be proportional to the radial entropy gradient in the unperturbed disk.
These findings are critical for the survival of protoplanets, and they should
ultimately find their way into population synthesis models.
