Growing and moving low-mass planets in non-isothermal disks

TL;DR

This study uses radiation-hydrodynamical simulations to analyze how realistic energy balance treatments affect low-mass planet migration and accretion in protoplanetary disks, revealing significant deviations from isothermal models.

Contribution

It introduces a 3D radiation-hydrodynamical approach to study planet-disk interactions, highlighting the impact of disk cooling efficiency on migration and accretion rates.

Findings

Accretion rate drops significantly compared to isothermal models.

Positive torque indicates outward migration under certain conditions.

Torque correlates with the radial entropy gradient.

Abstract

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.