Termination of an inward migration of a gap-opening planet triggered by dust feedback

Abstract

The planet migration due to the disk--planet interaction is one of the most important processes to determine the architecture of planetary systems. A sufficiently massive planet forms a density gap and migrates together with the gap. By carrying out two-dimensional and two-fluid (gas and dust grains) hydrodynamic simulations, we investigated the effects of the dust feedback on the migration of the gap-opening planet, which was not considered in previous studies. We found that the gas surface density at the outer edge of the gap becomes smaller due to the dust feedback, and thus the torque exerted from the outer disk decreases. This mechanism becomes effective as the gap becomes wider and deeper. In particular, when the mass of the planet is Jupiter-size and turbulent viscosity is $\alpha = 3\times 10^{-4}$, the planet can migrate outward due to the reduction of the torque exerted from the outer disk. Even for a smaller planet, the migration becomes significantly slow down. This termination of the inward migration triggered by the dust feedback may explain why ring and gap structures can be frequently observed within the protoplanetary disks.