Termination of Inward Migration for a Gap-opening Planet through Dust Feedback

Planetary migration due to disk–planet interaction is one of the most important processes determining 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 dust feedback on the migration of the gap-opening planet, which has not been considered in previous studies. We found that the gas surface density at the outer edge of the gap becomes smaller due to dust feedback, and thus the torque exerted from the outer disk decreases. This mechanism becomes more effective as the gap becomes wider and deeper. In particular, when the mass of the planet is Jupiter-sized and the turbulent viscosity is α = 3 × 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 slows down significantly. This termination of the inward migration triggered by dust feedback may explain why ring and gap structures can be frequently observed within protoplanetary disks.