Circumstellar Dust Distribution in Systems with Two Planets in Resonance

We investigate via numerical modeling the effects of two planets locked in resonance, and migrating outward, on the dust distribution of the natal circumstellar disk. We aim to test whether the dust distribution exhibits peculiar features arising from the interplay among the gravitational perturbations of the planets in resonance, the evolution of the gas, and its influence on the dust grain dynamics. We focus on the 3:2 and 2:1 resonance, where the trapping may be caused by the convergent migration of a Jupiter- and Saturn-mass planet, preceding the common gap formation and ensuing outward (or inward) migration. Models show that a common gap also forms in the dust component similarly to what a single, more massive planet would generate and that outward migration leads to a progressive widening of the dust gap and to a decoupling from the gas gap. As the system evolves, a significantly wider gap is observed in the dust distribution, which ceases to overlap with the gas gap in the inner disk regions. At the outer edge of the gas gap, outward migration of the planets produces an overdensity of dust particles, which evolve differently in the 3:2 and 2:1 resonances. For the 3:2 resonance, the dust trap at the gap's outer edge is partly efficient, and a significant fraction of the grains filters through the gap. For the 2:1 resonance, the trap is more efficient, and very few grains cross the gap, while the vast majority accumulate at the outer edge of the gap.