Recent high-spatial-resolution observations have revealed dust substructures in protoplanetary disks such as rings and gaps, which do not always correlate with gas (Andrews et al. 2018). Disk-planet interaction is one of the possible origins of the observed dust substructures in disks. Recent hydrodynamical simulations have revealed that a low-mass planet embedded in a disk induces gas flow with a complex three-dimensional structure (Ormel et al. 2015). A notable feature of the gas flow structure is the outflow of the gas, which occurs in the radial direction of the disk. Because the outflow of the gas could affect the radial drift of dust, it potentially forms dust substructures in disks.
In this study, we investigate the potential of gas flow induced by low-mass planets (?0.1-10 ME; Earth masses) to sculpt rings and gaps in dust profiles. We first perform three-dimensional hydrodynamical simulations that resolve the local gas flow past a planet. We then calculate the trajectories of dust influenced by the planet-induced gas flow. Finally, we compute the steady-state dust surface density by incorporating the influences of the planet-induced gas flow into a one-dimensional dust advection-diffusion model.
We find that the outflow of the gas toward the outside of the planetary orbit inhibits the radial drift of dust, leading to dust accumulation (the dust ring). The outflow toward the inside of the planetary orbit enhances the inward drift of dust, causing dust depletion around the planetary orbit (the dust gap). Under weak turbulence (α_diff<10^-4, where α_diff is the turbulence strength parameter), the gas flow induced by the planet with ~1-10 ME generates a dust ring and a gap in the distribution of small dust grains (<1 cm) with a radial extent of ?1-10 times the gas scale height around the planetary orbit without creating a gas gap and a pressure bump.