New Growth Mechanism of Dust Grains in Protoplanetary Disks with Magnetically Driven Disk Winds

Abstract We discovered a new growth mode of dust grains to kilometer-size bodies in protoplanetary disks that evolve via viscous accretion and magnetically driven disk winds (MDWs). solved an approximate coagulation equation with time-evolving consist both gas solid components using one-dimensional model. With grain growth, all particles initially drift inward toward the central star due drag force. However, radial profile pressure, P , is modified by MDW disperses inside-out manner. Consequently, local concentration created converging flux drifting at location convex-upward . When dimensionless stopping time, St, exceeds unity there, spontaneously reach growth-dominated state because positive feedback between suppressed enhanced accumulation from outer part. Once are drift-limited state, above-mentioned condition St for equivalent ? d /? g ? ? where dust-to-gas surface-density ratio pressure-gradient As consequence successful grains, ring-like structure containing planetesimal-size formed inner part disks. Such ring-shaped planetesimals expected play vital role subsequent planet formation.