Structure Formation in a Young Protoplanetary Disk by a Magnetic Disk Wind

Structure formation in young protoplanetary disks is investigated using a one-dimensional model including the formation and the evolution of disks. Recent observations with ALMA found that a ring-hole structure may be formed in young protoplanetary disks, even when the disk is embedded in the envelope. We present a one-dimensional model for the formation of a protoplanetary disk from a molecular cloud core and its subsequent long-term evolution within a single framework. Such long-term evolution has not been explored by numerical simulations due to the limitations of computational power. In our model, we calculate the time evolution of the surface density of the gas and dust with the wind mass loss and the radial drift of the dust in the disk. We find that the MHD disk wind is a viable mechanism for the formation of a ring-hole structure in young disks. We perform a parameter study of our model and derive conditions for the formation of ring-hole structures within 6 x 10(5) yr after the start of the collapse of the molecular cloud core. The final outcome of the disk shows five types of morphology; this can be understood by comparing the timescales of the viscous diffusion, the mass loss by MHD disk wind, and the radial drift of the dust. We discuss the implication of the model for the WL 17 system, which is suspected to be an embedded, yet transitional, disk.