Outflows driven by giant protoplanets

We investigate outflows driven by a giant protoplanet using three-dimensional MHD nested grid simulations. We consider a local region around the protoplanet in the protoplanetary disk, and we calculate three models: an unmagnetized disk model, a magnetized disk model having magnetic field azimuthally parallel to the disk, and a magnetic field perpendicular to the disk. Outflows with velocities of at least ∼10 km s^-1 are driven by the protoplanets in both magnetized disk models, while outflow does not appear in the unmagnetized disk model. Tubelike outflows along the azimuthal direction of the protoplanetary disk appear in the model with the magnetic field parallel to the disk. In this model, the magnetically dominated regions (i.e., density gap) are clearly contrasted from other regions, and spiral waves appear near the protoplanet. On the other hand, in the model with the magnetic field perpendicular to the disk, outflows are driven by a protoplanet with conelike structure just as seen in the outflow driven by a protostar. Magnetic field lines are strongly twisted near the protoplanet, and the outflows have well-collimated structures in this model. These outflows can be landmarks for searching exo-protoplanets in their formation stages. Our results indicate that the accretion rate onto the protoplanet tends to have a larger value than that expected from previous hydrodynamical calculations, since a fraction of the angular momentum of circumplanetary disk is removed by outflows, enhanced nonaxisymmetric patterns caused by magnetic field, and magnetic braking. Possible implications for observation are also briefly discussed.