Abstract
We investigate the migration mechanism of proto-Neptune using numerical calculation.Jupiter scatters only inner planetesimals,and forced to out of Neptune's gravity.The result of this scattering, net angular momentum that Neptune gains is positive.So Neptune migrates outward.In this reserch, we investigate the parameter dependence of migration velocity of proto-Neptune. The main parameters are distance between two planets and the mass of them. We calculate the torque between planets and planetesimals for more accurately result.