Circumplanetary Disk Formation

The development and evolution of a circumplanetary disk during the accretion of a giant planet is examined. The planet gains mass and angular momentum from infalling solar nebula material while simultaneously contracting due to luminosity losses. When the planet becomes rotationally unstable it begins to shed material into a circumplanetary disk. Viscosity causes the disk to spread to a moderate fraction of the Hill radius where it is assumed that a small fraction of the material escapes back into heliocentric orbit, carrying away most of the excess angular momentum. As the planet's contraction continues, its radius can become smaller than the spatial range of the inflow and material begins to fall directly onto the disk, which switches from a spin-out disk to an accretion disk as the planet completes its growth. We here develop a description of the circumplanetary disk, which is combined with models of the planet's contraction and the inflow rate including its angular momentum content to yield a solution for the time evolution of a planet-disk system.