We present a suite of three dimensional radiative gravitational hydrodynamics
models suggesting that binary stars may be quite capable of forming planetary
systems similar to our own. The new models with binary companions do not employ
any explicit artificial viscosity, and also include the third (vertical)
dimension in the hydrodynamic calculations, allowing for transient phases of
convective cooling. The calculations of the evolution of initially marginally
gravitationally stable disks show that the presence of a binary star companion
may actually help to trigger the formation of dense clumps that could become
giant planets. We also show that in models without binary companions, which
begin their evolution as gravitationally stable disks, the disks evolve to form
dense rings, which then break-up into self-gravitating clumps. These latter
models suggest that the evolution of any self-gravitating disk with sufficient
mass to form gas giant planets is likely to lead to a period of disk
instability, even in the absence of a trigger such as a binary star companion.Comment: 52 pages, 28 figure