Abstract
In this paper, the formation of a disk resulting from the collapse of a rigidly-rotating cloud is studied. The plane perpendicular to the angular velocity axis that contains the star is the locus where materials falling from both sides face each other with the consequent formation of a double layer shock structure. The shocked material that moves almost parallel to this plane is the material that forms the disk. A hydrodynamical axisymmetric and isothermal simulation is developed using as initial condition a ballistic approximation for the trajectories of the particles located in the vicinity of the star. The dynamical evolution of this material, including the material that is continuously incorporated from the cloud, drives the disk to a stationary configuration composed of two dense rings with constant specific angular momentum that sit on Keplerian positions. A feature like this can change the spectra of disks in deeply embedded stages.
