  The evolution and collapse of a gaseous toroidal vortex under the action of
self-gravitation are considered using the Hamiltonian mechanics approach. It is
shown that evolution occurs in three main stages separated by characteristic
time scales. First, a compression along the small radius to a quasi-equilibrium
state takes place, followed by a slower compression along the large radius to a
more stable compact vortex object. In the latter stage, the possibility of
effective scattering and ejection of particles along the vortex axis (jet
formation) is detected. As a result, mass, energy, and momentum losses take
place, and the vortex collapses.
