Plume Development of The Shoemaker-Levy 9 Comet Impact

We have studied the plume formation after a Jovian comet impact using the ZEUS-MP 2 hydrodynamics code. The three-dimensional models followed objects with 500, 750, and 1000 m diameters. Our simulations show the development of a fast, upward-moving component of the plume in the wake of the impacting comet that pinches off from the bulk of the cometary material similar to 50 km below the 1 bar pressure level, similar to 100 km above the depth of the greatest mass and energy deposition. The fast-moving component contains about twice the mass of the initial comet, but consists almost entirely ( \u3e 99.9%) of Jovian atmosphere rather than cometary material. The ejecta rise mainly along the impact trajectory, but an additional vertical velocity component due to buoyancy establishes itself within seconds of impact, leading to an asymmetry in the ejecta with respect to the entry trajectory. The mass of the upward-moving component follows a velocity distribution M( \u3e upsilon) approximately proportional to upsilon (1.4) (upsilon (1.6) for the 750 m and 500 m cases) in the velocity range 0.1 km s(-1) \u3c upsilon \u3c 10 km s(-1)