The impact of comet Shoemaker-Levy 9 on Jupiter

We have performed computational shock-physics simulations of the hypervelocity (60 km/s) impact of 1-3 km, water-ice spheres entering an H-He Jovian atmosphere. These conditions simulate the best current estimates for the collision of fragments of periodic Comet Shoemaker-Levy 9 with Jupiter in July, 1994. We used the Eulerian shock-physics code CTH, and its parallel version PCTH, to perform 2D analyses of penetration and breakup, and 3D analyses of the growth of the resulting fireball during the first 100 sec after fragment entry. Specific predictions of the time interval between fragment entry and fireball arrival into line-of-sight from the Earth can thus be made. For a fragment larger than about 1 km, we believe that the time of fireball arrival above Jupiter's limb will be directly observable from Earth. Measurements of this time by observers, in conjunction with our simulations, may allow mass of cometary fragments to be determined. (Author)