Sulfur chemistry in the wake of comet Shoemaker‐Levy 9

A curious and unexpected result of the impact of P/Shoemaker Levy 9 with Jupiter was the production of enormous amounts of molecular sulfur (S 2 ). Here we show that S 2 is the natural product of disequilibrium chemistry at low pressures in shocked jovian air, its formation a byproduct of hydrogen recombination. The species observed by the HST — S 2 , CS 2 , and H 2 S — imply that the G fragment penetrated the NH 4 SH cloud but did not reach the water table. A typical impact within or below the NH 4 SH clouds produces about 0.03–0.1 impactor masses of S 2 . Because comets are relatively hydrogen‐poor, SO 2 , not S 2 , is the major product of shocking a water‐rich comet, while S 2 , CS 2 , and OCS are major products of a dessicated comet. In all cases we find that as the gas cools S 2 converts to the stable low temperature allotrope S 8 , although other chemical fates not modeled here might intervene first.