THE COLLISION OF COMET SHOEMAKER-LEVY-9 WITH JUPITER - DETECTION AND EVOLUTION OF HCN IN THE STRATOSPHERE OF THE PLANET

We report submillimeter heterodyne observations of Jupiter taken with the JCMT during and after the infall of Comet Shoemaker-Levy 9 into th e planet. We detected the J=4-3 and J=3-2 rotational transitions of HC N in emission at many of the impact sites. Measurements suggest for fr agment G a mixing ratio of similar to 5x10(-8) above the 0.5-mbar pres sure level and a total HCN mass of 6 x 10(11)g. Subsequent observation s, made in September and November 1994, reveal that HCN is still prese nt but that the lines now appear in absorption. This results from a co oling of the stratospheric thermal profile between July and September. Chemical implications of the observed persistence of HCN in the Jovia n stratosphere for over 6 months are discussed.