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Abstract:

The Composite Infrared Spectrometer observed Jupiter in the thermal infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral infrared hot spots; determination of the variations with latitude of acetylene and ethane, the latter a tracer of atmospheric motion; observations of unexpected spatial distributions of carbon dioxide and hydrogen cyanide, both considered to be products of comet Shoemaker-Levy 9 impacts; characterization of the morphology of the auroral infrared hot spot acetylene emission; and a new evaluation of the energetics of the northern auroral infrared hot spot.

Abstract:

We have determined the following upper limits for the mole fraction of hydrogen halides in Jupiter's atmosphere from Cassini/CIRS observations: [HF] <2.7×10^-11, [HCl] <2.3×10^-9, [HBr]<1.0×10^-9, [HI] <7.6×10^-9. These limits are smaller than solar composition for HF and HCl, and support the halogens' condensation in ammonium salts predicted by thermochemical models for the upper jovian troposphere. © 2004 Published by Elsevier Inc.