DPS Pasadena Meeting 2000, 23-27 October 2000
Session 15. Outer Planets IV - Aurorae and Magnetospheres
Oral, Chairs: D. Hunten, L. Esposito, Tuesday, 2000/10/24, 8:30-10:00am, Little Theater (C107)

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[15.05] Galileo Observations of Jovian Aurora and Modeling of Polar Chemistry

J. Ajello (JPL), A. S. Wong, A. Y. T. Lee, Y. L. Yung (Caltech)

We analyze over 100 auroral spectra taken by the ultraviolet spectrometer (UVS) on board the Galileo Orbiter for both north and south polar regions of Jupiter. We calculate the avarage band emissions of H2 and Ly-\alpha, the color ratios and the brightness for each spectrum. With the cataloged data, we are able to determine the total input energy of the precipitating electrons and the mean energy of primary electrons with an electron energy deposition code.

We develop a new chemical model including aromatic compounds in the Jovian auroral thermosphere/ionosphere. The model is based on a previous model for hydrocarbon chemistry in the Jovian atmosphere and is constrained by observations from Voyager, Galileo and the Infrared Space Observatory. Precipitation of energetic electrons provides the major energy source for the production of benzene and other heavier aromatic hydrocarbons. The maximum mixing ratio of benzene in the polar model is 2 \times 10-9, a value that can be compared with the observed value of 2+2-1 \times 10-9 in the north polar auroral region. Sufficient quantities of the higher ring species are produced so that their saturated vapor pressures are exceeded. Condensation of these molecules is expected to lead to aerosol formation.

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