Session 2: Solar, Planetary and Space Physics

Title: Energetic Ion Distributions, Spectra and Periodicities (~5/10hr) observed by Ulysses in the outer high latitude dusk-side Jovian magnetosphere
Author(s): P.K. Marhavilas, G.C. Anagnostopoulos, E.T. Sarris

Examination of Ulysses' observations during the spacecraft fly-by of Jupiter reveals the following picture for energetic ions in the Jovian outer (high latitude) dusk-side magnetosphere: (1) The ion flux decreases as Ulysses moves toward higher south latitudes; more intense decrease was detected at higher energies. (2) At middle latitudes, the energy spectrum is well described by a power law over the whole energy range (~60 - ~4000 keV) covered by the HI-SCALE instrument. At higher latitudes, the spectrum is softer and is composed by two parts described by different power laws. (3) The spectral shape varies periodically (5/10hr period). The observations are explained in terms of a periodic motion of the s/c within a large scale region of energetic ions in the outer magnetosphere with different characteristics from the magnetodisc plasma sheet.