Title: Periodic signals in Ulysses' energetic
particle events upstream and downstream from the Jovian bow shock.
Author(s): P.K. Marhavilas, G.C. Anagnostopoulos, E.T. Sarris
We present results from a statistical
analysis of Jovian upstream energetic particle ion and electron events,
observed by the HI-SCALE instrument onboard Ulysses, during the inbound
and outbound trajectory of the spacecraft. A harmonic analysis on the
intensity time series of 192 distinct 61-77 KeV upstream ion events,
suggests a modulation with a period of ~40 min or ~15-20 min in 48% of
the total number of the events, at the significance level of P=0.05. In
some cases the periodicity is not significant in the ion intensities,
while it is significant in the ion anisotropy and/or spectral data. Our
analysis shows that the above periodic modulation was more frequently
observed on the out of the ecliptic trajectory (67 events), than on the
ecliptic trajectory (26 events).
A ~40/ 15-20 min periodicity was also found in energetic ion and
electron events in the magnetosheath.
The results from the statistical analysis of HI-SCALE measurements, are
consistent with a magnetospheric source for the majority of the upstream
events. The statistical results are also consistent with preferential
leakage of energetic ions from the south high latitude Jovian