Investigating the composition of Jupiter’s energetic heavy ion environment

Jupiter’s radiation belts are the most energetic, intense and ion-rich in the entire solar system. To constrain source, acceleration, and loss mechanisms, across an ion mass and energy range not typically accessible in other planetary magnetospheres, the composition and distribution of heavy ions within the Jovian magnetosphere should be first resolved. Relatively little is known about their global distribution and dynamics in the jovian magnetosphere, particularly  above several MeV/nucleon or for species different than sulfur or oxygen. In this work, we survey the full Heavy Ion Counter (HIC) dataset from the Galileo mission in order to characterize the composition of Jupiter’s >5 MeV/nucleon ions (Z>6), with an extra focus on minor species. We unambiguously resolve 10 different ion species, and provide estimates of their energy and distance dependent relative abundances. At least five new species are resolved (N, Ne, Si, K and possibly Ca and Fe), each likely mapping to different magnetospheric and/or weathering processes. A key finding is that abundances of species like Carbon, Neon and Silicon are reminiscent of those in solar energetic particles comparable to magnetospheric sulfur, indicating a considerable solar input into Jupiter’s heavy ion radiation belts. The same may apply for more abundant species like oxygen: its trapping region extends out to Ganymede’s distance, which would only be possible if oxygen is multiply charged, as it is the case for oxygen in solar energetic particle population.