High-Energy Charged Particles in the Innermost Jovian Magnetosphere

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Science  10 May 1996:
Vol. 272, Issue 5263, pp. 856-858
DOI: 10.1126/science.272.5263.856


The energetic particles investigation carried by the Galileo probe measured the energy and angular distributions of the high-energy particles from near the orbit of Io to probe entry into the jovian atmosphere. Jupiter's inner radiation region had extremely large fluxes of energetic electrons and protons; intensities peaked at ∼2.2RJ (where RJ is the radius of Jupiter). Absorption of the measured particles was found near the outer edge of the bright dust ring. The instrument measured intense fluxes of high-energy helium ions (∼62 megaelectron volts per nucleon) that peaked at ∼1.5RJ inside the bright dust ring. The abundances of all particle species decreased sharply at ∼1.35RJ; this decrease defines the innermost edge of the equatorial jovian radiation.