Electron Beams and Ion Composition Measured at Io and in Its Torus

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Science  18 Oct 1996:
Vol. 274, Issue 5286, pp. 401-403
DOI: 10.1126/science.274.5286.401


Intense, magnetic field-aligned, bidirectional, energetic (>15 kiloelectron volts) electron beams were discovered by the Galileo energetic particles detector during the flyby of Io. These beams can carry sufficient energy flux into Jupiter's atmosphere to produce a visible aurora at the footprint of the magnetic flux tube connecting Io to Jupiter. Composition measurements through the torus showed that the spatial distributions of protons, oxygen, and sulfur are different, with sulfur being the dominant energetic (>∼10 kiloelectron volts per nucleon) ion at closest approach.

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