Protons and Electrons in Jupiter's Magnetic Field: Results from the University of Chicago Experiment on Pioneer 10

Simpson, J. A.; Hamilton, D. C.; Lentz, G.; McKibben, R. B.; Mogro‐Campero, A.; Perkins, M. A.; Pyle, K. R.; Tuzzolino, A. J.; O’Gallagher, J.

doi:10.1126/science.183.4122.306

Cited by 112 publications

(42 citation statements)

References 8 publications

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“…However, on the outbound trajectory both of our lower energy proton fluxes show slight maxima at the time of the second peak reported by Simpson et al (1974).…”

Section: Harmonic Analysis Of Proton Angular Distributionsmentioning

confidence: 83%

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Energetic particles in the Jovian magnetosphere

Trainor¹,

McDonald²,

Teegarden³

et al. 1974

J. Geophys. Res.

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This paper presents a detailed account of the Pioneer 10 encounter with Jupiter as viewed by the Goddard‐University of New Hampshire cosmic ray experiment. Flux time histories of electrons and protons are given over a wide energy band. These show a marked variation with magnetic latitude, Significant removal of low‐energy protons by Io is apparent in the inner magnetosphere (≲6 RJ). Proton and electron energy spectra are given at various Jovicentric distances. The electron spectra are remarkably hard and constant in slope in the 0.12‐ to 8.0‐MeV interval, the electron spectral index having a value of 1.5–2.0 in the region outside 25 RJ. Proton spectra are shown to transform from a power law with indices in the 3–4.2 range to more nearly exponential forms in the inner regions (≲40 RJ). Extensive data are presented on the angular distributions of protons and electrons at various locations in the Jovicentric magnetosphere. In addition, a harmonic analysis of 1‐ to 2‐MeV proton angular distributions has been performed. Simple corotation is shown to exist out to ∼23 RJ. Beyond this point, other effects are contributing significantly to the particle anisotropies. Alpha/proton ratios are given as a function of Jovian radius and are compared to the earth and solar wind values.

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“…However, on the outbound trajectory both of our lower energy proton fluxes show slight maxima at the time of the second peak reported by Simpson et al (1974).…”

Section: Harmonic Analysis Of Proton Angular Distributionsmentioning

confidence: 83%

“…Simpson et al (1974), have pointed out a small latitude effect for the > 35 MeV protons. Those protons showed very strong maxima near L -3.6 Rj.…”

Section: Harmonic Analysis Of Proton Angular Distributionsmentioning

confidence: 99%

Energetic particles in the Jovian magnetosphere

Trainor¹,

McDonald²,

Teegarden³

et al. 1974

J. Geophys. Res.

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“…[2] Pioneer 10 observations made over 30 years ago revealed that Jupiter is a source of high energy electrons in the heliosphere [Simpson, 1974]. High energy electron data from Pioneer 10 showed a monotonic increase in the electron flux from 1 AU as the spacecraft approached Jupiter (at 5.2 AU) and a gradual decrease as the spacecraft receded from Jupiter [Pyle and Simpson, 1977].…”

Section: Introductionmentioning

confidence: 99%

Modulation of Jovian electrons at 1 AU during solar cycles 22–23

Kanekal

Baker

Blake

et al. 2003

Geophysical Research Letters

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[1] We report here, on the observation of Jovian electrons during the time period 1992 to 2002, using instruments on board SAMPEX and IMP8 at 1 AU. The Jovian electron flux diminished greatly from early 1996 to the end of 1997 and recovered subsequently and was observed till the end of 2001. The decrease in the Jovian flux was seen in three distinct instruments lasting for about two Jovian synodic periods. Such a dramatic and persistent decrease has not been observed before. The observed decrease could be due to changes at the source or variations in interplanetary conditions affecting transport of these particles. The latter may be solar cycle dependent as in the heliospheric modulation of cosmic rays. Long-term measurements from IMP8 suggest that solar cycle related propagation effects may not be responsible for the observed decrease. We suggest that either a change in the Jovian source strength or a softening of the Jovian electron energy spectrum produced the observed attenuation.

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“…In 1973, when Pioneer 10 was approaching Jupiter, unexpected relativistic electron increases were detected in interplanetary space (Chenette et al, 1974;Simpson et al, 1974;Teegarden et al, 1974). The intensity of electron fluxes increased as Pioneer 10 approached Jupiter, showing that the relativistic electrons accelerated in the Jovian magnetosphere were released into the interplanetary medium.…”

Section: Introductionmentioning

confidence: 92%

Jovian electron modulations by the solar wind interaction with the magnetosphere

2014

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Variations of energetic electrons released from the Jovian magnetosphere are investigated in detail by using data from three spacecraft, Pioneer 10, 11, and Ulysses. Analyses with the three spacecraft data confirmed that the Jovian electrons are modulated by the dynamic pressure of the solar wind at the position of Jupiter. It is also found that the release rate of energetic electrons is controlled by the polarity of IMF having dawn-dusk or latitudinal dependence. The enhancements of released electron flux were detected during the toward polarity of IMF when the spacecraft were located in the upstream or dawn side of Jupiter. On the other hand, Ulysses detected enhancement in away polarity of IMF when the spacecraft was on the duskside of southern hemisphere. We made a simulation to reproduce the electron variation of Jovian electrons observed by Pioneer 11 considering the convective and diffusive transport in the interplanetary medium. According to the simulation, the observed enhancements of electron flux originating from Jupiter are well represented by the coupling of both the source modulation at the Jovian magnetosphere and the transport effect in the interplanetary medium.

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Protons and Electrons in Jupiter's Magnetic Field: Results from the University of Chicago Experiment on Pioneer 10

Cited by 112 publications

References 8 publications

Energetic particles in the Jovian magnetosphere

Energetic particles in the Jovian magnetosphere

Modulation of Jovian electrons at 1 AU during solar cycles 22–23

Jovian electron modulations by the solar wind interaction with the magnetosphere

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