Observations of Energetic Ions and Electrons in Saturn's Magnetosphere

Trainor, J. H.; McDonald, F. B.; Schardt, A. W.

doi:10.1126/science.207.4429.421

Cited by 55 publications

(22 citation statements)

References 10 publications

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“…The measurements of Cassini at Saturn at about 20 R s are inside the Kronian magnetosphere Krimigis et al 2005). The shown Pioneer 11 measurements also correspond to the crossing of the magnetopause, which occurred at a distance of about 18 R s (Trainor et al 1980) as mentioned above. Voyager 1 and 2 data points are measured at a distance of 19 R s (Krimigis et al 1983), which was for Voyager 2 the crossing point of the magnetopause, whereas for Voyager 1 it was already 23 R s , so that the Voyager 2 measurement were made just inside the inner Kronian magnetosphere.…”

Section: Measurements Of the Magnetospheressupporting

confidence: 58%

“…The two lower data points measured by Voyager 2 correspond to a distance of about 13 R s (Krimigis et al 1983), whereas the two upper ones correspond to 11 R s (Maurice et al 1996a). The other data points of the Voyager 1, Cassini, and Pioneer 11 spacecraft are located in the range of 11 R s (Krimigis et al 1983;Krupp et al 2005;Krimigis et al 2005;Trainor et al 1980). At about 20 R s , the Cassini measurements at Jupiter and Saturn are shown here in direct comparison.…”

Section: Measurements Of the Magnetospheresmentioning

confidence: 94%

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Are there Kronian electrons in the inner heliosphere?

Lange

Fichtner

2008

A&A

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Context. As the largest in our solar system the Jovian magnetosphere is treated in the literature as the dominant source of a fewMeV electrons, which have been measured by various spacecraft. In particular, observations obtained with Ulysses have significantly broadened the available data base. Aims. We simulated the transports of MeV electrons in the heliosphere on the basis of a time-dependent, three-dimensional modulation model. For this purpose the cosmic rays, the Jovian and the Saturnian electron sources have been, for the first time, considered together in the simulation of electron fluxes. The simulated electron intensities are discussed along the Ulysses and Cassini trajectories. The Ulysses spacecraft already passed by the planet Jupiter twice (1992, 2004), and Cassini passed by Jupiter in 2001 and reached Saturn in the year 2004. The strength of the electron source at Jupiter is relatively well known and well modelled. To determine the source strength of Saturn in comparison to that of Jupiter, we compared all available spacecraft measurements at Jupiter/Saturn in the overlapping energy range. We study the general distribution of Kronian electrons by successively using three different strengths of the Saturn source in our simulations. In addition, the effects of the solar activity are taken into account by varying the velocity field of the solar wind and the anisotropic diffusion tensor. Methods. Studying the particle diffusion is particularly relevant, because the really unknown function in the used transport equation is the diffusion tensor. The Jovian and/or Kronian electrons are suitable for studying the transport of energetic particles because the source locations are well known. Results. At 1 MeV the intensities along the Ulysses and the Cassini trajectories are clearly influenced by the presence of Kronian electrons. Conclusions. Our results reveal that the electrons from the Kronian magnetosphere, as the second largest, cannot be neglected in the very-low MeV energy range.

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Section: Measurements Of the Magnetospheressupporting

confidence: 58%

Section: Measurements Of the Magnetospheresmentioning

confidence: 94%

Are there Kronian electrons in the inner heliosphere?

Lange

Fichtner

2008

A&A

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“…Observations of Saturnian trapped radiation were first made in September 1979 with instruments carried aboard Pioneer 11 Chenette et al, 1980;McDonald et al, 1980;Simpson et al, 1980a,b;Van Allen et al, 1980a,b;Thomsen and Van Allen, 1980;Trainor et al, 1980). Conspicuous results of Pioneer 11 observations included spatial distributions that showed evidence of absorption of trapped radiation by satellites and rings.…”

Section: Introductionmentioning

confidence: 96%

Energetic ions trapped in Saturn's inner magnetosphere

Armstrong¹,

Taherion²,

Manweiler³

et al. 2009

Planetary and Space Science

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“…Discovery of the magnetosphere of Saturn and many detailed features thereof have been reported in earlier papers [Wolfe et al, 1980;Smith et al, 1980;Simpson et al, 1980;Van Allen et al, 1980;Trainor et al, 1980;Fillius et al, 1980;and Acuna and Ness, 1980]. Note that all distances herein are given in units of the adopted equatorial radius of Saturn (1 R s = 60,000 km) and all times are Earth Received Time (ERT) in Universal Time (UT) of reception of the telemetry signal at the earth (Table 1).…”

Section: Introductionmentioning

confidence: 99%

“…6 3 5; 1 800 r < 2 500, An R = 6.480 + 5.9 4 2 X l10 4 r; 2 500 < r < 4,000 n R = 6.933 + 4.129 X i0 r; 4 000< r < 13 900 n R = 7.390 + 2.988 X l0 4 r. Elsewhere, the output of detector G is reliably attributable to protons 0.61 < E p 3.41 MeV, entering the detector through its conical collimator. The nearly total absence of energetic ions having Z a 2 appears to be assured by multi-element solid-state telescope results from other Pioneer 11 instruments [Simpson et al, 1980;Trainor et al, 1980;McDonald, private communication, 1980]. …”

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confidence: 99%

Sources and sinks of energetic electrons and protons in Saturn's magnetosphere

Allen¹,

Randall²,

Thomsen³

1980

J. Geophys. Res.

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This paper reports the results of continuing analysis and interpretation of energetic particle observations obtained by the University of Iowa instrument on Pioneer 11 during traversal of Saturn's magnetosphere in August–September 1979. On the basis of the radial dependence of the phase space density of very energetic protons (Ep >80 MeV) and estimates of the necessary source strength, it is reasonably certain that cosmic ray neutron albedo from the planet's atmosphere and Rings A and B is the source of such particles. At radial distance r=2.7 Rs and for Ep >80 MeV, the ratio of source strength 𝒮 to radial diffusion coefficient D is ∼2 × 10−24 cm−5. A reasonable pair of values is 𝒮 ∼7 × 10−15 cm−3 s−1 and D ∼1 × 10−10 Rs² s−1. The spectrum of electrons 0.040< Ee <(few MeV) and the radial dependence of the phase space density of such electrons are derived. The source of these electrons is at the magnetosheath. The source of protons Ep ∼1 MeV is also at the magnetosheath and may be either thermalized solar wind or energetic interplanetary protons which were unusually abundant at the time of Pioneer 11's encounter. Low energy electrons and protons experience strong losses inward of r ∼10 Rs, apparently attributable to the large inner satellites Rhea, Dione, Tethys, Enceladus, and Mimas and to a broad tenuous ring of particulate matter (Ring E) and/or gas. There were important temporal changes in the distributions of low energy electrons and protons within a period of ∼10 hours between inbound and outbound passes, probably caused by unusually disturbed interplanetary conditions.

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Observations of Energetic Ions and Electrons in Saturn's Magnetosphere

Cited by 55 publications

References 10 publications

Are there Kronian electrons in the inner heliosphere?

Are there Kronian electrons in the inner heliosphere?

Energetic ions trapped in Saturn's inner magnetosphere

Sources and sinks of energetic electrons and protons in Saturn's magnetosphere

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