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Relativistic electrons in Saturn's inner magnetosphere and an estimate of their synchrotron emission

Journal Article · · Journal of Geophysical Research; (USA)

Energetic electron data obtained by the University of Iowa instrument during Pioneer 11's two-way traversal of Saturn's inner magnetosphere in September 1979 are reviewed. There were substantial differences between inbound and outbound observations. It is argued that the inbound data are more likely to represent the time-stationary state. Adopting these inbound data, the authors develop a quantitative model for the spatial and spectral distributions of relativistic electrons. The principle features of this model are as follows: (1) the radial dependence of omnidirectional intensity J in the equatorial plane is given by J = k{prime}exp({minus}1.05 x)(1{minus}exp({minus}6.5 x)) where k{prime} = 1.28 {times} 10{sup 7} (cm{sup 2}s){sup {minus}1} and x = (r{minus}2.30) with r the radial distance in units of the planet's radius 60,000 km; (2) the latitudinal dependence of J is derived from observed pitch-angle distributions; (3) as shown previously, the energy spectrum is a relatively narrow one with characteristic energies E in MeV at various r as follows: 0.69 at 5.0; 1.10 at 4.0; 1.89 at 3.0; 2.62 at 2.5, and 3.05 at 2.30. The synchrotron emission of the entire population of relativistic electrons in Saturn's inner magnetosphere is estimated to be about 1 kW with a spectral maximum at 720 kHz. It is shown that this radiation will be very difficult, if not impossible, to observe, even in the near vicinity of the planet. The paper includes a crude but instructive explication of the truly enormous differences between the synchrotron emissions of the inner magnetospheres of Jupiter and Saturn.

OSTI ID:
6050811
Journal Information:
Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 94:A7; ISSN JGREA; ISSN 0148-0227
Country of Publication:
United States
Language:
English