Ulysses HISCALE Pages
Authors: T. P. Armstrong, Dept. of Physics and Astronomy, Univ. of Kansas; L. J. Lanzerotti, AT and T Bell Laboratories; R. E. Gold, S. M. Krimigis, and E. C. Roelof, Johns Hopkins Univ. Applied Physics Laboratory; K. A. Anderson and R. P. Lin, Space Science Laboratory, Univ. of Calif.-Berkeley; M. Pick, Observatorie de Paris, Meudon, France; George Simnett, Univ. of Birmingham, U.K.; E. T. Sarris, Democritos Univ. of Thrace, Greece; A. Balogh, Imperial College, London, U.K.; with crucial assistance from: Carol Maclennan, AT and T Bell Laboratories, James Tappin, Univ. of Birmingham, U.K., and T. H. Choo, Dept. of Physics and Astronomy, Univ. of Kansas.
Presented at: Goertz-Smith Symposium on the Magnetospheres of the Outer Planets, UCLA, June 22-26, 1992.
|Figure 1. LAN 2A and LAN 2B configurations||Figure 2. Spin plane clock angle (degrees) from spacecraft x-axis|
|Figure 3.||Figure 4.|
|Figure 5.||Figure 6.|
|Figure 7.||Figure 8.|
Table 1. Channels used:
|Figure 10 - ions||Figure 11 - electrons|
|Figure 12||Figure 13|
Ulysses and Voyager ion and electron observations are consistent with lossy radial transport of particles from a time-variable, large radial distance, low-latitude source. Solar wind is an obvious candidate.
Table 2 (modified on 4/27/92):
Figure 15. Ulysses trajectory in Jovian dipole coordinates
Data Analyses and Results
The observations show that during almost all the inbound and outbound passes the pitch angle distributions of electrons and ions are either very isotropic or strongly bi-directional (occurring particularly near the closest encounter). To study the energy fluxes and power inputs for the Jovian aurora, we chose two-hour observed data mostly close to Jupiter during the inbound (92:38:19:0 to 92:38:21:0) and outbound (92:40:01:0 to 92:40:03:0) passes. In this study we used:
Loss cone = arcsin (1 / R2)
Flux area ≈ π(Z22 - Z12)
where Zi = Ri * sin(Lat.i) for i-th data record.
Diff. Flux = Count Rate / G-Factor x Passband
Moreover, we assumed that both electrons and ions have a power-law spectrum, and the power index γ was estimated by
Diff. Flux =
We found that the assumed power-law spectrum agrees very well with both the
Ulysses electron and ion data. For the chosen data set, the average
γ is about 2.2 ~ 2.5 for ions and
about 1.54 ~ 2.2 for electrons, respectively.
With obtained values of γ
we can estimate average local energy flux by and local power input by Power Input = Energy Flux x Loss Cone x Flux Area
We found that the assumed power-law spectrum agrees very well with both the Ulysses electron and ion data. For the chosen data set, the average γ is about 2.2 ~ 2.5 for ions and about 1.54 ~ 2.2 for electrons, respectively.
With obtained values of γ we can estimate average local energy flux by
and local power input by
Power Input = Energy Flux x Loss Cone x Flux Area
|Figure 16||Figure 17 - Top: Spin average ions energy spectrum, inbound - LEMS 120 and LEMS 30; Bottom: Spin average electron energy spectrum, inbound - LEFS 60, LEFS 150, and WART 60|
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Last modified March 30, 2006