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| Titel |
The location and topology of electron beams in Io‘s wake |
| VerfasserIn |
S. Jacobsen, J. Saur, F. Neubauer, B. Bonfond, J.-C. Gérard, D. Grodent |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250028837
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| Zusammenfassung |
| The Galileo spacecraft measured hot field aligned electron beams near Io during three flybys.
We apply our 3D MHD model of the Io-Jupiter interaction to constrain the location and shape
of field aligned electron beams for the individual flyby scenarios.
Io continuously generates MHD waves by disturbing the Jovian magnetoplasma. Currents
carried by Alfvén waves propagate predominantly along the magnetic field lines. The waves
accelerate electrons as the number of charge carriers decreases on their way to
Jupiter. These energetic electrons precipitate into the Jovian ionosphere, visible as
prominent Io footprint emission in the Jovian aurora. On the other hand electrons
have to be accelerated upward to form the beams measured by Galileo. Unlike the
beam formation, the position and spatial structure of these beams has been poorly
discussed.
We adopt our 3D MHD model initial conditions to the individual flyby scenario and
determine the spatial morphology of beams in Io’s orbital plane. We compare our findings to
Galileo observations and find very good agreement. Moreover, we use our model to further
investigate in detail a recent concept which involves cross-hemisphere electron beams to
explain certain auroral features of the Io footprint emission such as a leading spot and
secondary spots [Bonfond et al., 2008].
Our results indicate that besides geometrical properties, such as Io’s position in the torus, the
incoming plasma density controls the travel path and topology of an electron beam. |
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