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| Titel |
Titan's plasma environment during a magnetosheath excursion: Real-time scenarios for Cassini's T32 flyby from a hybrid simulation |
| VerfasserIn |
S. Simon, U. Motschmann, G. Kleindienst, J. Saur, C. L. Bertucci, M. K. Dougherty, C. S. Arridge, A. J. Coates |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 27, no. 2 ; Nr. 27, no. 2 (2009-02-12), S.669-685 |
| Datensatznummer |
250016406
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| Publikation (Nr.) |
 copernicus.org/angeo-27-669-2009.pdf |
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| Zusammenfassung |
| With a Saturnian magnetopause average stand-off distance of about 21
planetary radii, Titan spends most of its time inside the rotating magnetosphere of
its parent planet. However, when Saturn's magnetosphere is
compressed due to high solar wind dynamic pressure, Titan can
cross Saturn's magnetopause in the subsolar region of its orbit and therefore
to interact with the shocked solar wind plasma in Saturn's magnetosheath. This
situation has been observed during the T32 flyby of the Cassini spacecraft on
13 June 2007. Until a few minutes before closest approach, Titan had been
located inside the Saturnian magnetosphere.
During the flyby, Titan encountered a sudden change in the direction and
magnitude of the ambient magnetic field. The density of the ambient plasma also
increased dramatically during the pass.
Thus, the moon's exosphere and
ionosphere were exposed to a sudden change in the upstream plasma conditions.
The resulting reconfiguration of Titan's plasma tail has been studied in
real-time by using a three-dimensional, multi-species hybrid simulation
model. The hybrid approximation treats the electrons of the plasma as a massless,
charge-neutralizing fluid, while ion dynamics are described by a kinetic
approach. In the simulations, the magnetopause crossing is modeled by a sudden change of the
upstream magnetic field vector as well as a modification of the upstream
plasma composition. We present real-time simulation results, illustrating how
Titan's induced magnetotail is reconfigured due to magnetic reconnection. The
simulations allow to determine a characteristic time scale for the erosion of
the original magnetic draping pattern that commences after Titan
has crossed Saturn's magnetopause. Besides, the influence of the plasma
composition in the magnetosheath on the reconfiguration process is discussed
in detail.
The question of whether the magnetopause
crossing is likely to yield a detachment of Titan's exospheric tail from the
satellite is investigated as well. |
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