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| Titel |
The electron density of Saturn's magnetosphere |
| VerfasserIn |
M. W. Morooka, R. Modolo, J.-E. Wahlund, M. André, A. I. Eriksson, A. M. Persoon, D. A. Gurnett, W. S. Kurth, A. J. Coates, G. R. Lewis, K. K. Khurana, M. Dougherty |
| 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. 7 ; Nr. 27, no. 7 (2009-07-29), S.2971-2991 |
| Datensatznummer |
250016604
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| Publikation (Nr.) |
 copernicus.org/angeo-27-2971-2009.pdf |
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| Zusammenfassung |
| We have investigated statistically the electron density below 5 cm−3 in
the magnetosphere of Saturn (7–80 RS, Saturn radii) using 44 orbits of
the floating potential data from the RPWS Langmuir probe (LP) onboard
Cassini. The density distribution shows a clear dependence on the distance
from the Saturnian rotation axis (√X2+Y2) as well as on the
distance from the equatorial plane (|Z|), indicating a
disc-like structure. From the characteristics of the density distribution,
we have identified three regions: the extension of the plasma disc, the
magnetodisc region, and the lobe regions. The plasma disc region is at L<15,
where L is the radial distance to the equatorial crossing of the dipole
magnetic field line, and confined to |Z|<5 RS. The
magnetodisc is located beyond L=15, and its density has a large
variability. The variability has quasi-periodic characteristics with a
periodicity corresponding to the planetary rotation. For Z>15 RS,
the magnetospheric density distribution becomes constant in Z. However, the
density still varies quasi-periodically with the planetary rotation also in
this region. In fact, the quasi-periodic variation has been observed all
over the magnetosphere beyond L=15. The region above Z=15 RS is
identified as the lobe region. We also found that the magnetosphere can
occasionally move latitudinally under the control of the density in the
magnetosphere and the solar wind. From the empirical distributions of the
electron densities obtained in this study, we have constructed an electron
density model of the Saturnian nightside magnetosphere beyond 7 RS. The
obtained model can well reproduce the observed density distribution, and can
thus be useful for magnetospheric modelling studies. |
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