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| Titel |
Magnetospheric mapping of the dayside UV auroral oval at Saturn using simultaneous HST images, Cassini IMF data, and a global magnetic field model |
| VerfasserIn |
E. S. Belenkaya, S. W. H. Cowley, J. D. Nichols, M. S. Blokhina, V. V. Kalegaev |
| 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 ; 29, no. 7 ; Nr. 29, no. 7 (2011-07-08), S.1233-1246 |
| Datensatznummer |
250017057
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| Publikation (Nr.) |
 copernicus.org/angeo-29-1233-2011.pdf |
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| Zusammenfassung |
| We determine the field-aligned mapping of Saturn's
auroras into the magnetosphere by combining UV images of the southern
dayside oval obtained by the Hubble Space Telescope (HST) with a global
model of the magnetospheric magnetic field. The model is tailored to
simulate prevailing conditions in the interplanetary medium, corresponding
to high solar wind dynamic pressure and variable interplanetary magnetic
field (IMF) strength and direction determined from suitably lagged field
data observed just upstream of Saturn's dayside bow shock by the Cassini
spacecraft. Two out of four images obtained in February 2008 when such
simultaneous data are available are examined in detail, exemplifying
conditions for northward and southward IMF. The model field structure in the
outer magnetosphere and tail is found to be very different in these cases.
Nevertheless, the dayside UV oval is found to have a consistent location
relative to the field structure in each case. The poleward boundary of the
oval is located close to the open-closed field boundary and thus maps to the
vicinity of the magnetopause, consistent with previous results. The
equatorward boundary of the oval then maps typically near the outer boundary
of the equatorial ring current appropriate to the compressed conditions
prevailing. Similar results are also found for related images from the
January 2004 HST data set. These new results thus show that the mapped
dayside UV oval typically spans the outer magnetosphere between the outer
part of the ring current and the magnetopause. It does not encompass the
region of primary corotation flow breakdown within the inner Enceladus
torus. |
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