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| Titel |
IMF dependence of Saturn's auroras: modelling study of HST and Cassini data from 12–15 February 2008 |
| VerfasserIn |
E. S. Belenkaya, I. I. Alexeev, M. S. Blokhina, E. J. Bunce, S. W. H. Cowley, J. D. Nichols, V. V. Kalegaev, V. G. Petrov, G. Provan |
| 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 ; 28, no. 8 ; Nr. 28, no. 8 (2010-08-19), S.1559-1570 |
| Datensatznummer |
250016871
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| Publikation (Nr.) |
 copernicus.org/angeo-28-1559-2010.pdf |
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| Zusammenfassung |
| To gain better understanding of auroral processes in
Saturn's magnetosphere, we compare ultraviolet (UV) auroral images obtained
by the Hubble Space Telescope (HST) with the position of the open-closed
field line boundary in the ionosphere calculated using a magnetic field
model that employs Cassini measurements of the interplanetary magnetic field
(IMF) as input. Following earlier related studies of pre-orbit insertion
data from January 2004 when Cassini was located ~ 1300 Saturn radii
away from the planet, here we investigate the interval 12–15 February
2008, when UV images of Saturn's southern dayside aurora were obtained by
the HST while the Cassini spacecraft measured the IMF in the solar wind just
upstream of the dayside bow shock. This configuration thus provides an
opportunity, unique to date, to determine the IMF impinging on Saturn's
magnetosphere during imaging observations, without the need to take account
of extended and uncertain interplanetary propagation delays. The paraboloid
model of Saturn's magnetosphere is then employed to calculate the
magnetospheric magnetic field structure and ionospheric open-closed field
line boundary for averaged IMF vectors that correspond, with appropriate
response delays, to four HST images. We show that the IMF-dependent open
field region calculated from the model agrees reasonably well with the area
lying poleward of the UV emissions, thus supporting the view that the
poleward boundary of Saturn's auroral oval in the dayside ionosphere lies
adjacent to the open-closed field line boundary. |
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