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| Titel |
Magnetospheric magnetic field modelling for the 2011 and 2012 HST Saturn aurora campaigns – implications for auroral source regions |
| VerfasserIn |
E. S. Belenkaya, S. W. H. Cowley, C. J. Meredith, J. D. Nichols, V. V. Kalegaev, I. I. Alexeev, O. G. Barinov, W. O. Barinova, M. S. Blokhina |
| 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 ; 32, no. 6 ; Nr. 32, no. 6 (2014-06-27), S.689-704 |
| Datensatznummer |
250121075
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| Publikation (Nr.) |
 copernicus.org/angeo-32-689-2014.pdf |
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| Zusammenfassung |
| A unique set of images of Saturn's northern polar UV
aurora was obtained by the Hubble Space Telescope in 2011 and 2012 at times
when the Cassini spacecraft was located in the solar wind just upstream of
Saturn's bow shock. This rare situation provides an opportunity to use the
Kronian paraboloid magnetic field model to examine source locations of the
bright auroral features by mapping them along field lines into the
magnetosphere, taking account of the interplanetary magnetic field (IMF)
measured near simultaneously by Cassini. It is found that the persistent
dawn arc maps to closed field lines in the dawn to noon sector, with an
equatorward edge generally located in the inner part of the ring current,
typically at ~ 7 Saturn radii (RS) near dawn, and a
poleward edge that maps variously between the centre of the ring current and
beyond its outer edge at ~ 15 RS, depending on the
latitudinal width of the arc. This location, together with a lack of
response in properties to the concurrent IMF, suggests a principal
connection with ring-current and nightside processes. The higher-latitude
patchy auroras observed intermittently near to noon and at later local times
extending towards dusk are instead found to straddle the model open–closed
field boundary, thus mapping along field lines to the dayside outer
magnetosphere and magnetopause. These emissions, which occur preferentially
for northward IMF directions, are thus likely associated with reconnection
and open-flux production at the magnetopause. One image for southward IMF
also exhibits a prominent patch of very high latitude emissions extending
poleward of patchy dawn arc emissions in the pre-noon sector. This is found
to lie centrally within the region of open model field lines, suggesting an
origin in the current system associated with lobe reconnection, similar to
that observed in the terrestrial magnetosphere for northward IMF. |
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