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| Titel |
Titan interaction with the Saturnian magnetosphere: Are we able to detect internal fields of Titan? |
| VerfasserIn |
Hanying Wei, Yingjuan Ma, Christopher Russell, Michele Dougherty |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093630
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| Publikation (Nr.) |
 EGU/EGU2014-8539.pdf |
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| Zusammenfassung |
| The Cassini spacecraft has made over ninety Titan flybys with good spatial coverage around
Titan and also spreading over three seasons in the Saturnian system (southern summer,
equinox and northern summer). These observations allow us not only to study the magnetic
field patterns generated by the interaction but also to investigate whether there are possible
magnetic signatures due to intrinsic or induced field from the interior of Titan. We find that in
general the observed fields above 1200 km altitudes are in good agreement with the expected
field-draping pattern according to the instantaneous upstream condition. However, the fields
at lower altitudes are more disordered. Due to the time-variable upstream conditions,
coupling between the neutral and ionized components of the atmosphere, and the
long magnetic-diffusion time scale at low altitudes, the magnetic fields at these
altitudes have a complex pattern, and are no longer consistent with the draping
pattern expected for the “current” upstream conditions. We use MHD simulation to
understand the diffusion time scales at these low altitudes and predict the fields
generated due to the ionosphere. After removing these externally generated fields, we
investigate whether there are signatures of intrinsic or induced fields from the interior of
Titan.
Titan interacts with the outer magnetosphere of Saturn and develops a complex pattern of
magnetic field in the surrounding plasma environment. The Cassini spacecraft has obtained
more than eighty Titan passes spreading over three seasons in the Saturnian system (southern
summer, equinox and northern summer). These observations allow us not only to study the
magnetic field patterns generated by the interaction but also to investigate whether there are
possible magnetic signatures due to intrinsic or induced field from the interior of Titan.
In general, when the upstream plasma flow encounters Titan, the plasma slows
down and diverts around Titan, and the magnetic field slowly diffuses into Titan’s
ionosphere and induces currents in the ionosphere. The resulting field pattern is that,
upstream fieldlines drape around Titan, and downstream fieldlines stretch into a
tail. Due to the time-variable upstream conditions, coupling between the neutral
and ionized components of the atmosphere, and the long magnetic-diffusion time
scale at low altitudes, the magnetic field at these altitudes has a complex pattern,
inconsistent with the draping pattern expected for the “current” upstream conditions. We
use observations together with MHD simulations to understand the diffusion time
scales and possible patterns of the low altitude fields. This knowledge allows us
to constrain both the intrinsic and induced magnetic field in the interior of Titan. |
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