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Ann. Geophys., 26, 1341-1343, 2008
www.ann-geophys.net/26/1341/2008/
© European Geosciences Union 2008
Comparing Jupiter and Saturn: dimensionless input rates from plasma sources within the magnetosphere
V. M. Vasyliūnas
Max-Planck-Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany
Abstract. The quantitative significance for a planetary magnetosphere of
plasma sources associated with a moon of the planet can be assessed
only by expressing the plasma mass input rate in dimensionless form,
as the ratio of the actual mass input to some reference value.
Traditionally, the solar wind mass flux through an area equal to the
cross-section of the magnetosphere has been used. Here I identify
another reference value of mass input, independent of the solar wind
and constructed from planetary parameters alone, which can be shown
to represent a mass input sufficiently large to prevent corotation
already at the source location. The source rate from Enceladus at
Saturn has been reported to be an order of magnitude smaller (in
absolute numbers) than that from Io at Jupiter. Both reference
values, however, are also smaller at Saturn than at Jupiter, by
factors ~40 to 60; expressed in dimensionless form, the
estimated mass input from Enceladus may be larger than that from Io
by factors ~4 to 6. The magnetosphere of Saturn may thus,
despite a lower mass input in kg s−1, intrinsically
be more heavily mass-loaded than the magnetosphere of Jupiter.
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