Magnetosphere - be caused by compositional convection in...

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Magnetosphere In addition to the intrinsic magnetic moment, Ganymede has an induced dipole magnetic field. [17] Its existence is connected with the variation of the Jovian magnetic field near the moon. The induced moment is directed radially to or from Jupiter following the direction of the varying part of the planetary magnetic field. The induced magnetic moment is an order of magnitude weaker than the intrinsic one. The field strength of the induced field at the magnetic equator is about 60 nT—half of that of the ambient Jovian field. [17] The induced magnetic field of Ganymede is similar to those of Callisto and Europa , indicating that this moon also has a subsurface water ocean with a high electrical conductivity . [17] Given that Ganymede is completely differentiated and has a metallic core, [5] [40] its intrinsic magnetic field is probably generated in a similar fashion to the Earth's: as a result of conducting material moving in the interior. [17] [40] The magnetic field detected around Ganymede is likely to
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Unformatted text preview: be caused by compositional convection in the core, [40] if the magnetic field is the product of dynamo action, or magnetoconvection. [17] [68] Despite the presence of an iron core, Ganymede's magnetosphere remains enigmatic, particularly given that similar bodies lack the feature. [5] Some research has suggested that, given its relatively small size, the core ought to have sufficiently cooled to the point where fluid motions and a magnetic field would not be sustained. One explanation is that the same orbital resonances proposed to have disrupted the surface also allowed the magnetic field to persist: with Ganymede's eccentricity pumped and tidal heating increased during such resonances, the mantle may have insulated the core, preventing it from cooling. [46] Another explanation is a remnant magnetization of silicate rocks in the mantle, which is possible if the satellite had a more significant dynamo-generated field in the past....
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