Effects of magnetospheric feedback on dynamo action
Abstract
The observation of the magnetic field at Mercury over thirty years ago was surprising and unexpected. First, the presence of a global magnetic field in a slow rotator was unforeseen, and second, its magnitude was two orders of magnitude lower than one would expect for a dynamo in a planet the size of Mercury. There are various theories that explain the magnetic field at Mercury, some contemplating the absence of an internal dynamo. With the new data collected by the MESSENGER mission we now expect a dynamo in Mercury's deep interior. This has left fewer theories that can explain the Hermean dynamo. In this paper we will present the feedback dynamo theory which accounts for the interaction of the internal dynamo with the active magnetosphere of the planet. We have found that this interaction may lead to ultra-weak dynamos as required for Mercury. We will analyze under which conditions dynamos are affected by this feedback and how different feedback dynamos compare to spacecraft measurements of Mercury's magnetic field.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2013
- Bibcode:
- 2013AGUSM.P33A..05G
- Keywords:
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- 1510 GEOMAGNETISM AND PALEOMAGNETISM / Dynamo: theories and simulations;
- 6235 PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS / Mercury;
- 5440 PLANETARY SCIENCES: SOLID SURFACE PLANETS / Magnetic fields and magnetism