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Entries for September 2006Sulfur's impact on core evolution and magnetic field generation on GanymedeRecently, we have been working to understand whether Ganymede may have a relatively exotic way of driving convection in a fluid portion of a metallic core that would in-turn generate its magnetic field. In the Earth, convection in the outer core is driven by some combination of thermally-generated buoyancy as the core cools and compositional buoyancy from the release of some light element at the inner core outer core boundary and then rising to shallower levels. The latter is energetically efficient because it isn't subject to the inefficiency of a heat engine. On Ganymede the same process may also hold, however the phase diagram of a potential core alloy (Fe-FeS) is different at the low pressures in Ganymede's core compared to the much higher ones deep in the Earth. This difference allows for the possibility that solid iron might precipitate shallow in the core and fall through the core and potentially driving the magnetic field. It is also possible that if the core is very sulfur rich solid FeS might float up from deep in the core and also drive core convection. Working Jonathan Aurnou (UCLA) and Andrew Dombard (APL) we have outlined the potential consequences of these relatively unique modes of core evolution in a recently published paper: Continue reading "Sulfur's impact on core evolution and magnetic field generation on Ganymede" | ||||
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