Sabine Stanley of the University of Toronto presented this week’s DTM seminar: “A Study of Planetary Magnetic Field Morphologies.” Stanley and colleagues use numerical dynamo modeling to study planetary magnetic fields in our Solar System. Dynamo action is occurring in Earth, Jupiter, and Saturn, where it produces axially dipolar-dominated magnetic fields. Dynamo action generates non-dipolar, non-axisymmetric fields in Uranus and Neptune. Mars and the Moon have remanent magnetic fields, most likely from dynamo action in their pasts. Currently, data are insufficient from Mercury to distinguish between dynamo action and a remanent field.

Stanley and colleagues use 3-D numerical dynamo modeling to study the dependence of magnetic field morphology on fluid shell thickness, inner core conductivity, Rayleigh number and the presence of stably stratified regions in the field--generating portions of planetary and satellite interiors.

In the case of Mercury, Stanley’s group looks at whether Mercury’s interior structure has the ability to sustain a dynamo, and what future observations could determine whether the field is dynamo or crustal in origin. Stanley pointed out the importance of the in-progress MESSENGER mission to Mercury and the upcoming BepiColombo mission in helping to answer these questions about the innermost planet.