The origin of the dynamo action in Jupiter-like planets
Updated: Feb 27, 2020
New experimental results on the conductive properties of metallic hydrogen suggest that magnetic field in gas giants could be generated much closer to the surface than previously thought.
Jupiter is the seat of the most powerful dynamo in our solar planetary system. Its magnetic field is generated by the convection of its liquid metallic hydrogen interior.
Here, we present a new experimentally based internal conductivity profile that could better account for Juno's new observations. We combine this new profile with a polytropic equation of state to study the dynamo action in 100 extrasolar giant planets from the current census and predict their dipole field strengths, magnetic moments, conducting core sizes and associated radio emission frequencies.
New experimental results on the conductive properties of Jupiter's liquid metallic core show the conductivity of fluid hydrogen at the corresponding depths are larger than currently assumed from previous experiments or predicted in ab-initio calculations.
Our new conductivity profile should be amenable to use in future MHD and magnetization studies of hydrogen-rich planets. We show that the sizes of conducting cores in most extrasolars giants is larger than previous estimates, but consistent with the results from Juno, suggesting that the dynamos in the more massive planets might be shallow-seated.