Magnetic reconnection near the planet as a possible driver of Jupiters mysterious polar auroras

Auroral emissions have been extensively observed at the Earth, Jupiter, and Saturn. These planets all have appreciable atmospheres and strong magnetic fields, and their auroras predominantly originate from a region encircling each magnetic pole. However, Jupiters auroras poleward of these main emissions are brighter and more dynamic, and the drivers responsible for much of these mysterious polar auroras have eluded identification to date. We propose that part of the solution may stem from Jupiters stronger magnetic field. We model large-scale Alfvenic perturbations propagating through the polar magnetosphere towards Jupiter, showing that the resulting <0.1 deflections of the magnetic field closest to the planet could trigger magnetic reconnection as near as ~0.2 Jupiter radii above the cloud tops. At Earth and Saturn this physics should be negligible, but reconnection electric field strengths above Jupiters poles can approach ~1 V m-1, typical of the solar corona. We suggest this near-planet reconnection could generate beams of high-energy electrons capable of explaining some of Jupiters polar auroras. Beyond this core idea, we go on to assess the potential source of triggering perturbations from the magnetosphere and explore the role of the ionosphere as a potential reason for hemispheric and local time asymmetries in the swirl emissions. Finally, we outline hypotheses that can be tested by observations made by the ongoing Juno mission.