Magnetic Reconnection Near the Planet as a Possible Driver of Jupiter’s Mysterious Polar Auroras

A. Masters, W. R. Dunn, T. S. Stallard, H. Manners, J. Stawarz

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Abstract

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, Jupiter’s 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 Jupiter’s stronger magnetic field. We model large-scale Alfvénic perturbations propagating through the polar magnetosphere toward 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 Jupiter’s 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 Jupiter’s polar auroras.
Original languageEnglish
Article numbere2021JA029544
Number of pages10
JournalJournal of Geophysical Research: Space Physics
Volume126
Issue number8
Early online date27 Jul 2021
DOIs
Publication statusPublished - Aug 2021
Externally publishedYes

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