Jupiter’s polar auroral bright spot observations by in situ measurements and remote sensing

This work presents the in situ observations and remote sensing during the Juno flyby over Jupiter’s auroral bright spot in the polar region. The data were collected from Juno-UVS, JEDI,Waves, and MAG instruments when Juno flew close to the bright spot position during perijove (PJ) 3, PJ15, and PJ33. The results show an enhancement of the high energy particle fluxes (30-1200 keV) observed by JEDI either during the crossing of a bright spot detected by Juno-UVS (PJ3) or, at least, very near (PJ15 and PJ33).
These particles are dominated by upward electrons, implying that the acceleration process took place below the spacecraft. In addition, theWaves instrument observes the intensification of whistler-mode waves at the same period of particle enhancement during PJ3 and PJ33, and before the observed enhanced particle flux for PJ15. These relationships suggest that a form of wave-particle interaction is taking place, which would contribute to the particle acceleration in both directions along the field lines and cause the UV auroral bright spot emission. Furthermore, the magnetic deviations observed by the MAG instrument suggest the presence of downward magnetic field-aligned currents. Although
the fixed position of bright spot in System III suggests that the processes giving rise to them are close to the planet, it remains possible that their root cause still lies further away in the magnetosphere (either at high or low latitude). Further understanding the polar bright spot phenomenon requires investigating the flux tubes topology connected to this region using MHD simulations, and additional Juno field and particle observations beneath the acceleration region.