Juno's multi-instruments observations during the flybys of auroral
bright spots in Jupiter's polar aurorae
Abstract
Juno’s arrival at Jupiter in 2016 revealed unprecedented details about
Jupiter’s ultraviolet aurorae thanks to its unique suite of remote
sensing and in situ instruments. Here we present results from in situ
observations during Juno flybys above specific bright auroral spots in
Jupiter’s polar aurora. We compare data observed by Juno-UVS, JEDI,
JADE, Waves, and MAG instruments when Juno was magnetically connected to
bright polar auroral spots during perijove 3 (PJ3), PJ15, and PJ33. The
highly energetic particles observed by JEDI show enhancements dominated
by upward electrons, which suggests that the particle acceleration
region takes place below the spacecraft. Moreover, both brightness and
upward particle flux were higher for the northern bright spot in PJ3
compared to the southern spots found in PJ15 and PJ33. In addition, we
notice the intensification of whistler-mode waves at the time of the
particle enhancements, suggesting that wave-particle interactions
contribute to the acceleration of particles which cause the UV aurorae.
The MAG data reveal magnetic perturbations during the PJ3 spot detection
by Juno, which suggests the presence of significant field-aligned
electric currents. While the stable position of the bright spots in
System III suggests that the phenomenon is fixed with respect to the
rotation of the planet, the presence of field-aligned currents leaves
open the possibility of an origin rooted much farther in the
magnetosphere.