Circular Auroral Feature on Jupiter observed by Juno-UVS

Juno discovers faint circularly expanding auroral features evolving over 1-2 minutes.
Emission characteristics are consistent with precipitating electrons ranging 80-160 keV.
Hue, V. et al. (2021) “Detection and characterization of circular expanding UV-emissions observed in Jupiter’s polar auroral regions”, https://doi.org/10.1029/2020JA028971

Circular auroral feature observed over consecutive Juno spins with UVS (PJ6)

Expansion rate measured on 4 best cases range from 3.3 to 7.7 km/s. 
Map to magnetospheric distances >100 RJ with no apparent local time preference. 
Potential interpretations include Kelvin–Helmholtz instabilities or magnetic reconnections.

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