Characterization of Jupiter’s auroral expanding concentric emissions observed in Jupiter’s polar auroral regions

Abstract:

Jupiter's polar auroral regions are the most dynamic part of the Jovian UV-aurora. They are thought to be magnetically connected to Jupiter's outer magnetosphere, and often exhibit flares evolving over short timescales. We present the analysis of an auroral feature identified in that region by the Ultraviolet Spectrograph on NASA's Juno mission (Juno-UVS), characterized as a faint (~100 kR) circles of UV emission expanding with time. As Juno spins at a rate of 2 rpm, UVS provides snapshots of regions smaller than the main auroral regions. Consecutive spins recorded over the same region allow identification and characterization of these auroral features. We characterize where the "raindrops"-like features occur within the auroral region. Their expansion rates range from 3.3-7.7 km/s, as measured from the 4 best cases recorded, which is above the soundspeed in Jupiter's ionosphere (1.7-2.3 km/s). We use model of Vogt et al. (2011, JGR 116, A03220; 2015, JGR 120, 2584-2599) coupled with the JRM09 magnetic field model to trace the origin of these emissions back to their origin in the magnetodisk. We discuss potential physical explanation of how such features form.