Exploring the Jovian auroral vertical structure: Juno’s view.

Jovian auroras, the most powerful in the Solar System, result from the interaction between the magnetosphere and the atmosphere of Jupiter. While the horizontal morphology of these phenomena is widely studied, their vertical structure, determined by the penetration depth of the magnetospheric electron into the auroral regions, remains relatively unexplored. Previous observations, including those from the Hubble Space Telescope (HST), the Galileo probe, and the Subaru telescope, have addressed this
question to a limited extent. Thanks to observations from the UltraViolet Spectrograph (Juno/UVS), we have thoroughly examined the vertical structure of the auroral emissions. Building on the recent study by Benmahi et al. (2024), which mapped the average energy of precipitating electrons in auroral regions, we have developed a relationship
between this average energy and the volume emission rate (VER) of H2 for two types of electron energy distribution: monoenergetic and kappa distribution.
Using brightness maps, we derived the three-dimensional VER structure of Jovian auroras in both northern and southern regions, across multiple spacecraft perijoves (PJ).We found that the average altitude of the VER peak in the main, polar and outer emission regions, excluding the Io footprint emission, is approximately ˜240 km for the case of monoenergetic distribution and ˜190 km for kappa distribution case. Our findings are, in average, consistent with measurements from the Galileo probe. This study contributes to a better understanding of the complexity of Jovian auroras and to highlight the importance of Juno observations to probe their vertical structure.