The Electrodynamic Interaction Between Io and Jupiter: Insights from Juno Observations

Juno’s highly elliptical polar orbits have enabled groundbreaking in-situ observations of the electrodynamic interaction between Jupiter and its volcanic moon, Io. These observations probe previously unexplored regions, including Io’s orbit, Jupiter’s ionosphere, and the intermediate space between them. Magnetic field data from multiple Juno traversals of field lines connected to Io’s orbit reveal intricate and dynamic magnetic signatures near flux tubes associated with Io’s position. This study introduces a methodology for modeling the distribution of currents along Io’s flux tube (IFT) and Alfvén wings, replicating the observed magnetic field signatures during Juno’s downstream encounters. We characterize the location, size, and morphology of the current-carrying regions and the current distribution within the IFT and Alfvén wings. The analysis reveals strong filamentation of field-aligned currents, with upward and downward currents splitting into secondary cells rather than forming uniform structures. A robust correlation between total field-aligned current intensity, particle energy flux, and Poynting flux highlights efficient energy transfer within the Jupiter-Io system. Using data from all Juno traversals up to perijove 42, we estimate the strength of this interaction, accounting for factors such as Io’s position within the plasma torus, its distance along the extended tail, and the magnetic field intensity at Jupiter’s ionospheric footprint. These findings provide critical new constraints on the complex interplay of electrodynamic processes in the Io-Jupiter system, advancing our understanding of magnetosphere-moon interactions in planetary environments.