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A 3D Model of the Io Plasma torus and Model Comparisons with Observations

Presentation #111.05 in the session Io (Poster + Lightning Talk)

Published onOct 23, 2023
A 3D Model of the Io Plasma torus and Model Comparisons with Observations

We present an empirical Io plasma torus (IPT) model derived from in-situ plasma measurements (Voyager), from spectral fitting of UV observations (Cassini), from ground based optical observations (Apache Point Observatory), and informed by physical chemistry modeling of the warm torus/ribbon/cold torus. Our model uses diffusive equilibrium to find the distribution along each magnetic field line given the reference density and temperature of each plasma species at the centrifugal equator. The model uses the Juno derived JRM33 internal magnetic field model (13th order) in addition to the Connerney+ (2020) external current-sheet model to define each magnetic field line. We assume each species is Maxwellian however we include hot electrons and hot O+ to model the non-thermal component. Our model is given in system-III coordinates and is available upon request. We explore the effects of system III/IV, local time, and temporal variability in plasma composition. Using our model we predict the densities and temperatures along Juno’s trajectory for Perijove (PJ) 1-76 and also for the future missions JUICE and Europa Clipper. Integrating over different line of sights (LOS) we predict emission in the UV and at optical wavelengths for different viewing geometries using our emission model the Colorado Io torus emission package 2 (CITEP 2). We find that given typical Voyager cold torus/ribbon S+ and O+ densities our model predicts too much emission to match recent ground based observations from APO of the torus in the optical. We explore how we have to change our model in order to better fit these observations and implications for the understanding the flow of mass and energy throughout the magnetosphere of Jupiter.

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