A persistent, large-scale, and ordered electrodynamic connection between Saturn and its main rings as revealed by Cassini/RPWS

Auroral hiss emissions are ubiquitous in planetary magnetospheres, particularly in regions
where electric current systems are present. They are generally diagnostics of

electrodynamic coupling between conductive bodies, thus making auroral and moon-
connected (e.g. Enceladus) magnetic field lines prime locations for their detection.

Auroral hiss propagates in the same direction as electron beams and are understood to
be generated by Landau resonance, i.e., when their parallel phase speeds match the
electron beam speed. Cassini's Grand Finale orbits afforded a unique opportunity to
directly sample magnetic field lines connected to the main rings. Using plasma wave data,
we provide strong evidence for the persistent and organized presence of auroral hiss
demonstrably associated with the main rings. Further, we find this phenomenon
consistent with plasma wave data during Saturn Orbital Insertion, when Cassini made an
equatorial pass over the main rings. This suggests the main rings facilitate the closure of
field-aligned currents by the action of radial currents across the rings.

Presenter’s name
A. H. Sulaiman and W. M. Farrell
Date of the meeting