A Multi-Instrument Study of Auroral Hiss Emissions at Saturn Observed With
Cassini
A.J. Kopf, D.A. Gurnett, G.B. Hospodarsky, W.S. Kurth, M.K. Dougherty, D.G.
Mitchell, J.S. Leisner
Over the last two years, the Cassini spacecraft has undergone a series of higher
inclination orbits, allowing investigation and measurements of the Saturnian
auroral zone. The Radio and Plasma Wave Science (RPWS) Investigation has
detected low frequency funnel-shaped whistler mode emissions along the auroral
field lines, much like the auroral hiss observed at Earth. The poleward and
equatorward flaring of the auroral hiss funnel on the frequency-time spectrogram
is the result of whistler mode waves propagating upward into a region of
diminishing plasma density. These detections are important in understanding the
auroral processes occurring at Saturn. The emissions usually display two
periodicities, one on a short time scale of roughly one hour and the second on a
time scale on the order of the SKR period. The short term variability appears
to align with the one-hour periodic bursts of upward propagating field-aligned
electrons at energies of tens to hundreds of keV. These detections also
correlate well to the field-aligned currents observed at Saturn. Ray tracing
calculations are underway to explain the funnel shape and determine the source
position.
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