HR: 0830h
AN: P21C-05    [Abstracts]
TI: Cassini Observations of Auroral Hiss-Like Emissions Near Saturn's Rings
AU: * Xin, L
EM: lei-xin@uiowa.edu
AF: Univ. of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Gurnett, D
EM: donald-gurnett@uiowa.edu
AF: Univ. of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Santolik, O
EM: ondrej.santolik@mff.cuni.cz
AF: Charles Univ., Mathematics and Physics, Prague, Czech Republic
AU: Kurth, W
EM: william-kurth@uiowa.edu
AF: Univ. of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Hospodarsky, G
EM: george-hospodarsky@uiowa.edu
AF: Univ. of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AB: A well-defined funnel-shaped electric field emission was detected by the plasma wave instrument onboard the Cassini spacecraft during its pass over the rings of Saturn on July 1, 2004. The funnel-shaped frequency-time characteristic is very similar to a type of whistler-mode emission called 'auroral hiss' that is commonly observed in Earth's auroral region. This is the first detection of such emissions at Saturn. Using a dipole magnetic field and a simple electron density model based on the electron density profile measured by Cassini, ray tracing computations have been performed to explain the funnel-shaped frequency-time spectrum. It is found that the source is located very close to the B ring at a distance of about 1.80 R_S (Saturn radii), near the synchronous rotation point in the rings. Terrestrial auroral hiss emissions are known to be caused by field-aligned low-energy (100 eV to 1 keV) electron beams associated with the auroral current system. The existence of similar emissions originating from near Saturn's rings suggest that an electrodynamic interaction between the rings and Saturn's co-rotating magnetospheric plasma may be driving a field-aligned system of beams and currents similar to those occurring in Earth's auroral regions.
DE: 5737 Magnetospheres (2756)
DE: 5759 Rings and dust
DE: 7871 Waves and instabilities
SC: Planetary Sciences [P]
MN: 2005 Joint Assembly