HR: 1330h
AN: SM22B-0253    [PDF]
TI: Whistler-Mode Resonance-Cone Emissions Generated by Jupiter's Moon Io
AU: * Xin, L
EM: lei-xin@uiowa.edu
AF: University of Iowa, Dept. of Physics & Astronomy, Iowa City, IA 52242 United States
AU: Gurnett, D A
EM: donald-gurnett@uiowa.edu
AF: University of Iowa, Dept. of Physics & Astronomy, Iowa City, IA 52242 United States
AU: Kivelson, M G
EM: mkivelson@igpp.ucla.edu
AF: UCLA, Inst. of Geophysics & Planetary Physics, Los Angeles, CA 90095 United States
AB: During the Galileo flyby of Jupiter's moon, Io, that occurred on October 6, 2001, a well-defined electric field emission was detected by the plasma wave instrument as the spacecraft approached the moon. The spectral characteristics of this emission are very similar to a type of whistler-mode emission called `auroral hiss' that is commonly observed in the Earth's auroral region. This paper gives a detailed analysis of the `auroral hiss' observed near Io. The electric field spectrum of the auroral hiss emission observed near Io has a sharp high-frequency cutoff at the electron cyclotron frequency and a funnel-shaped low-frequency cutoff similar to terrestrial auroral hiss. Strong magnetic field perturbations associated with the moon occur near the onset of the electric field noise. We propose that the observed emission is generated by an electron beam in a nearly field-aligned current sheet induced by the interaction of Io with the magnetic field of Jupiter. Using a ray-tracing analysis the position of the emission source is located assuming that the radiation source has either a point- or sheet-like geometry. The ray tracing analysis shows that the whistler-mode radiation originates very close to Io, at an altitude of about 0.15 R$_{\rm Io}$.
DE: 2732 Magnetosphere interactions with satellites and rings
DE: 2772 Plasma waves and instabilities
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting