HR: 1330h
AN: SM13A-11    [Abstracts]
TI: Equatorial electron beams at Jupiter; Signatures of Earth-like spatial structuring within Jupiters main auroral oval?
AU: * Mauk, B H
EM: Barry.Mauk@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laruel, MD 20723 United States
AU: Saur, J S
EM: saurjs1@saurs-pc.jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laruel, MD 20723 United States
AB: The regions of intense discrete aurora at Earth show high degrees of spatial structuring down to the less than 1 km scale. Specifically, intense and narrow auroral arcs associated with strong upward (with respect to Earth) magnetic field-aligned electric currents are often accompanied with adjacent regions of downward currents which constitute part of the return current of the auroral magnetosphere-ionosphere current system. Within Earth's near-equatorial magnetosphere, a distinct signature of these downward electric current regions has been discovered; intense, magnetic field-aligned, bi-directional electron beams with broad energy distributions extending at times to 10s of keV (Klumpar et al., 1988; interpreted by Carlson et al., 1998 with low altitude measurements). Such electron beams were observed by Galileo within Jupiter's middle, near equatorial magnetosphere between about 15 to greater than 30 RJ (Bhattacharya et al, 2001; Tomas et al., 2004; Frank and Paterson, 2004), and are undoubtedly related to beams observed at high latitudes by Ulysses (Lanzerotti et al, 1993). The equatorial beams occur within the region of space identified as mapping to Jupiter's main region of strong auroral emissions where, on average, it is thought that the global electric currents are upward with respect to Jupiter. We show here that the observed electron beams are highly transient or structured when observed in high time resolution. We argue that the beams represent evidence of Earth-like structuring within Jupiter's main aurora, with narrow regions of downward current imbedded with and accompanying regions of upward current, all within the broad region where, on average, the electric currents are upward with respect to Jupiter.
DE: 2704 Auroral phenomena (2407)
DE: 2708 Current systems (2409)
DE: 2756 Planetary magnetospheres (5443, 5737, 6030)
DE: 5719 Interactions with particles and fields
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly