HR: 14:55h
AN: P52B-06    [PDF]
TI: Energetic neutral atom images of Jupiter's magnetosphere: composition and time variability
AU: * Paranicas, C
EM: chris.paranicas@jhuapl.edu
AF: Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Mitchell, D G
EM: Donald.Mitchell@jhuapl.edu
AF: Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Mauk, B H
EM: Barry.Mauk@jhuapl.edu
AF: Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Krimigis, S M
AF: Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AB: During the Cassini flyby of Jupiter in late 2000/early 2001, the first ever images of Jupiter's magnetosphere in energetic neutral atom (ENA) flux were obtained. ENAs are typically created when singly-charged energetic ions undergo charge exchange with ambient neutral gas. Since little energy is lost in these collisions, neutrals leave the system along high speed, straight-line trajectories. The Cassini Magnetospheric Imaging Instrument's (MIMI) Ion and Neutral Camera (INCA) detected the fluxes of several to several hundred keV/nucleon ENAs for months leading up to closest approach on December 30, 2000 and for a few days past (after which the viewing geometry was unfavorable). The primary source of Jovian ENAs is the interaction of mirroring ions with the planet's exosphere, in a thin layer just above the denser atmosphere. A significant secondary contribution comes from the tori of neutral gas collocated with the orbits of Io and Europa (see, Mauk et al 2003). We will present the flux of ENAs detected as a function of composition and energy. Furthermore, we have calculated the ENA flux, in several energy bands, for spacecraft distances between about 150 to1000 Jovian radii. We have determined that to lowest order the emission signal is fairly constant, however there is evidence of time variability in the data. We will discuss the implications of composition and time variation for magnetospheric processes. Mauk, B. H., D. G. Mitchell, S. M. Krimigis, E. C. Roelof, and C. P. Paranicas, Energetic neutral atoms from a trans-Europa gas torus at Jupiter, Nature, 421, 920, 2003.
DE: 5719 Interactions with particles and fields
DE: 5780 Tori and exospheres
DE: 6218 Jovian satellites
DE: 6220 Jupiter
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting