HR: 0830h
AN: P21B-02    [Abstracts]
TI: Ring Ion Dynamics at Saturn and Their Potential Consequences
AU: * Luhmann, J G
EM: jgluhman@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720 United States
AU: Ledvina, S A
EM: ledvina@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720 United States
AU: Johnson, R E
EM: rej@virginia.edu
AF: Engineering Physics, University of Virginia, Charlottesville, VA 22901 United States
AU: Cravens, T E
EM: cravens@ku.edu
AF: Dept. of Physics and Astronomy, University of Kansas, Lawrence, KS 66045 United States
AB: The Cassini Orbiter CAPS and INMS detections of an ionosphere of Saturn's rings during SOI, coupled with the internal dipole field offset detected on previous missions, motivated the present numerical analysis of mass 32 and 16 singly charged ions in Saturn's inner magnetosphere. The combination of the source of heavy pickup ions in the plane of the rotational equator, at radial distances of ~1.4-2.4 Saturn radii, and the dipole offset combine to produce a heavy ion torus with suggested consequences yet to be observationally confirmed. Although the neutral atmosphere is expected to be roughly symmetric about the ring plane (Johnson et al. 2005), the modeled ion spatial distribution exhibits major North-South asymmetries due to asymmetric photo-ionization and the dipole offset, and also due to the fact that the ring ion source spans the radial distance where the Keplerian velocity is equal to the ion corotation velocity, Rc. We find that for R<Rc there is an implied zone of ring ion precipitation into Saturn's southern midlatitude hemisphere and, at the outer edge, the ring atmosphere can contribute heavy ion species to the inner magnetosphere. While the Cassini Orbiter is not destined to provide any further in-situ sampling of the ring ionosphere during its prime mission, its remote sensing capabilities in the UV and in energetic neutral atoms may yield some evidence for (or against) the presented modeling results.
DE: 5759 Rings and dust
DE: 6265 Planetary rings
DE: 6275 Saturn
SC: Planetary Sciences [P]
MN: 2005 Joint Assembly