HR: 11:05h
AN: P52A-04    [Abstracts]
TI: From Saturnian Ring Plasma to Energetic Magnetospheric Ions
AU: * Ip, W
EM: wingip@astro.ncu.edu.tw
AF: Institutes of Astronomy and Space Science, National Central University, 300 Jongdai Road, Chung Li, 32054 Taiwan
AB: Because of continuous collisional bombardments by interplanetary meteoroids, interstellar dust and dust particles of satellite origin, a tenuous exosphere could be built up in the Saturnian ring system. Photodissociation of the water molecules will lead to a composition dominated by oxygen molecules. Subsequent photoionization and electron impact ionization will lead to the formation of a thin layer of plasma disc embedded on one side of the ring plane. This storage zone is created by the vertical shift of the center of the axisymmetric magnetic field. With a nominal gas production rate of 2.5E27 O2/s and an equilibrium between impact vapor production and charge exchange loss, the neutral number density in the ring exosphere can be estimated to be about 8.3E5 molecules per c.c. and the ring plasma density to be about 300 per c.c. as constrained by the Voyager measurements in the inner Saturnian magnetosphere. The fast neutral atoms (FNAs) created by charge exchange loss of the trapped ring ions will be injected into the outer magnetosphere forming a thin gas disk. The inward radial diffusion of the pickup heavy ions could produce energetic ions with energy reaching as high as 30 keV at L = 5. It is in this manner that the ring system could have direct influence on the dynamics and composition of the Saturnian magnetosphere.
DE: 5737 Magnetospheres (2756)
DE: 5759 Rings and dust
DE: 6265 Planetary rings
DE: 6275 Saturn
DE: 2732 Magnetosphere interactions with satellites and rings
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting