DPS 35th Meeting, 1-6 September 2003
Session 40. Outer Planets/Gas Giants IV
Poster, Highlighted on, Friday, September 5, 2003, 3:30-6:00pm, Sierra Ballroom I-II

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[40.04] Plasma coupling in the ion kinetic limit: A comparison of Io, Pluto and comet Borrelly

P. A. Delamere, F. Bagenal (U. Colorado)

The interaction between a mass-loading plasma environment and an ambient magnetized plasma is commonly found throughout the solar system. Typically, the plasma interaction can be understood with magnetohydrodynamics (MHD), or a fluid description, but in the limit where ion kinetic effects are important the interaction can take on a fundamentally different character. We will explore three examples that compare the nature of plasma coupling from kinetic-mediated to fluid-mediated interactions. These include: a) Io's interaction with the plasma torus, b) and the interaction between Pluto's escaping atmosphere and the solar wind, and c) the solar wind interaction with comet Borrelly. Io represents an example where ion kinetics are relatively unimportant and an MHD approach can be adopted to study the Alfvénic coupling between Io and Jupiter. Pluto, on the other hand, is dominated by ion kinetic effects. Not only is the ion gyroradius at Pluto of both solar wind protons and pickup ions much larger than the obstacle scale size, but the solar wind ion inertial length is comparable to Pluto's diameter. Finally, comets represent an interesting intermediate case where at large distances from the sun the interaction is kinetic dominated and closer to the sun the interaction can be understood with a fluid description. In situ observations of comet Borrelly at 1.4 AU suggest that ion kinetic effects may be responsible for asymmetries in its plasma environment.

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.