AAS 203rd Meeting, January 2004
Session 134 Solar System and The Sun
Oral, Thursday, January 8, 2004, 2:00-3:30pm, Regency VI

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[134.03] Magnetic Effects at the Edge of the Solar System: MHD Instabilities, the de Laval nozzle effect and an Extended Jet

M. Opher (JPL/Caltech), P.C. Liewer (JPL), M. Velli (Departament of Astronomy and Space Science, Univ. of Firenzi), T. Gombosi, W. Manchester, D. DeZeeuw (Univ. of Michigan)

To model the interaction between the solar system and the interstellar wind magnetic fields, ionized and neutral components besides cosmic rays must be included. Recently (Opher et al. ApJL 2003) found, that by including the solar magnetic field in an high resolution run with the University of Michigan BATS-R-US code, a jet-sheet structure forms beyond the Termination Shock. Here we discuss the formation of the jet and its subsequent large period oscillation due to magnetohydrodynamic instabilities. We perform in a simplified two dimensional geometry resistive magnetohydrodynamic calculation of a plane fluid jet embedded in a neutral sheet with the profiles taken from our simulation. We find remarkable agreement with the full three dimensional evolution. We present an even higher resolution three dimensional case where the jet extends for 150AU beyond the Termination Shock. We compare the temporal evolution of the jet showing that the sinuous mode is the dominant mode that develops into a velocity-shear-instability with a growth rate of 5 \times 10-9 sec-1=0.027 years-1. As a result the outer edge of the heliosphere presents remarkable dynamics, such as turbulence and flows caused by the motion of the jet. Further study, e.g., including neutrals and the tilt of the solar rotation from the magnetic axis, is required before we can definitively address how this outer boundary behaves. Already, however, we can say that the magnetic field effects are a major player in this region changing our previous notion of how the solar system ends.

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© 2003. The American Astronomical Soceity.