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P. C. Liewer, M. Opher (Jet Propulsion Laboratory, California Institute of Technology), M. Velli (University of Florence, Italy), T. I. Gombosi, W. Manchester, D. L. DeZeeuw, G. Toth, I. Sokolov (Universtiy of Michigan)
The Sun traveling through the interstellar medium carves out a bubble of solar wind called the Heliosphere. Recent observations indicate that Voyager 1, now beyond 90 AU, is in a region unlike any encountered in it's 26 years of exploration. There is currently a controversy as to whether or not Voyager 1 has already crossed the Termination Shock, the first boundary of the Heliosphere (Krimigis et al. 2003; McDonald et al. 2003, Burlaga et al. 2003). The controversy stems from different interpretations of observations from several instruments. Contributing to this controversy is our poor understanding of the outer heliosphere. The region between the Termination Shock and the Heliopause, the Heliosheath, is one of the most unknown regions theoretically. In the Heliosheath magnetic effects are crucial, as the solar magnetic field is compressed at the Termination Shock by the slowing flow. Recently, our simulations showed that the Heliosheath is remarkably dynamic, with turbulent flows resulting from an unstable jet flow at the current sheet (Opher et al. 2003; 2004). In this talk we review these recent results, and present additional results from simulations of the unstable jet with a constant neutral atom background. Further studies which include additional effects such as the tilt between the solar rotation axis and the magnetic axis, are required before we can definitively address the structure and dynamics of the outer heliosphere. Already we can say that this region presents remarkable dynamics, with turbulent flows, indicating that the Heliosheath might be very different from what we previously thought.
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Bulletin of the American Astronomical Society, 36 #2
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