Abstract The global structure of the outer heliosphere under the interaction of the solar wind plasma with the interstellar medium is studied by means of MHD computer simulation in the axisymmetric system. The effect of the interplanetary magnetic field is taken into account in our simulation. The interplanetary helical (toroidal) magnetic field is found to play an important role in the outer heliosphere. Because the intensity of the helical magnetic field is maximum near the equator, and because the magnetic energy becomes of comparable order of magnitude to the flow energy just beyond the terminal shock, the direction of the subsonic solar wind flow in this region is distorted poleward by the magnetic pressure. Thus a collimated plasma flow channel is formed in the heliosheath along the solar rotation axis. This plasma flow is confirmed to be trapped and pinched by the surrounding helical magnetic field. The plasma flows outward along the axis and thus the domain of the heliosheath is found to be elongated along the axis. We have also examined the effect of the 11-year solar cycle variation on the heliospheric structure. The polarity of the helical magnetic field in the heliosheath changes with this variation. It is also found that the terminal shock is contracted by some 30 percent by the effect of the helical magnetic field. This result may make an encounter of the terminal shock by one of the deep space missions possible in the near future. This MHD analysis of the axisymmetric system also suggests what happens when the interstellar medium flow is oblique to the solar rotation axis. Both the northern and southern collimated flows along the axis will be also formed near the terminal shock in the heliosheath even for this case. But the orientation of these two flows will not stay parallel to the axis for long distance but will be bent toward the down-stream of the interstellar medium flow. Accordingly, a binary parallel flow structure will be formed in the tail of the outer heliosphere or even the tail itself will be split into the two parts.
MHD modeling of the outer heliosphere
Advances in Space Research ; 13 , 6 ; 227-236
1993-01-01
10 pages
Article (Journal)
Electronic Resource
English
MHD Modeling of the Outer Heliosphere
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