3-D magnetic field and current system in the heliosphere

Abstract

In this paper a global system of the magnetic field and current from the interaction of the solar wind plasma and the interstellar medium is modeled using a 3-D MHD simulation. The terminal shock, the heliopause and the outer shock are clearly determined in our simulation. In the heliosheath the toroidal magnetic field is found to increase with the distance from the sun. The magnetic field increases rapidly in the upstream region of the heliosheath and becomes maximum between the terminal shock and the heliopause. Hence a shell-type magnetic wall is found to be formed in the heliosheath. Because of this magnetic wall the radially expanding solar wind plasma changes its direction tailward in all latitudes except the equatorial region. Only the equatorial disk-like plasma flow is found to extend to the heliopause through the weak magnetic-field region around the equator. Two kinds of global current loops which sustain the toroidal magnetic field in the heliosphere are found in our simulation.

The influence of the 11-year solar cycle variation of the magnetic polarity is also examined. It is found that the polarity of the toroidal magnetic field in the heliosheath switches at every solar cycle change. Hence the heliosheath is found to consist of such magnetized plasma bubbles. The neutral sheets are found to extend between such magnetized plasma bubbles in the 3-D heliosheath in a complicated form. The magnetic-pressure effect on the heliosheath plasma structure is also examined.