Flow downstream of the heliospheric terminal shock - Magnetic field kinematics

A kinematic model of the interplanetary magnetic field in the heliosheath beyond the solar wind terminal shock is presented in order to evaluate the possible importance of MHD effects in that region of space. The need for this evaluation arises because the interplanetary magnetic field is compressed across the terminal shock and further amplified by the decreasing flow speed beyond the shock. Streamlines which approach the stagnation point before turning in the downstream direction lead to the strongest effects due to the extreme slowing of the solar wind and consequent compression of the embedded magnetic field. The magnetic volume force therefore cannot be neglected on streamlines that approach the heliopause in the upstream direction, where the volume containing them is a large fraction of the overall of the heliosheath in the upstream direction. The increase in the magnetic pressure may act to bring the upstream terminal shock significantly closer to the sun, potentially reconciling a conflict between models and observations.