Three‐dimensional Features of the Outer Heliosphere due to Coupling between the Interstellar and Interplanetary Magnetic Fields. II. The Presence of Neutral Hydrogen Atoms

Abstract

We investigate the effects of coupling the interstellar and interplanetary magnetic fields (ISMF and IMF) at the heliospheric interface while taking into account the momentum and energy transfer between the plasma and neutral components of the interacting solar wind (SW) and local interstellar medium (LISM). Investigation is performed on the basis of the multifluid model that treats different populations of neutral particles as fluids governed by separate sets of the Euler equations. As the properties of the local interstellar cloud (LIC) are rather poorly examined, with the exception of the interstellar plasma velocity and temperature, we assume several possible orientations of the ISMF. In particular, the case is considered where an ISMF vector is perpendicular to the LISM velocity vector and inclined at an angle of 60° toward the ecliptic plane of the Sun, as suggested in recent publications relating LIC properties to the radio emission observed by Voyager 1. Special attention is paid to the distribution of magnetic fields that can affect the cosmic-ray modulation throughout the heliosphere and the possibility of the heliospheric current sheet bending into one of the hemispheres. Differences are discussed between ideal MHD and multifluid calculations. Possibilities are analyzed for the IMF lines to cross the termination shock multiple times. Parameters are determined that affect the divergence between the neutral hydrogen and helium streamlines in the inner heliosphere.