Probing Heliospheric Asymmetries with an MHD-kinetic Model

摘要

New solar wind data from the Voyager 1 and Voyager 2 spacecraft, togetherwith the SOHO SWAN measurements of the direction that neutral hydrogen entersinto the inner heliosheath and neutral helium measurements provided by multipleobservations are expected to provide more reliable constraints on theionization ratio of the local interstellar medium (LISM) and the direction andmagnitude of the interstellar magnetic field (ISMF). In this paper we usecurrently the most sophisticated numerical model of the heliospheric interface,which is based on an MHD treatment of the ion flow and kinetic modeling ofneutral particles, to analyze an ISMF-induced asymmetry of the heliosphere inthe presence of the interplanetary magnetic field and neutral particles. It isshown that secondary hydrogen atoms modify the LISM properties leading to itsshock-free deceleration at the heliopause. We determine the deflection ofhydrogen atoms from their original trajectory in the unperturbed LISM and showthat it occurs not only in the plane defined by the ISMF and LISM velocityvectors, but also, to a lesser extent, perpendicular to this plane. We alsoconsider the possibility of using 2-3 kHz radio emission data to furtherconstrain the ISMF direction.