EFFECT OF VARYING STRENGTH AND ORIENTATION OF LOCAL INTERSTELLAR MAGNETIC FIELD ON CONFIGURATION OF EXTERIOR HELIOSPHERE : 3D MHD SIMULATIONS

Abstract

The aim of this paper is to present the effects of varying magnitude and orientation of the local interstellar mag- netic field on the heliospheric boundary region (the region be- tween the termination shock and the bow shock containing the heliopause). Other effects such as interstellar neutrals, cosmic rays and the asymmetry of the solar wind caused by its heli- olatitude dependence are disregarded. We calculate the shape and structure of the heliospheric boundary region for different interstellar Alfv ´ enic Mach numbers and various inclination an- gles between Very Local InterStellar Medium (VLISM) velocity and magnetic field vectors using a fully three-dimensional MHD computational analysis. The new results show the asymmetry of this region for inclination angles 0 << 90 and are in agreement with the Newtonian approximation theory (Fahr et al. 1986, 1988) concerning trends in the heliopause orientation and location. Unlike the NA model which only qualitatively indicates the effects of the VLISM magnetic field on the he- liospheric boundary region the present 3D MHD calculations reveal fully the nature of these effects by capturing all discon- tinuities including the termination shock, heliopause and bow shock. The numerical scheme employed in this study is fully im- plicit and conservative, using a Roe-type Riemann solver in a generalized coordinate system.