[P-EM18] Heliosphere and Interplanetary Space

[PEM18-06] Radial structure of heliospheric boundary region

*Shuichi Matsukiyo¹, Gary P. Zank², Haruichi Washimi³, Tohru Hada¹ (1.Faculty of Engineering Sciences, Kyushu University, 2.The Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 3.International Center for Space Weather Science and Education, Kyushu University)

Keywords:heliospheric boundaries, full particle-in-cell simulation

The kinetic structure of the heliospheric boundaries is investigated using one-dimensional full PIC (Particle-In-Cell) simulations. Both the termination shock and the heliopause are simultaneously reproduced in the simulation. The spatial scale of the heliopause increases as the angle between the heliopause normal and local magnetic field (referred to as the normal angle, hereafter) becomes increasingly oblique. The VLISM region, out side the heliopause, contains compressible flucturations in both magnetic field and plasma density. The fluctuations are originated from the inner heliosheath, the region between the termination shock and the heliopause, pass the heliopause, and propagate away from it. The total pressure, including the plasma pressure and magnetic pressure, at the heliopause is not constant when the normal angle is oblique in contrast to predictions based on MHD theory. In the oblique case, the solar wind plasma and interstellar plasma are able to inter-penetrate by moving along the local magnetic field. Since their bulk velocities along the magnetic field differ from each other, the distributions overlap in phase space so that the effective local plasma pressure parallel to the magnetic field is enhanced. This results in an increase that resembles a hump in the density and parallel pressure of the local plasma, which is not seen in magnetic field.