Influence of the interstellar magnetic field and 11-year cycle of solar activity on the heliopause nose location

Abstract

Context. The heliosphere is formed by the interaction between the solar wind (SW) plasma emanating from the Sun and a magnetised component of local interstellar medium (LISM) inflowing on the Sun. A separation surface called the heliopause (HP) forms between the SW and the LISM. Aims. In this article, we define the nose of the HP and investigate the variations in its location. These result from a dependence on the intensity and direction of the interstellar magnetic field (ISMF), which is still not well known but has a significant impact on the movement of the HP nose, as we try to demonstrate in this paper. Methods. We used a parametric study method based on numerical simulations of various forms of the heliosphere using a time-dependent three-dimensional magnetohydrodynamic (3D MHD) model of the heliosphere. Results. The results confirm that the nose of the HP is always in a direction that is perpendicular to the maximum ISMF intensity directly behind the HP. The displacement of the HP nose depends on the direction and intensity of the ISMF, with the structure of the heliosphere and the shape of the HP depending on the 11-year cycle of solar activity. Conclusions. In the context of the planned space mission to send the Interstellar Probe (IP) to a distance of 1000 AU from the Sun, our study may shed light on the question as to which direction the IP should be sent. Further research is needed that introduces elements such as current sheet, reconnection, cosmic rays, instability, or turbulence into the models.