Model of the solar wind interaction with the local interstellar medium: Numerical solution of self‐consistent problem

Abstract

A self‐consistent gasdynamic model of the solar wind interaction with the local interstellar medium (LISM), which took into account the mutual influence of the plasma component (electrons and protons) of the LISM and the LISM H atoms that penetrate into the heliosphere was constructed by Baranov et al. (1981) in the approximation of axial symmetry. This model, however, had a number of defects. In particular, the motion of the H atoms was described by hydrodynamical equations, although the mean free path of the H atoms and the characteristic length of the problem were comparable. An iterative method, that used a Monte Carlo simulation of H atom motion in the field of the plasma component hydrodynamic parameters, was suggested by Baranov et al. (1991) and only the first step of the iteration was realized (non‐self‐consistent problem solution). In this paper the results of the self‐consistent problem solution for a single set of the undisturbed solar wind and LISM parameters are presented. The structure of the upwind as well as wake regions of the flow is calculated. The geometrical pattern of the flow (bow shock, heliopause, termination shock, Mach disc, etc), the bulk velocity and the number densities of H atoms and plasma component are obtained and analyzed as a function of the distance from the Sun for different values of the polar angle. The effects of resonance charge exchange of the LISM H atoms as well as energetic H atoms “born” in the solar wind are taken into account. It is interesting to note that the effect of H atoms penetrating the solar wind results in the disappearance of the complicated flow structure as well as the supersonic regions between the heliopause and termination shock in the downwind region. In future we are going to compare our theoretical results with the results of Voyager 1/2, Pioneer 10/11, Ulysses spacecraft, and other experiments.

Termination shock response to large‐scale solar wind fluctuations

“…There is a density jump by about a factor of 4, however, since the termination shock is a strong shock. For this example with subsonic interstellar flow, the termination shock is nearly spherical and does not have the characteristic bullet shape typical of solutions for a supersonic interstellar flow [e.g., Baranov and Malama, 1993;Steinolfson et al, 1994]. The formation of a more spherical termination shock is one reason a subsonic interstellar flow solution is used for the initial state.…”

“…The thermodynamic conditions of the interstellar !/5 •* u medium are not well known, but if the speed of the solar ro system through this medium is supersonic, a bow shock o «r w forms beyond the heliopause to slow and deflect the interstel-»H j <u lar plasma. Baranov [1990] has reviewed this two-shock < S m odel of the solar wind/interstellar medium interaction. A "Z +> bow shock would not be expected to form when the speed of z j o> the solar system relative to that of the surrounding medium , at < 3…”

Bow shock nebulae of hot massive stars in a magnetized medium

“…The study of the interaction between our Sun and the LISM led to a large literature, including, amongst other, numerical investigations of the bow shock formed by the solar wind (see, e.g. Pogorelov & Matsuda 1998;Baranov & Malama 1993;Zank 2015, and references therein). If obvious similitudes between the bow shock of the Sun and those of our massive stars indicate that the physical processes governing the formation of circumstellar nebulae around OB stars such as electronic thermal conduction or the influence of the background local magnetic field have to be included in the modelling of those structures (Zank et al 2009), nevertheless, the bow shock of the Sun is, partly due to the differences in terms of effective temperature and wind velocity, on a totally different scale.…”

The Galactic Environment of the Sun: Interstellar Material Inside and Outside of the Heliosphere

“…The basic understanding of the related heliosphere-LIC interaction has been summarized in early reviews (Axford 1972;Fahr 1974;Holzer 1989;Thomas 1978), as well as con-temporary discussions (Fahr 1991;Baranov and Malama 1993;Ruciński et al 1993;Zank et al 1996;Izmodenov et al 1999aFahr et al 2000;Müller et al 2000;Heerikhuisen et al 2006).…”