Neutral component of the local interstellar medium

Abstract

Purpose This paper aims to review the current knowledge about the neutral component of the local interstellar medium (LISM), which due to the resonant charge exchange, photoionization and electron impact ionization processes has a profound impact on the heliosphere structure. Design/methodology/approach This work is based on the heliospheric literature review. Findings The summary of four major effects of neutral hydrogen atoms penetrating solar wind (SW), i.e. the disappearance of the complicated flow structure; the emergence of “hydrogen wall” in front of the heliopause (HP); decreasing distance of termination shock (TS), HP and bow shock (BS) layer from the Sun; and recently discovered by the Interstellar Boundary Explorer mission, a region of enhanced energetic neutral atom (ENA) emission seen in all sky maps as a ribbon. Practical implications In the context of constantly developing space technologies in aerospace engineering and prospective deep space missions, there is a need of general reviews about the interstellar space surroundings of the Sun and gathering the knowledge to help in theoretical, numerical and experimental investigations such as the optimization of the scientific equipment and spacecraft structure to work in specific conditions. Originality/value The survey encapsulate basic and relevant processes playing an important role in the physics of the nearest surroundings of the Sun and the latest results of numerical and experimental investigations focused on the neutral LISM component and its influence on the heliosphere, which is strongly desired in future works. Until now, not many of such reviews have been done.

Interstellar medium magnetic field in bow shock modelling

“…The impact of the interstellar (IS) magnetic field on bow shock shape, intensity and radiation properties has been a subject of research for almost 30 years, mainly using magnetohydrodynamic (MHD) models (Pogorelov and Semenov, 1997; Ratkiewicz et al , 1998), because the base theory of shock waves can be considered a part of fluid mechanics modelling. During the past few years, IS magnetic field has been implemented into kinetic particle-in-cell (PIC) models (Yang et al , 2016; Konior, 2017), but although particle interactions at the scale of the astrospheres or heliosphere may be properly described using the family of hybrid-kinetic PIC codes, this type of modelling is still under development (Ratkiewicz and Kotlarz, 2016; Konior et al , 2018).…”

Remarks about factors shaping the heliosphere

“…The two-dimensional (2D) model includes the interaction between the SW and LISM plasmas and the interaction of both plasmas with neutral hydrogen atoms via charge exchange and two kinds of cosmic rays, anomalous cosmic rays (ACR) and galactic cosmic rays (GCR), within a self-consistent approach. More about self-consistent models of the interaction between plasma and the LISM neutral component using the Monte Carlo method for description of the H-atom distribution function can be found in a review by Konior et al (2018).…”