Electron thermal conduction as a possible mechanism to make the inner heliosheath thnner

TL;DR

This paper investigates how electron thermal conductivity can significantly reduce the inner heliosheath's thickness, potentially explaining Voyager 1's early crossing of the heliopause by altering the plasma flow and boundary positions.

Contribution

It introduces a model considering highly effective electron thermal conduction, showing its impact on heliosheath thickness and boundary locations, a novel approach in heliospheric studies.

Findings

Inner heliosheath thickness reduced by 42 AU in the model

Heliospheric distance of the termination shock increased by 15 AU

Heliospheric distance of the heliopause decreased by 27 AU

Abstract

We show that the electron thermal conductivity may strongly affect the heliosheath plasma flow and the global pattern of the solar wind (SW) interaction with the local interstellar medium (LISM). In particular, it leads to strong reduction of the inner heliosheath thickness that makes possible to explain (qualitatively) why Voyager 1 (V1) has crossed the heliopause at unexpectedly small heliocentric distance of 122 AU. To estimate the effect of thermal conductivity we consider a limiting case when thermal conduction is very effective. To do that we assume the plasma flow in the entire heliosphere is nearly isothermal. Due to this effect, the heliospheric distance of the termination shock has increased by about 15 AU in V1 direction compared to the adiabatic case with gamma = 5/3. The heliospheric distance of the heliopause has decreased by about 27 AU. As a result, the thickness of the inner heliosheath in the model has decreased by about 42 AU and become equal to 32 AU.