The strong effect of electron thermal conduction on the global structure of the heliosphere

Abstract

ABSTRACTVoyager 1 and 2 crossed the heliopause at ∼122 au in 2012 and ∼119 au in 2018, respectively. It was quite a surprise because the thickness of the inner heliosheath obtained at that time by the existing time models of the global heliosphere was significantly larger (by 20–40 au). Until now, the problem of the heliosheath thickness has not been fully resolved. Earlier, in the frame of an oversimplified toy model of nearly isothermal solar wind plasma, it has been shown that the effect of electron thermal conduction may significantly reduce the thickness of the inner heliosheath. In this paper, we present the first results of our 3D kinetic-magnetohydrodynamic (MHD) model of the global heliosphere, where the effect of thermal electron conduction has been considered rigorously. The thermal conduction acts mainly along the magnetic field lines. Classical and saturated thermal fluxes are employed when appropriate. It is shown that the effects of thermal conduction are significant. The thickness of the inner heliospheric is reduced. It is a desired effect since it helps to reconcile the thickness obtained in the model with Voyager data. The other effects are the strong depletion of the heliosheath plasma temperature towards the heliopause and the increase of the plasma temperature in the supersonic solar wind upstream of the termination shock.