Modeling the astrosphere of LHS 1140 - On the differences of 3D (M)HD single- and multifluid simulations and the consequences for exoplanetary habitability

Kurzfassung

In this paper, the shock structure of the stellar wind and the corresponding astrosphere of LHS 1140 is investigated. Thereby, the results of four different model setups (i.e., hydrodynamic and ideal magnetohydrodynamic single- and multifluid models) are compared. It is shown that the multifluid MHD termination shock distances differ remarkably from those of other models. Based on the 3D multifluid MHD output the cosmic ray (CR) fluxes are deteremined and their influence on the exoplanetary atmosphere of LHS 1140 b is investigated. Since atmospheric chemistry processes, and with those, the derivation of transmission spectra features and information on biosignatures strongly depend on atmospheric exoplanetary ionization, our results show that for inactive cool stars such as LHS 1140 reliable GCR-induced background radiation information is mandatory to interpret, e.g., upcoming JWST data.