Erlangen 2026 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 6: Sun and Heliosphere I
EP 6.5: Vortrag
Mittwoch, 18. März 2026, 15:15–15:30, KH 01.019
Solar wind heat flux with kappa distributions — •Klaus Scherer1, Marian Lazar2, Horst Fichtner1, and Lukas Westrich1 — 1Institut für Theoretische Physik, Lehrstuhl IV: Plasma-Astroteilchenphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany — 2Centre for mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, 3001 Leuven, Belgium
In the collisionless solar wind between 0.3 and 5 au, the proton usually have Maxwellian velocity distributions, while the electron distributions exhibit extended tails in the anti-sunward direction and a (spherical) cut-off towards the Sun. In case such electron distributions are assumed to be Maxwellians the resulting heat flux was modelled and discussed in Hollweg (1974). We apply this approach replacing the Maxwellian by a Kappa distribution, using both the classical standard Kappa distribution (SKD) and the newer regularized Kappa distribution (RKD). In contrast to SKDs, RKDs allow the calculation of the heat flux for any positive value of the kappa parameter. We present (semi-)analytical results and employ them in a one-dimensional hydrodynamic model of the solar wind expansion to show the impact of the distribution function on the magnitude of the heat flux.
Keywords: Solar wind; collisonless heat flux; kappa distribution