Work

Collisionless Electron Heat Flux for the Nonequilibrium Solar Wind Plasma: Revisiting Hollweg’s Parameter

Year: 2026

Type: article

Abstract: Here, we discuss an extension of the modelling of the collisionless heat flux and the related parameter α , derived by Hollweg for a truncated Maxwellian to distributions with suprathermal tails. In the collisionless solar wind plasma, electrons and ions are described by a multitude of non-Maxwellian (nonequilibrium) velocity distributions, such as the standard, regularized κ , and Druyvesteyn distributions. We show that for these nonidealized distributions, the heat flux and the related parameter α can deviate significantly from the Maxwellian values derived by Hollweg. It is also shown that the heat flux is best described using a form that does not directly involve the truncation speed. Furthermore, we discuss the applicability of these distribution models for the nonrelativistic case, which constrains the κ values for the standard κ distribution to values above 4. In addition, we provide the possibility to easily obtain the heat flux parameter for a given solar wind environment.

Source: The Astrophysical Journal

DOI: 10.3847/1538-4357/ae993f

Authors: Klaus Scherer, Lukas Westrich, Marian Lazar, Horst Fichtner, Stefaan Poedts

Institutions: Ruhr University Bochum, Ilia State University, KU Leuven, Maria Curie-Skłodowska University

Language: English

Topic: Solar and Space Plasma Dynamics

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $4,499

Funders: Deutsche Forschungsgemeinschaft, KU Leuven, Stiftung Begabtenförderung Cusanuswerk