Influence of electrons on granulation-generated solar chromosphere heating and plasma outflows

¹ Institute of Physics, University of M. Curie-Skłodowska, Pl. M. Curie-Skłodowskiej 1, 20-031 Lublin, Poland
² Centre for mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium

Received: 12 March 2024
Accepted: 10 June 2024

Abstract

Context. It is known that the solar atmosphere exhibits a varying degree of ionization through its different layers. The ionization degree directly depends on plasma temperature, that is, the lower the temperature, the lower the ionization degree. As a result, the plasma in the lower atmospheric layers (the photosphere and the chromosphere) is only partially ionized, which motivates the use of a three-fluid model.

Aims. We consider, for the first time, the influence of electrons on granulation-generated solar chromosphere heating and plasma outflows. We attempt to detect variations in the ion temperature and plasma up- and downflows.

Methods. We performed 2.5D numerical simulations of the generation and evolution of granulation-generated waves, flows, and other granulation-associated phenomena with an adapted JOANNA code. This code solves the simplified three-fluid equations for ions (protons) and electrons and neutrals (hydrogen atoms) that are coupled by collision forces.

Results. Electron-neutral and electron–ion collisions provide extra heat in the low chromosphere and enhance plasma outflows in this region. The effect of electrons is small compared to ion–neutral collisions, which have a significantly greater effect on the heating process and the production of outflows. Ion–neutral collisions involve higher energy exchanges, making them the dominant mechanism over collisions with electrons.

Conclusions. Electrons do not play a major role in heating and producing outflows, primarily because their mass is much lower compared to that of neutrals and ions, resulting in lower energy transfer during collisions.