Ion-neutral interactions and non-equilibrium ionization in the solar chromosphere

Abstract

The thermal structure of the chromosphere is regulated through a complex interaction of various heating processes, radiative cooling, and the ionization degree of the plasma. Here we study the impact on the thermal properties of the chromosphere when including the combined action of non-equilibrium ionization (NEI) of hydrogen and helium and ion-neutral interaction effects. We have performed a 2.5D radiative magnetohydrodynamic simulation including ion-neutral interaction effects by solving the generalized Ohm's law (GOL) as well as NEI for hydrogen and helium using the Bifrost code. The GOL equation includes ambipolar diffusion and the Hall term. We compare this simulation with another simulation that computes the ionization in local thermodynamic equilibrium (LTE) including ion-neutral interaction effects. Our numerical models reveal substantial thermal differences in magneto-acoustic shocks, the wake behind the shocks, spicules, low-lying magnetic loops, and the transition region. In particular, we find that heating through ambipolar diffusion in shock wakes is substantially less efficient, while in the shock fronts themselves it is more efficient, under NEI conditions than when assuming LTE.

14 pages, 8 Figures, Accepted to be published in ApJ

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Cited by in corpus (10)

• The European Solar Telescope
• Spicules and downflows in the solar chromosphere
• Ambipolar diffusion in the Bifrost code
• Two-fluid Modeling of Acoustic Wave Propagation in Gravitationally Stratified Isothermal Media
• ALMA and IRIS Observations of the Solar Chromosphere II: Structure and Dynamics of Chromospheric Plage
• Evidence of multithermal nature of spicular downflows. Impact on solar atmospheric heating
• Effects of Cowling Resistivity in the Weakly-Ionized Chromosphere
• Two-fluid numerical model of chromospheric heating and plasma outflows in a quiet-Sun
• Fast magnetic wave could heat the solar low-beta chromosphere
• Doppler shifts of spectral lines formed in the solar transition region and corona