Non-Equilibrium Processes in the Solar Corona, Transition Region, Flares, and Solar Wind \textit{(Invited Review)}

We review the presence and signatures of the non-equilibrium processes, both non-Maxwellian distributions and non-equilibrium ionization, in the solar transition region, corona, solar wind, and flares. Basic properties of the non-Maxwellian distributions are described together with their influence on the heat flux as well as on the rates of individual collisional processes and the resulting optically thin synthetic spectra. Constraints on the presence of high-energy electrons from observations are reviewed, including positive detection of non-Maxwellian distributions in the solar corona, transition region, flares, and wind. Occurrence of non-equilibrium ionization is reviewed as well, especially in connection to hydrodynamic and generalized collisional-radiative modelling. Predicted spectroscopic signatures of non-equilibrium ionization depending on the assumed plasma conditions are summarized. Finally, we discuss the future remote-sensing instrumentation that can be used for detection of these non-equilibrium phenomena in various spectral ranges.Comment: Solar Physics, accepte

Plasma Diagnostics From Active Region and Quiet Sun Spectra Observed by Hinode/EIS: Quantifying the Departures from a Maxwellian Distribution

We perform plasma diagnostics, including that of the non-Maxwellian $\kappa$-distributions, in several structures observed in the solar corona by the Extreme-Ultraviolet Imaging Spectrometer (EIS) onboard the Hinode spacecraft. To prevent uncertainties due to the in-flight calibration of EIS, we selected spectral atlases observed shortly after the launch of the mission. One spectral atlas contains an observation of an active region, while the other is an off-limb quiet Sun region. To minimize the uncertainties of the diagnostics, we rely only on strong lines and we average the signal over a spatial area within selected structures. Multiple plasma parameters are diagnosed, such as the electron density, differential emission measure, and the non-Maxwellian parameter $\kappa$. To do that, we use a simple, well-converging iterative scheme based on refining the initial density estimates via the DEM and $\kappa$. We find that while the quiet Sun spectra are consistent with a Maxwellian distribution, the coronal loops and moss observed within active region are strongly non-Maxwellian with $\kappa$ $\lessapprox$ 3. These results were checked by calculating synthetic ratios using DEMs obtained as a function of $\kappa$. Ratios predicted using the DEMs assuming $\kappa$-distributions converged to the ratios observed in the quiet Sun and coronal loops. To our knowledge, this work presents a strong evidence of a presence of different electron distributions between two physically distinct parts of the solar corona.Comment: 23 pages, 8 figures, 4 table

Velocities of Flare Kernels and the Mapping Norm of Field Line Connectivity

International audienc

KAPPA: A Package for the Synthesis of Optically Thin Spectra for the Non-Maxwellian κ-Distributions. III. Improvements to Ionization Equilibrium and Extension to κ < 2

The KAPPA package is designed for calculations of optically thin spectra for the non-Maxwellian κ -distributions. This paper presents an extension of the database to allow calculations of the spectra for extreme values of κ < 2, which are important for accurate diagnostics of the κ -distributions in the outer solar atmosphere. In addition, two improvements were made to the ionization equilibrium calculations within the database. First, the ionization equilibrium calculations now include the effects of electron impact multi-ionization (EIMI). Although relatively unimportant for Maxwellian distribution, EIMI becomes important for some elements, such as Fe and low values of κ , where it modifies the ionization equilibrium significantly. Second, the KAPPA database now includes the suppression of dielectronic recombination at high electron densities, evaluated via the suppression factors. We find that at the same temperature, the suppression of dielectronic recombination is almost independent of κ . The ionization equilibrium calculations for the κ -distributions are now provided for a range of electron densities