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

Abstract

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.

arXiv commentSolar Physics, accepted

References in corpus (132)

• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• The Interface Region Imaging Spectrograph (IRIS)
• Ionization balance for optically thin plasmas: rate coefficients for all atoms and ions of the elements H to Ni
• An Observational Overview of Solar Flares
• On Solving the Coronal Heating Problem
• Kappa distributions: theory and applications in space plasmas
• Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence
• The stellar atmosphere simulation code Bifrost
• CHIANTI - An atomic database for Emission Lines. Version 8
• Differential Emission Measures from the Regularized Inversion of Hinode and SDO data
• Hot Explosions in the Cool Atmosphere of the Sun
• Implications of X-ray Observations for Electron Acceleration and Propagation in Solar Flares
• Electron Acceleration by Multi-Island Coalescence
• Dynamic Hydrogen Ionization
• Ionisation state, excited populations and emission of impurities in dynamic finite density plasmas. I: The generalised collisional-radiative model for light elements
• A new approach to analyzing solar coronal spectra and updated collisional ionization equilibrium calculations. II. Additional ionization rate coefficients
• A Unified Computational Model for Solar and Stellar Flares
• The Dynamic Formation of Prominence Condensations
• Dielectronic recombination data for dynamic finite-density plasmas I. Goals and methodology
• Radiative recombination data for modelling dynamic finite-density plasmas
• Resolving the electron temperature discrepancies in HII Regions and Planetary Nebulae: kappa-distributed electrons
• A publicly available simulation of an enhanced network region of the Sun
• Empirical Constraints on Proton and Electron Heating in the Fast Solar Wind
• Recent Advances in Understanding Particle Acceleration Processes in Solar Flares
• Evidence of Non-Thermal Particles in Coronal Loops Heated Impulsively by Nanoflares
• Fermi acceleration at fast shock in a solar flare and impulsive loop-top hard X-ray source
• High precision density measurements in the solar corona: I. Analysis methods and results for Fe XII and Fe XIII
• A Systematic Survey of High Temperature Emission in Solar Active Regions
• Deducing Electron Properties From Hard X-Ray Observations
• Non-equilibrium hydrogen ionization in 2D simulations of the solar atmosphere
• Microflares and the Statistics of X-ray Flares
• Ionization Equilibrium Timescales in Collisional Plasmas
• The Relationship Between Solar Radio and Hard X-ray Emission
• Observing coronal nanoflares in active region moss
• Relations between concurrent hard X-ray sources in solar flares
• Ellerman bombs at high resolution III. Simultaneous observations with IRIS and SST
• Properties of Energetic Ions in the Solar Atmosphere from γ -Ray and Neutron Observations
• RHESSI Line and Continuum Observations of Super-hot Flare Plasma
• The Formation of Kappa-Distribution Accelerated Electron Populations in Solar Flares
• Kappa Distribution Model for Hard X-Ray Coronal Sources of Solar Flares
• The Unresolved Fine Structure Resolved - IRIS observations of the Solar Transition Region
• A transonic collisionless model of the solar wind
• Multi-thermal dynamics and energetics of a coronal mass ejection in the low solar atmosphere
• A revised radiometric calibration for the Hinode/EIS instrument
• Patterns of Nanoflare Storm Heating Exhibited by an Active Region Observed with SDO/AIA
• A Global Wave-Driven MHD Solar Model with a Unified Treatment of Open and Closed Magnetic Field Topologies
• Properties of a solar flare kernel observed by Hinode and SDO
• The Electron Temperature and Anisotropy in the Solar Wind. I. Comparison of the Core and Halo Populations
• On-Orbit Degradation of Solar Instruments
• Energy Release and Particle Acceleration in Flares: Summary and Future Prospects
• Observations of Subarcsecond Bright Dots in the Transition Region above Sunspots with the Interface Region Imaging Spectrograph
• Why Is Non-thermal Line Broadening of Spectral Lines in The Lower Transition Region of the Sun Independent of Spatial Resolution?
• Numerical Simulations of Coronal Heating through Footpoint Braiding
• Particle acceleration and transport in reconnecting twisted loops in a stratified atmosphere
• Simultaneous IRIS and Hinode/EIS observations and modelling of the 27 October 2014 X 2.0 class flare
• The Absolute Calibration of the EUV Imaging Spectrometer on Hinode
• Non-equilibrium of Ionization and the Detection of Hot Plasma in Nanoflare-heated Coronal Loops
• Diagnosing the time-dependence of active region core heating from the emission measure: I. Low-frequency nanoflares
• Statistical Properties of Super-hot Solar Flares
• Alfvénic Wave Heating of the Upper Chromosphere in Flares
• Implications for electron acceleration and transport from non-thermal electron rates at looptop and footpoint sources in solar flares
• Detailed and simplified non-equilibrium helium ionization in the solar atmosphere
• Turbulent pitch-angle scattering and diffusive transport of hard-X-ray producing electrons in flaring coronal loops
• Solar Transition-Region Lines Observed by the Interface Region Imaging Spectrograph: Diagnostics for the O IV and Si IV Lines
• Kappa distribution and hard X-ray emission of solar flares
• A Statistical Survey of Hard X-ray Spectral Characteristics of Solar Flares with Two Footpoints
• KAPPA: A Package for Synthesis of optically thin spectra for the non-Maxwellian kappa-distributions based on the CHIANTI database
• Particle Acceleration at a Flare Termination Shock: Effect of Large-scale Magnetic Turbulence
• Suprathermal Electrons in the Solar Corona: Can Nonlocal Transport Explain Heliospheric Charge States?
• Density diagnostics derived from the OIV and SIV intercombination lines observed by IRIS
• Non-equilibrium helium ionization in an MHD simulation of the solar atmosphere
• Fermi Acceleration in Plasmoids interacting with Fast Shocks of Reconnection via Fractal Reconnection
• Acceleration of weakly collisional solar-type winds
• Misestimation of temperature when applying Maxwellian distributions to space plasmas described by kappa distributions
• H to Zn Ionization Equilibrium for the Non-Maxwellian Electron kappa-distributions: Updated Calculations
• EBIT Charge-Exchange Measurements and Astrophysical Applications
• Constraining the hard X-ray properties of the quiet Sun with new RHESSI observations
• Response of optical hydrogen lines to beam heating: I. Electron beams
• The first X-ray imaging spectroscopy of quiescent solar active regions with NuSTAR
• Ion Charge States in the Fast Solar Wind: New Data Analysis and Theoretical Refinements
• Non-equilibrium calcium ionisation in the solar atmosphere
• The Origin of Non-Maxwellian Solar Wind Electron Velocity Distribution Function: Connection to Nanoflares in the Solar Corona
• A Quantitative Model of Energy Release and Heating by Time-dependent, Localized Reconnection in a Flare with a Thermal Loop-top X-ray Source
• Suppression of Dielectronic Recombination Due to Finite Density Effects
• A Steady-State Picture of Solar Wind Acceleration and Charge State Composition Derived from a Global Wave-Driven MHD Model
• First evidence of non-Gaussian solar flare EUV spectral line profiles and accelerated non-thermal ion motion
• Effect of collisions and magnetic convergence on electron acceleration and transport in reconnecting twisted solar flare loops
• Time-Dependent Density Diagnostics of Solar Flare Plasmas Using SDO/EVE
• Non-Gaussian Velocity Distributions in Solar Flares from Extreme Ultraviolet Lines: A Possible Diagnostic of Ion Acceleration
• Sparkling EUV bright dots observed with Hi-C
• Signatures of impulsive localized heating in the temperature distribution of multi-stranded coronal loops
• Signatures of the non-Maxwellian $\kappa$-distributions in optically thin line spectra \subtitle{I. Theory and synthetic Fe IX--XIII spectra}
• On the spectral hardening at ~> 300 keV in solar flares
• A Simple Method for Modeling Collision Processes in Plasmas with a Kappa Energy Distribution
• Self-absorption in the solar transition region
• On the sensitivity of the GOES flare classification to properties of the electron beam in the thick target model
• Constraining Hot Plasma in a Non-flaring Solar Active Region with FOXSI Hard X-ray Observations
• Differential emission measure Analysis of a limb solar flare on 2012 July 19
• Thermal and non-thermal emission from reconnecting twisted coronal loops
• The Evolution of the EM Distribution in the Core of an Active Region
• Multi-thermal representation of the kappa-distribution of solar flare electrons and application to simultaneous X-ray and EUV observations
• Time Dependent Non-Equilibrium Ionization of Transition Region Lines Observed with IRIS
• Impulsive Phase Coronal Hard X-ray Sources in an X3.9 Class Solar Flare
• Stochastic acceleration by multi-island contraction during turbulent magnetic reconnection
• Origin and Ion Charge State Evolution of Solar Wind Transients during 4 -- 7 August 2011
• LEMUR: Large European Module for solar Ultraviolet Research. European contribution to JAXA's Solar-C mission
• Electron Distribution Functions in Solar Flares from combined X-ray and EUV Observations
• Imaging and Spectroscopic Observations of a Transient Coronal Loop: Evidence for the Non-Maxwellian $\kappa$-Distributions
• Suppression of energetic electron transport in flares by double layers
• The connection of Type II Spicules to the Corona
• Collisionless shocks in partly ionized plasma with cosmic rays: microphysics of non-thermal components
• Collisional and Radiative Processes in Optically Thin Plasmas
• Diagnostics of non-thermal distributions in solar flare spectra observed by RESIK and RHESSI
• Fire Hose instability driven by alpha particle temperature anisotropy
• Diagnosing transient ionization in dynamic events
• Theory of gyroresonance and free-free emissions from non-Maxwellian quasi-steady-state electron distributions
• Coronal Electron Confinement by Double Layers
• Temperature dependent growth rates of the upper-hybrid waves and solar radio zebra patterns
• Dynamics of double layers, ion acceleration and heat flux suppression during solar flares
• Suprathermal electron distributions in the solar transition region
• RESIK observations of He-like Ar X-ray line emission in solar flares
• X-ray Flare Spectra from the DIOGENESS Spectrometer and its concept applied to ChemiX on the Interhelioprobe spacecraft
• Coronal Electron Distribution in Solar Flares: Drift-Kinetic Model
• Half a Century of Kinetic Solar Wind Models
• Determining Energy Balance in the Flaring Chromosphere from Oxygen V Line Ratios
• Non-equilibrium ionization by a periodic electron beam. I. Synthetic coronal spectra and implications for interpretation of observations
• Flare Footpoint Regions and a Surge Observed by the Hinode/EUV Imaging Spectrometer (EIS), RHESSI, and SDO/AIA
• EUV flickering of solar coronal loops: a new diagnostic of coronal heating
• The Diagnostic Potential of Transition Region Lines under-going Transient Ionization in Dynamic Events
• Coronal Thick Target Hard X Ray Emissions and Radio Emissions
• Scaling of collision strengths for highly-excited states of ions of the H- and He-like sequences
• Thermalisation and hard X-ray bremsstrahlung efficiency of self-interacting solar flare fast electrons

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• Solar X-ray Monitor On Board the Chandrayaan-2 Orbiter: In-flight Performance and Science Prospects
• Solar Flare Arcade Modelling: Bridging the gap from 1D to 3D Simulations of Optically Thin Radiation
• On the importance of the nonequilibrium ionization of Si IV and O IV and the line-of-sight in solar surges
• Modelling ion populations in astrophysical plasmas: carbon in the solar transition region
• Spectroscopic diagnostics of the non-Maxwellian $\kappa$-distributions using SDO/EVE observations of the 2012 March 7 X-class flare
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• On the faintest solar coronal hard X-rays observed with FOXSI
• X-ray Spectra from Plasmas with High-Energy Electrons: kappa-distributions and e-e Bremsstrahlung
• How Nanoflares Produce Kinetic Waves, Nano-Type III Radio Bursts, and Non-Thermal Electrons in the Solar Wind
• Electron Weibel instability and~quasi-magnetostatic structures in~an~expanding collisionless plasma
• Multi-scale magnetic field structures in an expanding elongated plasma cloud with hot electrons subject to an external magnetic field
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• Plasma Diagnostics From Active Region and Quiet Sun Spectra Observed by Hinode/EIS: Quantifying the Departures from a Maxwellian Distribution