Solar Flares: Magnetohydrodynamic Processes

By Kazunari Shibata, T. Magara. 2011

715 citations recorded by the source corpus.

This paper outlines the current understanding of solar flares, mainly focused on magnetohydrodynamic (MHD) processes responsible for producing a flare. Observations show that flares are one of the most explosive phenomena in the atmosphere of the Sun, releasing a huge amount of energy up to about 1032 erg on the timescale of hours. Flares involve the heating of plasma, mass ejection, and particle acceleration that generates high-energy particles. The key physical processes for producing a flare are: the emergence of magnetic field from the solar interior to the solar atmosphere (flux emergence), local enhancement of electric current in the corona (formation of a current sheet), and rapid dissipation of electric current (magnetic reconnection) that causes shock heating, mass ejection, and particle acceleration. The evolution toward the onset of a flare is rather quasi-static when free energy is accumulated in the form of coronal electric current (field-aligned current, more precisely), while the dissipation of coronal current proceeds rapidly, producing various dynamic events that affect lower atmospheres such as the chromosphere and photosphere. Flares manifest such rapid dissipation of coronal current, and their theoretical modeling has been developed in accordance with observations, in which numerical simulations proved to be a strong tool reproducing the time-dependent, nonlinear evolution of a flare. We review the models proposed to explain the physical mechanism of flares, giving an comprehensive explanation of the key processes mentioned above. We start with basic properties of flares, then go into the details of energy build-up, release and transport in flares where magnetic reconnection works as the central engine to produce a flare.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4f2a0a882ed5dd1fe9169abaa28723d0ec4b2aeb

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In Astronomy and Astrophysics

Citations in the corpus

Statistical properties of superflares on solar-type stars based on 1-min cadence data (2015, methodology): “Solar flares are eruptive events in the solar atmosphere caused by the magnetic reconnection (e.g., Shibata and Magara 2011).”
Can Superflares Occur on Our Sun (2012, background): “A solar flare is an explosion generated by magnetic energy released near to sunspots in the solar atmosphere (e.g., Shibata & Magara 2011 for a review).”
Geomagnetic storms: historical perspective to modern view (2016, background): “1995; Benz 2008; Chen 2011; Shibata and Magara 2011).”
Magnetohydrodynamic Oscillations in the Solar Corona and Earth’s Magnetosphere: Towards Consolidated Understanding (2016, background): “Comprehensive reviews of recent achievements in the observational study and theoretical modelling of these phenomena can be found by Benz (2008), Chen (2011), Shibata and Magara (2011), Webb and Howard (2012).”
MAGNETIC FIELD STRUCTURES TRIGGERING SOLAR FLARES AND CORONAL MASS EJECTIONS (2012, background): “…ejections (CMEs), the most catastrophic eruptions in our solar system, are believed to occur through a type of storage-and-release phenomena, in which the free energy stored as a nonpotential magnetic field in the solar corona is abruptly unleashed (Priest & Forbes 2002; Shibata & Magara 2011).”
The standard flare model in three dimensions - I. Strong-to-weak shear transition in post-flare loops (2012, methodology): “We refer the reader to the recent review by Shibata & Magara (2011), for a complete description of these findings.”
MAGNETIC PROPERTIES OF SOLAR ACTIVE REGIONS THAT GOVERN LARGE SOLAR FLARES AND ERUPTIONS (2016, background): “This is reasonable because the ribbons indicate the heating of chromospheric plasma via thermal conduction and high-energy electrons driven by the reconnection, while the SXR loops are formed following chromospheric evaporation (see, e.g., Shibata & Magara 2011).”
The magnetic field in the solar atmosphere (2014, background): “Instead, we refer here to the comprehensive reviews on flare (Forbes et al., 2006; Chen, 2011) and CME models (Forbes, 2000; Shibata and Magara, 2011).”
Fast radio burst source properties and curvature radiation model (2017, background): “This is a well known process and is responsible for the energy release in solar flares (e.g. Shibata & Magara 2011).”