Solar Flares: Magnetohydrodynamic Processes
Kazunari Shibata,Tetsuya Magara +1 more
TLDR
The current understanding of solar flares, mainly focused on magnetohydrodynamic (MHD) processes responsible for producing a flare, can be found in this article, where the authors present a review of the models proposed to explain the physical mechanism of flares, giving an comprehensive explanation of the key processes.Abstract:
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.read more
Citations
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Journal ArticleDOI
Observations and Implications of Large-Amplitude Longitudinal Oscillations in a Solar Filament
Manuel Luna,Manuel Luna,Kalman J. Knizhnik,Kalman J. Knizhnik,Karin Muglach,Judith T. Karpen,H. R. Gilbert,Therese A. Kucera,Vadim M. Uritsky,Vadim M. Uritsky +9 more
TL;DR: In this article, an energetic disturbance triggered large-amplitude longitudinal oscillations in a nearby filament, and the triggering mechanism appears to be episodic jets connecting the energetic event with the filament threads.
Journal ArticleDOI
Evolutionary stages and triggering process of a complex eruptive flare with circular and parallel ribbons
TL;DR: In this article, a multi-wavelength study of a complex M-class solar eruptive flare that consists of three different sets of flare ribbons, viz. circular, parallel, and remote ribbons is presented.
Journal ArticleDOI
Magnetic Gradient: A Natural Driver of Solar Eruptions
TL;DR: In this paper, the magnetic-gradient pumping (MGP) mechanism was shown to be a natural driver of solar eruptions in solar atmospheric plasmas, and the authors demonstrated that the MGP mechanism is valid even in the partial ionized solar photosphere, chromosphere as well as in the corona.
Journal ArticleDOI
Relaxation of magnetic field relative to plasma density revealed from microwave zebra patterns associated with solar flares
Sijie Yu,Yihua Yan,Baolin Tan +2 more
TL;DR: In this paper, the authors investigated the variations of 74 microwave ZP structures observed by the Chinese Solar Broadband Radio Spectrometer (SBRS/Huairou) at 2.6-3.8 GHz in nine solar flares, and they found that the ratio between the plasma density scale height LN and the magnetic field scale height LB in emission sources displays a tendency to decrease during the flaring processes.
Journal ArticleDOI
Imaging and Spectroscopic Observations of a Filament Channel and the Implications for the Nature of Counter-streamings
TL;DR: In this paper, the authors proposed a method to determine the chirality of an erupting filament based on the skewness of the conjugate filament drainage sites, which suggests that the right-skewed drainage corresponds to sinistral chircality, whereas the left-sewed drainage correspond to dextral chricality, and that the upflows being located at brighter areas of the plage and downflows at weaker areas.
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