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Su Qing-Rui 《Solar physics》1990,127(1):139-147
Using a finite elements method, the magnetohydrostatic equation in a non-isothermal atmosphere is solved. The result is similar to the case in an isothermal atmosphere (Su, 1985). It is found that at some critical amount of shearing a magnetic island is formed and then breaks out to form an open magnetic configuration in which tearing-mode instability may occur. As the gradient of longitudinal magnetic field at some lower solar corona level increases, shearing loops containing strong currents are formed and the critical magnetic shearing parameter at which the magnetic island occurs, gets larger. In such a case, a lot of magnetic free energy is not easily released. It may be accumulated in a small volume above the polarity inversion line. As magnetic shearing increases, the magnetic free energy gets larger, until the magnetic shearing parameter reaches a higher critical value, a sudden change in magnetic configuration occurs. Such conditions may lead to high-energy solar eruptive phenomenon. 相似文献
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Su Qing-Rui 《Solar physics》1982,75(1-2):229-236
In this paper, we extend B. C. Low's study on nonlinear force-free magnetic fields. Based on Low's mathematical method, a revised boundary-value problem of the two-dimensional nonlinear force-free magnetic field is solved analytically. The solution shows that higher magnetic loops evolve towards preflare loops when the gradient of longitudinal magnetic field at the photospheric level and the angle (shear) included between the magnetic field line and magnetic neutral line increase with time. The density, temperature and the current density are higher in the preflare loops than in the high-lying magnetic loops. We believe it is the loops that provide conditions for the eruption of the flare.The original has been published in the Acta Astronomica Sinica
21 (1980), 152, in Chinese. The present paper completes the discussion and revises some of the preliminary results. 相似文献
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Su Qing-Rui 《Solar physics》1985,102(1-2):159-164
With the assumption that the magnetic field lines are radial at some quite high level in the solar corona, a non-constant shearing magnetic field is introduced into the magnetohydrostatic equations. It is found that a same critical amount of shearing a magnetic island is formed and then breaks out to form an open magnetic configuration in which resistive tearing-mode instability may occur, and may initiate a two-ribbon flare. In addition, high shearing magnetic fields are investigated. It is shown that high shearing magnetic configurations are weak two-dimensional neutral sheets, the instability of which has been studied by Janicke (1982). 相似文献
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The finite element method was used to solve a partial differential equation (magnetostatic equation) for multipolar magnetic regions. It is found that the height of magnetic field lines above the magnetic neutral line of a central strong bipolar magnetic field decreases as the field lines' footpoints approach the neutral line and also with increased magnetic shear. Both the electric current density and plasma pressure in the sheared low-lying loops are high. We suggest that the sheared low-lying loops may store the energies of large coronal mass ejections (CMEs) and filament eruptions. In addition, it is found that a lower pressure area exists above the low-lying loops and that it is similar in morphology to a coronal cavity. Above the lower pressure area there is a higher pressure area, which may be the source of CMEs. In this area magnetic shear leads to magnetic reconnection, which may be the cause of high coronal temperature. 相似文献
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