Non-isothermal atmosphere, solar wind, shearing and pressing magnetic field and preflare loops

Abstract

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.