Magnetohydrostatic equilibrium in solar coronal arcades

Abstract

We present a solution of magnetohydrostatic equations after including the effect of gravity. For low values of the parameters beta, there exist two solutions for the common boundary condition at the base of the corona. These two solutions correspond to two different magnetic configurations with different energies. The high-energy configuration may become unstable due to physical conditions and relax to the low-energy configuration, releasing an amount of the energy that may be observed in the form of a solar activity, such as two-ribbon flares. When the value of beta exceeds the critical limit, the magnetohydrostatic equations have no solution. If the system is forced to exceed beyond the critical limit, the magnetic field may show a violent behavior