On the nonlinear thermal evolution of solar corona structures

The thermal evolution of structures is investigated for different values of the size of structure. A simplified cooling function and a constant heatin g mechanism are assumed. Analytical criteria for thermal instability are ob tained. It is found that the response of the thermal structure not only dep ends on the amplitude of the disturbances, but also on whether the disturba nce increases or decreases the initial steady temperature. Additionally, th e evolution of the structure is examined numerically by using a time-depend ent code under the assumption that the inertia terms are small. In particul ar, the analytical criteria obtained for thermal instability are verified.