From Parker and thermal instabilities to the formation of giant molecular clouds
We study the Parker instability (PI) under the influence of heating and cooling processes. We distinguish two models with different heating functions. On the base of linear stability analysis, we find that the properties of PI in such a system are significantly different with respect to the adiabatic and isothermal cases. We find that in case of thermally stable equilibrium, PI operating in presence of additional heating sources, postulated by Reynolds et al. (1999), and cooling described by Dalgarno & McCray (1972), leads to a decrease of temperature in magnetic valleys. Numerical simulations show that this behavior promotes a transition of gas to thermally unstable regime. In consequence the gas density grows up by an order of magnitude and the condensed gas clumps acquire compact shapes. Our results lead to the conclusion that PI can trigger the formation of giant molecular clouds complexes.