j ghanbari - Department of Physics, Ferdowsi University, Mashad, Iran
m shadmehri - Department of Physics, Ferdowsi University, Mashad, Iran

This study demonstrates how thermal structures in the interstellar medium can emerge as a result of thermal instability. For a two-dimensional case, the steady state thermal structures was investigeted and it was shown that a large class of solutions exist. For a one-dimensional case the conductivity was found to be negligible. The effects of local cooling on the thermal instability were explored in some depth. In this case analytical results for time-dependent cooling function were presented, too. We studied nonlinear wave phenomena in thermal fluid systems, with a particular emphasis on presenting analytical results. When conductivity is proportional to temperature, the behavior of thermal waves is soliton like. For șlow thermal waves, approximate analytical results were presented. Extensions of this work are discussed briefly, together with possible astrophysical applications.

Interstellar medium, Instabilities, Thermal instability, Thermal Solitous