Propagation and Interaction of Waves in Non-ideal Interstellar Gas Clouds

This study uses the principles of weakly non-linear geometrical acoustics and the method of multiple time scales to analyze the propagation of high-frequency, small-amplitude waves in a non-ideal interstellar gas cloud. The governing equations are expressed as a one-dimensional quasi-linear hyperbolic system, representing compressible and unsteady flow in spherical geometry. Transport equations for resonantly interacting wave amplitudes are derived, and the non-linear evolution of non-resonant wave modes is investigated. The effects of gas non-ideality and interstellar conditions on wave dynamics are examined, particularly in relation to shock wave formation. These findings provide new insights into the complex relationship between non-ideal gas behavior, interstellar gas clouds, and shock wave development during high-frequency wave propagation.