Large-scale structures in the interstellar medium

Large-scale ordered structures in the interstellar medium (ISM) are commonly explained as a manifestation of the various instabilities inherent to the motion of partially ionized, magnetized interstellar gas. We examined the process of creation of large-scale coherent eddy structures in the ISM characterized by the existence of fully developed small-scale turbulence with nonzero values of the hydrodynamic and magnetic helicities. The instability analysis shows that in such media large-scale ordered structures with characteristic scale l similar to 1-100 pc are generated. The generation coefficient of large-scale structures is determined by both the value of the hydrodynamic helicity and the combined influence of the drag force and magnetic helicity.