Diffuse matter and cosmogony of stellar systems in researches by Shajn

Abstract

The main topic of long-term researches by G.A. Shajn is the nature of diffuse matter, its distribu-tion in the Galaxy and extragalactic systems, interaction with the interstellar medium and hot stars, the formation of emission and reflection nebulae and stars have become the main theme of researches by Shajn during some years. Based on the analysis of experimental data, mainly pho-tographic observations of nebulae in the Milky Way and extragalactic systems, he made conclu-sions and suggested well-founded hypotheses on a wide range of the considered problems, in-cluding those related to cosmogony. The structure of nebulae, their masses and sizes give a reason to the conclusion that most of them are formed not in the process of ejection of matter from the stars, but this is the objects, which are born and evolved, and quite often comprised in giant conglomerates of gas, dust and stars. The distribution of O-stars and nebulae in spiral branches points to their genetic relation and the fundamental role of the interstellar medium as a source of their formation. The structural features of nebulae are determined by the action of magnetohydrodynamic forces. Magnetic fields in a galaxy control the motion of diffuse gas-dust matter and ensure the maintenance of its spiral structure. These ideas continue being developed in modern directions of astrophysics.