Velocity Dispersion and H\(\boldsymbol{\alpha}\)-emission of Ionized Gas in Star-forming Regions

Abstract

To understand the nature of gas flows in star-forming regions of nearby galaxies, the relationship between the surface brightness values in the H\(\alpha\) line and the velocity dispersion of ionized gas, known as the ‘‘surface brightness–velocity dispersion’’ diagram, is often used. Based on three-dimensional gas-dynamic calculations, we examined the evolution of synthetic diagrams for supershells formed as a result of multiple supernova explosions in a star cluster located in the galactic disk. Based on the results of a study of changes in the shape and structure of the diagram depending on the gas density, its metallicity, and the disk scale height, it is possible to identify ranges of values in the diagram that are characteristic of young bubbles developing in dense or rarefied gas at large heights above the plane of the disk. We found that the structure of the diagram depends on the age of the supershells and the physical properties of the gas in the disk. For nearby dwarf galaxies, the structure of the observed ‘‘surface brightness–velocity dispersion’’ diagrams can only be explained by describing the dynamics of bubbles formed by multiple SN explosions in small star clusters of different ages.