Galactic astronomy. Structure and kinematics

An overview of the Milky Way Galaxy is provided and aspects of astronomical background are considered, taking into account positions and coordinate systems, proper motions, parallax, radial velocities, stellar spectra, magnitudes and colors, absolute energy distributions, and astronomical catalogs and atlases. The physical properties of stars and the interstellar medium are examined, giving attention to stellar distances, stellar masses, stellar radii, an analysis of stellar spectra, spiral arm and disk stars, spheroidal-component stars, stellar structure and evolution, pulsating variable stars, and questions of interstellar absorption. The space distribution of stars and the chemical elements in the Milky Way Galaxy are discussed along with the large-scale structure and stellar content of galaxies, the solar motion, the stellar residual-velocity distribution, and the rotation of galaxies. A description is presented of the large-scale distribution of gas in galaxies, taking into consideration the distribution of neutral hydrogen in the Milky Way Galaxy and in other galaxies, molecular clouds in the Milky Way Galaxy, and the galactic center.