This volume discusses the nature of interstellar matter on the basic physical principles. It also summarizes the present state of knowledge of interstellar medium, providing observational data. The overall equilibrium and dynamical state of interstellar gases are described.

Discusses the nature of interstellar matter, with a strong emphasis on basic physical principles. Summarizes the present state of knowledge about the interstellar medium and provides the latest observational data. Physics and chemistry of the interstellar medium are treated, with frequent references to observational results. The overall equilibrium and dynamical state of the interstellar gas are described, with discussions of explosions produced by star birth and star death and the initial phases of cloud collapse leading to star formation.

Interstellar Matter An Overview.
Elastic Collisions and Kinetic Equilibrium.
Radiative
Processes.
Excitation.
Ionization and
Dissociation.
Kinetic Temperature.
Optical
Properties of Grains.
Polarization and Grain
Alignment.
Physical Properties of Grains.
Dynamical Principles.
Overall Equilibrium.
Explosive Motions.
Gravitational Motion.
Symbols.
Index.