Physical and Dynamical Conditions in Interstellar Clouds

The most far-reaching result to come from the study of interstellar molecules has been the recognition of a new class of galactic structures - molecular clouds. These clouds appear to contain most of the mass of the interstellar medium and are the objects from which new stars are formed. Thus, a prerequisite for any understanding of the star formation process is a knowledge of the physical and dynamical conditions in molecular clouds.