This book deals with circumstellar dust shells. It is especially intended to provide a comprehensive presentation of the local and global aspects that determine the physical and chemical process constituting necessary ingredients of any conclusive description and hence of any reliable theoretical modeling of circumstellar dust shells. In this perspective, it puts forward a synthesis of all important observational, theoretical, and numerical aspects that have to be taken into account in any consistent modeling of such complex nonlinear dynamic systems.

Despite the impressive work dedicated to exploring the specific important processes taking place in cool circumstellar (dust) shells, hitherto there existed no publication on this subject based on an overall inclusive perspective. This situation urges the need for a detailed conclusive presentation covering the relevant complex processes and their intricate mutual interplay on which any realistic quantitative modeling of a circumstellar dust shell has to rely. Only such consistent models, based on first-principle physics and a realistic chemistry, are appropriate for being confronted with the observed facts by crucial tests. Thus, apart from inevitable simplifying assumptions, sometimes necessary for the basic physical or chemical characterization of certain processes, we always strive for a realistic approach in detail and generally for self-consistency – or at least for consistency – of the integral model description of a circumstellar dust shell comprising the essential local and global aspects: dynamics, thermodynamics, radiative transfer, chemistry, and grain growth.