From Molecules to Grains

Abstract

Cosmic dust is an ubiquiteous component of the interstellar medium, the presence of which has severe bearings both upon the observations and upon the physical description and realistic modelling of astronomical objects. In most dusty objects, the grain component is intimately interwoven with the gas component and the radiation field, and, hence strongly affects the thermodynamical, the hydrodynamical and the chemical structure of the object. Therefore any consistent description of the astrophysical dust complex has to rely upon a treatment where these aspects are properly taken into account. In general this complex comprises the following problems:–Formation of small stable molecular clusters out of the gaseous phase–Growth of these clusters to macroscopic specimens (primary condensates: grains, plates, etc.)–Destruction of grains (e.g. thermal evaporation, sputtering, shattering), and–Physical and chemical processing of already existing grains (e.g. coagulation, chemical and thermal transformation, etc....).