Much of the material in this book originated with lectures given for the Summer School on Radiative Transfer and Radiation Hydrodynamics at the Institute of Theoretical Astrophysics of the University of Oslo during June 1–11, 1999. Those lectures focused on the specifics of the dynamic coupling of radiation and matter, and on the detailed processes of the interaction. The other lecturers were Rob Rutten of the University of Utrecht, Phil Judge of the High Altitude Observatory in Boulder, Colorado, and Mats Carlsson of the University of Oslo, the organizer of the Summer School and the Director of the Institute. Their lectures treated the introduction to radiative transfer, atomic processes and spectral line diagnostics with special reference to the sun, and numerical methods in radiative transfer and radiation hydrodynamics. For that reason the original content of these lectures was light in those areas, especially in numerical methods. In putting the lectures into the present form some effort was invested to expand the coverage of the neglected topics.

The background for the theory of radiation hydrodynamics as presented here came from work at JILA, the Joint Institute for Laboratory Astrophysics of the University of Colorado and the National Bureau of Standards, as they were called then, in the late 1960s and 1970s. It originated with the need to treat radiation–matter coupling correctly in stellar pulsations and other areas of astrophysical fluid dynamics. The theory of radiatively-driven stellar winds developed out of that work. At this same time the Boulder School of radiative transfer was flourishing through the efforts of L. Auer, D. Hummer, J. Jefferies, D. Mihalas, R. Thomas, and many others. Some of the knowledge absorbed from these people, and their colleagues E. Avrett, W. Kalkofen, and G. Rybicki at the Harvard-Smithsonian Center for Astrophysics, made it into this book.