Dr. Watson will continue his theoretical research program related to astrophysical environments in which the matter is diffuse. The emphasis will be on astrophysical topics in which an improved understanding of the microscopic processes and physical aspects of radiative transfer is likely to play an important role. Theory for astrophysical masers will be a central goal. At the outset, Dr. Watson will focus on various aspects of the transfer of polarized maser radiation that potentially are involved in a full understanding of the recent detections of "Zeeman patterns" in the spectra of water masers in star forming regions. To do this, Dr. Watson will build upon current developments in making the theory considerably more realistic for polarized maser radiation. Dr. Watson will also perform research related to understanding the power of astrophysical masers and the implications for the energetics and dynamics of star forming and circumstellar regions. Although outstanding astrophysical issues ordinarily are phrased in global terms, such as star formation, dark matter in the Universe, and galaxy formation, the foundations for understanding the phenomena and for interpreting the relevant observations frequently depend in a critical way upon the detailed treatment of the physical processes. Of particular relevance to Dr. Watson's work is that much of our observational information in astronomy comes from studies of emission and absorption of spectral line radiation. The observed intensity of such radiation from diffuse astronomical environments can be particularly sensitive to the details of atomic, molecular, electronic, and radiative transfer processes. As astrophysical observations continue to be pursued with improved refinement and sensitivity, as well as new environments and wavelengths, it is reasonable to expect that research which emphasizes the role of the above physical processes will continue to play a significant part in the progress in many areas with broad impact in astronomy and astrophysics.
