Gehrz, Robert 95-28336 Classical novae and luminous evolved (post main sequence) stars are important sources of processed material that is recycled to the interstellar medium (ISM) in circumstellar outflows during stellar evolution. Quantitative information about the dust and gas ejected in these outflows is necessary to provide fundamental constraints on models of Galactic chemical evolution. Infrared (IR) photometry and spectroscopy are particularly powerful tools for evaluating the abundances of both solid and gaseous phases of circumstellar material. IR spectrophotometry, imaging and polarimetry can be used to deduce the physical characteristics of the circumstellar outflows and of the grains that form within them. A three year extension is planned to the University of Minnesota IR group's program to study circumstellar dust and gas through IR observations of the temporal development of classical nova explosions and the transient activity of luminous IR variable stars. The studies will characterize the nucleation and growth of astrophysical dust grains in circumstellar outflows, asses the contributions of solid and gas-phase matter that novae and IR variable stars make to the ISM, and provide information about the stages of stellar evolution that preceded the mass loss process. Successful fulfillment of many of the program objectives requires prompt observations of sudden, transient activity at many wavelengths. The study will build upon previous observations and will benefit from their capabilities to obtain timely, remote and simultaneous multi-wavelength observations of transient events with telescopes in Minnesota, Wyoming and Arizona. ***
