Ferland, Gary 96-17083 Dr. Ferland will continue to improve the large- scale code called Cloudy, which computes the spectrum of gas in photoionization or collisional balance, and will apply it to a number of problems in nebular astrophysics. Cloudy requires updates which reflect advances in the atomic data base which it uses and improvements in the numerical and computational methods used in the simulation. The code will be tested on ablating molecular clouds, the likely origin of some gas in quasars. For quasar studies the first step is to deduce the composition of their emitting gas from the spectrum, then to determine the dependencies of this spectrum on the shape of the ionizing continuum and to correlate this with observed changes in the spectral energy distribution.
