THE STRUCTURE OF CIRCUMSTELLAR SHELLS FRO M THEIR INTENSITY DISTRIBUTIONS

The reconstruction of the source function for a spherically symmetric circumstellar shell is treated in terms of the analysis of its intensi ty distribution. It is shown that this problem reduces to solving an i ll-defined inverse problem for Fredholm's integral equation of the 1st kind. In the case of an optically thick shell, the depth dependence o f the. volume absorption coefficient must be known for the kernel of t his equation to be calculated. For an optically thin shell, the law of variations in the volume emission coefficient with depth can be resto red from high angular resolution observations; if the intensity distri bution across the stellar disk is known, then it is, in principle, pos sible to obtain information about the volume absorption coefficient fr om the analysis of different regions of the intensity profile. The sol ution to the integral equation is sought on a compact set of convex no nnegative functions. Numerical experiments show high stability of the solution to random noise.