A method for empirical determination of stellar atmospheric structure

A technique for obtaining information on the temperature structure of a stellar atmosphere from spectral line data where only flux observations are available is discussed. The direct inversion of the flux integral to obtain the line source function can be circumvented by making the physically plausible assumptions of (1) source function equality in a multiplet and (2) the dominance of line absorption over continuum absorption at line center. Consistency of the technique is demonstrated by treating a synthetic spectrum as input data and attempting to recover the temperature structure of the input atmosphere. Using high quality solar spectrum scans obtained from K.P.N.O. we demonstrate the accuracy of source function equality for several Fe i multiplets and use one of these multiplets to obtain an empirical outer atmosphere for the Sun. Our empirical atmosphere agrees well with current solar models.