The Prediction of Model-Atmosphere Line Profiles with an Electronic Computer.

A program has been developed which will compute a line profile, formed under the assumption absorption and taking into account the effects of an assumed model atmosphere. The calculations, which included a detailed theory of the broadening of a spectral line, were performed using an electronic calculator (IBM 650). About 25 minutes are required to compute a line profile of fifteen points A comparison was made between the observed profiles of the magnesium triplet at X 5175 A and the predicted line profiles, using various abundances and two assumed model atmospheres. A curve of growth for this magnesium triplet was constructed by plouting the equivalent width, measured from the computed profiles, against the abundance used to calculate those profiles. Although the program is restricted at present to the prediction of any metal line whose ionization potential is between 7 and 13 ev, it can easily be to include other lines as well as other effects, such as turbulence.