SOME COMMENTS ON LIMB SHIFT OF SOLAR LINES .1. EFFECT OF PRESSURE SHIFTS ON IRON LINES IN SOLAR ATMOSPHERE

It has been suggested that pressure shifts are the sole cause for the systematic blue shift of solar fraunhofer lines (Hart, 1974). To check this we evaluate the significance of pressure shifts for Fe i lines. The observed wavelength shifts of a large number of lines are compared with the shifts calculated for the Lennard-Jones potential following Hindmarsh et al. (1967). The Lennard-Jones potential for the interatomic forces yield pressure shifts caused by neutral hydrogen, which explain only a small fraction of the observed blue shift. It is also shown that the quadratic Stark effect contributes insignificantly to the position of Fe i lines. Table I summarizes the average line shifts for iron lines at the center of the solar disk after correction for pressure shifts. © 1978 D. Reidel Publishing Company.