Measurement of f-Values in the Iron Spectrum and Applications to Solar and Stellar Atmospheres

The relative f-values of 48 spectral lines of Fe I have been derived from measurements of intensities in emission of lines excited in an electric furnace. The measurements were made photoelectrically. f-values were measured relative to King's previously determined values and are on the same scale. Lines with excitation potential of low term up to 3.5 volts are included. The f-values derived have been used to plot a solar curve of growth. The scatter of the points for high energy level lines is large. This is due mainly to the fact that lines whose low term is of odd parity are apparently consistently too strong in the sun and those of even parity too weak. On the other hand curves of growth for the giant stars γ Cygni and α Persei exhibit a much smaller scatter of points and no evidence of odd-even difference. Measurements of laboratory pressure shifts show systematic odd-even differences. These tests indicate that the effect observed in the sun is real and suggests that it may be due to the relatively high pressure in the solar atmosphere. If this is true the practice of using relative f-values derived from the solar curve of growth in the study of stellar atmospheres should be reconsidered.