THE WAVELENGTH DISPLACEMENTS OF SOME INFRARED LINES BETWEEN LIMB AND CENTER OF THE SUN

Abstract

The wavelength displacements between the solar limb and the center of the disk, (λL–λc), have been measured for six infrared solar lines, belonging to two multiplets of Sil. The displacements of the lines of one of the multiplets are the same, within the accuracy of the measurements; the displacements of the lines of the other multiplet, although varying somewhat amongst themselves, are systematically larger. This grouping of the results according to multiplet structure suggests that the wavelength displacement of solar lines across the disk is term-dependent. It is noted that the variation of the values (λL–λC) is, in its essential features, similar to the term-dependent variation of the differences [Formula: see text] between the published solar and laboratory wavelengths of silicon. Solar and laboratory data, taken together, appear to provide observational evidence that the observed wavelength variations across the solar disk are, at least in part, due to collision or field effects.