Hyperfine structure and the broadening of sunspot spectral lines

The combined effects of hyperfine structure and Zeeman splitting have been calculated for the a6D1/2–z6D1/2 line of Mn i at wavelength 4070.28 Å, which is observed as a broad line in sunspot spectra. An effective Z factor is defined to represent the mean position of the strong components of the line for fields above 500 G. This Z factor might provide a method of monitoring sunspot magnetic fields.