Depths of formation of magnetically sensitive absorption lines

Abstract

Characteristics of the depression contribution functions are studied for the Stokes line profiles formed in a magnetic field. The form of the depression functions depends mainly on the strength of splitting and the Zeeman component intensity, and is of a complicated character with a distinctly pronounces asymmetry. The depths of formation of magnetically sensitive lines are found by means of these contribution functions. The calculations reveal that the steep section of the line profile is formed higher than the profile center when a strong longitudinal magnetic field is present. The Stokes profiles that describe the polarization characteristics are formed only several kilometers higher than the Stokes profile that specifies the general depression of the unpolarized and polarized radiation. The averaged depth of formation of the whole line profile is practically independent of the magnetic field strength. The depths of formation of 17 photospheric lines usually used in magnetospectroscopic observations are calculated for the models of the quiet photosphere, a flux tube, and the sunspot umbra.