Line Contours in Sunspot Regions

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Abstract
Line contours have been measured for Fe I 6302.5 Å across sections of a sun-spot towards the west limb of the Sun. The contours were obtained in light plane polarized in the NS and EW planes. As simultaneously as possible, magnetic field strengths and directions and Evershed velocities have been measured in the fringed spectra taken through a Babinet prism, according to the method introduced by Treanor. The observations form the basis for an investigation of suggested abnormalities in the component intensities in Zeeman split lines. The contours observed in plane polarized light as above are free from the effects of telescope polarization and give a more sensitive test of observation and theory than contours obtained in natural light. The observed contours are compared with theoretical calculations based on Stepanov's theory of line formation for Zeeman components. Although the observed equivalent widths show a marked difference between the two polarization planes, this difference is quite in accord with the theory; moreover, when the effect of scattered light is taken into account the observed contours are not anomalous. The observational procedure now described is proposed as a sensitive method of investigating possible abnormalities in line contours in larger sunspots.

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