High-resolution echelle spectra were obtained for early K dwarfs in order to study the effects of stellar activity on photospheric absorption lines. Two classes of effects are noted in the ratio spectra: simple pseudoemission profiles resulting from the filling in of the line core, and profiles indicating that lines in some active stars have broader wings but shallower cores than their inactive counterparts. It is suggested that the present stellar activity effects may be the result of a shallower average photospheric temperature gradient due to nonradiative heating in the upper photosphere and additional effects inside the magnetic flux tubes.
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Basri et al. (1989) studied this question.