APPLICATION OF THE SPECTRAL SUBTRACTION TECHNIQUE TO THE CA-II-H-AND-K AND H-EPSILON LINES IN A SAMPLE OF CHROMOSPHERICALLY ACTIVE BINARIES

We present new spectroscopic observations in the Ca II H & K line regi on for a sample of 28 chromospherically active binary systems (RS CVn and BY Dra classes), with different activity levels. By using the spec tral subtraction technique (subtraction of a synthesized stellar spect rum constructed from reference stars of similar spectral type and lumi nosity class) we obtain the active-chromosphere contribution to the Ca II H & K lines and to the HE line when it is present. We have compare d the emission equivalent widths obtained with this technique with tho se obtained by reconstruction of the absorption line profile below the emission peak(s). The emissions arising from each individual star wer e obtained when it was possible to deblend the contribution of both co mponents. The Ca II line profiles corresponding to different seasons a nd orbital phases are analysed in order to determine the contribution of each component and to study the chromospheric activity variations.