Montes Gutiérrez, DavidCastro Rubio, Elisa DeFernández Figueroa, María JoséCornide Castro-Piñeiro, Manuel2023-06-202023-06-201995-120365-0138https://hdl.handle.net/20.500.14352/59662© 1995 EDP Sciences. This work has been supported by the Universidad Complutense de Madrid and the Spanish Dirección General de Investigación Científica y Técnica (DGICYT) under grant PB91-0348. We would like to thank the referee K.G. Strassmeier for suggesting several improvements and clarifications.We present new spectroscopic observations in the Ca II H & K line region for a sample of 28 chromospherically active binary systems (RS CVn and BY Dra classes), with different activity levels. By using the spectral subtraction technique (subtraction of a synthesized stellar spectrum constructed from reference stars of similar spectral type and luminosity class) we obtain the active-chromosphere contribution to the Ca II H & K lines and to the H_ε line when it is present. We have compared the emission equivalent widths obtained with this technique with those obtained by reconstruction of the absorption line profile below the emission peak(s). The emissions arising from each individual star were obtained when it was possible to deblend the contribution of both components. The Ca II line profiles corresponding to different seasons and orbital phases are analysed in order to determine the contribution of each component and to study the chromospheric activity variations.engjournal articlehttp://arxiv.org/pdf/astro-ph/9506025v1.pdfhttp://aas.aanda.org/open access52Late-type starsMain-sequence starsSolar-type starsRS-CVN systemAlpha emissionDraconis variablesProfilesCatalogDiscoveryAstrofísicaAstronomía (Física)