A study of short-period RS Canum Venaticorum and W Ursae Majoris binary systems: the global nature of Hα

Rotation versus emission characteristics of the H-alpha line are presented for several short period RS CVn and W UMa binary systems, with estimates for the chromospheric emission arising from each component star obtained by subtraction of the 'nonactive' model spectra reconstructed from comparison stars that were similar in spectral type to the component stars. A possible correlation between L(H-alpha)/L(bol) and the ratio between the rotational period and the convective time scale is seen for those components exhibiting emission. Such a correlation suggests that the H-alpha line is a good diagnostic for the study of the magnetic-related activity in late-type stellar systems.