Time-resolved spectroscopy of RS Canum Venaticorum short-period systems.: II.: RT Andromedae, WY Cancri, and XY Ursae Majoris

We present the second part of the results of our spectroscopic study of orbital phase resolution of short-period active binaries. In this paper we present the observations of the binaries RT And, WY Cnc, and XY UMa, for which we obtained simultaneous low-resolution spectra in the H alpha, H beta, and Ca II infrared triplet (IRT; 8498 and 8542 Angstrom) lines, and higher resolution spectra in H alpha for WY Cnc and XY UMa. H alpha and H beta emission excess was found in all the observed orbital phases of WY Cnc and XY UMa, while RT And showed Ha emission only during some orbital phases. We measure a clear Ca II (IRT) excess in all the spectra of the three binaries. The ratio of the flux excesses derived for these binaries, E-H alpha/E-H beta similar or equal to 1-3 and E-8542/E-8498 similar or equal to 1-3, give low values typical of solar plage structures. In the higher resolution H alpha spectra, we found emissions that can be associated with both stellar components of XY UMa and WY Cnc, indicating that the faint secondary stars in both binaries are active late-type dwarfs. Some H alpha emission components, which could originate in extended structures between the stars, were detected in both systems.