Time-resolved Spectroscopy of RS Canum Venaticorum Short-Period Systems. II. RT Andromedae, WY Cancri, and XY Ursae Majoris

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Abstract
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 Hα, Hβ, and Ca II infrared triplet (IRT; 8498 and 8542 Å) lines, and higher resolution spectra in Hα for WY Cnc and XY UMa. Hα and Hβ emission excess was found in all the observed orbital phases of WY Cnc and XY UMa, while RT And showed Hα 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, EHα/EHβ 1–3 and E8542/E8498 1–3, give low values typical of solar plage structures. In the higher resolution Hα 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 Hα emission components, which could originate in extended structures between the stars, were detected in both systems.