Spectroscopic and photometric observations of the short-period RS CVn-type star CG Cyg

Spectroscopic observations around the Hα line and BVR photometry of the eclipsing short-period RS CVn-star CG Cyg are presented. The solutions of the radial velocity curves and the light curves yielded the following masses and radii of the star components: $M_{\rm 1}=0.97~ M_{\odot}$, $M_{\rm 2}=0.80~M_{\odot}$, $R_{\rm 1}=1.00 ~R_{\odot}$, $R_{\rm 2}=0.83 ~R_{\odot}$. The measured rotational broadenings of the observed lines correspond to equatorial velocities $V_{\rm 1}=80$ km s-1 and $V_{\rm 2}=66$ km s-1. The distortions of our multicolor light curve were reproduced by two cool spots on the primary star. The strong absorption feature between the spectral lines of the two stars was explained by extended structure around the mass center of the system. The Hα emission line of the secondary star in the August spectra was attributed to a prolonged flare of this star.