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

Abstract

Abstract. Spectroscopic observations around the H α 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:The measured rotational broadenings of the observed lines correspond to equatorial velocities V 1 = 80 km s −1 and V 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 H α emission line of the secondary star in the August spectra was attributed to a prolonged flare of this star.

Long-term luminosity variations and period changes in CG Cygni

“…at quadrature longitudes. Photometric data obtained after 1991 have been analyzed by Heckert (1994Heckert ( , 1996Heckert ( , 1998, Dapergolas et al (2000) and Kjurkchieva (2003). They found similar results in that the wave-like distortions on the light curves could be represented by two cool spots on the primary component.…”

“…The 1992 V-light curve and the computed curve by using the WD code. Zeilik et al (1994) and Kjurkchieva (2003) detected some depression on the light curves at different orbital phases.…”

“…177 in the catalog of Chromospherically Active Binary Stars (Strassmeier et al 1993). Since its eclipsing nature was discovered by Williams (1922), many light curves have been obtained by various authors (Yü 1923;Milone et al 1979;Jassur 1980;Sowell et al 1987;Naftilan et al 1987;Bedford et al 1987;Dapergolas et al 1988Dapergolas et al , 1989aDapergolas et al ,b, 1994Zeilik et al 1989Zeilik et al , 1991Kjurkchieva et al 2003). These workers have shown that the light curve of CG Cyg changes over short and long time intervals.…”

“…A third minimum at phase 0.36 detected by Bedford et al (1987) was attributed to the circumstellar material located in the orbital plane. Such depressions in the light curve Send offprint requests to: M. Afşar, e-mail: afsar@astronomy.sci.ege.edu.tr Tables 2, 3 and 5 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/420/595 have been observed recently by Kjurkchieva et al (2003) at phases 0.17 and 0.78.…”

“…In addition, they noted that the variations in Hα do not seem to be related to the presence of photometric spots. The most recent spectroscopic observations in the spectral region around the Hα line of CG Cyg were made by Kjurkchieva et al (2003). They clearly revealed a third absorption line between the spectral profiles of the components both in the Hα and Fe I 6678 lines.…”