Photometry and spectroscopy of the RS CVn system σ Geminorum
Beijing Astronomical Observatory, Chinese Academy of Sciences, Bejing 100101, China
2 Chinese Academy of Sciences-Peking University joint Beijing Astrophysical Center, Beijing 100871, China
Send offprint request to: X.B. Zhang
Accepted: 31 August 1998
We present new UBV photoelectric photometry and high-resolution H spectroscopy of the RS CVn system σ Gem made in 1993-1994. A brief photometric analysis for the new light curves is carried out using the Wilson-Devinney method with spot approximation based on the Roche model. The result suggests the probable presence of two cool spots on the K1 III primary around the phases of and . The spot activity is discussed in connection with the chromospheric H emission. The enhanced H core emission is found to vary with phase and shows distinct anti-correlation with the spot regions. It may be an indication for the existence of plage regions on σ Gem.
Key words: stars: σ Gem; activity / binaries: close
© European Southern Observatory (ESO), 1999