Astron. Astrophys. Suppl. Ser. 137, 217-221
X.B. Zhang1,2 and R.X. Zhang1
Send offprint request: X.B. Zhang
1 - Beijing Astronomical Observatory, Chinese Academy of Sciences, Bejing 100101, China
e-mail: xzhang@class1.bao.ac.cn
2 - Chinese Academy of Sciences-Peking University joint Beijing
Astrophysical Center, Beijing 100871, China
Received July 22; accepted August 31, 1998
We present new UBV photoelectric photometry and high-resolution H spectroscopy of the RS CVn system 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 Gem.
Key words: stars: Gem; activity -- binaries: close
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