A&A Supplement Ser., Vol. 125, November I 1997, 475-478
Received November 20, 1996; accepted January 30, 1997
Shengbang Qian, Qingyao Liu, Yulan Yang, Shenghong Gu, and Zhangkui Huang
Send offprint request: Qian Shenbang
Yunnan Observatory, Academia Sinica, Kunming, China
New BV light curves of the short-period eclipsing binary system DD Mon have been obtained. Light-curve variability is seen in both B and V bands as compared with the light curves obtained in 1986 by Yamasaki et al. (1990). The light curves are analyzed by using Wilson-Devinney's synthetic light-curve program, and the present photometric solution reveals that DD Mon is a near-contact binary with the secondary component filling the Roche lobe. Combined with Yamasaki et al.'s (1990) spectroscopic results, absolute quantities of DD Mon are derived: mass of the primary , mass of the secondary , radius of the primary , radius of the secondary . These results show that the components of DD Mon have evolved away from the ZAMS and through a mass-transfer process to the present semi-detached state. The variation in shape of the light curve may be caused by the evolution of the system and the activity of dark spots.
keywords: stars: DD Mon -- binaries: eclipsing -- stars: fundamental parameters