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
e-mail: bily@public.km.yn.cn
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