Astrophysics and Space Science

, Volume 146, Issue 1, pp 1–12 | Cite as

Simultaneous light and velocity curve solution and probable starspot activities for the W UMa system U Pegasi

  • Zhai Di-Sheng
  • Lu Wen-Xian
  • Zhang Xiao-Yu


In view of the fair agreement between the photometricqptm by Zhaiet al. (1984) and the spectroscopic mass ratioqsp by Lu (1985), a simultaneous light and velocity curve solution was carried out for U Peg with the Wilson-Devinney program. For purpose of comparison, we performed separate light and velocity curve solutions and then the simultaneous photometric-spectroscopic solution. The improved absolute dimensions turned out to beM1=0.387±0.004M,M2=1.167±0.015M,R1=0.754±0.007R, andR2=1.236±0.004R. Based on the simultaneous solution, a thorough analysis was made for total of nineBV light curves of U Peg obtained from 1950 to 1984. It was found that (1) the complexities on light curves in 1958, 1961, and 1970 can be reproduced by spot model and there may be spot cycle with the period at least larger than 28 years; (2) the common envelope of the contact binary U Peg appears to be oscillation instability with the over-contact degree varied by a large percentage.


Large Percentage Light Curf Fair Agreement Velocity Curve Curve Solution 
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Copyright information

© Kluwer Academic Publishers 1988

Authors and Affiliations

  • Zhai Di-Sheng
    • 1
  • Lu Wen-Xian
    • 2
  • Zhang Xiao-Yu
    • 1
  1. 1.Beijing ObservatoryAcademia SinicaBeijingChina
  2. 2.Shanghai ObservatoryAcademia SinicaShanghaiChina

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