The study of W UMa binary systems give a wealth of information about its nature as well as about its parent body (if any), like clusters. In this paper, we present the I passband photometric solutions of four W UMa binaries in the open cluster Berkeley 39 using the latest version of W-D program. The result shows that, two binary systems are W-subtype W UMa binary systems and another two systems are H-subtype W UMa binary systems. No third body is found in any of the four systems. We found a correlation between the period and mass-ratio as well as temperature and mass-ratio for the respective variables which is similar to the relationship between mass ratio and total mass of the contact binaries as shown by van't Veer (1996) and Li et al. (2008).
We present the photometric solutions of the variable star V30 ⋆ that is in the foreground of intermediate open cluster NGC 7789. The observations were done in the V passband using the 2 m telescope at the IUCAA-Girawali Observatory in India. The analysis is done using the Wilson-Devinney Code ( 2003) and the fitted light curve is presented. The photometric solutions reveal a W-subtype contact configuration. The photometric mass ratio is found to be 0.395 and the absolute masses and radii for the components are deduced as 1.25M s and 0.97R s for the primary and 0.49M s and 0.93R s for the secondary, respectively. No signature of third light is found in the system.
We present the combined BVI multicolor photometric solutions of seven EW variables in the old open cluster Berkeley 39. The observations were carried out in the B and V passbands from the 2 m telescope at the IUCAA-Girawali Observatory in India. The analysis is done using the 2003 version of the Wilson-Devinney code and the fitted light curves are presented. The light curves appear to be symmetric in all the passbands. The photometric solutions suggest that the variables are W-type systems. The new ephemeris indicates that the orbital periods of the studied variables have not changed during the timespan of observations. Revised orbital period, absolute mass, radius and luminosity of the respective variables are presented. The absolute physical parameters of the variables follow the trend of field EW stars. Comparing the results obtained with the other theoretical works, we suggest that there is an excess loss of mass and angular momentum in these systems which may be due to their short period and relatively young age, possibly due to the presence of a third component or the initial detached period being less than 2 d.
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