Y. Ravi Kiron,¹ K. Sriram,² and P. Vivekananda Rao^1
1Department of Astronomy, Osmania University, Hyderabad 500 007, India
²Korea Astronomy and Space Science Institute, Hwaam 61-1, Yuseong, Daejeon, 305-348, Republic of Korea

Abstract. CCD photometric observations of the eclipsing contact binaries (EW type) V3 and V4 of the cluster NGC 2539 were made in the B and V bands using the 2m telescope at the IUCAA-Girawali Observatory in India. The light curves have been obtained and using the Wilson-Devinney code, the combined photometric solutions have been presented here. The photometric solutions have revealed that both V3 and V4 are W-type contact binary systems with mass ratios of 0.806 and 1.001 respectively. Revised orbital periods, absolute masses and radii of the components have been obtained. New ephemerides indicate that the orbital periods of the variables have not changed much during the time span of the observations from 2003 to 2009. The estimated absolute parameters for the two variables V3 and V4 are in close agreement with the field EW-type binaries (Gazeas & Stepien 2008). The distance estimate for V3 is 1712±48$pc indicating that this could be a field star in the background of the cluster, while that for V4 is 1183±32$pc, suggesting it to be a possible member of the cluster. No third light is found in the systems.

Keywords: stars: binaries: eclipsing -- stars: binaries: general -- stars: distances -- open clusters and associations: general

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