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Photometric study and period analysis of the W UM-type binary system QW Gem

Kun Wang


New multi-color photometric observations of the previously unstudied contact binary QW Gem are presented. Completely covered BV RI band light curves were obtained, including four new times of light minima. The light curves were simultaneously analyzed with the 2013 version of the Wilson-Devinney method, assuming a third light. The photometric solutions confirm that QW Gem is a W-type W UMa system with a fill-out factor of f ~ 17%. The absolute parameters of the components were determined to be Mp = 1.33 ± 0.03 M, Ms = 0.44 ± 0.01 M, Rp = 1.25 ± 0.01 R, Rs = 0.77 ± 0.01 R, Lp = 1.68 ± 0.03 L and Ls = 0.68 ± 0.01 L. The orbital period change of QW Gem was investigated by the O − C method using all available data. The results show that this binary system could have undergone a continuous orbital period decrease during the past two decades at a rate of about dP/dt = −2.55 × 10 −7 d yr−1. In addition, a small-amplitude oscillation was detected to be superimposed on a long-term decrease.


stars: binaries: eclipsing — stars: individual (QW Gem)

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