A Multicolour Photometric Study for the W Ursae Majoris Type Binary LR Camelopardalis

A CCD multicolour photometry for the eclipsing binary LR Camelopardalis, obtained on 2008 December 19 and 2010 January 29 and 30 at the Xinglong Station of NAOC, is presented. Using the Wilson–Devinney binary code, a photometric solution was simultaneously derived from $BVR$ light curves. The results show that LR Cam belongs to a W-type contact binary, with a mass ratio of $q =$ 0.300(1) and an overcontact degree of $f =$ 23.5(5)%, indicating that LR Cam is a weak-contact binary. The asymmetric light curves (i.e., the O’Connell effect) were modeled by a dark spot on the more massive component. From the ( $O-C$ ) curve of LR Cam, it is found that the orbital period shows a sine-like variation superimposed on a secular period increase. The quasi-sinusoidal variation, with $A =$ 0 $^{\rm d}\!\!\!.$ 0039(1), $P_{3} =$ 5.34(2) yr, and $e^\prime =$ 0.56(3), may more likely result from a light-time effect via the presence of a third body. The long-term period increases at a rate of $dP/dt = +$ 0.65(9) $\times$ 10 $^{-7}\ $ d yr $^{-1}$ , which may be interpreted by mass transfer from the less-massive component to the more-massive one. With mass transferring, LR Cam may evolve into a broken-contact binary.