New Photometric Investigation of the Low-Mass-Ratio Contact Binary Star V1853 Orionis.

Four-color charge-coupled device (CCD) light curves in the B, V, Rc and Ic bands of the total-eclipsing binary system V1853 Orionis (V1853 Ori) are presented. By comparing our light curves with those published by previous investigators, it is determined that the O'Connell effect on the light curves has disappeared. By analyzing those multi-color light curves with the Wilson-Devinney code (W-D code), it is discovered that V1853 Ori is an A-type intermediate-contact binary with a degree of contact factor of f = 33.3%(3.7%) and a mass ratio of q = 0.1896(0.0013). Combining our 10 newly determined times of light minima together with others published in the literature, the period changes of the system are investigated. We found that the general trend of the observed minus calculated (O - C) curve shows a downward parabolic variation that corresponds to a long-term decrease in the orbital period with a rate of dP/dt = -1.96(0.46) x 10(-7) d yr(-1). The long-term period decrease could be explained by mass transfer from the more-massive component to the less-massive one. By combining our photometric solutions with data from Gaia DR2, absolute parameters were derived as M-1 = 1.20 M-circle dot, M-2 = 0.23 M-circle dot, R-1 = 1.36 R-circle dot and R-2 = 0.66 R-circle dot. The long-term period decrease and intermediate-contact configuration suggest that V1853 Ori will evolve into a high fill-out overcontact binary.