The first photometric investigation and orbital period variation analysis of the W UMa type binary IK Bootis

Abstract

© The Author 2017. Published by Oxford University Press on behalf of the Astronomical Society of Japan. All rights reserved. With new CCD observations of the W UMa type binary IK Boo, we present the first investigation of photometric parameters and orbital period change. The BVRclight curve fit shows that IK Boo is a W-type contact system with a mass ratio of q = 1.146 and a shallow contact with a fill-out factor of f = 2.22%. The orbital period decrease was found to be a rate of −3.28 × 10−7d yr−1, corresponding to a mass transfer from the more massive to the less massive component with a rate of −2.83 × 10−6M yr−1. The inner and outer critical Roche lobes will contract and cause the contact degree to increase. Therefore, IK Boo may evolve into a deeper contact system. Furthermore, a possible cyclic variation was found with a period of 9.74 yr, which could be explained by the light-travel time effect due to the existence of a third companion in the system.