Photometric and periodic investigation of W type W UMa eclipsing binary BB Peg

Abstract

Photometry of the W UMa type eclipsing binary BB Peg in V and R Johnson filters was done during few nights in September and October 2016; the light curves were obtained in the Dr. Mojtahedi observatory of the University of Birjand. Data reduction is performed by using IRIS software. Orbital parameters are obtained from light curves analysis that is done using PHOEBE software. Then, radial velocity information is used to obtain the absolute parameters of the system. Some minimum light times of the system are obtained, and for finding a new ephemeris of the system, variations in the orbital period of BB Peg are analyzed through the addition of the new minimum light times to the O-C diagram. It seems that the period change is due to the light time effect. Using the third and fourth star, a justifiable fit is obtained. However, this fit is unconfirmed and may need revision when further data is obtained. Additionally, the variation can be attributed to other sources, such as magnetic cycles or non-conservative mass transfer from the system.