Revision of the photometric parameters of BS Cassiopeiae

Abstract

Seven charge-coupled device (CCD) photometric times of light minimum of the overcontact binary BS Cas which were obtained from 2007 August to November and one CCD light curve in the R band which was observed on 2007 September 24 and October 15, are presented. It is found that the light curve of BS Cas has characteristics like a typical EW-type light variation. The light curve obtained by us is symmetric and shows total eclipses, which is very useful for determining photometric parameters with high precision. Photometric solutions were derived by using the 2003 version of the Wilson–Devinney code. It shows that BS Cas is a W-subtype overcontact binary (f = 27.5% ± 0.4%) with a mass ratio of q = 2.7188 ± 0.0040. The temperature difference between the two components is 190 K. Analysis of the O–C curve suggests that the period of AE Phe shows a long-term continuous decrease at a rate of dP/dt = −2.45 × 10−7 d yr−1. The long-time period decrease can be explained by mass transfer from the primary to the secondary.