Explanation of the O’connell Effect of a Close Binary

Abstract

Based on the hypothesis that the circumstellar matter of a binary system is captured by its components a theoretical model for explaining the O’Connell effect of the close binary is given in this article. The results inferred from the model show that the late-type and/or short-period binaries can easily produce the obvious O’Connell effect and the occurrence of the O’Connell effect has no relation to the types of binaries. These conclusions are in accordance with the observed results. The observed O’Connell effects of six binary systems are explained by the model. For the three W-subtype W UMa binaries (i.e. YY Eri, BX Per and SW Lac), assuming that the density of the circumstellar matter captured by the primary is equal to that captured by the secondary, the densities of the circumstellar matter captured by the components are calculated and through further calculation it can be obtained that the amount of the O’Connell effect calculated is close to the one observed. As for the three A-subtype W UMa systems (i.e. CN And, FG Hya and AU Ser), assuming that the density of the circumstellar matter captured by one of the components is different from that captured by the other, the densities of the circumstellar matter captured by them are respectively calculated and the O’Connell effect theoretically calculated is compared with that observed, with the results showing that the consistency of the theoretically calculated O’Connell effect with the observed one is better than that obtained in the former case.