SIMBAD references

Complete BV light curves of the W Ursae Majoris binary V396 Mon are presented. The present CCD photometric observations reveal that the light curves of the system are obviously asymmetric, with the primary maximum brighter than the secondary maximum (the ``O'Connell effect''). The light curves are analyzed by means of the latest version of the Wilson-Devinney code. The results show that V396 Mon is a W-subtype W UMa contact binary with a mass ratio of 0.402. The asymmetry of the light curves is explained by a cool spot on the secondary component. The nature of the overluminosity of the secondary of a W UMa-type system is analyzed. It is shown that the overluminosity of the secondary is clearly related to the mass of the primary and that, for a W UMa system, the higher the mass of the primary, the greater the overluminosity of the secondary. In addition, the overluminosity of the secondary is also related to its own density: the lower the density of the secondary, the greater its overluminosity.