W Corvi, a contact binary with large temperature difference

The star W Corvi seems to be another member of the class of poorly understood close binaries in or near physical contact but far from thermal contact. Three new photoelectric light curves of W Crv in B and V colours, obtained for the years 1981/82, 1988 and 1993, confirm that this short-period (P=0.388 d) eclipsing binary star has substantially differing eclipse depths (0.6 mag brighter at secondary eclipse than at primary eclipse) and a variable light curve. During 1981, there was no difference in brightness between the two maxima, but in all other years with photoelectric data available, the star was 0.1 mag fainter at phase 0.75 than at phase 0.25. The symmetric 1981 light variation can be fitted in two fairly different ways, both requiring starspots: the first is a contact system with the secondary star temperature 83 per cent that of the primary, but with a bright spot on the inner face (at the neck) of the secondary; and the second is a possibly detached system with the secondary temperature 95 per cent that of the primary, but with a dark spot on the secondary star directly opposite the neck. The asymmetric 1988 and 1993 data require an additional dark spot on the visible side at phase 0.75. I discuss this star in the context of both evolutionary and luminosity transfer theory.