When ellipsoidal variables eclipse, they produce a light curve that is typified by the star system 0 Lyrae. Because the stars are distorted, the light curve away from an eclipse is not flat, but rather shows a smooth variation. Moreover, in general, the surface of a star is not uniformly bright, because of limb darkening, so that during an eclipse the amount of light from the eclipsed star that is blocked out varies through the eclipse and the eclipse is therefore not flat-bottomed. The distortion of the stars and gravity darkening exacerbates this effect. The light curve of the eclipsing system is never flat but shows a smooth variation throughout the cycle If the distortion and limb darkening are not too large, it is possible to make allowance for them. When allowance has been made, by a process that is called rectification of the light curve, the light curve should look much more like an Algol type; the analysis of the light curve can then proceed as before. In the star p Lyrae itself, the stars are so close and one of the stars is so distorted by the companion, that the outer layers are more attracted to the companion than to itself, and it spills matter down on to the com¬panion’s surface. Such a star is called a SEMI-DETACHED BINARY SYSTEM.

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