The eclipses of starspots

Formulae are set out from which the light loss may be derived in a close binary system in which a component affected by a starspot, of the type considered previously (Budding, 1977) is also in eclipse, in such a way that the starspot itself is undergoing eclipse. In this way the hitherto postponed problem of thecombination of eclipse and maculation effects — which are sometimes believed to be present, e.g., in RS CVn-stars — is treated, and shown to be reducible to expressions involving algebraic or elliptic integrals.A more practical approach using a small-spot approximation is given, and demonstrated on an example. Such an approach should be easy to manage by computer, and is expected to find a ready application in the analysis of active cool, close binaries.