Gravitational microlensing of binary stars: Analysis of the OGLE-5 and OGLE-6 light curves

The microlensing curves for the OGLE-5 and OGLE-6 events are analyzed using a model in which a binary background star is lensed by a paint-like gravit ational lens, taking into account the emission of the lensing object. The p arameters of the gravitational lenses are determined. In both cases, the le nses appear to be brown dwarfs with masses M-L < 0.3M.. Theoretical lensing curves constructed using this model are compared with theoretical curves f or models with a single lensed background star for the cases of both dark a nd emitting gravitational lenses. Near the brightness maxima, all three mod els fit the observations well. The main differences occur in the wings of t he light curves: using a binary background-star model provides a better des cription of the shallow wings of the light curves.