Lensing of Invisible Stars by Brown Dwarfs

To detect brown dwarfs in the dark galactic halo through gravitational lensing, experiments follow the luminosity of millions of stars to observe a few lensing events par year. The luminosity of a star too faint to be continuously followed can be temporarily increased above the detection limit by a lensing. The detection of these invisible stars would increase the number of events by a factor 2 to 7, and moreover their presence would confirm the lensing interpretation of events due to continuously monitored stars.