MICROLENSING SEARCH FOR PLANETS WITH TWO SIMULTANEOUSLY RISING SUNS

摘要

Among more than 200 extrasolar planet candidates discovered to date, there is no known planet orbiting around normal binary stars. In this Letter, we demonstrate that microlensing is a technique that can detect such planets. Microlensing discoveries of these planets are possible because the planet and host binary stars produce perturbations at a common region around center of mass of the binary stars and thus the signatures of both planet and binary can be detected in the light curves of high-magnification microlensing events. The ranges of the planetary and binary separations of systems for optimal detection vary depending on the planet mass. For a Jupiter-mass planet, we find that high detection efficiency is expected for planets located in the range of ～1-5 AU from the binary stars which are separated by ～0.15-0.5 AU.