THE SECOND MULTIPLE-PLANET SYSTEM DISCOVERED BY MICROLENSING: OGLE-2012-BLG-0026Lb, c—A PAIR OF JOVIAN PLANETS BEYOND THE SNOW LINE

Abstract

We report the discovery of a planetary system from observation of the high-magnification microlensing event OGLE-2012-BLG-0026. The lensing light curve exhibits a complex central perturbation with multiple features. We find that the perturbation was produced by two planets located near the Einstein ring of the planet host star. We identify 4 possible solutions resulting from the well-known close/wide degeneracy. By measuring both the lens parallax and the Einstein radius, we estimate the physical parameters of the planetary system. According to the best-fit model, the two planet masses are ~0.11 M_Jupiter and 0.68 M_Jupiter and they are orbiting a G-type main sequence star with a mass ~0.82 M_Sun. The projected separations of the individual planets are beyond the snow line in all four solutions, being ~3.8 AU and 4.6 AU in the best-fit solution. The deprojected separations are both individually larger and possibly reversed in order. This is the second multi-planet system with both planets beyond the snow line discovered by microlensing. This is the only such a system (other than the Solar System) with measured planet masses without sin(i) degeneracy. The planetary system is located at a distance 4.1 kpc from the Earth toward the Galactic center. It is very likely that extra light from stars other than the lensed star comes from the lens itself. If this is correct, it will be possible to obtain detailed information about the planet-host star from follow-up observation.