摘要：We report the discovery of a giant planet in the OGLE-2017-BLG-1522 microlensing event. The planetary perturbations were clearly identified by high-cadence survey experiments despite the relatively short event timescale of tE∼7.5 days. The Einstein radius is unusually small, θE=0.065 mas, implying that the lens system either has very low mass or lies much closer to the microlensed source than the Sun, or both. A Bayesian analysis yields component masses = - + - (M , M ) (46 , 0.75+ ) M host planet 25 79 0.40 1.26 J and source-lens distance = - D 0.99+ kpc LS 0.54 0.91 , implying that this is a browndwarf/ Jupiter system that probably lies in the Galactic bulge, a location that is also consistent with the relatively low lens-source relative proper motion μ=3.2±0.5mas yr−1. The projected companion-host separation is - 0.59+ au 0.11 0.12 , indicating that the planet is placed beyond the snow line of the host, i.e., asl∼0.12 au. Planet formation scenarios combined with the small companion-host mass ratio q∼0.016 and separation suggest that the companion could be the first discovery of a giant planet that formed in a protoplanetary disk around a brown-dwarf host.
关键词：binaries: general;brown dwarfs;gravitational lensing: micro;planetary systems
