Confirmation of the OGLE-2005-BLG-169 planet signature and characteristics with lens-source proper motion detection

الأصل · EN

We present Keck NIRC2 high angular resolution adaptive optics observations of the microlensing event OGLE-2005-BLG-169, taken 8.21 years after the discovery of this planetary system. For the first time for a microlensing planetary event, the source and the lens are completely resolved, providing a precise measurement of their heliocentric relative proper motion, μrel,helio=7.44 ± 0.17 mas yr⁻¹. This confirms and refines the initial model presented in the discovery paper and rules out a range of solutions that were allowed by the microlensing light curve. This is also the first time that parameters derived from a microlensing planetary signal are confirmed, both with Keck measurements, presented in this paper, and independent measurements obtained with the Hubble Space Telescope in I, V and B bands, presented in a companion paper. Hence, this new measurement of μrel,helio, as well as the measured brightness of the lens in H band, enabled the mass and distance of the system to be updated: a Uranus-mass planet (mp=13.2± 1.3 M⊕) orbiting a K5-type main sequence star (M*=0.65± 0.05 M) separated by a⊥=3.4± 0.3 AU, at the distance DL=4.0± 0.4 kpc from us.