OGLE-2015-BLG-0196: Ground-based Gravitational Microlens Parallax Confirmed By Space-Based Observation


Abstract in English

In this paper, we present the analysis of the binary gravitational microlensing event OGLE-2015-BLG-0196. The event lasted for almost a year and the light curve exhibited significant deviations from the lensing model based on the rectilinear lens-source relative motion, enabling us to measure the microlens parallax. The ground-based microlens parallax is confirmed by the data obtained from space-based microlens observations using the {it Spitzer} telescope. By additionally measuring the angular Einstein radius from the analysis of the resolved caustic crossing, the physical parameters of the lens are determined up to the two-fold degeneracy: $u_0<0$ and $u_0>0$ solutions caused by the well-known ecliptic degeneracy. It is found that the binary lens is composed of two M dwarf stars with similar masses $M_1=0.38pm 0.04 M_odot$ ($0.50pm 0.05 M_odot)$ and $M_2=0.38pm 0.04 M_odot$ ($0.55pm 0.06 M_odot$) and the distance to the lens is $D_{rm L}=2.77pm 0.23$ kpc ($3.30pm 0.29$ kpc). Here the physical parameters out and in the parenthesis are for the $u_0<0$ and $u_0>0$ solutions, respectively.

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