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

Abstract

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 $M_1=0.38\pm 0.04M_{\odot }$ ($0.50\pm 0.05M_{\odot })$ and $M_2=0.38\pm 0.04M_{\odot }$ ($0.55\pm 0.06M_{\odot }$) and the distance to the lens is $D_{\mathrm{L}}=2.77\pm 0.23$ kpc ($3.30\pm 0.29$ kpc). Here the physical parameters out and in the parenthesis are for the $u_0<0$ and $u_0>0$ solutions, respectively.

7 pages, 3 tables, 6 figures

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• Ground-based parallax confirmed by Spitzer: binary microlensing event MOA-2015-BLG-020
• Pixel Level Decorrelation in Service of the \textit{Spitzer} Microlens Parallax Survey
• OGLE-2014-BLG-1112LB: A Microlensing Brown Dwarf Detected Through the Channel of a Gravitational Binary-Lens Event
• The Science Case for an Extended Spitzer Mission