OGLE-2014-BLG-0289: Precise Characterization of a Quintuple-Peak Gravitational Microlensing Event

Abstract

We present the analysis of the binary-microlensing event OGLE-2014-BLG-0289. The event light curve exhibits very unusual five peaks where four peaks were produced by caustic crossings and the other peak was produced by a cusp approach. It is found that the quintuple-peak features of the light curve provide tight constraints on the source trajectory, enabling us to precisely and accurately measure the microlensing parallax $\ddot{I}{€}_{\mathrm{E}}$. Furthermore, the three resolved caustics allow us to measure the angular Einstein radius $\thetae$. From the combination of $\ddot{I}{€}_{\mathrm{E}}$ and $\thetae$, the physical lens parameters are uniquely determined. It is found that the lens is a binary composed of two M dwarfs with masses $M_1=0.52\pm 0.04M_{\odot }$ and $M_2=0.42\pm 0.03M_{\odot }$ separated in projection by $a_{\perp }=6.4\pm 0.5$ au. The lens is located in the disk with a distance of $D_{\mathrm{L}}=3.3\pm 0.3$~kpc. It turns out that the reason for the absence of a lensing signal in the {\it Spitzer} data is that the time of observation corresponds to the flat region of the light curve.

10 pages, 7 figures