OGLE-2016-BLG-1469L: Microlensing Binary Composed of Brown Dwarfs

Abstract

We report the discovery of a binary composed of two brown dwarfs, based on the analysis of the microlensing event OGLE-2016-BLG-1469. Thanks to detection of both finite-source and microlens-parallax effects, we are able to measure both the masses $M_1\sim 0.05M_{\odot }$, $M_2\sim 0.01M_{\odot }$, and distance $D_{\mathrm{L}}\sim 4.5$ kpc, as well as the projected separation $a_{\perp }\sim 0.33$ au. This is the third brown-dwarf binary detected using the microlensing method, demonstrating the usefulness of microlensing in detecting field brown-dwarf binaries with separations less than 1 au.

8 pages, 8 figures