OGLE-2016-BLG-1266: A Probable Brown-Dwarf/Planet Binary at the Deuterium Fusion Limit
We report the discovery, via the microlensing method, of a new very-low-mass binary system. By combining measurements from Earth and from the Spitzer telescope in Earth-trailing orbit, we are able to measure the microlensing parallax of the event, and find that the lens likely consists of an (12.0 \pm 0.6) M3 + (15.7 \pm 1.5) M3 super-Jupiter / brown-dwarf pair. The binary is located at a distance of (3.08 \pm 0.18) kpc in the Galactic Plane, and the components have a projected separation of (0.43 \pm 0.03) AU. Two alternative solutions with much lower likelihoods are also discussed, an 8- and 6-M3 model and a 90- and 70-M3 model. Although disfavored at the 3-o and 5-o levels, these alternatives cannot be rejected entirely. We show how the more-massive of these models could be tested with future direct imaging.