* Astronomy

Title: OGLE-2016-BLG-1469L: Microlensing Binary Composed of Brown Dwarfs
Author: C. Han, A. Udalski, T. Sumi, A. Gould, M. D. Albrow, S.-J. Chung, Y. K. Jung, Y.-H. Ryu, I.-G. Shin, J. C. Yee, W. Zhu, S.-M. Cha, S.-L. Kim, D.-J. Kim, C.-U. Lee, Y. Lee, B.-G. Park, I. Soszynski, P. Mróz, P. Pietrukowicz, M. K. Szymanski, J. Skowron R. Poleski, S. Kozlowski, K. Ulaczyk, M. Pawlak, F. Abe, Y. Asakura, D. P. Bennett, I. A. Bond, A. Bhattacharya, M. Donachie, M. Freeman, A. Fukui, Y. Hirao, Y. Itow, N. Koshimoto, M. C. A. Li, C. H. Ling, K. Masuda, Y. Matsubara, Y. Muraki, M. Nagakane, K. Ohnishi, H. Oyokawa, N. J. Rattenbury, To. Saito, A. Sharan, D. J. Sullivan, D. Suzuki, P. J. Tristram, T. Yamada, T. Yamada, A. Yonehara, R. Barry

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_1~0.05 solar masses, M_2~0.01 solar masses, and distance D_L~4.5 kpc, as well as the projected separation a_\perp~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.

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