* Astronomy

Title: OGLE-2013-BLG-0102LA,B: Microlensing binary with components at star/brown-dwarf and brown-dwarf/planet boundaries
Author: Y. K. Jung, A. Udalski, T. Sumi, C. Han, A. Gould, J. Skowron, S. Kozlowski, R. Poleski, L. Wyrzykowski, M. K. Szymanski, G. Pietrzynski, I. Soszynski, K. Ulaczyk, P. Pietrukowicz, P. Mróz, M. Kubiak, F. Abe, D. P. Bennett, I. A. Bond, C. S. Botzler, M. Freeman, A. Fukui, D. Fukunaga, Y. Itow, N. Koshimoto, P. Larsen, C. H. Ling, K. Masuda, Y. Matsubara, Y. Muraki, S. Namba, K. Ohnishi, L. Philpott, N. J. Rattenbury, To. Saito, D. J. Sullivan, D. Suzuki, P. J. Tristram, N. Tsurumi, K. Wada, N. Yamai, P. C. M. Yock, A. Yonehara, M. Albrow, J.-Y. Choi, D. L. DePoy, B. S. Gaudi, K.-H. Hwang, C.-U. Lee, H. Park, S. Owen, R. W. Pogge, I.-G. Shin, J. C. Yee

We present the analysis of the gravitational microlensing event OGLE-2013-BLG-0102. The light curve of the event is characterized by a strong short-term anomaly superposed on a smoothly varying lensing curve with a moderate magnification A_max~1.5. It is found that the event was produced by a binary lens with a mass ratio between the components of q=0.13 and the anomaly was caused by the passage of the source trajectory over a caustic located away from the barycenter of the binary. From the analysis of the effects on the light curve due to the finite size of the source and the parallactic motion of the Earth, the physical parameters of the lens system are determined. The measured masses of the lens components are M₁=0.096±0.013 solar masses and M₂=0.012±0.002 solar masses, which correspond to near the hydrogen-burning and deuterium-burning mass limits, respectively. The distance to the lens is 3.04±0.31 kpc and the projected separation between the lens components is 0.80±0.08 AU.

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