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Published February 20, 2012 | Published
Journal Article Open

Microlensing Binaries Discovered through High-magnification Channel

Abstract

Microlensing can provide a useful tool to probe binary distributions down to low-mass limits of binary companions. In this paper, we analyze the light curves of eight binary-lensing events detected through the channel of high-magnification events during the seasons from 2007 to 2010. The perturbations, which are confined near the peak of the light curves, can be easily distinguished from the central perturbations caused by planets. However, the degeneracy between close and wide binary solutions cannot be resolved with a 3σ confidence level for three events, implying that the degeneracy would be an important obstacle in studying binary distributions. The dependence of the degeneracy on the lensing parameters is consistent with a theoretical prediction that the degeneracy becomes severe as the binary separation and the mass ratio deviate from the values of resonant caustics. The measured mass ratio of the event OGLE-2008-BLG-510/MOA-2008-BLG-369 is q ~ 0.1, making the companion of the lens a strong brown dwarf candidate.

Additional Information

© 2012 American Astronomical Society. Received 2011 September 15; accepted 2011 December 1; published 2012 February 1. Work by C.H. was supported by Creative Research Initiative Program (2009-0081561) of National Research Foundation of Korea. The OGLE project has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No. 246678. Work by B.S.G. and A.G. was supported in part by NSF grant AST-1103471. Work by B.S.G., A.G., R.W.P., and J.C.Y. was supported in part by NASA grant NNX08AF40G. Work by J.C.Y. was supported by a National Science Foundation Graduate Research Fellowship under grant No. 2009068160. Work by M.H. was supported by Qatar National Research Fund and Deutsche Forschungsgemeinschaft. TheMOA experiment was supported by JSPS22403003, JSPS20340052, JSPS18253002, and JSPS17340074. T.S. was supported by the grants JSPS18749004, MEXT19015005, and JSPS20740104. F.F., D.R., and J.S. were supported by the Communauté française de Belgique-Actions de recherche concert ées-Académie universitaire Wallonie-Europe.

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August 22, 2023
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