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Characterizing lenses and lensed stars of high-magnification single-lens gravitational microlensing events with lenses passing over source starts

Citation

Choi, J-Y and Shin, I-G and Park, S-Y and Han, C and Gould, A and Sumi, T and Udalski, A and Beaulieu, J-P and Street, R and Dominik, M and Cole, AA and Greenhill, JG and The MuFUN Collaboration, The MOA Collaboration, The OGLE Collaboration, The PLANET Collaboration, The RoboNet Collaboration, The MiNDSTEp Consortium, Characterizing lenses and lensed stars of high-magnification single-lens gravitational microlensing events with lenses passing over source starts, The Astrophysical Journal, 751, (1) Article 41. ISSN 0004-637X (2012) [Refereed Article]


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Copyright Statement

Copyright 2012 The American Astronomical Society

DOI: doi:10.1088/0004-637X/751/1/41

Abstract

We present the analysis of the light curves of nine high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/MOA-2011-BLG-325. For all of the events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For seven events, we measure the Einstein radii and the lens-source relative proper motions. Among them, five events are found to have Einstein radii of less than 0.2 mas, making the lenses very low mass star or brown dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein radius of θE ~ 0.08 mas combined with the short timescale of tE ~ 2.7 days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of ~0.84 M is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we did not find planetary signals for any of the events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio.

Item Details

Item Type:Refereed Article
Keywords:Galaxy: bulge; gravitational lensing: micro
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Stellar Astronomy and Planetary Systems
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Cole, AA (Associate Professor Andrew Cole)
Author:Greenhill, JG (Dr John Greenhill)
ID Code:79939
Year Published:2012
Web of Science® Times Cited:21
Deposited By:Mathematics and Physics
Deposited On:2012-10-15
Last Modified:2017-11-06
Downloads:0

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