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

Authors

J. Y. Choi, Chungbuk National University
I. G. Shin, Chungbuk National University
S. Y. Park, Chungbuk National University
C. Han, Chungbuk National University
A. Gould, The Ohio State University
T. Sumi, Osaka University
A. Udalski, Uniwersytet Warszawski
J. P. Beaulieu, Institut d’Astrophysique de Paris
R. Street, Las Cumbres Observatory Global Telescope Network, Inc
M. Dominik, University of St Andrews
W. Allen
L. A. Almeida, Instituto Nacional de Pesquisas Espaciais
M. Bos, Molehill Astronomical Observatory
G. W. Christie, Stardome Observatory, Auckland
D. L. Depoy, Texas A&M University
S. Dong, Institute for Advanced Studies
J. Drummond, Possum Observatory
A. Gal-Yam, Weizmann Institute of Science Israel
B. S. Gaudi, The Ohio State University
C. B. Henderson, The Ohio State University
L. W. Hung, University of California, Los Angeles
F. Jablonski, Instituto Nacional de Pesquisas Espaciais
J. Janczak, The Ohio State University
C. U. Lee, Korea Astronomy and Space Science Institute
F. Mallia, Campo Catino Austral Observatory
A. Maury, Campo Catino Austral Observatory
J. McCormick, Farm Cove Observatory
D. McGregor, The Ohio State University
L. A.G. Monard, Bronberg Observatory
D. Moorhouse, Kumeu Observatory
J. A. Muñoz, Universitat de València
T. Natusch, Stardome Observatory, Auckland
C. Nelson, The University of Arizona

Document Type

Article

Publication Date

5-20-2012

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 t E 2.7days 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. © 2012. The American Astronomical Society. All rights reserved.

Publication Source (Journal or Book title)

Astrophysical Journal

Recommended Citation

Choi, J., Shin, I., Park, S., Han, C., Gould, A., Sumi, T., Udalski, A., Beaulieu, J., Street, R., Dominik, M., Allen, W., Almeida, L., Bos, M., Christie, G., Depoy, D., Dong, S., Drummond, J., Gal-Yam, A., Gaudi, B., Henderson, C., Hung, L., Jablonski, F., Janczak, J., Lee, C., Mallia, F., Maury, A., McCormick, J., McGregor, D., Monard, L., Moorhouse, D., Muñoz, J., Natusch, T., & Nelson, C. (2012). Characterizing lenses and lensed stars of high-magnification single-lens gravitational microlensing events with lenses passing over source stars. Astrophysical Journal, 751 (1) https://doi.org/10.1088/0004-637X/751/1/41