CHARACTERIZING LENSES AND LENSED STARS OF HIGH-MAGNIFICATION SINGLE-LENS GRAVITATIONAL MICROLENSING EVENTS WITH LENSES PASSING OVER SOURCE STARS

Journal Article · Sun May 20 00:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/751/1/41· OSTI ID:22037253

Choi, J -Y; Shin, I -G; Park, S -Y; Han, C ^[1]; Gould, A; Gaudi, B S; Henderson, C B ^[2]; Sumi, T ^[3]; Udalski, A ^[4]; Beaulieu, J -P ^[5]; Street, R ^[6]; Dominik, M ^[7]; Allen, W ^[8]; Almeida, L A ^[9]; Bos, M ^[10]; Christie, G W ^[11]; Depoy, D L ^[12]; Dong, S ^[13]; Drummond, J ^[14]; Gal-Yam, A ^[15] ; Consortium, MiNDSTEp; others, and

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1. Department of Physics, Institute for Astrophysics, Chungbuk National University, Cheongju 371-763 (Korea, Republic of)
2. Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210 (United States)
3. Department of Earth and Space Science, Osaka University, Osaka 560-0043 (Japan)
4. Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland)
5. Institut d'Astrophysique de Paris, UMR7095 CNRS-Universite Pierre and Marie Curie, 98 bis boulevard Arago, 75014 Paris (France)
6. Las Cumbres Observatory Global Telescope Network, 6740B Cortona Dr, Suite 102, Goleta, CA 93117 (United States)
7. School of Physics and Astronomy, SUPA, University of St. Andrews, North Haugh, St. Andrews, KY16 9SS (United Kingdom)
8. Vintage Lane Observatory, Blenheim (New Zealand)
9. Instituto Nacional de Pesquisas Espaciais/MCTI, Sao Jose dos Campos, Sao Paulo (Brazil)
10. Molehill Astronomical Observatory, North Shore (New Zealand)
11. Auckland Observatory, P.O. Box 24-180, Auckland (New Zealand)
12. Department of Physics, Texas A and M University, College Station, TX (United States)
13. Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)
14. Possum Observatory, Patutahi (New Zealand)
15. Benoziyo Center for Astrophysics, Weizmann Institute (Israel)

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 {theta}{sub E} {approx} 0.08 mas combined with the short timescale of t{sub E} {approx} 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 {approx}0.84 M{sub Sun} 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.

• OSTI ID: 22037253
• Journal Information: Astrophysical Journal, Vol. 751, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTRONOMY
ASTROPHYSICS
BRIGHTNESS
DIAGRAMS
GALAXIES
GRAVITATIONAL LENSES
MASS
PLANETS
PROPER MOTION
STARS
VISIBLE RADIATION