Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars

J.-Y Choi; S.-Y Park; C. Han; A. Gould; T. Sumi; S. Hardis; M. Mathiasen; A. Udalski; J.-P. Beaulieu; Uffe Gråe Jørgensen; Kennet Bomann West Harpsøe; Jesper Fælling Skottfelt

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

Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars

J.-Y Choi, S.-Y Park, C. Han, A. Gould, T. Sumi, S. Hardis, M. Mathiasen, A. Udalski, J.-P. Beaulieu, Uffe Gråe Jørgensen, Kennet Bomann West Harpsøe, Jesper Fælling Skottfelt

Astrophysics and Planetary Science

27 Citations (Scopus)

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 θ_E 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.

Original language	English
Journal	Astrophysical Journal
Volume	751
Issue number	1
Pages (from-to)	41
ISSN	0004-637X
DOIs	https://doi.org/10.1088/0004-637X/751/1/41
Publication status	Published - 20 May 2012

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Choi, J. -Y., Park, S. -Y., Han, C., Gould, A., Sumi, T., Hardis, S., Mathiasen, M., Udalski, A., Beaulieu, J-P., Jørgensen, U. G., Harpsøe, K. B. W., & Skottfelt, J. F. (2012). Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars. Astrophysical Journal, 751(1), 41. https://doi.org/10.1088/0004-637X/751/1/41

Choi, J-Y, Park, S-Y, Han, C, Gould, A, Sumi, T, Hardis, S, Mathiasen, M, Udalski, A, Beaulieu, J-P, Jørgensen, UG, Harpsøe, KBW & Skottfelt, JF 2012, 'Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars', Astrophysical Journal, vol. 751, no. 1, pp. 41. https://doi.org/10.1088/0004-637X/751/1/41

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title = "Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars",

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.",

author = "J.-Y Choi and S.-Y Park and C. Han and A. Gould and T. Sumi and S. Hardis and M. Mathiasen and A. Udalski and J.-P. Beaulieu and J{\o}rgensen, {Uffe Gr{\aa}e} and Harps{\o}e, {Kennet Bomann West} and Skottfelt, {Jesper F{\ae}lling}",

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T1 - Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars

AU - Choi, J.-Y

AU - Park, S.-Y

AU - Han, C.

AU - Gould, A.

AU - Sumi, T.

AU - Hardis, S.

AU - Mathiasen, M.

AU - Udalski, A.

AU - Beaulieu, J.-P.

AU - Jørgensen, Uffe Gråe

AU - Harpsøe, Kennet Bomann West

AU - Skottfelt, Jesper Fælling

PY - 2012/5/20

Y1 - 2012/5/20

N2 - 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.

AB - 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.

U2 - 10.1088/0004-637X/751/1/41

DO - 10.1088/0004-637X/751/1/41

M3 - Journal article

SN - 0004-637X

VL - 751

SP - 41

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

ER -

Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars

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