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

J. -Y. Choi, I. -G. Shin, S. -Y. Park, C. Han*, A. Gould, T. Sumi, A. Udalski, J. -P. Beaulieu, R. Street, M. Dominik, W. Allen, L. A. Almeida, M. Bos, G. W. Christie, D. L. Depoy, S. Dong, J. Drummond, A. Gal-Yam, B. S. Gaudi, C. B. HendersonL. -W. Hung, F. Jablonski, J. Janczak, C. -U. Lee, F. Mallia, A. Maury, J. McCormick, D. McGregor, L. A. G. Monard, D. Moorhouse, J. A. Munoz, T. Natusch, C. Nelson, B. -G. Park, R. W. Pogge, T. -G. "TG" Tan, G. Thornley, J. C. Yee, F. Abe, E. Barnard, J. Baudry, D. P. Bennett, I. A. Bond, C. S. Botzler, M. Freeman, A. Fukui, K. Furusawa, F. Hayashi, J. B. Hearnshaw, S. Hosaka, Y. Itow, K. Kamiya, P. M. Kilmartin, S. Kobara, A. Korpela, W. Lin, C. H. Ling, S. Makita, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, M. Nagaya, K. Nishimoto, K. Ohnishi, T. Okumura, K. Omori, Y. C. Perrott, N. Rattenbury, To Saito, L. Skuljan, D. J. Sullivan, D. Suzuki, K. Suzuki, W. L. Sweatman, S. Takino, P. J. Tristram, K. Wada, P. C. M. Yock, M. K. Szymanski, M. Kubiak, G. Pietrzynski, I. Soszynski, R. Poleski, K. Ulaczyk, L. Wyrzykowski, S. Kozllowski, P. Pietrukowicz, M. D. Albrow, E. Bachelet, V. Batista, C. S. Bennett, R. Bowens-Rubin, S. Brillant, A. Cassan, A. Cole, E. Corrales, Ch. Coutures, S. Dieters, D. Dominis Prester, J. Donatowicz, P. Fouque, J. Greenhill, S. R. Kane, J. Menzies, K. C. Sahu, J. Wambsganss, A. Williams, M. Zub, A. Allan, D. M. Bramich, P. Browne, N. Clay, S. Fraser, K. Horne, N. Kains, C. Mottram, C. Snodgrass, I. Steele, Y. Tsapras, K. A. Alsubai, V. Bozza, M. J. Burgdorf, S. Calchi Novati, P. Dodds, S. Dreizler, F. Finet, T. Gerner, M. Glitrup, F. Grundahl, S. Hardis, K. Harpsoe, T. C. Hinse, M. Hundertmark, U. G. Jorgensen, E. Kerins, C. Liebig, G. Maier, L. Mancini, M. Mathiasen, M. T. Penny, S. Proft, S. Rahvar, D. Ricci, G. Scarpetta, S. Schaefer, F. Schoenebeck, J. Skottfelt, J. Surdej, J. Southworth, F. Zimmer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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 theta(E) similar to 0.08 mas combined with the short timescale of t(E) similar to 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 similar to 0.84M(circle dot) 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 languageEnglish
Article number41
Number of pages14
JournalAstrophysical Journal
Volume751
Issue number1
DOIs
Publication statusPublished - 20 May 2012

Keywords

  • Galaxy: bulge
  • gravitational lensing: micro
  • STELLAR ATMOSPHERE MODELS
  • GALACTIC BULGE
  • LIGHT CURVES
  • CHEMICAL EVOLUTION
  • DWARF
  • PHOTOMETRY
  • PLANETS
  • GIANT
  • SIGNATURES
  • SYSTEMS

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