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arXiv · 0907.3471

Mass measurement of a single unseen star and planetary detection efficiency for OGLE 2007-BLG-050

V. Batista·Subo Dong·A. Gould·J. P. Beaulieu·A. Cassan·G. W. Christie·C. Han·A. Udalski·W. Allen·D. L. DePoy·A. Gal-Yam·B. S. Gaudi·B. Johnson·S. Kaspi·C. U. Lee·D. Maoz·J. McCormick·I. McGreer·B. Monard·T. Natusch·E. Ofek·B. -G. Park·R. W. Pogge·D. Polishook·A. Shporer·M. D. Albrow·D. P. Bennett·S. Brillant·M. Bode·D. M. Bramich·M. Burgdorf·J. A. R. Caldwell·H. Calitz·A. Cole·K. H. Cook·Ch. Coutures·S. Dieters·M. Dominik·D. Dominis Prester·J. Donatowicz·P. Fouqué·J. Greenhill·M. Hoffman·K. Horne·U. G. Jørgensen·N. Kains·S. Kane·D. Kubas·J. B. Marquette·R. Martin·P. Meintjes·J. Menzies·K. R. Pollard·K. C. Sahu·C. Snodgrass·I. Steele·Y. Tsapras·J. Wambsganss·A. Williams·M. Zub·Ł. Wyrzykowski·M. Kubiak·M. K. Szymański·G. Pietrzyński·I. Soszyński·O. Szewczyk·K. Ulaczyk·F. Abe·I. A. Bond·A. Fukui·K. Furusawa·J. B. Hearnshaw·S. Holderness·Y. Itow·K. Kamiya·P. M. Kilmartin·A. Korpela·W. Lin·C. H. Ling·K. Masuda·Y. Matsubara·N. Miyake·Y. Muraki·M. Nagaya·K. Ohnishi·T. Okumura·Y. C. Perrott·N. Rattenbury·To. Saito·T. Sako·L. Skuljan·D. Sullivan·T. Sumi·W. L. Sweatman·P. J. Tristram·P. C. M. Yock
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Abstract

We analyze OGLE-2007-BLG-050, a high magnification microlensing event (A ~ 432) whose peak occurred on 2 May, 2007, with pronounced finite-source and parallax effects. We compute planet detection efficiencies for this event in order to determine its sensitivity to the presence of planets around the lens star. Both finite-source and parallax effects permit a measurement of the angular Einstein radius \theta_E = 0.48 +/- 0.01 mas and the parallax \pi_E = 0.12 +/- 0.03, leading to an estimate of the lens mass M = 0.50 +/- 0.14 M_Sun and its distance to the observer D_L = 5.5 +/- 0.4 kpc. This is only the second determination of a reasonably precise (<30%) mass estimate for an isolated unseen object, using any method. This allows us to calculate the planetary detection efficiency in physical units (r_\perp, m_p), where r_\perp is the projected planet-star separation and m_p is the planet mass. When computing planet detection efficiency, we did not find any planetary signature and our detection efficiency results reveal significant sensitivity to Neptune-mass planets, and to a lesser extent Earth-mass planets in some configurations. Indeed, Jupiter and Neptune-mass planets are excluded with a high confidence for a large projected separation range between the planet and the lens star, respectively [0.6 - 10] and [1.4 - 4] AU, and Earth-mass planets are excluded with a 10% confidence in the lensing zone, i.e. [1.8 - 3.1] AU.

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V. Batista, Subo Dong, A. Gould, J. P. Beaulieu, A. Cassan, G. W. Christie, C. Han, A. Udalski, W. Allen, D. L. DePoy, A. Gal-Yam, B. S. Gaudi, B. Johnson, S. Kaspi, C. U. Lee, D. Maoz, J. McCormick, I. McGreer, B. Monard, T. Natusch, E. Ofek, B. -G. Park, R. W. Pogge, D. Polishook, A. Shporer, M. D. Albrow, D. P. Bennett, S. Brillant, M. Bode, D. M. Bramich, M. Burgdorf, J. A. R. Caldwell, H. Calitz, A. Cole, K. H. Cook, Ch. Coutures, S. Dieters, M. Dominik, D. Dominis Prester, J. Donatowicz, P. Fouqué, J. Greenhill, M. Hoffman, K. Horne, U. G. Jørgensen, N. Kains, S. Kane, D. Kubas, J. B. Marquette, R. Martin, P. Meintjes, J. Menzies, K. R. Pollard, K. C. Sahu, C. Snodgrass, I. Steele, Y. Tsapras, J. Wambsganss, A. Williams, M. Zub, Ł. Wyrzykowski, M. Kubiak, M. K. Szymański, G. Pietrzyński, I. Soszyński, O. Szewczyk, K. Ulaczyk, F. Abe, I. A. Bond, A. Fukui, K. Furusawa, J. B. Hearnshaw, S. Holderness, Y. Itow, K. Kamiya, P. M. Kilmartin, A. Korpela, W. Lin, C. H. Ling, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, M. Nagaya, K. Ohnishi, T. Okumura, Y. C. Perrott, N. Rattenbury, To. Saito, T. Sako, L. Skuljan, D. Sullivan, T. Sumi, W. L. Sweatman, P. J. Tristram, P. C. M. Yock. 2009-07-20. Mass measurement of a single unseen star and planetary detection efficiency for OGLE 2007-BLG-050. https://doi.org/10.1051/0004-6361/200912923

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