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

V. Batista*, S. 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. NatuschE. 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. D. 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, P. Wyrzykowski, M. Kubiak, M. K. Szymánski, G. Pietrzýnski, I. Soszýnski, 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, T. Saito, T. Sako, L. Skuljan, D. Sullivan, T. Sumi, W. L. Sweatman, P. J. Tristram, P. C.M. Yock

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Aims. We analyze OGLE-2007-BLG-050, a high magnification microlensing event (Ã432) 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.Methods. Both finite-source and parallax effects permit a measurement of the angular Einstein radius E=0.48±0.01 mas and the parallax πE=0.12±0.03, leading to an estimate of the lens mass M=0.50±0.14 M and its distance to the observer DL=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,m), where r is the projected planet-star separation and mp is the planet mass.Results. When computing planet detection efficiency, we did not find any planetary signature, i.e. none of the planetary configurations provides a δX 2 improvement higher than 60, 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.

Original languageEnglish
Pages (from-to)467-478
Number of pages12
JournalAstronomy and Astrophysics
Issue number1
StatePublished - 2 Dec 2009


  • Gravitational lensing
  • Planetary systems
  • Stars: individual: OGLE 2007-BLG-050
  • Techniques: photometric


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