OGLE-2005-BLG-153: Microlensing discovery and characterization of a very low mass binary

K. H. Hwang, A. Udalski, C. Han, Y. H. Ryu, I. A. Bond, J. P. Beaulieu, M. Dominik, K. Horne, A. Gould, B. S. Gaudi, M. Kubiak, M. K. Szymański, G. Pietrzyński, I. Soszyński, O. Szewczyk, K. Ulaczyk, Wyrzykowski, F. Abe, C. S. Botzler, J. B. HearnshawY. Itow, K. Kamiya, P. M. Kilmartin, K. Masuda, Y. Matsubara, M. Motomura, Y. Muraki, S. Nakamura, K. Ohnishi, C. Okada, N. Rattenbury, To Saito, T. Sako, M. Sasaki, D. J. Sullivan, T. Sumi, P. J. Tristram, J. N. Wood, P. C.M. Yock, T. Yoshioka, M. Albrow, D. P. Bennett, D. M. Bramich, S. Brillant, J. A.R. Caldwell, J. J. Calitz, A. Cassan, K. H. Cook, E. Corrales, C. Coutures, M. Desort, S. Dieters, D. Dominis, J. Donatowicz, P. Fouqué, J. Greenhill, K. Harpsøe, K. Hill, M. Hoffman, U. G. Jørgensen, S. Kane, D. Kubas, R. Martin, J. B. Marquette, P. Meintjes, J. Menzies, K. Pollard, K. Sahu, I. Steele, C. Vinter, J. Wambsganss, A. Williams, K. Woller, M. Burgdorf, C. Snodgrass, M. Bode, D. L. Depoy, C. U. Lee, B. G. Park, R. W. Pogge

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9 Citations (Scopus)


The mass function and statistics of binaries provide important diagnostics of the star formation process. Despite this importance, the mass function at low masses remains poorly known due to observational difficulties caused by the faintness of the objects. Here we report the microlensing discovery and characterization of a binary lens composed of very low mass stars just above the hydrogen-burning limit. From the combined measurements of the Einstein radius and microlens parallax, we measure the masses of the binary components of 0.10±0.01 M and 0.09±0.01 M. This discovery demonstrates that microlensing will provide a method to measure the mass function of all Galactic populations of very low mass binaries that is independent of the biases caused by the luminosity of the population.

Original languageEnglish
Pages (from-to)797-802
Number of pages6
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 1 Nov 2010



  • Binaries
  • General - gravitational lensing
  • Micro

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Hwang, K. H., Udalski, A., Han, C., Ryu, Y. H., Bond, I. A., Beaulieu, J. P., Dominik, M., Horne, K., Gould, A., Gaudi, B. S., Kubiak, M., Szymański, M. K., Pietrzyński, G., Soszyński, I., Szewczyk, O., Ulaczyk, K., Wyrzykowski, Abe, F., Botzler, C. S., ... Pogge, R. W. (2010). OGLE-2005-BLG-153: Microlensing discovery and characterization of a very low mass binary. Astrophysical Journal, 723(1), 797-802. https://doi.org/10.1088/0004-637X/723/1/797