Microlensing discovery of a tight, low-mass-ratio planetary-mass object around an old field brown dwarf

C. Han, Y. K. Jung, A. Udalski, T. Sumi, B. S. Gaudi, A. Gould, D. P. Bennett, Y. Tsapras, M. K. Szymański, M. Kubiak, G. Pietrzyński, I. Soszyński, J. Skowron, S. Kozłowski, R. Poleski, K. Ulaczyk, Wyrzykowski, P. Pietrukowicz, F. Abe, I. A. BondC. S. Botzler, P. Chote, M. Freeman, A. Fukui, K. Furusawa, P. Harris, Y. Itow, C. H. Ling, K. Masuda, Y. Matsubara, Y. Muraki, K. Ohnishi, N. J. Rattenbury, To Saito, D. J. Sullivan, W. L. Sweatman, D. Suzuki, P. J. Tristram, K. Wada, P. C M Yock, V. Batista, G. Christie, J. Y. Choi, D. L. Depoy, Subo Dong, K. H. Hwang, A. Kavka, C. U. Lee, L. A G Monard, T. Natusch, H. Ngan, H. Park, R. W. Pogge, I. Porritt, I. G. Shin, T. G. Tan, J. C. Yee, Khalid Al-Subai, V. Bozza, D. M. Bramich, P. Browne, M. Dominik, K. Horne, M. Hundertmark, S. Ipatov, N. Kains, C. Liebig, C. Snodgrass, I. A. Steele, R. A. Street

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Observations of accretion disks around young brown dwarfs (BDs) have led to the speculation that they may form planetary systems similar to normal stars. While there have been several detections of planetary-mass objects around BDs (2MASS 1207-3932 and 2MASS 0441-2301), these companions have relatively large mass ratios and projected separations, suggesting that they formed in a manner analogous to stellar binaries. We present the discovery of a planetary-mass object orbiting a field BD via gravitational microlensing, OGLE-2012-BLG-0358Lb. The system is a low secondary/primary mass ratio (0.080 ± 0.001), relatively tightly separated (0.87 AU) binary composed of a planetary-mass object with 1.9 ± 0.2 Jupiter masses orbiting a BD with a mass 0.022 M. The relatively small mass ratio and separation suggest that the companion may have formed in a protoplanetary disk around the BD host in a manner analogous to planets.

Original languageEnglish
Article number38
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 20 Nov 2013
Externally publishedYes



  • brown dwarfs
  • gravitational lensing: micro
  • planetary systems

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Han, C., Jung, Y. K., Udalski, A., Sumi, T., Gaudi, B. S., Gould, A., Bennett, D. P., Tsapras, Y., Szymański, M. K., Kubiak, M., Pietrzyński, G., Soszyński, I., Skowron, J., Kozłowski, S., Poleski, R., Ulaczyk, K., Wyrzykowski, Pietrukowicz, P., Abe, F., ... Street, R. A. (2013). Microlensing discovery of a tight, low-mass-ratio planetary-mass object around an old field brown dwarf. Astrophysical Journal, 778(1), [38]. https://doi.org/10.1088/0004-637X/778/1/38