A cold Neptune-mass planet OGLE-2007-BLG-368Lb: Cold Neptunes are common.

T. Sumi, D. P. Bennett, I. A. Bond, A. Udalski, V. Batista, Martin Dominik, P. Fouque, D. Kubas, A. Gould, B. Macintosh, K. Cook, S. Dong, L. Skuljan, A. Cassan, F. Abe, C. S. Botzler, A. Fukui, K. Furusawa, J. B. Hearnshaw, Y. ItowK. Kamiya, P. M. Kilmartin, A. Korpela, W. Lin, C. H. Ling, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, M. Nagaya, T. Nagayama, K. Ohnishi, T. Okumura, Y. C. Perrott, N. Rattenbury, To Saito, T. Sako, D. J. Sullivan, W. L. Sweatman, P. J. Tristram, P. C. M. Yock, J. P. Beaulieu, A. Cole, Ch Coutures, M. F. Duran, J. Greenhill, F. Jablonski, Ettore Pedretti, Keith Douglas Horne, Noé Kains, MOA Collaboration, OGLE Collaboration, PLANET Collaboration, MicroFUN Collaboration

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180 Citations (Scopus)

Abstract

We present the discovery of a Neptune-mass planet OGLE-2007-BLG-368Lb with a planet-star mass ratio of q = [9.5 +/- 2.1] x 10(-5) via gravitational microlensing. The planetary deviation was detected in real-time thanks to the high cadence of the Microlensing Observations in Astrophysics survey, real-time light-curve monitoring and intensive follow-up observations. A Bayesian analysis returns the stellar mass and distance at M-l = 0.64(-0.26)(+0.21) M-circle dot and D-l = 5.9(-1.4)(+ 0.9) kpc, respectively, so the mass and separation of the planet are M-p = 20(-8)(+7) M-circle plus and a = 3.3(-0.8)(+1.4) AU, respectively. This discovery adds another cold Neptune-mass planet to the planetary sample discovered by microlensing, which now comprises four cold Neptune/super-Earths, five gas giant planets, and another sub-Saturn mass planet whose nature is unclear. The discovery of these 10 cold exoplanets by the microlensing method implies that the mass ratio function of cold exoplanets scales as dN(pl)/d log q alpha q(-0.7+/-0.2) with a 95% confidence level upper limit of n < -0.35 ( where dN(pl)/d log q alpha q(n)). As microlensing is most sensitive to planets beyond the snow-line, this implies that Neptune-mass planets are at least three times more common than Jupiters in this region at the 95% confidence level.

Original languageEnglish
Pages (from-to)1641-1653
Number of pages13
JournalAstrophysical Journal
Volume710
Issue number2
DOIs
Publication statusPublished - 20 Feb 2010

Keywords

  • gravitational lensing: micro
  • planetary systems
  • GRAVITATIONAL LENSING EXPERIMENT
  • SURFACE BRIGHTNESS RELATIONS
  • MICROLENSING OPTICAL DEPTH
  • CLUMP ABSOLUTE MAGNITUDE
  • EXTRA-SOLAR PLANETS
  • GALACTIC DARK HALO
  • HIGH-MAGNIFICATION
  • SUPER-EARTHS
  • DWARF STARS
  • IMAGE SUBTRACTION

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