A COLD NEPTUNE-MASS PLANET OGLE-2007-BLG-368Lb: COLD NEPTUNES ARE COMMON

作者：Sumi T^*; Bennett D P; Bond I A; Udalski A; Batista V; Dominik M; Fouque P; Kubas D; Gould A; Macintosh B; Cook K; Dong S; Skuljan L; Cassan A; Abe F; Botzler C S; Fukui A; Furusawa K; Hearnshaw J B; Itow Y; Kamiya K; Kilmartin P M; Korpela A; Lin W; Ling C H; Masuda K; Matsubara Y; Miyake N; Muraki Y; Nagaya M; Nagayama T; Ohnishi K; Okumura T; Perrott Y C; Rattenbury N; Saito To; Sako T; Sullivan D J

来源：Astrophysical Journal, 2010, 710(2): 1641-1653.

DOI：10.1088/0004-637X/710/2/1641

• gravitational lensing: micro
• planetary systems

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.

• 出版日期2010-2-20