En sub-Jupiter i kredsløb omkring en M-dværg

[BjarneModerator Super Nova]

Spitzer Microlensing Parallax for OGLE-2016-BLG-1067: a sub-Jupiter Orbiting an M-dwarf in the Disk

We report the discovery of a sub-Jupiter mass planet orbiting beyond the snow line of an M-dwarf most likely in the Galactic disk as part of the joint Spitzer and ground-based monitoring of microlensing planetary anomalies toward the Galactic bulge. The microlensing parameters are strongly constrained by the light curve modeling and in particular by the Spitzer-based measurement of the microlens parallax, π_E. However, in contrast to many planetary microlensing events, there are no caustic crossings, so the angular Einstein radius, θ_E has only an upper limit based on the light curve modeling alone. Additionally, the analysis leads us to identify 8 degenerate configurations: the four-fold microlensing parallax degeneracy being doubled by a degeneracy in the caustic structure present at the level of the ground-based solutions. To pinpoint the physical parameters, and at the same time to break the parallax degeneracy, we make use of a series of arguments: the χ² hierarchy, the Rich argument, and a prior Galactic model. The preferred configuration is for a host at D_L=3.73_-0.67^+0.66 kpc with mass M_L=0.30_-0.12^+0.15 M_⊙, orbited by a Saturn-like planet with M_planet=0.43_-0.17^+0.21 M_Jup at projected separation a_⊥=1.70_-0.39^+0.38 au, about 2.1 times beyond the system snow line. Therefore, it adds to the growing population of sub-Jupiter planets orbiting near or beyond the snow line of M-dwarfs discovered by microlensing. Based on the rules of the real-time protocol for the selection of events to be followed up with Spitzer, this planet will not enter the sample for measuring the Galactic distribution of planets.

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