Authors:Sumi et alAbstract:We present the discovery of the first Neptune analog exoplanet, MOA-2013-BLG-605Lb. This planet has a mass similar to that of Neptune or a super-Earth and it orbits at 9∼14 times the expected position of the snow-line, asnow, which is similar to Neptune's separation of 11asnow from the Sun. The planet/host-star mass ratio is q=(3.6±0.7)×10−4 and the projected separation normalized by the Einstein radius is s=2.39±0.05. There are three degenerate physical solutions and two of these are due to a new type of degeneracy in the microlensing parallax parameters, which we designate "the wide degeneracy". The three models have (i) a Neptune-mass planet with a mass of Mp=21+6−7Mearth orbiting a low-mass M-dwarf with a mass of Mh=0.19+0.05−0.06M⊙, (ii) a mini-Neptune with Mp=7.9+1.8−1.2Mearth orbiting a brown dwarf host with Mh=0.068+0.019−0.011M⊙ and (iii) a super-Earth with Mp=3.2+0.5−0.3Mearth orbiting a low-mass brown dwarf host with Mh=0.025+0.005−0.004M⊙. The 3-D planet-host separations are 4.6+4.7−1.2 AU, 2.1+1.0−0.2 AU and 0.94+0.67−0.02 AU, which are 8.9+10.5−1.4, 12+7−1 or 14+11−1 times larger than asnow for these models, respectively. The Keck AO observation confirm that the lens is faint. This discovery suggests that Neptune-like planets orbiting at ∼11asnow are quite common. They may be as common as planets at ∼3asnow, where microlensing is most sensitive, so processes similar to the one that formed Uranus and Neptune in our own Solar System may be quite common in other solar systems.
Wednesday, February 10, 2016
MOA-2013-BLG-605Lb: a Neptune Analog Around an M Dwarf
Posted by Will Baird at 8:00 AM
Labels: cold neptune, exomoon detection, giant planets, ice giant, m dwarf exoplanets, micro lensing, MOA-2013-BLG-605Lb, neptune class
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