Spitzer Microlensing Parallax for OGLE-2016-BLG-1067: a sub-Jupiter Orbiting an M-dwarf in the Disk
2018
We report the discovery of a sub-
Jupiter mass
planetorbiting beyond the
snow lineof 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 curvemodeling and in particular by the Spitzer-based measurement of the
microlens
parallax, $\pi_\mathrm{E}$. However, in contrast to many planetary microlensing events, there are no caustic crossings, so the angular
Einstein radius, $\theta_\mathrm{E}$ has only an upper limit based on the
light curvemodeling alone. Additionally, the analysis leads us to identify 8 degenerate configurations: the four-fold microlensing
parallaxdegeneracy 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
parallaxdegeneracy, we make use of a series of arguments: the $\chi^2$ hierarchy, the Rich argument, and a prior Galactic model. The preferred configuration is for a host at $D_L=3.73_{-0.67}^{+0.66}~\mathrm{kpc}$ with mass $M_\mathrm{L}=0.30_{-0.12}^{+0.15}~\mathrm{M_\odot}$, orbited by a
Saturn-like
planetwith $M_\mathrm{
planet}=0.43_{-0.17}^{+0.21}~\mathrm{M_\mathrm{Jup}}$ at projected separation $a_\perp = 1.70_{-0.39}^{+0.38}~\mathrm{au}$, about 2.1 times beyond the system
snow line. Therefore, it adds to the growing population of sub-
Jupiter
planetsorbiting near or beyond the
snow lineof M-dwarfs discovered by microlensing. Based on the rules of the real-
time protocolfor the selection of events to be followed up with Spitzer, this
planetwill not enter the sample for measuring the Galactic distribution of
planets.
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