Wednesday, August 23, 2017

OGLE-2013-BLG-1761Lb: A SuperJupiter Orbiting a M/K Dwarf Star

OGLE-2013-BLG-1761Lb: A Massive Planet around an M/K Dwarf 
Hirao et al

We report the discovery and the analysis of the planetary microlensing event, OGLE-2013-BLG-1761. There are some degenerate solutions in this event because the planetary anomaly is only sparsely sampled. However, the detailed light-curve analysis ruled out all stellar binary models and shows the lens to be a planetary system. There is the so-called close/wide degeneracy in the solutions with the planet/host mass ratio of q ~ (7.0 ± 2.0) × 10−3 and q ~ (8.1 ± 2.6) × 10−3 with the projected separation in Einstein radius units of s = 0.95 (close) and s = 1.18 (wide), respectively. The microlens parallax effect is not detected, but the finite source effect is detected. Our Bayesian analysis indicates that the lens system is located ${D}_{{\rm{L}}}={6.9}_{-1.2}^{+1.0}\,\mathrm{kpc}$ away from us and the host star is an M/K dwarf with a mass of ${\text{}}{M}_{{\rm{L}}}={0.33}_{-0.19}^{+0.32}\,{\text{}}{M}_{\odot }$ orbited by a super-Jupiter mass planet with a mass of ${\text{}}{m}_{{\rm{P}}}={2.7}_{-1.5}^{+2.5}\,{M}_{\mathrm{Jup}}$ at the projected separation of ${a}_{\perp }={1.8}_{-0.5}^{+0.5}\,\mathrm{au}$. The preference of the large lens distance in the Bayesian analysis is due to the relatively large observed source star radius. The distance and other physical parameters may be constrained by the future high-resolution imaging by large ground telescopes or HST. If the estimated lens distance is correct, then this planet provides another sample for testing the claimed deficit of planets in the Galactic bulge.

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