2016ApJ...824..139H

We report the discovery of a planet by the microlensing method, OGLE-2012-BLG-0724Lb. Although the duration of the planetary signal for this event was one of the shortest seen for a planetary event, the anomaly was well covered thanks to high-cadence observations taken by the survey groups OGLE and MOA. By analyzing the light curve, this planetary system is found to have a mass ratio q=(1.58±0.15)×{10}^{-3} . By conducting a Bayesian analysis, we estimate that the host star is an M dwarf with a mass of {M}_{L}={0.29}{-0.16}^{+0.33} {M}_☉ located at {D}_{L}={6.7}{-1.2}^{+1.1} kpc away from the Earth and the companion's mass is {m}_{¶}={0.47}{-0.26}^{+0.54} {M}_{Jup} . The projected planet-host separation is {a}_⊥={1.6}_{-0.3}^{+0.4} AU . Because the lens-source relative proper motion is relatively high, future high-resolution images would detect the lens host star and determine the lens properties uniquely. This system is likely a Saturn-mass exoplanet around an M dwarf, and such systems are commonly detected by gravitational microlensing. This adds another example of a possible pileup of sub-Jupiters (0.2m_{¶}/{M}{Jup}\lt 1) in contrast to a lack of Jupiters ( ∼1–2 {M}_{Jup} ) around M dwarfs, supporting the prediction by core accretion models that Jupiter-mass or more massive planets are unlikely to form around M dwarfs.