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Register a new userOGLE-2018-BLG-1269Lb: A Jovian Planet With A Bright, $I=16$ Host
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We report the discovery of a planet in the microlensing event OGLE-2018-BLG-1269, with planet-host mass ratio $q sim 6times10^{-4}$, i.e., $0.6$ times smaller than the Jupiter/Sun mass ratio. Combined with the $Gaia$ parallax and proper motion, a strong one-dimensional constraint on the microlens parallax vector allows us to significantly reduce the uncertainties of lens physical parameters. A Bayesian analysis that ignores any information about light from the host yields that the planet is a cold giant $(M_{2} = 0.69_{-0.22}^{+0.44},M_{rm J})$ orbiting a Sun-like star $(M_{1} = 1.13_{-0.35}^{+0.72},M_{odot})$ at a distance of $D_{rm L} = 2.56_{-0.62}^{+0.92},{rm kpc}$. The projected planet-host separation is $a_{perp} = 4.61_{-1.17}^{+1.70},{rm au}$. Using {it Gaia} astrometry, we show that the blended light lies $lesssim 12,$mas from the host and therefore must be either the host star or a stellar companion to the host. An isochrone analysis favors the former possibility at $>99.6%$. The host is therefore a subgiant. For host metallicities in the range of $0.0 leq {rm [Fe/H]} leq +0.3$, the host and planet masses are then in the range of $1.16 leq M_{1}/M_{odot} leq 1.38$ and $0.74 leq M_{2}/M_{rm J} leq 0.89$, respectively. Low host metallicities are excluded. The brightness and proximity of the lens make the event a strong candidate for spectroscopic followup both to test the microlensing solution and to further characterize the system.
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We report the discovery of the planet OGLE-2018-BLG-0532Lb, with very obvious signatures in the light curve that lead to an estimate of the planet-host mass ratio $q=M_{rm planet}/M_{rm host}simeq 1times10^{-4}$. Although there are no obvious systematic residuals to this double-lens/single-source (2L1S) fit, we find that $chi^2$ can be significantly improved by adding either a third lens (3L1S, $Deltachi^2=81$) or second source (2L2S, $Deltachi^2=65$) to the lens-source geometry. After thorough investigation, we conclude that we cannot decisively distinguish between these two scenarios and therefore focus on the robustly-detected planet. However, given the possible presence of a second planet, we investigate to what degree and with what probability such additional planets may affect seemingly single-planet light curves. Our best estimates for the properties of the lens star and the secure planet are: a host mass $Msim 0.25,M_odot$, system distance $D_Lsim 1,$kpc and planet mass $m_{p,1}= 8,M_oplus$ with projected separation $a_{1,perp}=1.4,$au. However, there is a relatively bright $I=18.6$ (and also relatively blue) star projected within $<50,$mas of the lens, and if future high-resolution images show that this is coincident with the lens, then it is possible that it is the lens, in which case, the lens would be both more massive and more distant than the best-estimated values above.
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We report the discovery of a several-Jupiter mass planetary companion to the primary lens star in microlensing event OGLE-2005-BLG-071. Precise (<1%) photometry at the peak of the event yields an extremely high signal-to-noise ratio detection of a deviation from the light curve expected from an isolated lens. The planetary character of this deviation is easily and unambiguously discernible from the gross features of the light curve. Detailed modeling yields a tightly-constrained planet-star mass ratio of q=m_p/M=0.0071+/-0.0003. This is the second robust detection of a planet with microlensing, demonstrating that the technique itself is viable and that planets are not rare in the systems probed by microlensing, which typically lie several kpc toward the Galactic center.
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