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Register a new userKMT-2018-BLG-1292: A Super-Jovian Microlens Planet in the Galactic Plane
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We report the discovery of KMT-2018-BLG-1292Lb, a super-Jovian $M_{rm planet} = 4.5pm 1.3,M_J$ planet orbiting an F or G dwarf $M_{rm host} = 1.5pm 0.4,M_odot$, which lies physically within ${cal O}(10,pc)$ of the Galactic plane. The source star is a heavily extincted $A_Isim 5.2$ luminous giant that has the lowest Galactic latitude, $b=-0.28^circ$, of any planetary microlensing event. The relatively blue blended light is almost certainly either the host or its binary companion, with the first explanation being substantially more likely. This blend dominates the light at $I$ band and completely dominates at $R$ and $V$ bands. Hence, the lens system can be probed by follow-up observations immediately, i.e., long before the lens system and the source separate due to their relative proper motion. The system is well characterized despite the low cadence $Gamma=0.15$--$0.20,{rm hr^{-1}}$ of observations and short viewing windows near the end of the bulge season. This suggests that optical microlensing planet searches can be extended to the Galactic plane at relatively modest cost.
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At $q=1.81pm 0.20 times 10^{-5}$, KMT-2018-BLG-0029Lb has the lowest planet-host mass ratio $q$ of any microlensing planet to date by more than a factor of two. Hence, it is the first planet that probes below the apparent pile-up at $q=5$--10 $times 10^{-5}$. The event was observed by {it Spitzer}, yielding a microlens-parallax $pi_{rm E}$ measurement. Combined with a measurement of the Einstein radius $theta_{rm E}$ from finite-source effects during the caustic crossings, these measurements imply masses of the host $M_{rm host}=1.14^{+0.10}_{-0.12}, M_odot$ and planet $M_{rm planet} = 7.59^{+0.75}_{-0.69},M_oplus$, system distance $D_L = 3.38^{+0.22}_{-0.26},,{rm kpc}$ and projected separation $a_perp = 4.27^{+0.21}_{-0.23},{rm au}$. The blended light, which is substantially brighter than the microlensed source, is plausibly due to the lens and could be observed at high resolution immediately.
We report the discovery of a super-Jovian planet in the microlensing event KMT-2016-BLG-1836, which was found by the Korea Microlensing Telescope Networks high-cadence observations (Gamma ~ 4~{hr}^{-1}). The planet-host mass ratio q ~ 0.004. A Bayesian analysis indicates that the planetary system is composed of a super-Jovian M_{planet} = 2.2_{-1.1}^{+1.9} M_{J} planet orbiting an M or K dwarf M_{rm host} = 0.49_{-0.25}^{+0.38} M_{Sun}, at a distance of D_{L} = 7.1_{-2.4}^{+0.8} kpc. The projected planet-host separation is 3.5^{+1.1}_{-0.9} AU, implying that the planet is located beyond the snowline of the host star. Future high-resolution images can potentially strongly constrain the lens brightness and thus the mass and distance of the planetary system. Without considering detailed detection efficiency, selection or publication biases, we find a potential mass ratio desert at -3.7 lesssim log q lesssim -3.0 for the 31 published KMTNet planets.
We aim to find missing microlensing planets hidden in the unanalyzed lensing events of previous survey data. For this purpose, we conduct a systematic inspection of high-magnification microlensing events, with peak magnifications $A_{rm peak}gtrsim 30$, in the data collected from high-cadence surveys in and before the 2018 season. From this investigation, we identify an anomaly in the lensing light curve of the event KMT-2018-BLG-1025. The analysis of the light curve indicates that the anomaly is caused by a very low mass-ratio companion to the lens. We identify three degenerate solutions, in which the ambiguity between a pair of solutions (solutions B) is caused by the previously known close--wide degeneracy, and the degeneracy between these and the other solution (solution A) is a new type that has not been reported before. The estimated mass ratio between the planet and host is $qsim 0.8times 10^{-4}$ for the solution A and $qsim 1.6times 10^{-4}$ for the solutions B. From the Bayesian analysis conducted with measured observables, we estimate that the masses of the planet and host and the distance to the lens are $(M_{rm p}, M_{rm h}, D_{rm L})sim (6.1~M_oplus, 0.22~M_odot, 6.7~{rm kpc})$ for the solution A and $sim (4.4~M_oplus, 0.08~M_odot, 7.5~{rm kpc})$ for the solutions B. The planet mass is in the category of a super-Earth regardless of the solutions, making the planet the eleventh super-Earth planet, with masses lying between those of Earth and the Solar systems ice giants, discovered by microlensing.
We report the discovery of a giant planet in the KMT-2016-BLG-1397 microlensing event, which was found by The Korea Microlensing Telescope Network (KMTNet) alone. The time scale of this event is t_E = 40.0 +- 0.5 days and the mass ratio between the lens star and its companion is q = 0.016 +- 0.002. The planetary perturbation in the light curve is a smooth bump, resulting in the classical binary-lens/binary-source (2L1S/1L2S) degeneracy. We measure the V - I color of the (putative) two sources in the 1L2S model, and then effectively rule out the binary source solution. The finite-source effect is marginally detected. Combined with the limits on the blend flux and the probability distribution of the source size normalized by the Einstein radius rho, a Bayesian analysis yields the lens mass M_L = 0.45+0.33-0.28 M_sun, at distance of D_L = 6.60+1.10-1.30 kpc. Thus the companion is a super-Jupiter of a mass m_p = 7.0+5.2-4.3 M_J , at a projected separation r = 5.1+1.5-1.7 AU, indicating that the planet is well beyond the snow line of the host star.
We announce the discovery of a microlensing planetary system, in which a sub-Saturn planet is orbiting an ultracool dwarf host. We detect the planetary system by analyzing the short-timescale ($t_{rm E}sim 4.4$~days) lensing event KMT-2018-BLG-0748. The central part of the light curve exhibits asymmetry due to the negative deviations in the rising part and the positive deviations in the falling part. We find that the deviations are explained by a binary-lens model with a mass ratio between the lens components of $qsim 2times 10^{-3}$. The short event timescale together with the small angular Einstein radius, $theta_{rm E}sim 0.11$~mas, indicate that the mass of the planet host is very small. The Bayesian analysis conducted under the assumption that the planet frequency is independent of the host mass indicates that the mass of the planet is $M_{rm p}=0.18^{+0.29}_{-0.10}~M_{rm J}$, and the mass of the host, $M_{rm h}= 0.087^{+0.138}_{-0.047}~M_odot$, is near the star/brown dwarf boundary, but the estimated host mass is sensitive to the assumption about the planet hosting probability. High-resolution follow-up observations would lead to revealing the nature of the planet host.
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