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Register a new userOGLE-2018-BLG-0567Lb and OGLE-2018-BLG-0962Lb: Two Microlensing Planets through Planetary-Caustic Channel
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We present the analyses of two microlensing events, OGLE-2018-BLG-0567 and OGLE-2018-BLG-0962. In both events, the short-lasting anomalies were densely and continuously covered by two high-cadence surveys. The light-curve modeling indicates that the anomalies are generated by source crossings over the planetary caustics induced by planetary companions to the hosts. The estimated planet/host separation (scaled to the angular Einstein radius $theta_{rm E}$) and mass ratio are $(s, q) = (1.81, 1.24times10^{-3})$ and $(s, q) = (1.25, 2.38times10^{-3})$, respectively. From Bayesian analyses, we estimate the host and planet masses as $(M_{rm h}, M_{rm p}) = (0.24_{-0.13}^{+0.16},M_{odot}, 0.32_{-0.16}^{+0.34},M_{rm J})$ and $(M_{rm h}, M_{rm p}) = (0.55_{-0.29}^{+0.32},M_{odot}, 1.37_{-0.72}^{+0.80},M_{rm J})$, respectively. These planetary systems are located at a distance of $7.07_{-1.15}^{+0.93},{rm kpc}$ for OGLE-2018-BLG-0567 and $6.47_{-1.73}^{+1.04},{rm kpc}$ for OGLE-2018-BLG-0962, suggesting that they are likely to be near the Galactic bulge. The two events prove the capability of current high-cadence surveys for finding planets through the planetary-caustic channel. We find that most published planetary-caustic planets are found in Hollywood events in which the source size strongly contributes to the anomaly cross section relative to the size of the caustic.
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We report the discovery of a planet in a binary that was discovered from the analysis of the microlensing event OGLE-2018-BLG-1700. We identify the triple nature of the lens from the fact that the complex anomaly pattern can be decomposed into two parts produced by two binary-lens events, in which one binary pair has a very low mass ratio of $sim 0.01$ between the lens components and the other pair has a mass ratio of $sim 0.3$. We find two sets of degenerate solutions, in which one solution has a projected separation between the primary and its stellar companion less than the angular Einstein radius $thetae$ (close solution), while the other solution has a separation greater than $thetae$ (wide solution). From the Bayesian analysis with the constraints of the event time scale and angular Einstein radius together with the location of the source lying in the far disk behind the bulge, we find that the planet is a super-Jupiter with a mass of $4.4^{+3.0}_{-2.0}~M_{rm J}$ and the stellar binary components are early and late M-type dwarfs with masses $0.42^{+0.29}_{-0.19}~M_odot$ and $0.12^{+0.08}_{-0.05}~M_odot$, respectively, and the planetary system is located at a distance of $D_{rm L}=7.6^{+1.2}_{-0.9}~{rm kpc}$. The planet is a circumstellar planet according to the wide solution, while it is a circumbinary planet according to the close solution. The projected primary-planet separation is $2.8^{+3.2}_{-2.5}~{rm au}$ commonly for the close and wide solutions, but the primary-secondary binary separation of the close solution, $0.75^{+0.87}_{-0.66}~{rm au}$, is widely different from the separation, $10.5^{+12.1}_{-9.2}~{rm au}$, of the wide solution.
We report a multiplanetary system found from the analysis of microlensing event OGLE-2018-BLG-1011, for which the light curve exhibits a double-bump anomaly around the peak. We find that the anomaly cannot be fully explained by the binary-lens or binary-source interpretations and its description requires the introduction of an additional lens component. The 3L1S (3 lens components and a single source) modeling yields three sets of solutions, in which one set of solutions indicates that the lens is a planetary system in a binary, while the other two sets imply that the lens is a multiplanetary system. By investigating the fits of the individual models to the detailed light curve structure, we find that the multiple-planet solution with planet-to-host mass ratios $sim 9.5times 10^{-3}$ and $sim 15times 10^{-3}$ are favored over the other solutions. From the Bayesian analysis, we find that the lens is composed of two planets with masses $1.8^{+3..4}_{-1.1}~M_{rm J}$ and $2.8^{+5.1}_{-1.7}~M_{rm J}$ around a host with a mass $0.18^{+0.33}_{-0.10}~M_odot$ and located at a distance $7.1^{+1.1}_{-1.5}~{rm kpc}$. The estimated distance indicates that the lens is the farthest system among the known multiplanetary systems. The projected planet-host separations are $a_{perp,2}=1.8^{+2.1}_{-1.5}~{rm au}$ ($0.8^{+0.9}_{-0.6}~{rm au}$) and $a_{perp,3}=0.8^{+0.9}_{-0.6}~{rm au}$, where the values of $a_{perp,2}$ in and out the parenthesis are the separations corresponding to the two degenerate solutions, indicating that both planets are located beyond the snow line of the host, as with the other four multiplanetary systems previously found by microlensing.
We report the analysis of the microlensing event OGLE-2018-BLG-0677. A small feature in the light curve of the event leads to the discovery that the lens is a star-planet system. Although there are two degenerate solutions that could not be distinguished for this event, both lead to a similar planet-host mass ratio. We perform a Bayesian analysis based on a Galactic model to obtain the properties of the system and find that the planet corresponds to a super-Earth/sub-Neptune with a mass $M_{mathrm{planet}} = {3.96}^{+5.88}_{-2.66}mathrm{M_oplus}$. The host star has a mass $ M_{mathrm{host}} = {0.12}^{+0.14}_{-0.08}mathrm{M_odot}$. The projected separation for the inner and outer solutions are ${0.63}^{+0.20}_{-0.17}$~AU and ${0.72}^{+0.23}_{-0.19}$~AU respectively. At $Deltachi^2=chi^2({rm 1L1S})-chi^2({rm 2L1S})=46$, this is by far the lowest $Deltachi^2$ for any securely-detected microlensing planet to date, a feature that is closely connected to the fact that it is detected primarily via a dip rather than a bump.
We present the analysis of the microlensing event KMT-2018-BLG-1743. The light curve of the event, with a peak magnification $A_{rm peak}sim 800$, exhibits two anomaly features, one around the peak and the other on the falling side of the light curve. An interpretation with a binary lens and a single source (2L1S) cannot describe the anomalies. By conducting additional modeling that includes an extra lens (3L1S) or an extra source (2L2S) relative to a 2L1S interpretation, we find that 2L2S interpretations with a planetary lens system and a binary source best explain the observed light curve with $Deltachi^2sim 188$ and $sim 91$ over the 2L1S and 3L1S solutions, respectively. Assuming that these $Deltachi^2$ values are adequate for distinguishing the models, the event is the fourth 2L2S event and the second 2L2S planetary event. The 2L2S interpretations are subject to a degeneracy, resulting in two solutions with $s>1.0$ (wide solution) and $s<1.0$ (close solution). The masses of the lens components and the distance to the lens are $(M_{rm host}/M_odot, M_{rm planet}/M_{rm J}, D_{rm L}/{rm kpc}) sim (0.19^{+0.27}_{-0.111}, 0.25^{+0.34}_{-0.14}, 6.48^{+0.94}_{-1.03})$ and $sim (0.42^{+0.34}_{-0.25}, 1.61^{+1.30}_{-0.97}, 6.04^{+0.93}_{-1.27})$ according to the wide and close solutions, respectively. The source is a binary composed of an early G dwarf and a mid M dwarf. The values of the relative lens-source proper motion expected from the two degenerate solutions, $mu_{rm wide}sim 2.3 $mas yr$^{-1}$ and $mu_{rm close} sim 4.1 $mas yr$^{-1}$, are substantially different, and thus the degeneracy can be broken by resolving the lens and source from future high-resolution imaging observations.
We report observations of the binary microlensing event OGLE-2018-BLG-0022, provided by the ROME/REA Survey, which indicate that the lens is a low-mass binary star consisting of M3 (0.375+/-0.020 Msun) and M7 (0.098+/-0.005 Msun) components. The lens is unusually close, at 0.998+/-0.047 kpc, compared with the majority of microlensing events, and despite its intrinsically low luminosity, it is likely that AO observations in the near future will be able to provide an independent confirmation of the lens masses.
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