Binary Source Microlensing Event OGLE-2016-BLG-0733: Interpretation of a Long-term Asymmetric Perturbation

Jung, Youn Kil; Udalski, A.; Yee, Jennifer C.; Sumi, T.; Gould, Andrew; Han, Cheongho; Albrow, M. D.; Lee, C. U.; Kim, S. L.; Chung, Sun-Ju; Hwang, Kyu-Ha; Ryu, Yoon-Hyun; Shin, In-Gu; Zhu, Wei; M., S.; Kim, D. J.; Lee, Y.; Park, B. G.; Pogge, Richard W.; Pietrukowicz, P.; Kozłowski, S.; Poleski, R.; Skowron, J.; Mróz, P.; Szymański, M. K.; Pawlak, M.; Ulaczyk, K.; Abe, F.; Bennett, D. P.; Barry, Richard; Bond, I. A.; Asakura, Y.; Bhattacharya, Aparna; Donachie, M.; Freeman, Matthew; Fukui, A.; Hirao, Yuki; Itow, Y.; Koshimoto, Naoki; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Oyokawa, H.; Rattenbury, N. J.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yamada, Tōru; Yonehara, A.

doi:10.3847/1538-3881/aa5d07

Cited by 42 publications

(22 citation statements)

References 49 publications

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“…The "binary-source/planet degeneracy" is an accidental degeneracy, which causes difficulty in distinguishing a short-term planetary anomaly from the anomaly produced by a subset of binary-source events with a small flux ratio between the binary-source stars and the close approach of the faint source companion to the lens (Gaudi 1998). It was recently found that this degeneracy not only applies to a shortterm anomaly but also can extend to various cases of planetary lens system configurations (Jung et al 2017;Shin et al 2019;Dominik et al 2019). events, various types of degeneracies have been newly identified.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb

Han

Yee

Udalski

et al. 2019

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We report the discovery of the microlensing planet OGLE-2018-BLG-0740Lb. The planet is detected with a very strong signal of ∆χ 2 ∼ 4630, but the interpretation of the signal suffers from two types of degeneracies. One type is caused by the previously known close/wide degeneracy, and the other is caused by an ambiguity between two solutions, in which one solution requires to incorporate finite-source effects, while the other solution is consistent with a point-source interpretation. Although difficult to be firmly resolved based on only the photometric data, the degeneracy is resolved in strong favor of the point-source solution with the additional external information obtained from astrometric and spectroscopic observations. The small astrometric offset between the source and baseline object supports that the blend is the lens and this interpretation is further secured by the consistency of the spectroscopic distance estimate of the blend with the lensing parameters of the point-source solution. The estimated mass of the host is 1.0 ± 0.1 M ⊙ and the mass of the planet is 4.5 ± 0.6 M J (close solution) or 4.8 ± 0.6 M J (wide solution) and the lens is located at a distance of 3.2 ± 0.5 kpc. The bright nature of the lens, with I ∼ 17.1 (V ∼ 18.2), combined with its dominance of the observed flux suggest that radial-velocity (RV) follow-up observations of the lens can be done using high-resolution spectrometers mounted on large telescopes, e.g., VLT/ESPRESSO, and this can potentially not only measure the period and eccentricity of the planet but also probe for close-in planets. We estimate that the expected RV amplitude would be ∼ 60 sin i m s −1 .

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Section: Introductionmentioning

confidence: 99%

Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb

Han

Yee

Udalski

et al. 2019

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“…The degeneracy between 2L1S and 1L2S interpretations can often be severe, as demonstrated in the cases OGLE-2002-BLG-055 (Gaudi & Han 2004), MOA-2012-BLG-486 (Hwang et al 2013), and OGLE-2014-BLG-1186 (Dominik et al 2019). Besides the short-term anomaly considered by Gaudi (1998), it was shown that the 2L1S/1L2S degeneracy could extend to various cases of planetary lens system configurations from the analysis of anomalies in the cases of OGLE-2016-BLG-0733 by Jung et al (2017) and KMT-2017-BLG-0962 and KMT-2017-BLG-1119 by Shin et al (2019).…”

Section: Binary-lens (2l1s) Interpretationsmentioning

confidence: 93%

OGLE-2018-BLG-1011Lb,c: Microlensing Planetary System with Two Giant Planets Orbiting a Low-mass Star

Han¹,

Bennett²,

Udalski³

et al. 2019

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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 ∼ 9.5 × 10 −3 and ∼ 15 × 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 J and 2.8 +5.1 −1.7 M J around a host with a mass 0.18 +0.33 −0.10 M ⊙ and located at a distance 7.1 +1.1 −1.5 kpc. The estimated distance indicates that the lens is the farthest system among the known multiplanetary systems. The projected planet-host separations are a ⊥,2 = 1.8 +2.1 −1.5 au (0.8 +0.9 −0.6 au) and a ⊥,3 = 0.8 +0.9 −0.6 au, where the values of a ⊥,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.

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“…A binary source model is also a possible alternative explanation of the second anomaly (Gaudi 1998;Jung et al 2017a). In this event, a hypothetical second source star is expected to be very faint and highly magnified, since the apparent duration of the anomaly is very short (∼ 1 day) compared to that of the primary event (∼ 1 month), and we do not see any excess flux when the primary source was demagnified (compared to the single lens-single source model) at the first anomaly.…”

Section: Binary Source Modelmentioning

confidence: 99%

A Likely Detection of a Two-planet System in a Low-magnification Microlensing Event

Suzuki

Bennett

Udalski

et al. 2018

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We report on the analysis of a microlensing event OGLE-2014-BLG-1722 that showed two distinct short term anomalies. The best fit model to the observed light curves shows that the two anomalies are explained with two planetary mass ratio companions to the primary lens. Although a binary source model is also able to explain the second anomaly, it is marginally ruled out by 3.1 σ. The 2-planet model indicates that the first anomaly was caused by planet "b" with a mass ratio of q = (4.5 +0.7 −0.6 ) × 10 −4 and projected separation in unit of the A Microlensing Observations in Astrophysics (MOA) CollaborationEinstein radius, s = 0.753 ± 0.004. The second anomaly reveals planet "c" with a mass ratio of q 2 = (7.0 +2.3 −1.7 ) × 10 −4 with ∆χ 2 ∼ 170 compared to the single planet model. Its separation has two degenerated solutions: the separation of planet c is s 2 = 0.84 ± 0.03 and s 2 = 1.37 ± 0.04 for the close and wide models, respectively. Unfortunately, this event dose not show clear finite source and microlensing parallax effects, thus we estimated the physical parameters of the lens system from Bayesian analysis. This gives that the masses of planet b and c are m b = 56 +51 −33 M ⊕ and m c = 85 +86 −51 M ⊕ , respectively, and they orbit a late type star with a mass of M host = 0.40 +0.36 −0.24 M located at D L = 6.4 +1.3 −1.8 kpc from us. The projected distance between the host and planets are r ⊥,b = 1.5 ± 0.6 AU for planet b, and r ⊥,c = 1.7 +0.7 −0.6 AU and r ⊥,c = 2.7 +1.1 −1.0 AU for close and wide models of planet c. If the 2-planet model is true, then this is the third multiple planet system detected by using the microlensing method, and the first multiple planet system detected in the low magnification events, which are dominant in the microlensing survey data. The occurrence rate of multiple cold gas giant systems is estimated using the two such detections and a simple extrapolation of the survey sensitivity of 6 year MOA microlensing survey (Suzuki et al. 2016) combined with the 4 year µFUN detection efficiency (Gould et al. 2010). It is estimated that 6 ± 2 % of stars host two cold giant planets.

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Binary Source Microlensing Event OGLE-2016-BLG-0733: Interpretation of a Long-term Asymmetric Perturbation

Cited by 42 publications

References 49 publications

Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb

Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb

OGLE-2018-BLG-1011Lb,c: Microlensing Planetary System with Two Giant Planets Orbiting a Low-mass Star

A Likely Detection of a Two-planet System in a Low-magnification Microlensing Event

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