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1. KMT-2021-BLG-0171Lb and KMT-2021-BLG-1689Lb: Two Microlensing Planets in the KMTNet High-Cadence Fields With Followup Observations

Author

Hongjing Yang, Weicheng Zang, Andrew Gould, Jennifer C Yee, Kyu-Ha Hwang, Grant Christie, Takahiro Sumi, Jiyuan Zhang, Shude Mao, Michael D Albrow, Sun-Ju Chung, Cheongho Han, Youn Kil Jung, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W Pogge, John Drummond, Dan Maoz, Jennie McCormick, Tim Natusch, Matthew T Penny, Wei Zhu, Ian A Bond, Fumio Abe, Richard Barry, David P Bennett, Aparna Bhattacharya, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Greg Olmschenk, Clément Ranc, Nicholas J Rattenbury, Yuki Satoh, Hikaru Shoji, Stela Ishitani Silva, Daisuke Suzuki, Yuzuru Tanaka, Paul J Tristram, Tsubasa Yamawaki, and Atsunori Yonehara

Subjects
Astronomy
Abstract

Follow-up observations of high-magnification gravitational microlensing events can fully exploit their intrinsic sensitivity to detect extrasolar planets, especially those with small mass ratios. To make followup observations more uniform and efficient, we develop a system, HighMagFinder, to automatically alert possible ongoing high-magnification events based on the real-time data from the Korea Microlensing Telescope Network (KMTNet). We started a new phase of follow-up observations with the help of HighMagFinder in 2021. Here we report the discovery of two planets in high-magnification microlensing events, KMT- 2021-BLG-0171 and KMT-2021-BLG-1689, which were identified by the HighMagFinder. We find that both events suffer the ‘central-resonant’ caustic degeneracy. The planet-host mass-ratio is q ∼4.7 × 10−5 or q ∼2.2 × 10−5 for KMT-2021-BLG-0171, and q ∼2.5 × 10−4 or q ∼1.8 × 10−4 for KMT-2021-BLG-1689. Together with two other events, four cases that suffer such degeneracy have been discovered in the 2021 season alone, indicating that the de generate solutions may have been missed in some previous studies. We also propose a quantitative factor to weight the probability of each solution from the phase space. The resonant interpretations for the two events are disfavoured under this consideration. This factor can be included in future statistical studies to weight degenerate solutions.

Published
2022
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2. Asteroid Lightcurves From the Moa-Ii Survey: A Pilot Study

Author

A J Cordwell, N J Rattenbury, M T Bannister, P Cowan, Fumio Abe, Richard Barry, David P Bennett, Aparna Bhattacharya, Ian A Bond, Hirosane Fujii, Akihiko Fukui, Yoshitaka Itow, Stela Ishitani Silva, Yuki Hirao, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Yutaka Matsubara, Sho Matsumoto, Yasushi Muraki, Shota Miyazaki, Arisa Okamura, Clément Ranc, Yuki Satoh, Takahiro Sumi, Daisuke Suzuki, Paul J Tristram, Taiga Toda, Hibiki Yama, and Atsunori Yonehara

Subjects
Astronomy, Astrophysics
Abstract

The Microlensing Observations in Astrophysics (MOA-II) survey has performed high cadence, wide field observations of the Galactic Bulge from New Zealand since 2005. The hourly cadence of the survey during eight months of the year, across nearly 50 deg2 of sky, provides an opportunity to sample asteroid lightcurves in the broad MOA-R filter. We perform photometry of a subset of bright asteroids numbered observed by the survey. We obtain 26 asteroid rotation periods, including for two asteroids where no prior data exist, and present evidence for the possible non-principal axis rotation of (2011) Veteraniya. This archival search could be extended to several thousands of asteroids brighter than 22nd magnitude.

Published
2022
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3. KMT-2021-BLG-0322: Severe Degeneracy Between Triple-lens and Higher-order Binary-lens Interpretations

Author

Cheongho Han, Andrew Gould, Yuki Hirao, Chung-Uk Lee, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Youn Kil Jung, Doeon Kim, Shude Mao, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Hyoun Woo Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Fumio Abe, Richard Barry, David P Bennett, Aparna Bhattacharya, Ian Bond, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Clement Ranc, Nicholas J. Rattenbury, Yuki Satoh, Hikaru Shoji, Takahiro Sumi, Daisuke Suzuki, Yuzuru Tanaka, Paul J. Tristram, Tsubasa Yamawaki, and Atsunori Yonehara

Subjects
Instrumentation And Photography
Abstract

We investigate the microlensing event KMT-2021-BLG-0322, for which the light curve exhibits three distinctive sets of caustic-crossing features. It is found that the overall features of the light curve are approximately described by a binary-lens (2L1S) model, but the model leaves substantial residuals. We test various interpretations with the aim of explaining the residuals. Methods. We find that the residuals can be explained either by considering a nonrectilinear lens-source motion caused by the microlens-parallax and lens-orbital effects or by adding a low-mass companion to the binary lens (3L1S model). The degeneracy between the higher-order 2L1S model and the 3L1S model is very severe, making it difficult to single out a correct solution based on the photometric data. This degeneracy was known before for two previous events (MACHO-97-BLG-41 and OGLE-2013-BLG-0723),which led to the false detections of planets in binary systems, and thus the identification of the degeneracy for KMT-2021-BLG-0322illustrates that the degeneracy can be not only common but also very severe, emphasizing the need to check both interpretations of deviations from 2L1S models. Results. From the Bayesian analysis conducted with the measured lensing observables of the event timescale, angular Einstein radius, and microlens parallax, it was estimated that the binary lens components have masses(M1,M2)=(0.62+0.25−0.26M,0.07+0.03−0.03M), for both2L1S and 3L1S solutions, and the mass of the tertiary lens component according to the 3L1S solution isM3=6.40+2.64−2.78MJ.

Published
2021
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4. Systematic KMTNet Planetary Anomaly Search. I. OGLE-2019-BLG-1053Lb, a BuriedTerrestrial Planet

Author

Weicheng Zang, Kyu-Ha Hwang, Andrzej Udalski, Tianshu Wang, Wei Zhu, Takahiro Sumi, Jennifer C. Yee, Andrew Gould, Shude Mao, Xiangyu Zhang, Michael D. Albrow, Sun-Ju Chung, Cheongho Han, Youn Kil Jung, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Przemek Mróz, Jan Skowron, Radoslaw Poleski, Michał K. Szymański, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Mariusz Gromadzki, Ian A. Bond, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Greg Olmschenk, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Hikaru Shoji, Stela Ishitani Silva, Daisuke Suzuki, Yuzuru Tanaka, Paul J. Tristram, Tsubasa Yamawaki, Atsunori Yonehara, Geoffery Bryden, B. Scott Gaudi, and Samson Johnson

Subjects
Astronomy
Abstract

In order to exhume the buried signatures of “missing planetary caustics” in Korea Microlensing Telescope Network (KMTNet) data, we conducted a systematic anomaly search of the residuals from point-source point-lens fits, based on a modified version of the KMTNet Event Finder algorithm. This search revealed the lowest-mass-ratio planetary caustic to date in the microlensing event OGLE-2019-BLG-1053, for which the planetary signal had not been noticed before. The planetary system has a planet–host mass ratio ofq= (1.25±0.13) × 10−5. A Bayesian analysis yielded estimates of the mass of the host star, Mhost =-0.61+0.29 -0.24 Mo, the mass of its planet, Mplanet =-2.48 +1.19 -0.98 Mo, the projected planet – host separation, a^= 3.4 +0.5/-0.5 au, and the lens distance, DL =-6.8 +0.6 -0.90kpc.The discovery of this very-low-mass-ratio planet illustrates the utility of our method and opens a new window for a large and homogeneous sample to study the microlensing planet–host mass ratio function down to q∼ 10−5.

Published
2021
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5. New giant planet beyond the snow line for an extended MOA exoplanet microlens sample

Author

Clément Ranc, David P Bennett, Richard K Barry, Naoki Koshimoto, Jan Skowron, Yuki Hirao, Ian A Bond, Takahiro Sumi, Lars Bathe-Peters, Fumio Abe, Aparna Bhattacharya, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Stela Ishitani Silva, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Gregory Olmschenk, Nicholas J Rattenbury, Yuki Satoh, Hikaru Shoji, Daisuke Suzuki, Yuzuru Tanaka, Paul J Tristram, Tsubasa Yamawaki, and Atsunori Yonehara

Subjects
Astronomy
Abstract

Characterizing a planet detected by microlensing is hard if the planetary signal is weak or the lens-source relative trajectory is far from caustics. However, statistical analyses of planet demography must include those planets to accurately determine occurrence rates. As part of a systematic modelling effort in the context of a >10-yr retrospective analysis of MOA’s survey observations to build an extended MOA statistical sample, we analyse the light curve of the planetary microlensing event MOA-2014-BLG-472. This event provides weak constraints on the physical parameters of the lens, as a result of a planetary anomaly occurring at low magnification in the light curve. We use a Bayesian analysis to estimate the properties of the planet, based on a refined Galactic model and the assumption that all Milky Way’s stars have an equal planet-hosting probability. We find that a lens consisting of a 1.9(+2.2,−1.2)M(J) giant planet orbiting a 0.31(+0.36,−0.19)Mꙩ host at a projected separation of 0.75±0.24au is consistent with the observations and is most likely, based on the Galactic priors. The lens most probably lies in the Galactic bulge, at 7.2(+0.6,−1.7)kpc from Earth. The accurate measurement of the measured planet-to-host star mass ratio will be included in the next statistical analysis of cold planet demography detected by microlensing.

Published
2021
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6. KMT-2019-BLG-0371 and the Limits of Bayesian Analysis

Author

Yun Hak Kim, Sun-Ju Chung, Jennifer C Yee, A Udalski, Ian A Bond, Youn Kil Jung, Andrew Gould, Michael D Albrow, Cheongho Han, Kyu-Ha Hwang, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W Pogge, Radek Poleski, Przemek Mroz, Jan Skowron, Michal K Szymanski, Igor Soszynski, Pawel Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A Rybicki, Patryk Iwanek, Marcin Wrona, Mariusz Gromadzki, Fumio Abe, Richard Barry, David P Bennett, Aparna Bhattacharya, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Yoshitaka Itow, Yuki Hirao, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Clément Ranc, Nicholas J Rattenbury, Yuki Satoh, Hikaru Shoji, Takahiro Sumi, Daisuke Suzuki, Paul J Tristram, Yuzuru Tanaka, Tsubasa Yamawaki, and Atsunori Yonehara

Subjects
Astrophysics
Abstract

We show that the perturbation at the peak of the light curve of microlensing event KMT-2019-BLG-0371 is explained by a model with a mass ratio between the host star and planet of q ∼ 0.08. Due to the short event duration (t(sub E) ∼ 6.5 days), the secondary object in this system could potentially be a massive giant planet. A Bayesian analysis shows that the system most likely consists of a host star with a mass M(sub h) = 0.09(+0.14/-0.05) M⨀ and a massive giant planet with a mass = M(sub h) = 7.70(+11.34/-3.90) M(sub Jup). However, the interpretation of the secondary as a planet (i.e., as having M(sub p) < 13M(sub Jup)) rests entirely on the Bayesian analysis. Motivated by this event, we conduct an investigation to determine which constraints meaningfully affect Bayesian analyses for microlensing events. We find that the masses inferred from such a Bayesian analysis are determined almost entirely by the measured value of θ(sub E) and are relatively insensitive to other factors such as the direction of the event (l,b), the lens–source relative proper motion μ(sub rel), or the specific Galactic model prior.

Published
2021
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7. KMT-2019-BLG-0842Lb: A Cold Planet below the Uranus/Sun Mass Ratio

Author

Youn Kil Jung, Andrzej Udalski, Weicheng Zang, Ian A. Bond, Jennifer C. Yee, Cheongho Han, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Kyu-Ha Hwang, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Przemek Mróz, Michał Krzysztof Szymański, Jan Skowron, Radek Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Martin Donachie, Hirosame Fujii, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Yukei Kamei, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Shota Miyazaki, Yasushi Muraki, Masayuki Nagakane, Clément Ranc, Nicholas j. Rattenbury, Yuki Satoh, Hikaru Shoji, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, Takeharu Yamakawa, Tsubasa Yamamwaki, and Atsunori Yonehara

Subjects
Astronomy, Astrophysics
Abstract

We report the discovery of a cold planet with a very low planet/host mass ratio of q = (4.09 ± 0.27) × 10^−5, which is similar to the ratio of Uranus/Sun (q = 4.37 × 10^−5) in the solar system. The Bayesian estimates for the host mass, planet mass, system distance, and planet–host projected separation are M(host) = 0.76 ± 0.40Mꙩ, M(planet) = 10.3 ± 5.5Mꚛ, D(L) = 3.3 ± 1.3 kpc, and a(⊥) = 3.3 ± 1.4 au, respectively. The consistency of the color and brightness expected from the estimated lens mass and distance with those of the blend suggests the possibility that the most blended light comes from the planet host, and this hypothesis can be established if high-resolution images are taken during the next (2020) bulge season. We discuss the importance of conducting optimized photometry and aggressive follow-up observations for moderately or very high magnification events to maximize the detection rate of planets with very low mass ratios.

Published
2020
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8. OGLE-2017-BLG-0406: Spitzer Microlens Parallax Reveals Saturn-mass Planet Orbiting M-dwarf Host in the Inner Galactic Disk

Author

Yuki Hirao, David P. Bennett, Yoon-Hyun Ryu, Naoki Koshimoto, Andrzej Udalski, Jennifer C. Yee, Takahiro Sumi, Ian A. Bond, Yossi Shvartzvald, Fumio Abe, Richard K. Barry, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yoshitaka Itow, Iona Kondo, Man Cheung Alex Li, Yutaka Matsubara, Taro Matsuo, Shota Miyazaki, Yasushi Muraki, Masayuki Nagakane, Clément Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Hiroshi Shibai, Daisuke Suzuki, Paul J. Tristram, Atsunori Yonehara, J. Skowron, R. Poleski, P. Mróz, M. K. Szymański, I. Soszyński, S. Kozłowski, P. Pietrukowicz, K. Ulaczyk, K. Rybicki, P. Iwanek, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Cheongho Han, Kyu-Ha Hwang, Youn Kil Jung, In-Gu Shin, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Charles A. Beichman, Geoffery Bryden, Sebastiano Calchi Novati, Sean Carey, B. Scott Gaudi, Calen B. Henderson, Wei Zhu, Etienne Bachelet, Greg Bolt, Grant Christie, Markus Hundertmark, Tim Natusch, Dan Maoz, Jennie McCormick, Rachel A. Street, Thiam-Guan Tan, Yiannis Tsapras, U. G. Jørgensen, M. Dominik, V. Bozza, J. Skottfelt, C. Snodgrass, S. Ciceri, R. Figuera Jaimes, D. F. Evans, N. Peixinho, T. C. Hinse, M. J. Burgdorf, J. Southworth, S. Rahvar, S. Sajadian, M. Rabus, C. von Essen, Y. I. Fujii, J. Campbell-White, S. Lowry, C. Helling, L. Mancini, L. Haikala, and Ryo Kandori

Subjects
Astronomy, Astrophysics
Abstract

We report the discovery and analysis of the planetary microlensing event OGLE-2017-BLG-0406, which was observed both from the ground and by the Spitzer satellite in a solar orbit. At high magnification, the anomaly in the light curve was densely observed by ground-based-survey and follow-up groups, and it was found to be explained by a planetary lens with a planet/host mass ratio of q = 7.0 x 10^-4 from the light-curve modeling. The ground-only and Spitzer-"only" data each provide very strong one-dimensional (1D) constraints on the 2D microlens parallax vector π(E). When combined, these yield a precise measurement of π(E) and of the masses of the host M(host) = 0.56 ± 0.07 Mꙩ and planet M(planet) = 0.41 ± 0.05 M(Jup). The system lies at a distance D(L) = 5.2 ± 0.5 kpc from the Sun toward the Galactic bulge, and the host is more likely to be a disk population star according to the kinematics of the lens. The projected separation of the planet from the host is a(┴) = 3.5 ± 0.3 au (i.e., just over twice the snow line). The Galactic-disk kinematics are established in part from a precise measurement of the source proper motion based on OGLE-IV data. By contrast, the Gaia proper-motion measurement of the source suffers from a catastrophic 10σ error.

Published
2020
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9. One Planet or Two Planets? The Ultra-sensitive Extreme-magnification Microlensing Event KMT-2019-BLG-1953

Author

Cheongho Han, Doeon Kim, Youn Kil Jung, Andrew Gould, Ian A. Bond, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Chung-Uk Lee, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Woong-Tae Kim, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Yoshitaka Itow, Yuki Hirao, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Hikaru Shoji, Haruno Suematsu, Takahiro Sumi, Daisuke Suzuki, Yuzuru Tanaka, Paul J. Tristram, Tsubasa Yamawaki, and Atsunori Yonehara

Subjects
Astronomy, Astrophysics
Abstract

We present the analysis of a very high-magnification (A ~ 900) microlensing event KMT-2019-BLG-1953. A single-lens single-source (1L1S) model appears to approximately delineate the observed light curve, but the residuals from the model exhibit small but obvious deviations in the peak region. A binary-lens (2L1S) model with a mass ratio of q ~ 2 × 10^−3 improves the fits by Δχ2 = 181.8, indicating that the lens possesses a planetary companion. From additional modeling by introducing an extra planetary lens component (3L1S model) and an extra source companion (2L2S model), it is found that the residuals from the 2L1S model further diminish, but claiming these interpretations is difficult due to the weak signals with Δχ2 = 16.0 and 13.5 for the 3L1S and 2L2L models, respectively. From a Bayesian analysis, we estimate that the host of the planets has a mass of M(host)=0.31 (+0.37, -0.17) Mꙩ and that the planetary system is located at a distance of D9L)=7.04 (+1.10, -1.33) kpc toward the Galactic center. The mass of the securely detected planet is M(p)=0.64 (+0.76, -0.35) M(J). The signal of the potential second planet could have been confirmed if the peak of the light curve had been more densely observed by follow-up observations, and thus the event illustrates the need for intensive follow-up observations for very high-magnification events even in the current generation of high-cadence surveys.

Published
2020
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10. A Wide-orbit Exoplanet OGLE-2012-BLG-0838Lb

Author

R. Poleski, Daisuke Suzuki, A. Udalski, Xiaojia Xie, J. C. Yee, Naoki Koshimoto, B. S. Gaudi, A. Gould, J. Skowron, M. K. Szymanski, I. Soszynski, P. Pietrukowicz, S. Kozlowski, L. Wyrzykowski, K. Ulaczyk, Fumio Abe, Richard K Barry, David P Bennett, Aparna Bhattacharya, Ian A. Bond, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Yoshitaka Itow, Yuki Hirao, Yuhei Kamei, Iona Kondo, Man Cheung Alex Li, Yutaka Matsubara, Shota Miyazaki, Yasushi Muraki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Yuki K. Satoh, Hikaru Shoji, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Paul J. Tristram, Takeharu Yamakawa, Tsubasa Yamawaki, Atsunori Yonehara, C. Han, Subo Dong, K. M. Morzinski, J. R. Males, L. M. Close, R. W. Pogge, J.-P. Beaulieu, and J.-B. Marquette

Subjects
Astronomy
Abstract

We present the discovery of a planet on a very wide orbit in the microlensing event OGLE-2012-BLG-0838. The signal of the planet is well separated from the main peak of the event and the planet–star projected separation is found to be twice the Einstein ring radius, which corresponds to a projected separation of ≈4au. Similar planets around low-mass stars are very hard to find using any technique other than microlensing. We discuss microlensing model fitting in detail and discuss the prospects for measuring the mass and distance of the lens system directly.

Published
2020
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11. Candidate Brown-dwarf Microlensing Events with Very Short Timescales and Small Angular Einstein Radii

Author

Cheongho Han, Chung Uk Lee, Andrzej Udalski, Andrew Gould, Ian A. Bond, Valerio Bozza, Michael D. Albrow, Sun Ju Chung, Kyu Ha Hwang, Youn Kil Jung, Yoon-Hyun Ryu, In Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Weicheng Zang, Sang Mok Cha, Dong-Jin Kim, Hyoun Woo Kim, Seung Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong Gon Park, Richard W. Pogge, M. James Jee, Doeon Kim, Przemek Mroz, Michal K. Szymański, Jan Skowron, Radek Poleski, Igor Soszynski, Pawel Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Fumio Abe, Barry Richardson, David P. Bennett, Aparna Bhattacharya, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Yoshitaka Itow, Yuki Hirao, Yuhei Kamei, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Yuki Satoh, Hikaru Shoji, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, Takeharu Yamakawa, Tsubasa Yamawaki, and and Atsunori Yonehara

Subjects
Astronomy, Astrophysics
Abstract

Short-timescale microlensing events are likely to be produced by substellar brown dwarfs (BDs), but it is difficult to securely identify BD lenses based on only event timescales because short-timescale events can also be produced by stellar lenses with high relative lens-source proper motions. In this paper, we report three strong candidate BD-lens events found from the search for lensing events not only with short timescales (t(E) ≲ 6 days) but also with very small angular Einstein radii (θ(E) ≲ 0.05 mas) among the events that have been found in the 2016–2019 observing seasons. These events include MOA-2017-BLG-147, MOA-2017-BLG-241, and MOA-2019-BLG-256, in which the first two events are produced by single lenses and the last event is produced by a binary lens. From the Monte Carlo simulations of Galactic events conducted with the combined t(E) and θ(E) constraint, it is estimated that the lens masses of the individual events are 0.051 (sup +0.100, sub -0.027) M(ʘ), 0.044 (sup +0.090, sub -0.023) M(ʘ), and 0.046 (sup +0.067, sub -0.023) M(ʘ)/0.038 (sup +0.056, sub -0.019) M(ʘ) and the probability of the lens mass smaller than the lower limit of stars is ~80% for all events. We point out that routine lens mass measurements of short-timescale lensing events require survey-mode space-based observations.

Published
2020
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12. Spitzer Microlensing Parallax Reveals Two Isolated Stars in the Galactic Bulge

Author

Weicheng Zang, Yossi Shvartzvald, Tianshu Wang, Andrzej Udalski, Chung-Uk Lee, Takahiro Sumi, Jesper Skottfelt, Shun-Sheng Li, Shude Mao, Wei Zhu, Jennifer C. Yee, Sebastiano Calchi Novati, Charles A. Beichman, Geoffery Bryden, Sean Carey, B. Scott Gaudi, Calen B. Henderson, Przemek Mróz, Jan Skowron, Radoslaw Poleski, Michał K. Szymański, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Etienne Bachelet, Grant Christie, Jonathan Green, Steve Hennerley, Dan Maoz, Tim Natusch, Richard W. Pogge, Rachel A. Street, Yiannis Tsapras, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Cheongho Han, Kyu-Ha Hwang, Youn Kil Jung, Yoon-Hyun Ryu, In-Gu Shin, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Ian A. Bond, Fumio Abe, Richard K Barry, David P Bennett, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Daisuke Suzuki, Paul J. Tristram, Atsunori Yonehara, Martin Dominik, Markus Hundertmark, Uffe G. Jørgensen, Sohrab Rahvar, Sedighe Sajadian, Colin Snodgrass, Valerio Bozza, Martin J. Burgdorf, Daniel F. Evans, R. Figuera Jaimes, Yuri I. Fujii, Luigi Mancini, Penelope Longa-Peña, Christiane Helling, Nuno Peixinho, Markus Rabus, John Southworth, Eduardo Unda-Sanzana, and Carolina von Essen

Subjects
Astrophysics, Astronomy
Abstract

We report the mass and distance measurements of two single-lens events from the 2017 Spitzer microlensing campaign. The ground-based observations yield the detection of finite-source effects, and the microlens parallaxes are derived from the joint analysis of ground-based observations and Spitzer observations. We find that the lens of OGLE-2017-BLG-1254 is a 0.60 ± 0.03 M⊙ star with D(LS) = 0.53 ± 0.11 kpc, where D(LS) is the distance between the lens and the source. The second event, OGLE-2017-BLG-1161, is subject to the known satellite parallax degeneracy, and thus is either a 0.51(sup +0.12, sub 3-0.10)M⊙ star with D(LS) = 0.40 ± 0.12 kpc or a 0.38(sup +0.13, sub -0.12) M⊙ star with D(LS) = 0.53 ± 0.19 kpc. Both of the lenses are therefore isolated stars in the Galactic bulge. By comparing the mass and distance distributions of the eight published Spitzer finite-source events with the expectations from a Galactic model, we find that the Spitzer sample is in agreement with the probability of finite-source effects occurring in single-lens events.

Published
2020
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13. OGLE-2018-BLG-1700L: Microlensing Planet in Binary Stellar System

Author

Cheongho Han, Chung-Uk Lee, Andrzej Udalski, Andrew Gould, Ian A. Bond, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Youn Kil Jung, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, M. James Jee, Doeon Kim, Przemek Mróz, Michał K. Szymański, Jan Skowron, Radek Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Fumio Abe, Richard K Barry, David P Bennett, Aparna Bhattacharya, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Yoshitaka Itow, Yuki Hirao, Yuhei Kamei, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, Takeharu Yamakawa, and Atsunori Yonehara

Subjects
Astrophysics, Astronomy
Abstract

We report 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 anomaly pattern can be decomposed into two parts produced by two binary-lens events, in which one binary pair has a mass ratio of ∼0.01 between the lens components and the other pair has a mass ratio of ∼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 θ(E) (close solution), while the other solution has a separation greater than θ(E) (wide solution). From the Bayesian analysis with the constraints of the event timescale and angular Einstein radius, we find that the planet has a mass of 4.4(sup +3.0, sub -2.0) M(J) and the stellar binary components have masses of 0.42 (sup +0.29, sub -0.19) M(ʘ) and 0.12 (sup +0.08, sub -0.05) M(ʘ) , respectively, and the distance to the lens is D(L) = 7.6 (sup +1.2, sub -0.9) kpc. The planet is a circumstellar planet according to the wide solution, while it is a circumbinary planet according to the close solution.

Published
2020
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14. OGLE-2018-BLG-0799Lb: a q ∼ 2.7 × 10−3 planet with Spitzer parallax

Author

Weicheng Zang, Yossi Shvartzvald, Andrzej Udalski, Jennifer C Yee, Chung-Uk Lee, Takahiro Sumi, Xiangyu Zhang, Hongjing Yang, Shude Mao, Sebastiano Calchi Novati, Andrew Gould, Wei Zhu, Charles A Beichman, Geoffery Bryden, Sean Carey, B Scott Gaudi, Calen B Henderson, Przemek Mróz, Jan Skowron, Radoslaw Poleski, Michał K Szymański, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A Rybicki, Patryk Iwanek, Marcin Wrona, Michael D Albrow, Sun-Ju Chung, Cheongho Han, Kyu-Ha Hwang, Youn Kil Jung, Yoon-Hyun Ryu, In-Gu Shin, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W Pogge, Ian A Bond, Fumio Abe, Richard Barry, David P Bennett, Aparna Bhattacharya, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Clément Ranc, Nicholas J Rattenbury, Yuki Satoh, Hikaru Shoji, Daisuke Suzuki, Yuzuru Tanaka, Paul J Tristram, Tsubasa Yamawaki, Atsunori Yonehara, Etienne Bachelet, Markus P G Hundertmark, R Figuera Jaimes, Dan Maoz, Matthew T Penny, Rachel A Street, and Yiannis Tsapras

Subjects
Space and Planetary Science, Astronomy and Astrophysics
Abstract

We report the discovery and analysis of a planet in the microlensing event OGLE-2018-BLG-0799. The planetary signal was observed by several ground-based telescopes, and the planet-host mass ratio is q = (2.65 ± 0.16) × 10−3. The ground-based observations yield a constraint on the angular Einstein radius θE, and the microlensing parallax vector $\boldsymbol{{\pi} }_{\rm E}$, is strongly constrained by the Spitzer data. However, the 2019 Spitzer baseline data reveal systematics in the Spitzer photometry, so there is ambiguity in the magnitude of the parallax. In our preferred interpretation, a full Bayesian analysis using a Galactic model indicates that the planetary system is composed of an $M_{\rm planet} = 0.26_{-0.11}^{+0.22}M_{\rm J}$ planet orbiting an $M_{\rm host} = 0.093_{-0.038}^{+0.082}~\mathrm{M}_{\odot }$, at a distance of $D_{\rm L} = 3.71_{-1.70}^{+3.24}$ kpc. An alternate interpretation of the data shifts the localization of the minima along the arc-shaped microlens parallax constraints. This, in turn, yields a more massive host with median mass of $0.13 {\, \mathrm{M}_{\odot }}$ at a distance of 6.3 kpc. This analysis demonstrates the robustness of the osculating circles formalism, but shows that further investigation is needed to assess how systematics affect the specific localization of the microlens parallax vector and, consequently, the inferred physical parameters.

Published
2022

15. KELT-24b: A 5M(J) Planet on a 5.6 day Well-aligned Orbit around the Young V=8.3 F-star HD 93148

Author

Joseph E. Rodriguez, Jason D. Eastman, George Zhou, Samuel N. Quinn, Thomas G. Beatty, Kaloyan Penev, Marshall C. Johnson, Phillip A. Cargile, David W. Latham, Allyson Bieryla, Karen A. Collins, Courtney Dressing, David R Ciardi, Howard M. Relles, Gabriel Murawski, Taku Nishiumi, Atsunori Yonehara, Ryo Ishimaru, Fumi Yoshida, Joao Gregorio, Michael B. Lund, Daniel J. Stevens, Keivan G. Stassun, B. Scott Gaudi, Knicole Colon, Joshua Pepper, Norio Narita, Supachai Awiphan, Pongpichit Chuanraksasat, Paul Benni, Roberto Zambelli, Lehman H. Garrison, Maurice L. Wilson, Matthew A. Cornachione, Sharon X. Wang, Jonathan Labadie-Bartz, Romy Rodríguez, Robert J. Siverd, Xinyu Yao, Daniel Bayliss, Perry Berlind, Michael L. Calkins, Jessie L. Christiansen, David H Cohen, Dennis M. Conti, Ivan A. Curtis, D. L. Depoy, Gilbert A. Esquerdo, Phil Evans35, Dax Feliz, Benjamin J Fulton, Thomas W.-S. Holoien, David J. James, Tharindu Jayasinghe, Hannah Jang-condell, Eric L. N. Jensen, John A. Johnson, Michael D. Joner, Somayeh Khakpash, John F. Kielkopf, Rudolf B. Kuhn, Mark Manner, Jennifer L. Marshall, Kim K. McLeod, Nate McCrady, Thomas E. Oberst, Ryan J. Oelkers, Matthew T. Penny, Phillip A. Reed, David H. Sliski, B. J. Shappee, Denise C. Stephens, Chris Stockdale, Thiam-Guan Tan, Mark Trueblood, Pat Trueblood, Steven Villanueva Jr, Robert A. Wittenmyer, and Jason T. Wright

Subjects
Astronomy
Abstract

We present the discovery of KELT-24 b, a massive hot Jupiter orbiting a bright (V=8.3 mag, K=7.2 mag) young F-star with a period of 5.6 days. The host star, KELT-24 (HD 93148), has a Teff=-+65094950K, a mass of M*=+1.4600.0590.055Me, a radius of R*=1.506±0.022Re, and an age of +0.780.420.61Gyr. Its planetary companion (KELT-24 b) has a radius of RP=1.272±0.021RJ and a mass of MP=-+5.180.220.21MJ, and from Doppler tomographic observations, we find that the planet’s orbit is well aligned to its host star’s projected spin axis (l=-+2.63.65.1). The young age estimated for KELT-24 suggests that it only recently started to evolve from the zero-age main sequence. KELT-24 is the brightest star known to host a transiting giant planet with a period between 5 and 10 days. Although the circularization timescale is much longer than the age of the system, we do not detect a large eccentricity or significant misalignment that is expected from dynamical migration. The brightness of its host star and its moderate surface gravity make KELT-24b an intriguing target for detailed atmospheric characterization through spectroscopic emission measurements since it would bridge the current literature results that have primarily focused on lower mass hot Jupiters and a few brown dwarfs.

Published
2019
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16. OGLE-2018-BLG-1011Lb,c: Microlensing Planetary System with Two Giant Planets Orbiting a Low-mass Star

Author

Cheongho Han, David P Bennett, Andrzej Udalski, Andrew Gould, Ian A. Bond, Yossi Shvartzvald, Kay-Sebastian Nikolaus, Markus Hundertmark, Valerio Bozza, Arnaud Cassan, Yuki Hirao, Etienne Bachelet, Pascal Fouqué, Michael D. Albrow, Sun-Ju Chung, Kyeongsoo Hong, Kyu-Ha Hwang, Chung-Uk Lee, Yoon-Hyun Ryu, In-Gu Shin, Jennifer C. Yee, Youn Kil Jung, Sang-Mok Cha, Doeon Kim, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Przemek Mróz, Michał K. Szymański, Jan Skowron, Radek Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Fumio Abe, Richard Barry, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yoshitaka Itow, Kohei Kawasaki, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, Atsunori Yonehara, Shude Mao, Tianshu Wang, Weicheng Zang, Wei Zhu, Matthew T. Penny, Charles A. Beichman, Geoffery Bryden, Sebastiano Calchi Novati, B. Scott Gaudi, Calen B. Henderson, Savannah Jacklin, and Keivan G. Stassun

Subjects
Astrophysics, Astronomy
Abstract

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 (three 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 X 10(exp −3) and ∼15 X 10(eap −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 (sup +3.4, sub -1.1) M(J) and 2.8 (sup +5.8, sub -1.7) M(J) around a host with a mass 0.18 (sup +0.33,sub - 0.10) M(ʘ) and located at a distance 7.1(sup +1.1, sub -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 (sup +2.1, sub -1.5)au (0.8 (sup +0.9,sub -0.6 au) and a(⊥,3) = 0.8 (sup +0.9, sub -0.6)au , where the values of a(⊥,2) inside and outside 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.

Published
2019
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17. Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb

Author

Cheongho Han, Jennifer C. Yee, Andrzej Udalski, Ian A. Bond, Valerio Bozza, Arnaud Cassan, Yuki Hirao, Subo Dong, Juna A. Kollmeier, Nidia Morrell, Konstantina Boutsia, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Kyu-Ha Hwang, Chung-Uk Lee, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Youn Kil Jung, Doeon Kim, Woong-Tae Kim, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Kyeongsoo Hong, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Weicheng Zang, Przemek Mróz, Michał K. Szymański, Jan Skowron, Radek Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Fumio Abe, Richard Barry, David P Bennett, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yoshitaka Itow, Kohei Kawasaki, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, and Atsunori Yonehara

Subjects
Astrophysics, Astronomy
Abstract

We report the discovery of the microlensing planet OGLE-2018-BLG-0740Lb. The planet is detected with a very strong signal of Δχ(exp 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 the incorporation of 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(ʘ) 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 radialvelocity (RV) follow-up observations of the lens can be done using high-resolution spectrometers mounted on large telescopes, e.g., Very Large Telescope/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.

Published
2019
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18. Spitzer Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M Dwarf

Author

Youn Kil Jung, Andrew Gould, Andrzej Udalski, Takahiro Sumi, Jennifer C. Yee, Yossi Shvartzvald, Weicheng Zang, Cheongho Han, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Yoon-Hyun Ryu, In-Gu Shin, Wei Zhu, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Przemek Mroz, Michalł K. Szymański, Jan Skowron, Radek Poleski, Igor Soszynski, Pawel Pietrukowicz, Szymon Kozłowski, Krzystof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Charles A. Beichman, Geoffery Bryden, Sebastiano Calchi Novati, Sean Carey, B. Scott Gaudi, Calen B. Henderson, Fumio Abe, Richard Barry, David P Bennett, Ian A. Bond, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Shota Miyazaki, Yasushi Muraki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Daisuke Suzuki, Paul J. Tristram, Atsunori Yonehara, Savannah Jacklin, Matthew T. Penny, and Keivan G. Stassun

Subjects
Astronomy
Abstract

We report the discovery of a Spitzer microlensing planet OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio q ~ 2 × 10(exp −4). The planetary signal, which is characterized by a short (~1 day) "bump" on the rising side of the lensing light curve, was densely covered by ground-based surveys. We find that the signal can be explained by a bright source that fully envelops the planetary caustic, i.e., a "Hollywood" geometry. Combined with the source proper motion measured from Gaia, the Spitzer satellite parallax measurement makes it possible to precisely constrain the lens physical parameters. The preferred solution, in which the planet perturbs the minor image due to lensing by the host, yields a Uranus-mass planet with a mass of M(p) = 13.9 ± 1.6 M(⊕) orbiting a mid M-dwarf with a mass of M(h) = 0.23 ± 0.03 M(⊙). There is also a second possible solution that is substantially disfavored but cannot be ruled out, for which the planet perturbs the major image. The latter solution yields M(p) = 1.2 ± 0.2 M(⊕) and M(h) = 0.15 ± 0.02 M(⊙). By combining the microlensing and Gaia data together with a Galactic model, we find in either case that the lens lies on the near side of the Galactic bulge at a distance D(L) ~ 6 ± 1 kpc. Future adaptive optics observations may decisively resolve the major image/minor image degeneracy.

Published
2019
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19. OGLE-2015-BLG-1670Lb: A Cold Neptune beyond the Snow Line in the Provisional WFIRST Microlensing Survey Field

Author

Clément Ranc, David P Bennett, Yuki Hirao, Andrzej Udalski, Cheongho Han, Ian A. Bond, Jennifer C. Yee, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Kyu-Ha Hwang, Youn-Kil Jung, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Weicheng Zang, Wei Zhu, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yong-Seok Lee, Byeong-Gon Park, Richard W. Pogge, Fumio Abe, Richard K Barry, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yoshitaka Itow, Kohei Kawasaki, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Shota Miyazaki, Yasushi Muraki, Masayuki Nagakane, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, and Atsunori Yonehara

Subjects
Astrophysics, Astronomy
Abstract

We present the analysis of the microlensing event OGLE-2015-BLG-1670, detected in a high-extinction field very close to the Galactic plane. Due to the dust extinction along the line of sight, this event was too faint to be detected before it reached the peak of magnification. The microlensing light-curve models indicate a high-magnification event with a maximum of A(max)≳ 200, very sensitive to planetary deviations. An anomaly in the light curve has been densely observed by the microlensing surveys MOA, KMTNet, and OGLE. From the light-curve modeling, we find a planetary anomaly characterized by a planet-to-host mass ratio, q=(1.00 (sup+0.18, sub -0.16) x 10(exp -4), at the peak recently identified in the mass-ratio function of microlensing planets. Thus, this event is interesting to include in future statistical studies about planet demography. We have explored the possible degeneracies and find two competing planetary models resulting from the s ↔ 1/s degeneracy. However, because the projected separation is very close to s = 1, the physical implications for the planet for the two solutions are quite similar, except for the value of s. By combining the light-curve parameters with a Galactic model, we have estimated the planet mass M(2)=17.9(sup +9.6,sub-8.8)M(ꚛ) and the lens distance D(L) = 6.7(sup +1.0, sub -1.3) kpc, corresponding to a Neptune-mass planet close to the Galactic bulge. Such events with a low absolute latitude (|b| ≈1ᵒ.1) are subject to both high extinction and more uncertain source distances, two factors that may affect the mass measurements in the provisional Wide Field Infrared Survey Telescope fields. More events are needed to investigate the potential trade-off between the higher lensing rate and the difficulty in measuring masses in these low-latitude fields.

Published
2019
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20. OGLE-2018-BLG-0022: First Prediction of an Astrometric Microlensing Signal from a Photometric Microlensing Event

Author

Cheongho Han, Ian A. Bond, Andrzej Udalski, Andrew Gould, Valerio Bozza, Yuki Hirao, Arnaud Cassan, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Chung-Uk Lee, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Youn Kil Jung, Doeon Kim, Woong-Tae Kim, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Weicheng Zang, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yoshitaka Itow, Kohei Kawasaki, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, Atsunori Yonehara, Przemek Mroz, Michal K. Szymanski, Jan Skowron, Radek Poleski, Igor Soszynski, Pawel Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Charles A. Beichman, Geoffery Bryden, Sean Carey, B. Scott Gaudi, Calen B. Henderson, and Sebastiano Calchi Novatil

Subjects
Astrophysics, Astronomy
Abstract

In this work, we present the analysis of the binary microlensing event OGLE-2018-BLG-0022 that is detected toward the Galactic bulge field. The dense and continuous coverage with the high-quality photometry data from ground-based observations combined with the space-based Spitzer observations of this long timescale event enables us to uniquely determine the masses M 1 = 0.40 ± 0.05 M ⊙ and M 2 = 0.13 ± 0.01 M ⊙ of the individual lens components. Because the lens-source relative parallax and the vector lens-source relative proper motion are unambiguously determined, we can likewise unambiguously predict the astrometric offset between the light centroid of the magnified images (as observed by the Gaia satellite) and the true position of the source. This prediction can be tested when the individual-epoch Gaia astrometric measurements are released.

Published
2019
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21. OGLE-2014-BLG-0962 and a Comparison of Galactic Model Priors to Microlensing Data

Author

Yutong Shan, Jennifer C. Yee, Andrzej Udalski, Ian A. Bond, Yossi Shvartzvald, In-Gu Shin, Youn-Kil Jung, Sebastiano Calchi Novati, Charles A. Beichman, Sean Carey, B. Scott Gaudi, Andrew Gould, Richard W. Pogge, Radoslaw Poleski, Jan Skowron, Szymon Kozłowski, Przemyslaw Mroz, Pawel Pietrukowicz, Michal K. Szymanski, Igor Soszynski, Krzysztof Ulaczyk, Lukasz Wyrzykowski, Fumio Abe, Richard K Barry, David P Pearson, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Kohei Kawasaki, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, Atsunori Yonehara, Dan Maoz, Shai Kaspi, and Matan Friedmann

Subjects
Astrophysics
Abstract

OGLE-2014-BLG-0962 (OB140962) is a stellar binary microlensing event that was well covered by observations from the Spitzer satellite as well as ground-based surveys. Modeling yields a unique physical solution: a mid-M+M-dwarf binary with M(prim) = 0.20 ± 0.01 M(☉) and M(sec) = 0.16 ± 0.01 M(☉), with projected separation of 2.0 ± 0.3 au. The lens is only D(LS) = 0.41 ± 0.06 kpc in front of the source, making OB140962 a bulge lens and the most distant Spitzer binary lens to date. In contrast, because the Einstein radius (θ(E) = 0.143 ± 0.007 mas) is unusually small, a standard Bayesian analysis, conducted in the absence of parallax information, would predict a brown dwarf binary. We compare the results of Bayesian analysis using two commonly used Galactic model priors to the measured values for a set of Spitzer lenses. We find all models tested predict lens properties consistent with the Spitzer data. Furthermore, we illustrate the methodology for probing the Galactic distribution of planets by comparing the cumulative distance distribution of the Spitzer two-body lenses to that of the Spitzer single lenses.

Published
2019
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22. Two new free-floating or wide-orbit planets from microlensing

Author

Przemek Mróz, Andrzej Udalski, David P. Bennett, Yoon-Hyun Ryu, Takahiro Sumi, Yossi Shvartzvald, Jan Skowron, Radosław Poleski, Paweł Pietrukowicz, Szymon Kozłowski, Michał K. Szymanski, Łukasz Wyrzykowski, Igor Soszynski, Krzysztof Ulaczyk, Krzysztof Rybicki, Patryk Iwanek, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Cheongho Han, Kyu-Ha Hwang, Youn Kil Jung, In-Gu Shin, Jennifer C. Yee, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Fumio Abe, Richard Barry, Aparna Bhattacharya, Ian A. Bond, Martin Donachie, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Kohei Kawasaki, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clément Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Daisuke Suzuki, Paul J. Tristram, Atsunori Yonehara, Dan Maoz, Shai Kaspi, and Matan Friedmann

Subjects
Astronomy, Astrophysics
Abstract

Planet formation theories predict the existence of free-floating planets that have been ejected from their parent systems. Although they emit little or no light, they can be detected during gravitational microlensing events. Microlensing events caused by rogue planets are characterized by very short timescales t(E) (typically below two days) and small angular Einstein radii θ(E)) (up to several μas). Here we present the discovery and characterization of two ultra-short microlensing events identified in data from the Optical Gravitational Lensing Experiment (OGLE) survey, which may have been caused by free-floating or wide-orbit planets. OGLE-2012-BLG-1323 is one of the shortest events discovered thus far (t(E) = 0.155 ± 0.005 d, θ(E) = 2.37 ± 0.10μas) and was caused by an Earth-mass object in the Galactic disk or a Neptune-mass planet in the Galactic bulge. OGLE-2017-BLG-0560 (t(E) = 0.905 ± 0.005 d, θ(E) = 38.7 ± 1.6μas) was caused by a Jupiter-mass planet in the Galactic disk or a brown dwarf in the bulge. We rule out stellar companions up to a distance of 6.0 and 3.9 au, respectively. We suggest that the lensing objects, whether located on very wide orbits or free-floating, may originate from the same physical mechanism. Although the sample of ultrashort microlensing events is small, these detections are consistent with low-mass wide-orbit or unbound planets being more common than stars in the Milky Way.

Published
2019
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23. OGLE-2016-BLG-0156: Microlensing Event with Pronounced Microlens-parallax Effects Yielding a Precise Lens Mass Measurement

Author

Youn Kil Jung, Cheongho Han, Ian A. Bond, Andrzej Udalski, Andrew Gould, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Chung-Uk Lee, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, M. James Jee, Doeon Kim, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Fumio Abe, Richard K Barry, David P Bennett, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Kohei Kawasaki, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, Atsunori Yonehara, Przemek Mroz, Radek Poleski, Jan Skowron, Michal K. Szymanski, Igor Soszynski, Szymon Kozlowski, Pawel Pietrukowicz, Krzysztof Ulaczyk, and Michal Pawlak

Subjects
Astrophysics
Abstract

We analyze the gravitational binary-lensing event OGLE-2016-BLG-0156, for which the lensing light curve displays pronounced deviations induced by microlens-parallax effects. The light curve exhibits three distinctive widely separated peaks and we find that the multiple-peak feature provides a very tight constraint on the microlens-parallax effect, enabling us to precisely measure the microlens parallax . All the peaks are densely and continuously covered from high-cadence survey observations using globally located telescopes and the analysis of the peaks leads to the precise measurement of the angular Einstein radius . From the combination of the measured and , we determine the physical parameters of the lens. It is found that the lens is a binary composed of two M dwarfs with masses M(1) = 0.18 ± 0.01 M(⊙) and M(2) = 0.16 ± 0.01 M(⊙) located at a distance D(L) = 1.35 ± 0.09 kpc. According to the estimated lens mass and distance, the flux from the lens comprises an important fraction, ~25%, of the blended flux. The bright nature of the lens combined with the high relative lens-source motion, μ = 6.94 ± 0.50 mas/yr, suggests that the lens can be directly observed from future high-resolution follow-up observations.

Published
2019
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24. Spitzer Microlensing of MOA-2016-BLG-231L: A Counter-rotating Brown Dwarf Binary in the Galactic Disk

Author

Sun-Ju Chung, Andrew Gould, Jan Skowron, Ian A. Bond, Wei Zhu, Michael D. Albrow, Youn Kil Jung, Cheongho Han, Kyu-Ha Hwang, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Yun-Hak Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Andrzej Udalski, Radek Poleski, Przemek Mroz, Pawel Pietrukowicz, Michal K. Szymanski, Igor Soszynski, Szymon Kozłowski, Krzysztof Ulaczyk, Michal Pawlak, Charles A. Beichman, Geoffery Bryden, Sebastiano Calchi Novati, Sean Carey, B. Scott Gaudi, Calen B. Henderson, Fumio Abe, Richard Barry, David Bennett, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Kohei Kawasaki, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clement Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, and Atsunori Yonehara

Subjects
Astrophysics
Abstract

We analyze the binary microlensing event MOA-2016-BLG-231, which was observed from the ground and from Spitzer. The lens is composed of very-low-mass brown dwarfs (BDs) with M(1)= 21(+12, -5) M(J) and M(2)=9(+5. -2) M(J), and it is located in the Galactic disk D(L)=2.85(+0.88, -0.50) kpc. This is the fifth binary brown dwarf discovered by microlensing, and the BD binary is moving counter to the orbital motion of disk stars. Constraints on the lens physical properties come from late-time, non-caustic-crossing features of the Spitzer light curve. Thus, MOA-2016-BLG-231 shows how Spitzer plays a crucial role in resolving the nature of BDs in binary BD events with short timescales (≲10 days).

Published
2019
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25. KMT-2021-BLG-0912Lb: A microlensing super Earth around a K-type star

Author

Steve Hennerley, Hongjing Yang, Naoki Koshimoto, Yasushi Muraki, Yongseok Lee, Paul J. Tristram, Atsunori Yonehara, David P. Bennett, Yoshitaka Itow, Akihiko Fukui, John Drummond, Jennifer C. Yee, Doeon Kim, Yoon-Hyun Ryu, Byeong-Gon Park, Hirosane Fujii, Daisuke Suzuki, Rintaro Kirikawa, Shota Miyazaki, Stela Ishitani Silva, Yuki Satoh, Aparna Bhattacharya, Takahiro Sumi, Ian A. Bond, Subo Dong, Dong-Jin Kim, Nicholas J. Rattenbury, Arisa Okamura, Richard Barry, Shude Mao, Zhuokai Liu, Tony Cooper, Fumio Abe, Chung-Uk Lee, Cheongho Han, Sho Matsumoto, Taiga Toda, Hibiki Yama, Yuki Hirao, Jonathan Green, Youn Kil Jung, In-Gu Shin, Kyu-Ha Hwang, Yossi Shvartzvald, Clément Ranc, Weicheng Zang, Andrew Gould, Michael D. Albrow, Sun-Ju Chung, Richard W. Pogge, Yutaka Matsubara, Iona Kondo, Matthew T. Penny, Dong-Joo Lee, Plamen Dimitrov, Sang-Mok Cha, Seung-Lee Kim, and Dan Maoz

Subjects
Physics, Earth and Planetary Astrophysics (astro-ph.EP), Super-Earth, Einstein ring, Star (game theory), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Type (model theory), Light curve, Gravitational microlensing, Astrophysics - Astrophysics of Galaxies, symbols.namesake, Space and Planetary Science, Planet, Astrophysics of Galaxies (astro-ph.GA), symbols, Anomaly (physics), Astrophysics - Earth and Planetary Astrophysics
Abstract

The light curve of the microlensing event KMT-2021-BLG-0912 exhibits a very short anomaly relative to a single-lens single-source form. We investigate the light curve for the purpose of identifying the origin of the anomaly. We model the light curve under various interpretations. From this, we find four solutions, in which three solutions are found under the assumption that the lens is composed of two masses (2L1S models), and the other solution is found under the assumption that the source is comprised of a binary-star system (1L2S model). The 1L2S model is ruled out based on the contradiction that the faint source companion is bigger than its primary, and one of the 2L1S solutions is excluded from the combination of the relatively worse fit, blending constraint, and lower overall probability, leaving two surviving solutions with the planet/host mass ratios of $q\sim 2.8\times 10^{-5}$ and $\sim 1.1\times 10^{-5}$. A subtle central deviation supports the possibility of a tertiary lens component, either a binary companion to the host with a very large or small separation or a second planet lying near the Einstein ring, but it is difficult to claim a secure detection due to the marginal fit improvement, lack of consistency among different data sets, and difficulty in uniquely specifying the nature of the tertiary component. With the observables of the event, it is estimated that the masses of the planet and host are $\sim (6.9~M_\oplus, 0.75~M_\odot)$ according to one solution and $\sim (2.8~M_\oplus, 0.80~M_\odot)$ according to the other solution, indicating that the planet is a super Earth around a K-type star, regardless of the solution., 11 pages, 10 figures, 7 tables

Published
2021

26. New Giant Planet beyond the Snow Line for an Extended MOA Exoplanet Microlens Sample

Author

David P. Bennett, Stela Ishitani Silva, Yoshitaka Itow, Martin Donachie, Greg Olmschenk, Aparna Bhattacharya, Iona Kondo, Paul J. Tristram, Nicholas J. Rattenbury, Jan Skowron, Clément Ranc, H. Fujii, Yutaka Matsubara, Man Cheung Alex Li, Ian A. Bond, Yuki Hirao, Tsubasa Yamawaki, Hikaru Shoji, Daisuke Suzuki, Rintaro Kirikawa, Lars Bathe-Peters, Yuzuru Tanaka, Shota Miyazaki, Yasushi Muraki, Atsunori Yonehara, Fumio Abe, Yuki Satoh, Richard K. Barry, Takahiro Sumi, Akihiko Fukui, Naoki Koshimoto, Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), NASA Goddard Space Flight Center (GSFC), University of Maryland [College Park], University of Maryland System, The University of Tokyo (UTokyo), National Astronomical Observatory of Japan (NAOJ), University of Warsaw (UW), Osaka University [Osaka], Massey University, Harvard University [Cambridge], University of Cambridge [UK] (CAM), Nagoya University, University of Auckland [Auckland], Instituto de Astrofisica de Canarias (IAC), Catholic University of America, Universities Space Research Association (USRA), University of Canterbury [Christchurch], and Kyoto Sangyo University

Subjects
010504 meteorology & atmospheric sciences, Milky Way, gravitational lensing, detection, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, 01 natural sciences, Planet, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Giant planet, Astronomy and Astrophysics, Mass ratio, Light curve, Astrophysics - Astrophysics of Galaxies, Exoplanet, Stars, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, micro -planets and satellites, Astrophysics - Earth and Planetary Astrophysics
Abstract

Characterizing a planet detected by microlensing is hard if the planetary signal is weak or the lens-source relative trajectory is far from caustics. However, statistical analyses of planet demography must include those planets to accurately determine occurrence rates. As part of a systematic modeling effort in the context of a $>10$-year retrospective analysis of MOA's survey observations to build an extended MOA statistical sample, we analyze the light curve of the planetary microlensing event MOA-2014-BLG-472. This event provides weak constraints on the physical parameters of the lens, as a result of a planetary anomaly occurring at low magnification in the light curve. We use a Bayesian analysis to estimate the properties of the planet, based on a refined Galactic model and the assumption that all Milky Way's stars have an equal planet-hosting probability. We find that a lens consisting of a $1.9^{+2.2}_{-1.2}\,\mathrm{M}_\mathrm{J}$ giant planet orbiting a $0.31^{+0.36}_{-0.19}\,\mathrm{M}_\odot$ host at a projected separation of $0.75\pm0.24\,\mathrm{au}$ is consistent with the observations and is most likely, based on the Galactic priors. The lens most probably lies in the Galactic bulge, at $7.2^{+0.6}_{-1.7}\mathrm{kpc}$ from Earth. The accurate measurement of the measured planet-to-host star mass ratio will be included in the next statistical analysis of cold planet demography detected by microlensing., accepted for publication in the Monthly Notices of the Royal Astronomical Society, 19 pages, 7 figures, 2 tables

Published
2021

27. KMT-2019-BLG-0371 and the Limits of Bayesian Analysis

Author

Hikaru Shoji, Kyu-Ha Hwang, Dong-Jin Kim, Daisuke Suzuki, Igor Soszyński, Przemek Mróz, Richard K. Barry, Sang-Mok Cha, Yoon-Hyun Ryu, Yun Hak Kim, Chung-Uk Lee, Richard W. Pogge, Yutaka Matsubara, Tsubasa Yamawaki, Patryk Iwanek, Andrzej Udalski, Michał K. Szymański, Ian A. Bond, Radek Poleski, Krzysztof Ulaczyk, Rintaro Kirikawa, Yuzuru Tanaka, Iona Kondo, Byeong-Gon Park, Nicholas J. Rattenbury, Jan Skowron, Naoki Koshimoto, Paweł Pietrukowicz, Marcin Wrona, Cheongho Han, David P. Bennett, Seung-Lee Kim, Akihiko Fukui, Aparna Bhattacharya, Jennifer C. Yee, Yongseok Lee, Hyoun-Woo Kim, Shota Miyazaki, Yoshitaka Itow, Martin Donachie, Paul J. Tristram, Michael D. Albrow, Sun-Ju Chung, Krzysztof A. Rybicki, Hirosane Fujii, Dong-Joo Lee, Andrew Gould, Clément Ranc, Weicheng Zang, Fumio Abe, Yuki Hirao, Youn Kil Jung, Yossi Shvartzvald, Yuki Satoh, Takahiro Sumi, Yasushi Muraki, Atsunori Yonehara, Mariusz Gromadzki, In-Gu Shin, and Szymon Kozłowski

Subjects
Physics, Earth and Planetary Astrophysics (astro-ph.EP), Bayesian probability, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Statistical physics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics - Earth and Planetary Astrophysics
Abstract

We show that the perturbation at the peak of the light curve of microlensing event KMT-2019-BLG-0371 is explained by a model with a mass ratio between the host star and planet of $q \sim 0.08$. Due to the short event duration ($t_{\rm E} \sim 6.5\ $ days), the secondary object in this system could potentially be a massive giant planet. A Bayesian analysis shows that the system most likely consists of a host star with a mass $M_{\rm h} = 0.09^{+0.14}_{-0.05}M_{\odot}$ and a massive giant planet with a mass $M_{\rm p} = 7.70^{+11.34}_{-3.90}M_{\rm Jup}$. However, the interpretation of the secondary as a planet (i.e., as having $M_{\rm p} < 13 M_{\rm Jup}$) rests entirely on the Bayesian analysis. Motivated by this event, we conduct an investigation to determine which constraints meaningfully affect Bayesian analyses for microlensing events. We find that the masses inferred from such a Bayesian analysis are determined almost entirely by the measured value of $\theta_{\rm E}$ and are relatively insensitive to other factors such as the direction of the event $(\ell, b)$, the lens-source relative proper motion $\mu_{\rm rel}$, or the specific Galactic model prior., Comment: 23pages, 7 figures

Published
2021

28. KMT-2019-BLG-1715: Planetary Microlensing Event with Three Lens Masses and Two Source Stars

Author

Yuki Hirao, Yossi Shvartzvald, Iona Kondo, Yuki Satoh, Takahiro Sumi, Jennifer C. Yee, Woong-Tae Kim, Kyu-Ha Hwang, Rintaro Kirikawa, Yuzuru Tanaka, Patryk Iwanek, Nicholas J. Rattenbury, Jan Skowron, Paweł Pietrukowicz, Tsubasa Yamawaki, Daisuke Suzuki, Seung-Lee Kim, Haruno Suematsu, Yongseok Lee, Hikaru Shoji, Cheongho Han, T. Yamakawa, Shota Miyazaki, Man Cheung Alex Li, Hirosane Fujii, Dong-Jin Kim, Paul J. Tristram, Yoon-Hyun Ryu, Michael D. Albrow, Sun-Ju Chung, Radek Poleski, Ian A. Bond, Szymon Kozłowski, Igor Soszyński, Andrew Gould, Clément Ranc, Weicheng Zang, Richard K. Barry, Martin Donachie, Aparna Bhattacharya, Mariusz Gromadzki, Przemek Mróz, Dong-Joo Lee, Krzysztof A. Rybicki, Richard W. Pogge, Yutaka Matsubara, Hyoun-Woo Kim, Krzysztof Ulaczyk, Yasushi Muraki, Atsunori Yonehara, In-Gu Shin, David P. Bennett, Yoshitaka Itow, Sang-Mok Cha, Chung-Uk Lee, Andrzej Udalski, Michał K. Szymański, Youn Kil Jung, Fumio Abe, Marcin Wrona, Byeong-Gon Park, Chun-Hwey Kim, Akihiko Fukui, and Doeon Kim

Subjects
Physics, Earth and Planetary Astrophysics (astro-ph.EP), 010504 meteorology & atmospheric sciences, Event (relativity), Astronomy, Lens (geology), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics, 0105 earth and related environmental sciences
Abstract

We investigate the gravitational microlensing event KMT-2019-BLG-1715, of which light curve shows two short-term anomalies from a caustic-crossing binary-lensing light curve: one with a large deviation and the other with a small deviation. We identify five pairs of solutions, in which the anomalies are explained by adding an extra lens or source component in addition to the base binary-lens model. We resolve the degeneracies by applying a method, in which the measured flux ratio between the first and second source stars is compared with the flux ratio deduced from the ratio of the source radii. Applying this method leaves a single pair of viable solutions, in both of which the major anomaly is generated by a planetary-mass third body of the lens, and the minor anomaly is generated by a faint second source. A Bayesian analysis indicates that the lens comprises three masses: a planet-mass object with $\sim 2.6~M_{\rm J}$ and binary stars of K and M dwarfs lying in the galactic disk. We point out the possibility that the lens is the blend, and this can be verified by conducting high-resolution followup imaging for the resolution of the lens from the source., Comment: 11 pages, 13 figures, 7 tables

Published
2021

29. MOA-2006-BLG-074: recognizing xallarap contaminants in planetary microlensing

Author

Akihiko Fukui, Rintaro Kirikawa, Greg Olmschenk, Clément Ranc, Yuki Hirao, Daisuke Suzuki, Aparna Bhattacharya, Yutaka Matsubara, Ian A. Bond, Martin Donachie, Yoshitaka Itow, Yuki Satoh, Shota Miyazaki, Takahiro Sumi, P. Rota, Naoki Koshimoto, S. Ishitani Silva, D. P. Bennett, Yasushi Muraki, Paul J. Tristram, Atsunori Yonehara, Man Cheung Alex Li, Richard K. Barry, Valerio Bozza, Fumio Abe, and Hirosane Fujii

Subjects
Binary number, FOS: Physical sciences, Astrophysics, Gravitational microlensing, Binary stars, 01 natural sciences, Gravitational microlensing exoplanet detection, Planet, 0103 physical sciences, Binary star, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, Earth and Planetary Astrophysics (astro-ph.EP), 010308 nuclear & particles physics, Xallarap effect, Xallarap, Astronomy and Astrophysics, Light curve, Astrophysics - Astrophysics of Galaxies, Binary source microlensing, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Orbital motion, Caustic (optics), Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

MOA-2006-BLG-074 was selected as one of the most promising planetary candidates in a retrospective analysis of the MOA collaboration: its asymmetric high-magnification peak can be perfectly explained by a source passing across a central caustic deformed by a small planet. However, after a detailed analysis of the residuals, we have realized that a single lens and a source orbiting with a faint companion provides a more satisfactory explanation for all the observed deviations from a Paczynski curve and the only physically acceptable interpretation. Indeed the orbital motion of the source is constrained enough to allow a very good characterization of the binary source from the microlensing light curve. The case of MOA-2006-BLG-074 suggests that the so-called xallarap effect must be taken seriously in any attempts to obtain accurate planetary demographics from microlensing surveys., 14 pages, 8 figures, accepted by AAS

Published
2021

30. OGLE-2018-BLG-1185b : A Low-Mass Microlensing Planet Orbiting a Low-Mass Dwarf

Author

Man Cheung Alex Li, Yuri I. Fujii, H.-W. Kim, Michael D. Albrow, Valerio Bozza, Igor Soszyński, Hirosane Fujii, Patryk Iwanek, John Southworth, Yossi Shvartzvald, S. Kozlowski, Hikaru Shoji, Iona Kondo, Yuki Hirao, S. Ishitani Silva, M. T. Penny, Sean Carey, J. Campbell-White, Nicholas J. Rattenbury, Jan Skowron, D. Maoz, Joachim Wambsganss, Penélope Longa-Peña, G. Bryden, D.-J. Kim, Yuki Satoh, Takahiro Sumi, S. Calchi Novati, S. J. Chung, David P. Bennett, Akihiko Fukui, Shude Mao, Sohrab Rahvar, Shinyoung Kim, U. G. Jørgensen, Yiannis Tsapras, B. S. Gaudi, Yasushi Muraki, Yongseok Lee, Atsunori Yonehara, Fumio Abe, Andrzej Udalski, Ian A. Bond, Keith Horne, Daisuke Suzuki, J. Tregloan-Reed, Arnaud Cassan, Jesper Skottfelt, Yoshitaka Itow, Paul J. Tristram, Colin Snodgrass, Michał K. Szymański, Nuno Peixinho, R. W. Pogge, Shota Miyazaki, Wei Zhu, M. Wrona, C.-U. Lee, Greg Olmschenk, Duk-Hang Lee, Sang-Mok Cha, Byeong-Gon Park, E. Khalouei, Kyu-Ha Hwang, Youn Kil Jung, P. Pietrukowicz, Radosław Poleski, Naoki Koshimoto, P. Mróz, C. A. Beichman, Yoshimi Matsubara, Andrew Gould, Clément Ranc, Martin Dominik, R. A. Street, Weicheng Zang, Rintaro Kirikawa, Yuzuru Tanaka, Martin Donachie, C. Han, Richard K. Barry, Tobias C. Hinse, Krzysztof Ulaczyk, M. Hundertmark, Abhijit Saha, Sami Dib, Aparna Bhattacharya, Martin Burgdorf, Krzysztof A. Rybicki, Tsubasa Yamawaki, Yoon-Hyun Ryu, Calen B. Henderson, Sedighe Sajadian, Jennifer C. Yee, Etienne Bachelet, M. Rabus, D. M. Bramich, In-Gu Shin, European Commission, University of St Andrews. School of Physics and Astronomy, and University of St Andrews. St Andrews Centre for Exoplanet Science

Subjects
010504 meteorology & atmospheric sciences, Star (game theory), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, Q1, 01 natural sciences, Gravitational microlensing exoplanet detection, Spitzer Space Telescope, 0103 physical sciences, QB460, QB Astronomy, Astrophysics::Solar and Stellar Astrophysics, Satellite microlensing parallax, 010303 astronomy & astrophysics, QB600, QC, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, QB, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Astronomy and Astrophysics, 3rd-DAS, Planetary system, Mass ratio, Light curve, Exoplanet, QC Physics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Low Mass, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the analysis of planetary microlensing event OGLE-2018-BLG-1185, which was observed by a large number of ground-based telescopes and by the $Spitzer$ Space Telescope. The ground-based light curve indicates a low planet-host star mass ratio of $q = (6.9 \pm 0.2) \times 10^{-5}$, which is near the peak of the wide-orbit exoplanet mass-ratio distribution. We estimate the host star and planet masses with a Bayesian analysis using the measured angular Einstein radius under the assumption that stars of all masses have an equal probability to host this planet. The flux variation observed by $Spitzer$ was marginal, but still places a constraint on the microlens parallax. Imposing a conservative constraint that this flux variation should be $\Delta f_{\rm Spz} < 4$ instrumental flux units indicates a host mass of $M_{\rm host} = 0.37^{+0.35}_{-0.21}\ M_\odot$ and a planet mass of $m_{\rm p} = 8.4^{+7.9}_{-4.7}\ M_\oplus$. A Bayesian analysis including the full parallax constraint from $Spitzer$ suggests smaller host star and planet masses of $M_{\rm host} = 0.091^{+0.064}_{-0.018}\ M_\odot$ and $m_{\rm p} = 2.1^{+1.5}_{-0.4}\ M_\oplus$, respectively. Future high-resolution imaging observations with $HST$ or ELTs could distinguish between these two scenarios and help to reveal the planetary system properties in more detail., Comment: 30 pages, 11 figures, 5 tables, Accepted for publication in Astronomical Journal (AJ)

Published
2021

31. The frequency of snowline-region planets from four-years of OGLE-MOA-Wise second-generation microlensing

Author

Richard K. Barry, P. J. Tristram, M. Friedmann, Grzegorz Pietrzyński, Nicholas J. Rattenbury, Jan Skowron, Łukasz Wyrzykowski, Yasushi Muraki, Y. Wakiyama, Atsunori Yonehara, P. Mróz, Daisuke Suzuki, C. H. Ling, S. Kozlowski, Takahiro Sumi, T. Saito, David P. Bennett, D. Maoz, Yoshitaka Itow, Yossi Shvartzvald, Fumio Abe, Akihiko Fukui, K. Ohnishi, Yutaka Matsubara, Krzysztof Ulaczyk, M. Freeman, Denis J. Sullivan, Andrzej Udalski, Michał K. Szymański, Shai Kaspi, K. Inayama, Ian A. Bond, Aparna Bhattacharya, Igor Soszyński, Kimiaki Masuda, P. Pietrukowicz, Radosław Poleski, and Naoki Koshimoto

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Physics, 010308 nuclear & particles physics, Brown dwarf, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Planetary system, Gravitational microlensing, 01 natural sciences, Exoplanet, Article, Microlensing Observations in Astrophysics, Gravitational lens, Space and Planetary Science, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Planetary mass, Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We present a statistical analysis of the first four seasons from a "second-generation" microlensing survey for extrasolar planets, consisting of near-continuous time coverage of 8 deg$^2$ of the Galactic bulge by the OGLE, MOA, and Wise microlensing surveys. During this period, 224 microlensing events were observed by all three groups. Over 12% of the events showed a deviation from single-lens microlensing, and for $\sim$1/3 of those the anomaly is likely caused by a planetary companion. For each of the 224 events we have performed numerical ray-tracing simulations to calculate the detection efficiency of possible companions as a function of companion-to-host mass ratio and separation. Accounting for the detection efficiency, we find that $55^{+34}_{-22}\%$ of microlensed stars host a snowline planet. Moreover, we find that Neptunes-mass planets are $\sim10$ times more common than Jupiter-mass planets. The companion-to-host mass ratio distribution shows a deficit at $q\sim10^{-2}$, separating the distribution into two companion populations, analogous to the stellar-companion and planet populations, seen in radial-velocity surveys around solar-like stars. Our survey, however, which probes mainly lower-mass stars, suggests a minimum in the distribution in the super-Jupiter mass range, and a relatively high occurrence of brown-dwarf companions., Comment: 24 pages, 13 figures, 2 tables. 2016, MNRAS, 457, 4089

Published
2020

32. OGLE-2013-BLG-0911Lb: A Secondary on the Brown-dwarf Planet Boundary around an M Dwarf

Author

Hiroshi Shibai, Valerio Bozza, Markus Rabus, N. Kains, R. W. Pogge, Shota Miyazaki, Y. Kamei, Giuseppe D'Ago, Darren L. DePoy, David P. Bennett, Man Cheung Alex Li, Michael D. Albrow, Masayuki Nagakane, P. Verma, Yoshitaka Itow, Shude Mao, Ian A. Bond, K. Ohnishi, S. KozŁowski, Daniel F. Evans, S. Calchi Novati, Dan Maoz, M. Friedmann, C. H. Ling, Jennifer C. Yee, P. Mróz, Nicholas J. Rattenbury, Haruno Suematsu, Jan Skowron, M. Hundertmark, To. Saito, Shai Kaspi, John Southworth, I. Porritt, Eamonn Kerins, Etienne Bachelet, Daisuke Suzuki, Akihiko Fukui, Ilan Manulis, Wise Team, Arnaud Cassan, Jesper Skottfelt, Yuki Hirao, Colin Snodgrass, Yutaka Matsubara, Andrzej Udalski, Tobias C. Hinse, Michał K. Szymański, C.-U. Lee, H. Ngan, Avishay Gal-Yam, Nuno Peixinho, Krzysztof Ulaczyk, R. W. Schmidt, Fumio Abe, Yossi Shvartzvald, Martin Donachie, Denis J. Sullivan, R. Figuera Jaimes, Gaetano Scarpetta, Hirosane Fujii, Luigi Mancini, Iain A. Steele, Andrew Gould, Clément Ranc, Tim Natusch, J. W. Menzies, A. Sharan, Iona Kondo, Taro Matsuo, Rachel Street, Yasushi Muraki, Atsunori Yonehara, T. Yamakawa, Keith Horne, Takahiro Sumi, Simona Ciceri, Jennie McCormick, G. W. Christie, Joachim Wambsganss, U. G. Jørgensen, Yiannis Tsapras, A. Popovas, P. Pietrukowicz, Radosław Poleski, Naoki Koshimoto, Łukasz Wyrzykowski, Martin Dominik, D. M. Bramich, Igor Soszyński, Heidi Korhonen, Richard K. Barry, Aparna Bhattacharya, RoboNet Collabofratino, Martin Burgdorf, Sohrab Rahvar, Paul J. Tristram, Science & Technology Facilities Council, University of St Andrews. School of Physics and Astronomy, and University of St Andrews. St Andrews Centre for Exoplanet Science

Subjects
astro-ph.SR, Extrasolar gas giants, 010504 meteorology & atmospheric sciences, Exoplanet astronomy, astro-ph.GA, Microlensing, Brown dwarf, FOS: Physical sciences, Boundary (topology), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Gravitational microlensing, M dwarf stars, 01 natural sciences, Einstein radius, Planet, 0103 physical sciences, Exoplanet detection methods, QB Astronomy, Astrophysics::Solar and Stellar Astrophysics, Exoplanet systems, 010303 astronomy & astrophysics, QC, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, QB, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Brown dwarfs, Settore FIS/05, Exoplanets, Order (ring theory), Astronomy and Astrophysics, 3rd-DAS, Mass ratio, Astrophysics - Astrophysics of Galaxies, QC Physics, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), astro-ph.EP, High Energy Physics::Experiment, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We present the analysis of the binary-lens microlensing event OGLE-2013-BLG-0911. The best-fit solutions indicate the binary mass ratio of q~0.03 which differs from that reported in Shvartzvald+2016. The event suffers from the well-known close/wide degeneracy, resulting in two groups of solutions for the projected separation normalized by the Einstein radius of s~0.15 or s~7. The finite source and the parallax observations allow us to measure the lens physical parameters. The lens system is an M-dwarf orbited by a massive Jupiter companion at very close (M_{host}=0.30^{+0.08}_{-0.06} M_{Sun}, M_{comp}=10.1^{+2.9}_{-2.2} M_{Jup}, a_{exp}=0.40^{+0.05}_{-0.04} au) or wide (M_{host}=0.28^{+0.10}_{-0.08} M_{Sun}, M_{comp}=9.9^{+3.8}_{-3.5}M_{Jup}, a_{exp}=18.0^{+3.2}_{-3.2} au) separation. Although the mass ratio is slightly above the planet-brown dwarf (BD) mass-ratio boundary of q=0.03 which is generally used, the median physical mass of the companion is slightly below the planet-BD mass boundary of 13M_{Jup}. It is likely that the formation mechanisms for BDs and planets are different and the objects near the boundaries could have been formed by either mechanism. It is important to probe the distribution of such companions with masses of ~13M_{Jup} in order to statistically constrain the formation theories for both BDs and massive planets. In particular, the microlensing method is able to probe the distribution around low-mass M-dwarfs and even BDs which is challenging for other exoplanet detection methods., Comment: 22 pages, 10 figures, Accepted for publication in The Astronomical Journal

Published
2020

33. Candidate Brown-dwarf Microlensing Events with Very Short Timescales and Small Angular Einstein Radii

Author

David P. Bennett, Yoshitaka Itow, Yoon-Hyun Ryu, Kyu-Ha Hwang, D. J. Sullivan, Ian A. Bond, Cheongho Han, Tsubasa Yamawaki, Szymon Kozłowski, Valerio Bozza, Igor Soszyński, Yuki Hirao, T. Yamakawa, Haruno Suematsu, Marcin Wrona, Yossi Shvartzvald, Yongseok Lee, Byeong-Gon Park, In-Gu Shin, Yuhei Kamei, Hikaru Shoji, Jennifer C. Yee, Krzysztof Ulaczyk, Chung-Uk Lee, Paul J. Tristram, Hirosane Fujii, Andrzej Udalski, Michał K. Szymański, Andrew Gould, Patryk Iwanek, Daisuke Suzuki, M. James Jee, Nicholas J. Rattenbury, Jan Skowron, Masayuki Nagakane, Michael D. Albrow, Sun-Ju Chung, Akihiko Fukui, Yasushi Muraki, Doeon Kim, Hyoun-Woo Kim, Atsunori Yonehara, Radek Poleski, Przemek Mróz, Shota Miyazaki, Fumio Abe, Clément Ranc, Weicheng Zang, Man Cheung Alex Li, Yuki Satoh, Takahiro Sumi, Seung-Lee Kim, Sang-Mok Cha, Dong-Jin Kim, Richard Barry, Richard W. Pogge, Yutaka Matsubara, Martin Donachie, Dong-Joo Lee, Iona Kondo, Youn Kil Jung, Naoki Koshimoto, Aparna Bhattacharya, Krzysztof A. Rybicki, and Paweł Pietrukowicz

Subjects
010504 meteorology & atmospheric sciences, Monte Carlo method, Brown dwarf, Binary number, FOS: Physical sciences, Astrophysics, Gravitational microlensing, 01 natural sciences, law.invention, symbols.namesake, law, 0103 physical sciences, Einstein, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Event (probability theory), Physics, Earth and Planetary Astrophysics (astro-ph.EP), Brown dwarfs, Astronomy and Astrophysics, Lens (optics), Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, symbols, Astrophysics - Earth and Planetary Astrophysics
Abstract

Short-timescale microlensing events are likely to be produced by substellar brown dwarfs (BDs), but it is difficult to securely identify BD lenses based on only event timescales $t_{\rm E}$ because short-timescale events can also be produced by stellar lenses with high relative lens-source proper motions. In this paper, we report three strong candidate BD-lens events found from the search for lensing events not only with short timescales ($t_{\rm E} \lesssim 6~{\rm days}$) but also with very small angular Einstein radii ($\theta_{\rm E}\lesssim 0.05~{\rm mas}$) among the events that have been found in the 2016--2019 observing seasons. These events include MOA-2017-BLG-147, MOA-2017-BLG-241, and MOA-2019-BLG-256, in which the first two events are produced by single lenses and the last event is produced by a binary lens. From the Bayesian analysis conducted with the combined $t_{\rm E}$ and $\theta_{\rm E}$ constraint, it is estimated that the lens masses of the individual events are $0.051^{+0.100}_{-0.027}~M_\odot$, $0.044^{+0.090}_{-0.023}~M_\odot$, and $0.046^{+0.067}_{-0.023}~M_\odot/0.038^{+0.056}_{-0.019}~M_\odot$ and the probability of the lens mass smaller than the lower limit of stars is $\sim 80\%$ for all events. We point out that routine lens mass measurements of short time-scale lensing events require survey-mode space-based observations., Comment: 9 pages, 6 figures

Published
2020

35. Systematic KMTNet Planetary Anomaly Search. II. Six New q < 2 × 10−4 Mass-ratio Planets

Author

Kyu-Ha Hwang, Weicheng Zang, Andrew Gould, Andrzej Udalski, Ian A. Bond, Hongjing Yang, Shude Mao, Michael D. Albrow, Sun-Ju Chung, Cheongho Han, Youn Kil Jung, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Przemek Mróz, Radek Poleski, Jan Skowron, Michał K. Szymański, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Mariusz Gromadzki, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Hirosame Fujii, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Brandon Munford, Yutaka Matsubara, Shota Miyazaki, Yasushi Muraki, Greg Olmschenk, Clément Ranc, Nicholas J. Rattenbury, Yuki K. Satoh, Hikaru Shoji, Stela Ishitani Silva, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, Atsunori Yonehara, Xiangyu Zhang, Wei Zhu, Matthew T. Penny, and Pascal Fouqué

Subjects
Space and Planetary Science, Astronomy and Astrophysics
Abstract

We apply the automated AnomalyFinder algorithm of Paper I to 2018–2019 light curves from the ≃13 deg2 covered by the six KMTNet prime fields, with cadences Γ ≥ 2 hr−1. We find a total of 11 planets with mass ratios q < 2 × 10−4, including 6 newly discovered planets, 1 planet that was reported in Paper I, and recovery of 4 previously discovered planets. One of the new planets, OGLE-2018-BLG-0977Lb, is in a planetary caustic event, while the other five (OGLE-2018-BLG-0506Lb, OGLE-2018-BLG-0516Lb, OGLE-2019-BLG-1492Lb, KMT-2019-BLG-0253, and KMT-2019-BLG-0953) are revealed by a “dip” in the light curve as the source crosses the host-planet axis on the opposite side of the planet. These subtle signals were missed in previous by-eye searches. The planet-host separations (scaled to the Einstein radius), s, and planet-host mass ratios, q, are, respectively, (s, q × 105) = (0.88, 4.1), (0.96 ± 0.10, 8.3), (0.94 ± 0.07, 13), (0.97 ± 0.07, 18), (0.97 ± 0.04, 4.1), and (0.74, 18), where the “ ± ” indicates a discrete degeneracy. The 11 planets are spread out over the range − 5 < log q < − 3.7 . Together with the two planets previously reported with q ∼ 10−5 from the 2018–2019 nonprime KMT fields, this result suggests that planets toward the bottom of this mass-ratio range may be more common than previously believed.

Published
2022

36. An Earth-mass planet in a time of COVID-19: KMT-2020-BLG-0414Lb

Author

Tsubasa Yamawaki, Iona Kondo, Yoon-Hyun Ryu, M. T. Penny, H. Fujii, S. J. Chung, C.-U. Lee, Akihiko Fukui, C. Han, Hikaru Shoji, Xiangyu Zhang, Andreea Petric, Yuki Satoh, Jennifer C. Yee, Man Cheung Alex Li, Rintaro Kirikawa, Takahiro Sumi, Naoki Koshimoto, Yuzuru Tanaka, Martin Donachie, Yuki Hirao, In-Gu Shin, Yasushi Muraki, H.-W. Kim, Y. K. Jung, Yongseok Lee, L. de Almeida, Yoshimi Matsubara, Atsunori Yonehara, Kyu-Ha Hwang, Wei Zhu, Todd Burdullis, Byeong-Gon Park, Yossi Shvartzvald, Stela Ishitani Silva, Fumio Abe, Aparna Bhattacharya, Pascal Fouqué, D.-J. Kim, Sang-Mok Cha, P. J. Tristram, Michael D. Albrow, Duk-Hang Lee, Andrew Gould, Clément Ranc, J. D. do Nascimento, W. Zang, R. W. Pogge, Shota Miyazaki, Shinyoung Kim, Ian A. Bond, D. Maoz, Shude Mao, John Drummond, Nicholas J. Rattenbury, Daisuke Suzuki, Thiam-Guan Tan, Richard K. Barry, David P. Bennett, Yoshitaka Itow, and Greg Olmschenk

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Diagram, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Mass ratio, Earth mass, Light curve, Gravitational microlensing, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Einstein radius, Space and Planetary Science, Planet, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Parallax, 010303 astronomy & astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery of KMT-2020-BLG-0414Lb, with a planet-to-host mass ratio $q_2 = 0.9$--$1.2 \times 10^{-5} = 3$--$4~q_{\oplus}$ at $1\sigma$, which is the lowest mass-ratio microlensing planet to date. Together with two other recent discoveries ($4 \lesssim q/q_\oplus \lesssim 6$), it fills out the previous empty sector at the bottom of the triangular $(\log s, \log q)$ diagram, where $s$ is the planet-host separation in units of the angular Einstein radius $\theta_{\rm E}$. Hence, these discoveries call into question the existence, or at least the strength, of the break in the mass-ratio function that was previously suggested to account for the paucity of very low-$q$ planets. Due to the extreme magnification of the event, $A_{\rm max}\sim 1450$ for the underlying single-lens event, its light curve revealed a second companion with $q_3 \sim 0.05$ and $|\log s_3| \sim 1$, i.e., a factor $\sim 10$ closer to or farther from the host in projection. The measurements of the microlens parallax $\pi_{\rm E}$ and the angular Einstein radius $\theta_{\rm E}$ allow estimates of the host, planet, and second companion masses, $(M_1, M_2, M_3) \sim (0.3M_{\odot}, 1.0M_{\oplus}, 17M_{J})$, the planet and second companion projected separations, $(a_{\perp,2}, a_{\perp,3}) \sim (1.5, 0.15~{\rm or}~15)$~au, and system distance $D_{\rm L} \sim 1$ kpc. The lens could account for most or all of the blended light ($I \sim 19.3$) and so can be studied immediately with high-resolution photometric and spectroscopic observations that can further clarify the nature of the system. The planet was found as part of a new program of high-cadence follow-up observations of high-magnification events. The detection of this planet, despite the considerable difficulties imposed by Covid-19 (two KMT sites and OGLE were shut down), illustrates the potential utility of this program., Comment: 23 pages, 5 figures; to be submitted to RAA

Published
2021

37. OGLE-2019-BLG-0960 Lb: the Smallest Microlensing Planet

Author

Greg Olmschenk, Steve Hennerley, Igor Soszyński, Yuki Satoh, Yoon-Hyun Ryu, David P. Bennett, Paul J. Tristram, Sebastiano Calchi Novati, Daisuke Suzuki, Szymon Kozłowski, M. Hundertmark, Richard W. Pogge, Yutaka Matsubara, Ian A. Bond, Jennie McCormick, Cheongho Han, Takahiro Sumi, Yoshitaka Itow, Hyoun-Woo Kim, Akihiko Fukui, G. W. Christie, Paweł Pietrukowicz, Krzysztof Ulaczyk, Man Cheung Alex Li, Jennifer C. Yee, Mariusz Gromadzki, Rintaro Kirikawa, Iona Kondo, Sang-Mok Cha, Yuzuru Tanaka, Youn Kil Jung, Fumio Abe, In-Gu Shin, Patryk Iwanek, Yiannis Tsapras, Seung-Lee Kim, Martin Donachie, Etienne Bachelet, Jonathan T. Green, Shude Mao, Nicholas J. Rattenbury, Samson A. Johnson, Rachel Street, Jan Skowron, Tim Natusch, Dong-Joo Lee, Yuki Hirao, Yossi Shvartzvald, Stela Ishitani Silva, Geoffery Bryden, Richard K. Barry, Yasushi Muraki, Matthew T. Penny, Byeong-Gon Park, Aparna Bhattacharya, Atsunori Yonehara, Sean Carey, Yongseok Lee, Krzysztof A. Rybicki, Dan Maoz, Shota Miyazaki, Hirosane Fujii, Calen B. Henderson, Andrew Marmont, Przemek Mróz, Tsubasa Yamawaki, Wei Zhu, Radosław Poleski, Naoki Koshimoto, Charles Beichman, Hikaru Shoji, Dong-Jin Kim, Kyu-Ha Hwang, B. Scott Gaudi, Michael D. Albrow, Sun-Ju Chung, Chung-Uk Lee, Andrzej Udalski, Michał K. Szymański, Andrew Gould, Clément Ranc, Weicheng Zang, and Marcin Wrona

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Physics, 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Planet, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the analysis of OGLE-2019-BLG-0960, which contains the smallest mass-ratio microlensing planet found to date (q = 1.2--1.6 x 10^{-5} at 1-sigma). Although there is substantial uncertainty in the satellite parallax measured by Spitzer, the measurement of the annual parallax effect combined with the finite source effect allows us to determine the mass of the host star (M_L = 0.3--0.6 M_Sun), the mass of its planet (m_p = 1.4--3.1 M_Earth), the projected separation between the host and planet (a_perp = 1.2--2.3 au), and the distance to the lens system (D_L = 0.6--1.2 kpc). The lens is plausibly the blend, which could be checked with adaptive optics observations. As the smallest planet clearly below the break in the mass-ratio function (Suzuki et al. 2016; Jung et al. 2019), it demonstrates that current experiments are powerful enough to robustly measure the slope of the mass-ratio function below that break. We find that the cross-section for detecting small planets is maximized for planets with separations just outside of the boundary for resonant caustics and that sensitivity to such planets can be maximized by intensively monitoring events whenever they are magnified by a factor A > 5. Finally, an empirical investigation demonstrates that most planets showing a degeneracy between (s > 1) and (s < 1) solutions are not in the regime (|log s| >> 0) for which the "close"/"wide" degeneracy was derived. This investigation suggests a link between the "close"/"wide" and "inner/outer" degeneracies and also that the symmetry in the lens equation goes much deeper than symmetries uncovered for the limiting cases., 32 pages, 15 figures, 5 tables. Submitted to AAS Journals

Published
2021

38. Systematic KMTNet Planetary Anomaly Search. I. OGLE-2019-BLG-1053Lb, a Buried Terrestrial Planet

Author

Patryk Iwanek, Andrew Gould, Clément Ranc, B. Scott Gaudi, Weicheng Zang, Sang-Mok Cha, Geoffery Bryden, Nicholas J. Rattenbury, Jan Skowron, Chung-Uk Lee, Igor Soszyński, Andrzej Udalski, Jennifer C. Yee, Michał K. Szymański, Ian A. Bond, Daisuke Suzuki, Cheongho Han, Iona Kondo, In-Gu Shin, Dong-Jin Kim, Akihiko Fukui, Tsubasa Yamawaki, David P. Bennett, Xiangyu Zhang, Rintaro Kirikawa, Samson A. Johnson, Tianshu Wang, Shude Mao, Hyoun-Woo Kim, Yoon-Hyun Ryu, Calen B. Henderson, Martin Donachie, Yuzuru Tanaka, H. Fujii, Yoshitaka Itow, Michael D. Albrow, Greg Olmschenk, Dong-Joo Lee, Kyu-Ha Hwang, Fumio Abe, Mariusz Gromadzki, Przemek Mróz, Sebastiano Calchi Novati, Paul J. Tristram, M. Wrona, Richard W. Pogge, Sean Carey, Yutaka Matsubara, Yasushi Muraki, Yuki Satoh, Man Cheung Alex Li, Krzysztof Ulaczyk, Byeong-Gon Park, Yongseok Lee, Shota Miyazaki, Atsunori Yonehara, Takahiro Sumi, Paweł Pietrukowicz, Yuki Hirao, Youn Kil Jung, Seung-Lee Kim, Charles Beichman, Sun-Ju Chung, Hikaru Shoji, Yossi Shvartzvald, Radosław Poleski, Naoki Koshimoto, Wei Zhu, Stela Ishitani Silva, Aparna Bhattacharya, Krzysztof A. Rybicki, Szymon Kozłowski, and Richard K. Barry

Subjects
Physics, Space and Planetary Science, Terrestrial planet, Astronomy and Astrophysics, Anomaly (physics), Astrophysics - Astrophysics of Galaxies, Astrophysics - Earth and Planetary Astrophysics, Astrobiology
Abstract

In order to exhume the buried signatures of "missing planetary caustics" in the KMTNet data, we conducted a systematic anomaly search to the residuals from point-source point-lens fits, based on a modified version of the KMTNet EventFinder algorithm. This search reveals the lowest mass-ratio planetary caustic to date in the microlensing event OGLE-2019-BLG-1053, for which the planetary signal had not been noticed before. The planetary system has a planet-host mass ratio of $q = (1.25 \pm 0.13) \times 10^{-5}$. A Bayesian analysis yields estimates of the mass of the host star, $M_{\rm host} = 0.61_{-0.24}^{+0.29}~M_\odot$, the mass of its planet, $M_{\rm planet} = 2.48_{-0.98}^{+1.19}~M_{\oplus}$, the projected planet-host separation, $a_\perp = 3.4_{-0.5}^{+0.5}$ au, and the lens distance of $D_{\rm L} = 6.8_{-0.9}^{+0.6}$ kpc. The discovery of this very low mass-ratio planet illustrates the utility of our method and opens a new window for a large and homogeneous sample to study the microlensing planet-host mass-ratio function down to $q \sim 10^{-5}$., Comment: published by AJ

Published
2021

39. The lowest mass ratio planetary microlens: OGLE 2016–BLG–1195Lb

Author

Igor Soszyński, Aparna Bhattacharya, Fumio Abe, David P. Bennett, Masayuki Nagakane, Yasushi Muraki, Richard K. Barry, To. Saito, Man Cheung Alex Li, Yutaka Matsubara, Michał Pawlak, Atsunori Yonehara, Phil Evans, K. Ohnishi, C. H. Ling, Yoshitaka Itow, Yuichiro Asakura, Krzysztof Ulaczyk, A. Sharan, Daisuke Suzuki, T. Yamada, Kimiaki Masuda, Ian A. Bond, P. Pietrukowicz, Radosław Poleski, Naoki Koshimoto, Clément Ranc, Martin Donachie, Denis J. Sullivan, P. Mróz, Nicholas J. Rattenbury, Jan Skowron, Andrzej Udalski, Michał K. Szymański, Yuki Hirao, Valerio Bozza, Paul J. Tristram, Akihiko Fukui, Takahiro Sumi, and S. Kozlowski

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Physics, Solar mass, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Mass ratio, Earth mass, Light curve, Gravitational microlensing, 01 natural sciences, Exoplanet, Space and Planetary Science, Planet, 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, Planetary mass, Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report discovery of the lowest mass ratio exoplanet to be found by the microlensing method in the light curve of the event OGLE~2016--BLG--1195. This planet revealed itself as a small deviation from a microlensing single lens profile from an examination of the survey data soon after the planetary signal. The duration of the planetary signal is $\sim 2.5\,$hours. The measured ratio of the planet mass to its host star is $q = 4.2\pm 0.7 \times10^{-5}$. We further estimate that the lens system is likely to comprise a cold $\sim$3 Earth mass planet in a $\sim\,$2 AU wide orbit around a 0.2 Solar mass star at an overall distance of 7.1 kpc., 8 pages, 5 figures, accepted for publication in MNRAS

Published
2017

40. The 2L1S/1L2S Degeneracy for Two Microlensing Planet Candidates Discovered by the KMTNet Survey in 2017

Author

C. Han, C.-U. Lee, Yutaka Matsubara, Akihiko Fukui, Aparna Bhattacharya, Paul J. Tristram, Fumio Abe, Masayuki Nagakane, T. Yamakawa, D.-J. Kim, Hirosane Fujii, Iona Kondo, Pascal Fouqué, Martin Donachie, In-Gu Shin, Hyoun-Woo Kim, Yasushi Muraki, Yoon-Hyun Ryu, Naoki Koshimoto, Denis J. Sullivan, Daisuke Suzuki, Yongseok Lee, Atsunori Yonehara, Harmon Suematsu, Sang-Mok Cha, Richard K. Barry, Shinyoung Kim, Jennifer C. Yee, Byeong-Gon Park, Y. Kamei, David P. Bennett, Ian A. Bond, Y. K. Jung, Nicholas J. Rattenbury, Yoshitaka Itow, Yuki Hirao, R. W. Pogge, Shota Miyazaki, Yossi Shvartzvald, Michael D. Albrow, Duk-Hang Lee, Andrew Gould, Clément Ranc, Weicheng Zang, Kyu-Ha Hwang, Takahiro Sumi, S. J. Chung, Man Cheung Alex Li, and Matthew T. Penny

Subjects
Physics, Earth and Planetary Astrophysics (astro-ph.EP), planets and satellites: detection, Proper motion, 010504 meteorology & atmospheric sciences, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, gravitational lensing: micro, Gravitational microlensing, 01 natural sciences, law.invention, Telescope, Space and Planetary Science, Planet, law, 0103 physical sciences, Degeneracy (biology), Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Astrophysics - Earth and Planetary Astrophysics
Abstract

著者人数: 49名 (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 鈴木, 大介), Number of authors: 49 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS): Suzuki, Daisuke), Accepted: 2019-09-20, 資料番号: SA1190158000

Published
2019

41. OGLE-2018-BLG-1700L: Microlensing Planet in Binary Stellar System

Author

Igor Soszyński, Patryk Iwanek, Cheongho Han, Shota Miyazaki, Nicholas J. Rattenbury, Jan Skowron, In-Gu Shin, David P. Bennett, Hirosane Fujii, Yoshitaka Itow, Byeong-Gon Park, Andrew Gould, Clément Ranc, Daisuke Suzuki, Haruno Suematsu, Weicheng Zang, Masayuki Nagakane, Kyu-Ha Hwang, Paul J. Tristram, Takahiro Sumi, Radek Poleski, Ian A. Bond, Martin Donachie, Sang-Mok Cha, Denis J. Sullivan, Iona Kondo, Man Cheung Alex Li, M. James Jee, Dong-Joo Lee, Chung-Uk Lee, Akihiko Fukui, Andrzej Udalski, Michał K. Szymański, Doeon Kim, Jennifer C. Yee, Yuki Hirao, Przemek Mróz, Yossi Shvartzvald, Fumio Abe, Michael D. Albrow, Sun-Ju Chung, Richard W. Pogge, Yutaka Matsubara, Yuhei Kamei, Krzysztof Ulaczyk, Szymon Kozłowski, Youn Kil Jung, Dong-Jin Kim, Yoon-Hyun Ryu, Richard K. Barry, M. Wrona, Aparna Bhattacharya, Hyoun-Woo Kim, Krzysztof A. Rybicki, Yasushi Muraki, Yongseok Lee, Atsunori Yonehara, T. Yamakawa, Paweł Pietrukowicz, Seung-Lee Kim, and Naoki Koshimoto

Subjects
Physics, Earth and Planetary Astrophysics (astro-ph.EP), 010504 meteorology & atmospheric sciences, Binary number, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Mass ratio, Gravitational microlensing, 01 natural sciences, Einstein radius, 13. Climate action, Space and Planetary Science, Primary (astronomy), Planet, 0103 physical sciences, Binary star, Astrophysics::Earth and Planetary Astrophysics, Circumbinary planet, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Astrophysics - Earth and Planetary Astrophysics
Abstract

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., 10 pages, 8 figures

Published
2019

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

Author

B. Scott Gaudi, Masayuki Nagakane, Andrzej Udalski, Man Cheung Alex Li, Michał K. Szymański, Radek Poleski, Charles Beichman, Jennifer C. Yee, Sun-Ju Chung, Kohei Kawasaki, Igor Soszyński, Matthew T. Penny, Paweł Pietrukowicz, Dong-Jin Kim, M. Hundertmark, Keivan G. Stassun, Etienne Bachelet, Chung-Uk Lee, Byeong-Gon Park, In-Gu Shin, Cheongho Han, Marcin Wrona, Richard Barry, Sebastiano Calchi Novati, Youn Kil Jung, Fumio Abe, Andrew Gould, Clément Ranc, Yasushi Muraki, Weicheng Zang, Yongseok Lee, Atsunori Yonehara, D. J. Lee, K. H. Hwang, Richard W. Pogge, Aparna Bhattacharya, Paul J. Tristram, Daisuke Suzuki, Yutaka Matsubara, Seung-Lee Kim, Michael D. Albrow, Haruno Suematsu, Arnaud Cassan, Yoon-Hyun Ryu, Kay-Sebastian Nikolaus, David P. Bennett, Hyoun-Woo Kim, K. A. Rybicki, Szymon Kozłowski, Krzysztof Ulaczyk, Pascal Fouqué, Valerio Bozza, Sang-Mok Cha, Kyeongsoo Hong, Yoshitaka Itow, Wei Zhu, Geoffery Bryden, Martin Donachie, Tianshu Wang, Shota Miyazaki, Denis J. Sullivan, Naoki Koshimoto, Calen B. Henderson, Savannah Jacklin, Shude Mao, Patryk Iwanek, Przemek Mróz, Nicholas J. Rattenbury, Jan Skowron, Ian A. Bond, Iona Kondo, Akihiko Fukui, Doeon Kim, Takahiro Sumi, Yuki Hirao, and Yossi Shvartzvald

Subjects
gravitational lensing: micro, planetary systems, Physics, Earth and Planetary Astrophysics (astro-ph.EP), 010504 meteorology & atmospheric sciences, Lens (geology), Binary number, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Planetary system, Gravitational microlensing, Light curve, 01 natural sciences, Space and Planetary Science, Planet, 0103 physical sciences, Anomaly (physics), Low Mass, 010303 astronomy & astrophysics, Astrophysics - Earth and Planetary Astrophysics, 0105 earth and related environmental sciences
Abstract

著者人数: Leading authors 13名, The KMTNet Collaboration 18名, The OGLE Collaboration 11名, The MOA Collaboration 22名, The CFHT Collaboration 5名, The UKIRT Microlensing Team 7名, 全66名 (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 鈴木, 大介), Number of authors: Leading authors 13, The KMTNet Collaboration 18, The OGLE Collaboration 11, The MOA Collaboration 22, The CFHT Collaboration 5, The UKIRT Microlensing Team 7, Total 66 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS): Suzuki, Daisuke), Accepted: 2019-07-02, 資料番号: SA1190106000

Published
2019

43. OGLE-2015-BLG-1649Lb: A gas giant planet around a low-mass dwarf

Author

M. Hundertmark, Man Cheung Alex Li, Nicholas J. Rattenbury, Jan Skowron, R. W. Schmidt, Igor Soszyński, Daisuke Suzuki, Yasushi Muraki, Y. Kamei, Atsunori Yonehara, Arnaud Cassan, Jean-Philippe Beaulieu, Jesper Skottfelt, Keith Horne, S. Kozlowski, Heidi Korhonen, Ian A. Bond, D. M. Bramich, Akihiko Fukui, Clément Ranc, John Southworth, Michael I. Andersen, Masayuki Nagakane, Martin Donachie, Denis J. Sullivan, Etienne Bachelet, Joachim Wambsganss, Richard K. Barry, Hirosane Fujii, Iain A. Steele, Nuno Peixinho, Andrzej Udalski, Michał K. Szymański, J. W. Menzies, Aparna Bhattacharya, U. G. Jørgensen, Yiannis Tsapras, Shota Miyazaki, Martin Burgdorf, Sohrab Rahvar, Yutaka Matsubara, Tobias C. Hinse, M. Rabus, Krzysztof Ulaczyk, Paul J. Tristram, P. Mróz, Haruno Suematsu, Giuseppe D'Ago, T. Yamakawa, Chien-Hsiu Lee, Daniel F. Evans, Shude Mao, Fumio Abe, Colin Snodgrass, Valerio Bozza, P. Pietrukowicz, Radosław Poleski, Naoki Koshimoto, Martin Dominik, R. Figuera Jaimes, Yuki Hirao, Iona Kondo, Taro Matsuo, Rachel Street, Takahiro Sumi, David P. Bennett, Yoshitaka Itow, Hiroshi Shibai, P. Longa, Osaka University [Osaka], Astronomical Observatory [Warsaw], Faculty of Physics [Warsaw] (FUW), University of Warsaw (UW)-University of Warsaw (UW), Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Department of Physics [Notre Dame], University of Notre Dame [Indiana] (UND), University of Auckland [Auckland], Nagoya University, Department of Physics [Osaka], Osaka University, NASA Goddard Space Flight Center (GSFC), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Ohio State University [Columbus] (OSU), Space Science Department of ESA, European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Max-Planck-Institut für Sonnensystemforschung (MPS), Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University of Copenhagen = Københavns Universitet (KU), Kuopio Unit [FMI], Finnish Meteorological Institute (FMI), Instituto de Astrofisica de Canarias (IAC), University of St Andrews. School of Physics and Astronomy, University of St Andrews. St Andrews Centre for Exoplanet Science, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), and University of Copenhagen = Københavns Universitet (UCPH)

Subjects
Gas giant, Exoplanet astronomy, NDAS, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, 01 natural sciences, 0103 physical sciences, QB Astronomy, Astrophysics::Solar and Stellar Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, QB600, QC, Astrophysics::Galaxy Astrophysics, QB, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Exoplanet astronomy (486), Astronomy, Astronomy and Astrophysics, QC Physics, Space and Planetary Science, astro-ph.EP, Astrophysics::Earth and Planetary Astrophysics, Low Mass, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Gravitational microlensing (672), QB799, Astrophysics - Earth and Planetary Astrophysics
Abstract

著者人数: 69名 (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 鈴木, 大介), Number of authors: 69 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS): Suzuki, Daisuke), Accepted: 2019-09-25, 資料番号: SA1190157000

Published
2019

44. $Spitzer$ Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M-dwarf

Author

C. Han, Richard Barry, Seung-Lee Kim, K. A. Rybicki, Chung-Uk Lee, Akihiko Fukui, Tianshu Wang, Fumio Abe, Shude Mao, Paul J. Tristram, Naoki Koshimoto, Takahiro Sumi, Sebastiano Calchi Novati, Masayuki Nagakane, Sang-Mok Cha, Igor Soszyński, Dong-Jin Kim, Richard W. Pogge, Yutaka Matsubara, Geoffery Bryden, Man Cheung Alex Li, W. Zang, Jennifer C. Yee, R. Poleski, Wei Zhu, S. Miyazaki, Haruno Suematsu, D. J. Lee, Yoon-Hyun Ryu, Andrzej Udalski, Clément Ranc, Michał K. Szymański, Calen B. Henderson, Keivan G. Stassun, Yasushi Muraki, Yuki Hirao, Yongseok Lee, Atsunori Yonehara, Yossi Shvartzvald, Aparna Bhattacharya, In-Gu Shin, Martin Donachie, Denis J. Sullivan, Pascal Fouqué, Spitzer Team, Przemek Mróz, Michael D. Albrow, Marcin Wrona, David P. Bennett, B. G. Park, Ian A. Bond, Sean Carey, B. Scott Gaudi, Szymon Kozłowski, Yoshitaka Itow, Youn Kil Jung, Iona Kondo, Matthew T. Penny, Charles A. Beichman, Andrew Gould, Paweł Pietrukowicz, Hyoun-Woo Kim, K. Ulaczyk, K. H. Hwang, Savannah Jacklin, Sun-Ju Chung, Daisuke Suzuki, Patryk Iwanek, Nicholas J. Rattenbury, and Jan Skowron

Subjects
Physics, Earth and Planetary Astrophysics (astro-ph.EP), Proper motion, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Mass ratio, Planetary system, Light curve, Gravitational microlensing, 01 natural sciences, Space and Planetary Science, Planet, Bulge, 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, Low Mass, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery of a $Spitzer$ microlensing planet OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio $q \sim 2\times10^{-4}$. The planetary signal, which is characterized by a short $(\sim 1~{\rm day})$ "bump" on the rising side of the lensing light curve, was densely covered by ground-based surveys. We find that the signal can be explained by a bright source that fully envelops the planetary caustic, i.e., a "Hollywood" geometry. Combined with the source proper motion measured from $Gaia$, the $Spitzer$ satellite parallax measurement makes it possible to precisely constrain the lens physical parameters. The preferred solution, in which the planet perturbs the minor image due to lensing by the host, yields a Uranus-mass planet with a mass of $M_{\rm p} = 13.9\pm1.6~M_{\oplus}$ orbiting a mid M-dwarf with a mass of $M_{\rm h} = 0.23\pm0.03~M_{\odot}$. There is also a second possible solution that is substantially disfavored but cannot be ruled out, for which the planet perturbs the major image. The latter solution yields $M_{\rm p} = 1.2\pm0.2~M_{\oplus}$ and $M_{\rm h} = 0.15\pm0.02~M_{\odot}$. By combining the microlensing and $Gaia$ data together with a Galactic model, we find in either case that the lens lies on the near side of the Galactic bulge at a distance $D_{\rm L} \sim 6\pm1~{\rm kpc}$. Future adaptive optics observations may decisively resolve the major image/minor image degeneracy., 34 pages, 8 figures, Submitted to AAS journal

Published
2019

45. OGLE-2018-BLG-0022: First Prediction of an Astrometric Microlensing Signal from a Photometric Microlensing Event

Author

B. Scott Gaudi, K. A. Rybicki, Valerio Bozza, Andrzej Udalski, Michał K. Szymański, Yasushi Muraki, Jennifer C. Yee, Yongseok Lee, Paweł Pietrukowicz, Atsunori Yonehara, Masayuki Nagakane, Aparna Bhattacharya, Marcin Wrona, Seung-Lee Kim, David P. Bennett, Radek Poleski, Calen B. Henderson, Yoshitaka Itow, Sean Carey, K. H. Hwang, Takahiro Sumi, Andrew Gould, Woong-Tae Kim, Clément Ranc, Paul J. Tristram, Youn Kil Jung, Weicheng Zang, Kohei Kawasaki, Szymon Kozłowski, Przemek Mróz, Byeong-Gon Park, Dong-Jin Kim, Charles Beichman, D. J. Lee, Sun-Ju Chung, Ian A. Bond, Yuki Hirao, Man Cheung Alex Li, Richard W. Pogge, Cheongho Han, Yutaka Matsubara, Yossi Shvartzvald, Michael D. Albrow, Akihiko Fukui, Yoon-Hyun Ryu, Hyoun-Woo Kim, Doeon Kim, Daisuke Suzuki, Geoffery Bryden, Iona Kondo, Richard Barry, Krzysztof Ulaczyk, Arnaud Cassan, Shota Miyazaki, Naoki Koshimoto, Martin Donachie, Denis J. Sullivan, Patryk Iwanek, Nicholas J. Rattenbury, Jan Skowron, Igor Soszyński, In-Gu Shin, Chung-Uk Lee, Fumio Abe, Haruno Suematsu, and Sang-Mok Cha

Subjects
Physics, Proper motion, binaries: general, gravitational lensing: micro, 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy, Centroid, Astronomy and Astrophysics, Gravitational microlensing, 01 natural sciences, Photometry (optics), Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Bulge, 0103 physical sciences, Satellite, Parallax, 010303 astronomy & astrophysics, Event (particle physics), Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

著者人数: Leading authors 7名, The KMTNet Collaboration 20名, The MOA Collaboration 23名, The OGLE Collaboration 11名, Spitzer Microlensing Team 5名, 全66名 (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 鈴木, 大介), Number of authors: Leading authors 7, The KMTNet Collaboration 20, The MOA Collaboration 23, The OGLE Collaboration 11, Spitzer Microlensing Team 5, Total 66 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS): Suzuki, Daisuke), Accepted: 2019-04-02, 資料番号: SA1190031000

Published
2019

46. OGLE-2014-BLG-0962 and a Comparison of Galactic Model Priors to Microlensing Data

Author

Łukasz Wyrzykowski, Kohei Kawasaki, Masayuki Nagakane, Takahiro Sumi, Nicholas J. Rattenbury, Jan Skowron, Charles Beichman, Andrew Gould, Clément Ranc, Y. K. Jung, Haruno Suematsu, Daisuke Suzuki, Radosław Poleski, Naoki Koshimoto, Iona Kondo, Yasushi Muraki, Jennifer C. Yee, Atsunori Yonehara, Richard Barry, Yutong Shan, Yuki Hirao, Fumio Abe, David P. Bennett, M. Friedmann, Sean Carey, Yossi Shvartzvald, Yoshitaka Itow, Akihiko Fukui, Paweł Pietrukowicz, Spitzer Team, Paul J. Tristram, Shota Miyazaki, Szymon Kozłowski, P. Mróz, Man Cheung Alex Li, Richard W. Pogge, Yutaka Matsubara, Ian A. Bond, Krzysztof Ulaczyk, Dan Maoz, Igor Soszyński, In-Gu Shin, Aparna Bhattacharya, Shai Kaspi, Martin Donachie, Denis J. Sullivan, Sebastiano Calchi Novati, B. Scott Gaudi, Andrzej Udalski, and Michał K. Szymański

Subjects
Physics, methods: statistical, Astronomy and Astrophysics, Astrophysics, gravitational lensing: micro, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, Galaxy: bulge, Methods statistical, binaries: general, Space and Planetary Science, Bulge, stars: low-mass, Prior probability, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

著者人数: 49名ほか (所属. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS): 鈴木, 大介), 資料番号: SA1180374000

Published
2019

47. Spitzer Microlensing Parallax for OGLE-2016-BLG-1067: A Sub-Jupiter Orbiting an M Dwarf in the Disk

Author

Charles A. Beichman, Radosław Poleski, Naoki Koshimoto, Yasushi Muraki, Yongseok Lee, Atsunori Yonehara, Clément Ranc, K. Kawasaki, David P. Bennett, Michał Pawlak, Yoshitaka Itow, Hyoun-Woo Kim, Takahiro Sumi, Richard Barry, Andrew Gould, K. H. Hwang, Paweł Pietrukowicz, Wei Zhu, Igor Soszyński, Nicholas J. Rattenbury, Jan Skowron, Sang-Mok Cha, Masayuki Nagakane, Yuki Hirao, K. Ulaczyk, W. Zang, Yossi Shvartzvald, Michael D. Albrow, Y. Asakura, Sean Carey, Spitzer Team, Ian A. Bond, Daisuke Suzuki, Geoffery Bryden, In-Gu Shin, Valerio Bozza, Paul J. Tristram, S. Miyazaki, C. H. Ling, P. Evans, Seung-Lee Kim, To. Saito, S. Calchi Novati, Chung-Uk Lee, C. Han, D. J. Lee, Dong-Jin Kim, Jennifer C. Yee, Fumio Abe, Andrzej Udalski, B. G. Park, Michał K. Szymański, Szymon Kozłowski, Man Cheung Alex Li, K. Ohnishi, S. J. Chung, Aparna Bhattacharya, Youn Kil Jung, Yoon-Hyun Ryu, Calen B. Henderson, Przemek Mróz, Martin Donachie, Denis J. Sullivan, B. S. Gaudi, Akihiko Fukui, Richard W. Pogge, Yutaka Matsubara, T. Yamada, and A. Sharan

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Physics, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, gravitational lensing: micro, planetary systems, Space and Planetary Science, Astrophysics::Cosmology and Extragalactic Astrophysics, Planetary system, Gravitational microlensing, 01 natural sciences, Jupiter, 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, Parallax, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics, 0105 earth and related environmental sciences
Abstract

We report the discovery of a sub-Jupiter mass planet orbiting beyond the snow line of an M-dwarf most likely in the Galactic disk as part of the joint Spitzer and ground-based monitoring of microlensing planetary anomalies toward the Galactic bulge. The microlensing parameters are strongly constrained by the light curve modeling and in particular by the Spitzer-based measurement of the microlens parallax, $\pi_\mathrm{E}$. However, in contrast to many planetary microlensing events, there are no caustic crossings, so the angular Einstein radius, $\theta_\mathrm{E}$ has only an upper limit based on the light curve modeling alone. Additionally, the analysis leads us to identify 8 degenerate configurations: the four-fold microlensing parallax degeneracy being doubled by a degeneracy in the caustic structure present at the level of the ground-based solutions. To pinpoint the physical parameters, and at the same time to break the parallax degeneracy, we make use of a series of arguments: the $\chi^2$ hierarchy, the Rich argument, and a prior Galactic model. The preferred configuration is for a host at $D_L=3.73_{-0.67}^{+0.66}~\mathrm{kpc}$ with mass $M_\mathrm{L}=0.30_{-0.12}^{+0.15}~\mathrm{M_\odot}$, orbited by a Saturn-like planet with $M_\mathrm{planet}=0.43_{-0.17}^{+0.21}~\mathrm{M_\mathrm{Jup}}$ at projected separation $a_\perp = 1.70_{-0.39}^{+0.38}~\mathrm{au}$, about 2.1 times beyond the system snow line. Therefore, it adds to the growing population of sub-Jupiter planets orbiting near or beyond the snow line of M-dwarfs discovered by microlensing. Based on the rules of the real-time protocol for the selection of events to be followed up with Spitzer, this planet will not enter the sample for measuring the Galactic distribution of planets., Comment: Submitted to AAS Journals

Published
2019

48. Spitzer Microlensing of MOA-2016-BLG-231L : A Counter-Rotating Brown Dwarf Binary in the Galactic Disk

Author

Cheongho Han, David P. Bennett, Sang-Mok Cha, Kyu-Ha Hwang, Yasushi Muraki, Martin Donachie, Denis J. Sullivan, Atsunori Yonehara, Yongseok Lee, Yun Hak Kim, Wei Zhu, K. Kawasaki, Yoshitaka Itow, Hyoun-Woo Kim, Charles Beichman, Youn Kil Jung, Masayuki Nagakane, Shota Miyazaki, Sean Carey, Akihiko Fukui, Radek Poleski, Dong-Joo Lee, Yoon-Hyun Ryu, B. Scott Gaudi, Dong-Jin Kim, Ian A. Bond, Paweł Pietrukowicz, Andrew Gould, Clément Ranc, Nicholas J. Rattenbury, Jan Skowron, Chung-Uk Lee, Weicheng Zang, Andrzej Udalski, Michał K. Szymański, In-Gu Shin, Richard Barry, Seung-Lee Kim, Michał Pawlak, Igor Soszyński, Calen B. Henderson, Przemek Mróz, Yuki Hirao, Michael D. Albrow, Sun-Ju Chung, Naoki Koshimoto, Paul J. Tristram, Geoffery Bryden, Jennifer C. Yee, Sebastiano Calchi Novati, Yossi Shvartzvald, Man Cheung Alex Li, Richard W. Pogge, Yutaka Matsubara, Krzysztof Ulaczyk, Takahiro Sumi, Iona Kondo, Aparna Bhattacharya, Byeong-Gon Park, Fumio Abe, Szymon Kozłowski, Daisuke Suzuki, and Haruno Suematsu

Subjects
Physics, 010504 meteorology & atmospheric sciences, Brown dwarf, Binary number, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, gravitational lensing: micro, Gravitational microlensing, Light curve, 01 natural sciences, Stars, binaries: general, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, 0103 physical sciences, Orbital motion, Counter rotating, Disc, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, brown dwarfs
Abstract

著者人数: 63名ほか(所属. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS): 鈴木, 大介), Accepted: 2018-12-11, 資料番号: SA1180353000

Published
2019

49. OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensing

Author

R. Figuera Jaimes, Man Cheung Alex Li, Daniel Huber, Andrew A. Cole, K. H. Hwang, Calen B. Henderson, Masayuki Nagakane, I.-G. Shin, Wei Zhu, Sohrab Rahvar, Yasushi Muraki, Nuno Peixinho, C.-U. Lee, Steve Hennerley, Yuri I. Fujii, M. Rabus, Paul J. Tristram, Yongseok Lee, Andrzej Udalski, G. Bryden, Michał K. Szymański, C. von Essen, Penélope Longa-Peña, Radek Poleski, Atsunori Yonehara, Eduardo Unda-Sanzana, D. J. Lee, Lauri K. Haikala, Szymon Kozłowski, Naoki Koshimoto, Patryk Iwanek, B. S. Gaudi, Julie Green, Przemek Mróz, P. Fouqué, Daniel F. Evans, Thomas Henning, Jennifer C. Yee, M. Hundertmark, J.-P. Beaulieu, Iona Kondo, Richard W. Pogge, Yutaka Matsubara, Martin Dominik, K. Hill, Akihiko Fukui, Nicholas J. Rattenbury, Etienne Bachelet, Jan Skowron, Richard Barry, Tobias C. Hinse, Tianshu Wang, Michael D. Albrow, Igor Soszyński, Krzysztof Ulaczyk, Fumio Abe, Shota Miyazaki, Yoon-Hyun Ryu, S. Calchi Novati, Rachel Street, Aparna Bhattacharya, K. A. Rybicki, Byeong-Gon Park, Martin Donachie, Denis J. Sullivan, J. W. Blackman, J. Drummond, Sedighe Sajadian, Tim Natusch, Sang-Mok Cha, Takahiro Sumi, Martin Burgdorf, Daisuke Suzuki, Andrew Gould, Clément Ranc, Yuki Hirao, Weicheng Zang, Jesper Skottfelt, Yossi Shvartzvald, G. W. Christie, Luigi Mancini, Haruno Suematsu, I. Porritt, Dong-Jin Kim, S. S. Li, Ian A. Bond, John Southworth, D. Maoz, Shude Mao, Sean Carey, David P. Bennett, Yoshitaka Itow, Y. K. Jung, Valerio Bozza, Charles A. Beichman, Hyoun-Woo Kim, Chang S. Han, Colin Snodgrass, Christiane Helling, Paweł Pietrukowicz, Subo Dong, U. G. Jørgensen, Yiannis Tsapras, Seung-Lee Kim, S. J. Chung, University of St Andrews. School of Physics and Astronomy, and University of St Andrews. St Andrews Centre for Exoplanet Science

Subjects
oscillations [stars], Red giant, fundamental parameters [stars], DWARF STARS, Astrophysics, gravitational lensing: micro, 01 natural sciences, STANDARD, Angular diameter, Bulge, QB460, PROGRAM, QB Astronomy, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, QB, Earth and Planetary Astrophysics (astro-ph.EP), Physics, PLANET PHOTOMETRY, 3rd-DAS, Astrophysics - Solar and Stellar Astrophysics, stars: fundamental parameters, stars: oscillations, Astrophysics::Earth and Planetary Astrophysics, astro-ph.SR, STELLAR OSCILLATIONS, Brown dwarf, FOS: Physical sciences, asteroseismology, Astrophysics::Cosmology and Extragalactic Astrophysics, SUBGIANTS, Gravitational microlensing, Asteroseismology, Settore FIS/05 - Astronomia e Astrofisica, ANGULAR SIZES, SYSTEMS, 0103 physical sciences, Solar and Stellar Astrophysics (astro-ph.SR), DISTANCES, Astrophysics::Galaxy Astrophysics, 010308 nuclear & particles physics, Astronomy and Astrophysics, Light curve, SURFACE BRIGHTNESS RELATIONS, Space and Planetary Science, astro-ph.EP, micro [gravitational lensing], Parallax, QB799, Astrophysics - Earth and Planetary Astrophysics
Abstract

著者人数: 105名 (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 鈴木, 大介), Number of authors: 105 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS): Suzuki, Daisuke), Accepted: 2019-07-03, 資料番号: SA1190108000

Published
2019

50. OGLE-2016-BLG-0156: Microlensing Event With Pronounced Microlens-Parallax Effects Yielding Precise Lens Mass Measurement

Author

Paweł Pietrukowicz, Naoki Koshimoto, Kohei Kawasaki, Seung-Lee Kim, K. H. Hwang, Yasushi Muraki, Dong-Jin Kim, Yongseok Lee, Atsunori Yonehara, Chung-Uk Lee, David P. Bennett, Nicholas J. Rattenbury, Ian A. Bond, Jan Skowron, Yoshitaka Itow, Hyoun-Woo Kim, Richard Barry, Sun-Ju Chung, Daisuke Suzuki, Masayuki Nagakane, Fumio Abe, Aparna Bhattacharya, Radek Poleski, Sang-Mok Cha, Byeong-Gon Park, Yuki Hirao, Yossi Shvartzvald, Akihiko Fukui, Paul J. Tristram, Cheongho Han, Igor Soszyński, Haruno Suematsu, Doeon Kim, Iona Kondo, D. J. Lee, In-Gu Shin, Youn Kil Jung, Szymon Kozłowski, Richard W. Pogge, Yutaka Matsubara, Krzysztof Ulaczyk, Martin Donachie, Denis J. Sullivan, Takahiro Sumi, Andrzej Udalski, Michał K. Szymański, Michał Pawlak, M. James Jee, Yoon-Hyun Ryu, Michael D. Albrow, Przemek Mróz, Andrew Gould, Clément Ranc, Man Cheung Alex Li, Shota Miyazaki, and Jennifer C. Yee

Subjects
010504 meteorology & atmospheric sciences, Flux, FOS: Physical sciences, gravitational lensing: micro, Astrophysics, Gravitational microlensing, 01 natural sciences, law.invention, Einstein radius, Gravitation, law, 0103 physical sciences, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, Microlens, Earth and Planetary Astrophysics (astro-ph.EP), Astronomy and Astrophysics, Light curve, Lens (optics), Astrophysics - Solar and Stellar Astrophysics, binaries: general, Space and Planetary Science, Parallax, Astrophysics - Earth and Planetary Astrophysics
Abstract

We analyze the gravitational binary-lensing event OGLE-2016-BLG-0156, for which the lensing light curve displays pronounced deviations induced by microlens-parallax effects. The light curve exhibits 3 distinctive widely-separated peaks and we find that the multiple-peak feature provides a very tight constraint on the microlens-parallax effect, enabling us to precisely measure the microlens parallax $\pi_{\rm E}$. All the peaks are densely and continuously covered from high-cadence survey observations using globally located telescopes and the analysis of the peaks leads to the precise measurement of the angular Einstein radius $\theta_{\rm E}$. From the combination of the measured $\pi_{\rm E}$ and $\theta_{\rm E}$, we determine the physical parameters of the lens. It is found that the lens is a binary composed of two M dwarfs with masses $M_1=0.18\pm 0.01\ M_\odot$ and $M_2=0.16\pm 0.01\ M_\odot$ located at a distance $D_{\rm L}= 1.35\pm 0.09\ {\rm kpc}$. According to the estimated lens mass and distance, the flux from the lens comprises an important fraction, $\sim 25\%$, of the blended flux. The bright nature of the lens combined with the high relative lens-source motion, $\mu=6.94\pm 0.50\ {\rm mas}\ {\rm yr}^{-1}$, suggests that the lens can be directly observed from future high-resolution follow-up observations., Comment: 9 pages, 9 figures

Published
2019
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