Browsing by Author "Penny MT"

Now showing 1 - 6 of 6
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    Kepler K2 Campaign 9 – II. First space-based discovery of an exoplanet using microlensing
    (Oxford University Press, 2023-04-01) Specht D; Poleski R; Penny MT; Kerins E; McDonald I; Chung-Uk L; Udalski A; Bond IA; Shvartzvald Y; Zang W; Street RA; Hogg DW; Gaudi BS; Barclay T; Barentsen G; Howell SB; Mullally F; Henderson CB; Bryson ST; Caldwell DA; Haas MR; Van Cleve JE; Larson K; McCalmont K; Peterson C; Putnam D; Ross S; Packard M; Reedy L; Albrow MD; Sun-Ju C; Jung YK; Gould A; Han C; Kyu-Ha H; Yoon-Hyun R; In-Gu S; Yang H; Yee JC; Sang-Mok C; Dong-Jin K; Seung-Lee K; Dong-Joo L; Lee Y; Byeong-Gon P; Pogge RW; Szymański MK; Soszyński I; Ulaczyk K; Pietrukowicz P; Kozłowski SZ; Skowron J; Mróz P; Mao S; Fouqué P; Zhu W; Abe F; Barry R; Bennett DP; Bhattacharya A; Fukui A; Fujii H; Hirao Y; Itow Y; Kirikawa R; Kondo I; Koshimoto N; Matsubara Y; Matsumoto S; Miyazaki S; Muraki Y; Olmschenk G; Ranc C; Okamura A; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Silva SI; Toda T; Tristram PJ; Vandorou A; Yama H; Beichman C; Bryden G; Novati SC
    We present K2-2016-BLG-0005Lb, a densely sampled, planetary binary caustic-crossing microlensing event found from a blind search of data gathered from Campaign 9 of the Kepler K2 mission (K2C9). K2-2016-BLG-0005Lb is the first bound microlensing exoplanet discovered from space-based data. The event has caustic entry and exit points that are resolved in the K2C9 data, enabling the lens-source relative proper motion to be measured. We have fitted a binary microlens model to the Kepler data and to simultaneous observations from multiple ground-based surveys. Whilst the ground-based data only sparsely sample the binary caustic, they provide a clear detection of parallax that allows us to break completely the microlensing mass-position-velocity degeneracy and measure the planet’s mass directly. We find a host mass of 0.58 ± 0.04 M and a planetary mass of 1.1 ± 0.1 MJ. The system lies at a distance of 5.2 ± 0.2 kpc from Earth towards the Galactic bulge, more than twice the distance of the previous most distant planet found by Kepler. The sky-projected separation of the planet from its host is found to be 4.2 ± 0.3 au which, for circular orbits, deprojects to a host separation a = 4.4+−0149 au and orbital period P = 13+−29 yr. This makes K2-2016-BLG-0005Lb a close Jupiter analogue orbiting a low-mass host star. According to current planet formation models, this system is very close to the host mass threshold below which Jupiters are not expected to form. Upcoming space-based exoplanet microlensing surveys by NASA’s Nancy Grace Roman Space Telescope and, possibly, ESA’s Euclid mission, will provide demanding tests of current planet formation models.
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    KMT-2021-BLG-1547Lb: Giant microlensing planet detected through a signal deformed due to source binarity
    (EDP Sciences, France, 2023-10) Han C; Zang W; Jung YK; Bond IA; Chung S-J; Albrow MD; Gould A; Hwang K-H; Ryu Y-H; Shin I-G; Shvartzvald Y; Yang H; Yee JC; Cha S-M; Kim D; Kim D-J; Kim S-L; Lee C-U; Lee D-J; Lee Y; Park B-G; Pogge RW; Monard B; Qian Q; Liu Z; Maoz D; Penny MT; Zhu W; Abe F; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hamada R; Hirao Y; Ishitani Silva S; Itow Y; Kirikawa R; Kondo I; Koshimoto N; Matsubara Y; Miyazaki S; Muraki Y; Olmschenk G; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Tomoyoshi M; Tristram PJ; Vandorou A; Yama H; Yamashita K
    Aims. We investigate the previous microlensing data collected by the KMTNet survey in search of anomalous events for which no precise interpretations of the anomalies had been suggested. From this investigation, we find that the anomaly in the lensing light curve of the event KMT-2021-BLG-1547 is approximately described by a binary-lens (2L1S) model with a lens possessing a giant planet, but the model leaves unexplained residuals. Methods. We investigated the origin of the residuals by testing more sophisticated models that include either an extra lens component (3L1S model) or an extra source star (2L2S model) on top of the 2L1S configuration of the lens system. From these analyses, we find that the residuals from the 2L1S model originate from the existence of a faint companion to the source. The 2L2S solution substantially reduces the residuals and improves the model fit by δ x 2 = 67.1 with respect to the 2L1S solution. The 3L1S solution also improves the fit, but its fit is worse than that of the 2L2S solution by δ x 2 = 24.7. Results. According to the 2L2S solution, the lens of the event is a planetary system with planet and host masses (Mp/MJ, Mh/M·) = (1.47-0.77+0.64, 0.72-0.38+0.32) lying at a distance DL = 5.07-1.50+0.98 kpc, and the source is a binary composed of a subgiant primary of a late G or an early K spectral type and a main-sequence companion of a K spectral type. The event demonstrates the need for sophisticated modeling of unexplained anomalies if one wants to construct a complete microlensing planet sample.
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    MOA-2020-BLG-135Lb: A New Neptune-class Planet for the Extended MOA-II Exoplanet Microlens Statistical Analysis
    (IOP Publishing on behalf of the American Astronomical Society, 2022-09-01) Silva SI; Ranc C; Bennett DP; Bond IA; Zang W; Abe F; Barry R; Bhattacharya A; Fujii H; Fukui A; Hirao Y; Itow Y; Kirikawa R; Kondo I; Koshimoto N; Matsubara Y; Matsumoto S; Miyazaki S; Muraki Y; Olmschenk G; Okamura A; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Toda T; Tristram PJ; Vandorou A; Yama H; Petric A; Burdullis T; Fouqué P; Mao S; Penny MT; Zhu W; Rau G
    We report the light-curve analysis for the event MOA-2020-BLG-135, which leads to the discovery of a new Neptune-class planet, MOA-2020-BLG-135Lb. With a derived mass ratio of q = 1.52-0.31+0.39 ´ 10-4 and separation s ≈ 1, the planet lies exactly at the break and likely peak of the exoplanet mass-ratio function derived by the Microlensing Observations in Astrophysics (MOA) Collaboration. We estimate the properties of the lens system based on a Galactic model and considering two different Bayesian priors: one assuming that all stars have an equal planet-hosting probability and the other that planets are more likely to orbit more-massive stars. With a uniform host mass prior, we predict that the lens system is likely to be a planet of mass mplanet = 11.3-6.9+19.2 MÅ and a host star of mass Mhost = 0.23-0.14+0.39 M☉, located at a distance DL = 7.9-1.0+1.0 kpc. With a prior that holds that planet occurrence scales in proportion to the host-star mass, the estimated lens system properties are mplanet = 25-15+22 MÅ, Mhost = 0.53-0.32+0.42 M☉, and DL = 8.3-1.0+0.9 kpc. This planet qualifies for inclusion in the extended MOA-II exoplanet microlens sample.
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    MOA-2020-BLG-208Lb: Cool Sub-Saturn-mass Planet within Predicted Desert
    (American Astronomical Society, 2023-03) Olmschenk G; Bennett DP; Bond IA; Zang W; Jung YK; Yee JC; Bachelet E; Abe F; Barry RK; Bhattacharya A; Fujii H; Fukui A; Hirao Y; Silva SI; Itow Y; Kirikawa R; Kondo I; Koshimoto N; Matsubara Y; Matsumoto S; Miyazaki S; Munford B; Muraki Y; Okamura A; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Toda T; Tristram PJ; Vandorou A; Yama H; Albrow MD; Cha S-M; Chung S-J; Gould A; Han C; Hwang K-H; Kim D-J; Kim H-W; Kim S-L; Lee C-U; Lee D-J; Lee Y; Park B-G; Pogge RW; Ryu Y-H; Shin I-G; Shvartzvald Y; Christie G; Cooper T; Drummond J; Green J; Hennerley S; McCormick J; Monard LAG; Natusch T; Porritt I; Tan T-G; Mao S; Maoz D; Penny MT; Zhu W; Bozza V; Cassan A; Dominik M; Hundertmark M; Jaimes RF; Kruszyńska K; Rybicki KA; Street RA; Tsapras Y; Wambsganss J; Wyrzykowski L; Zieliński P; Rau G
    We analyze the MOA-2020-BLG-208 gravitational microlensing event and present the discovery and characterization of a new planet, MOA-2020-BLG-208Lb, with an estimated sub-Saturn mass. With a mass ratio q=3.17-0.26+0.28×10-4, the planet lies near the peak of the mass-ratio function derived by the MOA collaboration and near the edge of expected sample sensitivity. For these estimates we provide results using two mass-law priors: one assuming that all stars have an equal planet-hosting probability, and the other assuming that planets are more likely to orbit around more massive stars. In the first scenario, we estimate that the lens system is likely to be a planet of mass mplanet=46-24+42M⊕ and a host star of mass Mhost=0.43-0.23+0.39M⊙, located at a distance DL=7.49-1.13+0.99kpc . For the second scenario, we estimate mplanet=69-34+37M⊕, Mhost=0.66-0.32+0.35M⊙, and DL=7.81-0.93+0.93kpc . The planet has a projected separation as a fraction of the Einstein ring radius s=1.3807-0.0018+0.0018 . As a cool sub-Saturn-mass planet, this planet adds to a growing collection of evidence for revised planetary formation models
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    Systematic KMTNet Planetary Anomaly Search. II. Six New q < 2 × 10−4 Mass-ratio Planets
    (IOP Publishing on behalf of the American Astronomical Society, 2022-02-01) Hwang K-H; Zang W; Gould A; Udalski A; Bond IA; Yang H; Mao S; Albrow MD; Chung S-J; Han C; Jung YK; Ryu Y-H; Shin I-G; Shvartzvald Y; Yee JC; Cha S-M; Kim D-J; Kim H-W; Kim S-L; Lee C-U; Lee D-J; Lee Y; Park B-G; Pogge R; Mróz P; Poleski R; Skowron J; Szymański MK; Soszyński I; Pietrukowicz P; Kozłowski S; Ulaczyk K; Rybicki KA; Iwanek P; Wrona M; Gromadzki M; Abe F; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hirao Y; Itow Y; Kirikawa R; Kondo I; Koshimoto N; Munford B; Matsubara Y; Miyazaki S; Muraki Y; Olmschenk G; Ranc C; Rattenbury NJ; Satoh YK; Shoji H; Silva SI; Sumi T; Suzuki D; Tristram PJ; Yonehara A; Zhang X; Zhu W; Penny MT; Fouqué P
    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 . 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.
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    Systematic KMTNet planetary anomaly search: V. Complete sample of 2018 prime-field
    (EDP Sciences, 2022-08-08) Gould A; Han C; Zang W; Yang H; Hwang K-H; Udalski A; Bond IA; Albrow MD; Chung S-J; Jung YK; Ryu Y-H; Shin I-G; Shvartzvald Y; Yee JC; Cha S-M; Kim D-J; Kim H-W; Kim S-L; Lee C-U; Lee D-J; Lee Y; Park B-G; Pogge RW; Mróz P; Szymanski MK; Skowron J; Poleski R; Soszyński I; Pietrukowicz P; Kozłowski S; Ulaczyk K; Rybicki KA; Iwanek P; Wrona M; Abe F; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hirao Y; Silva SI; Kirikawa R; Kondo I; Koshimoto N; Matsubara Y; Matsumoto S; Miyazaki S; Muraki Y; Okamura A; Olmschenk G; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Toda T; Tristram PJ; Vandorou A; Yama H; Beichman C; Bryden G; Novati SC; Gaudi BS; Henderson CB; Penny MT; Jacklin S; Stassun KG
    We complete the analysis of all 2018 prime-field microlensing planets identified by the Korea Microlensing Telescope Network (KMTNet) Anomaly Finder. Among the ten previously unpublished events with clear planetary solutions, eight are either unambiguously planetary or are very likely to be planetary in nature: OGLE-2018-BLG-1126, KMT-2018-BLG-2004, OGLE-2018-BLG-1647, OGLE-2018-BLG-1367, OGLE-2018-BLG-1544, OGLE-2018-BLG-0932, OGLE-2018-BLG-1212, and KMT-2018-BLG-2718. Combined with the four previously published new Anomaly Finder events and 12 previously published (or in preparation) planets that were discovered by eye, this makes a total of 24 2018 prime-field planets discovered or recovered by Anomaly Finder. Together with a paper in preparation on 2018 subprime planets, this work lays the basis for the first statistical analysis of the planet mass-ratio function based on planets identified in KMTNet data. By systematically applying the heuristic analysis to each event, we identified the small modification in their formalism that is needed to unify the so-called close-wide and inner-outer degeneracies.