Browsing by Author "Yang H"

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    Analysis of the Full Spitzer Microlensing Sample. I. Dark Remnant Candidates and Gaia Predictions
    (American Astronomical Society, 2024-11-10) Rybicki KA; Shvartzvald Y; Yee JC; Novati SC; Ofek EO; Bond IA; Beichman C; Bryden G; Carey S; Henderson C; Zhu W; Fausnaugh MM; Wibking B; Udalski A; Poleski R; Mróz P; Szymański MK; Soszyński I; Pietrukowicz P; Kozłowski S; Skowron J; Ulaczyk K; Iwanek P; Wrona M; Ryu Y-H; Albrow MD; Chung S-J; Gould A; Han C-H; Hwang K-H; Jung YK; Shin I-G; Yang H; Zang W; 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; Abe F; Barry R; Bennett DP; Bhattacharya A; Fukui A; Hamada R; Hamada S; Hamasaki N; Hirao Y; Ishitani Silva S; Itow Y; Kirikawa R; Koshimoto N; Matsubara Y; Miyazaki S; Muraki Y; Nagai T; Nunota K; Olmschenk G; Ranc C; Rattenbury NJ; Satoh YK; Sumi T; Suzuki D; Tristram PJ; Vandorou A; Yama H; Wyrzykowski Ł; Howil K; Kruszyńska K
    In the pursuit of understanding the population of stellar remnants within the Milky Way, we analyze the sample of ∼950 microlensing events observed by the Spitzer Space Telescope between 2014 and 2019. In this study we focus on a subsample of nine microlensing events, selected based on their long timescales, small microlensing parallaxes, and joint observations by the Gaia mission, to increase the probability that the chosen lenses are massive and the mass is measurable. Among the selected events we identify lensing black holes and neutron star candidates, with potential confirmation through forthcoming release of the Gaia time-series astrometry in 2026. Utilizing Bayesian analysis and Galactic models, along with the Gaia Data Release 3 proper-motion data, four good candidates for dark remnants were identified: OGLE-2016-BLG-0293, OGLE-2018-BLG-0483, OGLE-2018-BLG-0662, and OGLE-2015-BLG-0149, with lens masses of 3.0-1.3+1.8M☉, 4.7-2.1+3.2 M☉, 3.15-0.64+0..66 M☉ and 1.40-0.55+0.75 M☉, respectively. Notably, the first two candidates are expected to exhibit astrometric microlensing signals detectable by Gaia, offering the prospect of validating the lens masses. The methodologies developed in this work will be applied to the full Spitzer microlensing sample, populating and analyzing the timescale (tE) versus parallax (πE) diagram to derive constraints on the population of lenses in general and massive remnants in particular.
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    Author Correction: Dense sampling of bird diversity increases power of comparative genomics.
    (2021-04) Feng S; Stiller J; Deng Y; Armstrong J; Fang Q; Reeve AH; Xie D; Chen G; Guo C; Faircloth BC; Petersen B; Wang Z; Zhou Q; Diekhans M; Chen W; Andreu-Sánchez S; Margaryan A; Howard JT; Parent C; Pacheco G; Sinding M-HS; Puetz L; Cavill E; Ribeiro ÂM; Eckhart L; Fjeldså J; Hosner PA; Brumfield RT; Christidis L; Bertelsen MF; Sicheritz-Ponten T; Tietze DT; Robertson BC; Song G; Borgia G; Claramunt S; Lovette IJ; Cowen SJ; Njoroge P; Dumbacher JP; Ryder OA; Fuchs J; Bunce M; Burt DW; Cracraft J; Meng G; Hackett SJ; Ryan PG; Jønsson KA; Jamieson IG; da Fonseca RR; Braun EL; Houde P; Mirarab S; Suh A; Hansson B; Ponnikas S; Sigeman H; Stervander M; Frandsen PB; van der Zwan H; van der Sluis R; Visser C; Balakrishnan CN; Clark AG; Fitzpatrick JW; Bowman R; Chen N; Cloutier A; Sackton TB; Edwards SV; Foote DJ; Shakya SB; Sheldon FH; Vignal A; Soares AER; Shapiro B; González-Solís J; Ferrer-Obiol J; Rozas J; Riutort M; Tigano A; Friesen V; Dalén L; Urrutia AO; Székely T; Liu Y; Campana MG; Corvelo A; Fleischer RC; Rutherford KM; Gemmell NJ; Dussex N; Mouritsen H; Thiele N; Delmore K; Liedvogel M; Franke A; Hoeppner MP; Krone O; Fudickar AM; Milá B; Ketterson ED; Fidler AE; Friis G; Parody-Merino ÁM; Battley PF; Cox MP; Lima NCB; Prosdocimi F; Parchman TL; Schlinger BA; Loiselle BA; Blake JG; Lim HC; Day LB; Fuxjager MJ; Baldwin MW; Braun MJ; Wirthlin M; Dikow RB; Ryder TB; Camenisch G; Keller LF; DaCosta JM; Hauber ME; Louder MIM; Witt CC; McGuire JA; Mudge J; Megna LC; Carling MD; Wang B; Taylor SA; Del-Rio G; Aleixo A; Vasconcelos ATR; Mello CV; Weir JT; Haussler D; Li Q; Yang H; Wang J; Lei F; Rahbek C; Gilbert MTP; Graves GR; Jarvis ED; Paten B; Zhang G
    In Supplementary Table 1 of this Article, 23 samples (B10K-DU-029-32, B10K-DU-029-33, B10K-DU-029-36 to B10K-DU-029-44, B10K-DU- 029-46, B10K-DU-029-47, B10K-DU-029-49 to B10K-DU-029-53, B10K-DU- 029-75 to B10K-DU-029-77, B10K-DU-029-80, and B10K-DU-030-03; styled in boldface in the revised table) were assigned to the incorrect institution. Supplementary Table 1 has been amended to reflect the correct source institution for these samples, and associated data (tissue, museum ID/source specimen ID, site, state/province, latitude, longitude, date collected and sex) have been updated accordingly. The original table is provided as Supplementary Information to this Amendment, and the original Article has been corrected online.
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    Brown dwarf companions in binaries detected in the 2021 season high-cadence microlensing surveys
    (EDP Sciences on behalf of The European Southern Observatory, 2023-10) Han C; Jung YK; Bond IA; Chung S-J; Albrow MD; Gould A; Hwang K-H; Lee C-U; Ryu Y-H; Shin I-G; Shvartzvald Y; Yang H; Yee JC; Zang W; Cha S-M; Kim D-J; Kim D-J; Kim S-L; Lee D-J; Lee Y; Park B-G; Pogge RW; Abe F; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hamada R; Hirao Y; Ishitani Silva S; Itow Y; Kirikawa R; 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. As a part of the project aiming to build a homogeneous sample of binary-lens (2L1S) events containing brown dwarf (BD) companions, we investigate the 2021 season microlensing data collected by the Korea Microlensing Telescope Network (KMTNet) survey. Methods. For this purpose, we first identified 2L1S events by conducting systematic analyses of anomalous lensing events. We then selected candidate BD companion events by applying the criterion that the mass ratio of the lens components is lower than qth∼ 0.1. Results. From this procedure, we find four events including KMT-2021-BLG-0588, KMT-2021-BLG-1110, KMT-2021-BLG-1643, and KMT-2021-BLG-1770, for which the estimated mass ratios are q∼ 0.10, 0.07, 0.08, and 0.15, respectively. Event KMT-2021-BLG-1770 was selected as a candidate even though the mass ratio is slightly greater than qth because the lens mass expected from the measured short timescale of the event, tE∼ 7.6 days, is low. From the Bayesian analyses, we estimate that the primary and companion masses are (M1/M⊙,M2/M⊙) = (0.54- 0.24+0.31, 0.053- 0.023+0.031) for KMT-2021-BLG-0588L, (0.74- 0.35+0.27, 0.055- 0.026+0.020) for KMT-2021-BLG-1110L, (0.73- 0.17+0.24,0.061- 0.014+0.020) for KMT-2021-BLG-1643L, and (0.13- 0.07+0.18, 0.020- 0.011+0.028) for KMT-2021-BLG-1770L. It is estimated that the probabilities that the lens companions are in the BD mass range are 82%, 85%, 91%, and 59% for the individual events. To confirm the BD nature of the lens companions found in this and previous works by directly imaging the lenses from future high-resolution adaptive-optics (AO) followup observations, we provide the lens-source separations expected in 2030, which is the approximate year of the first AO light on 30 m class telescopes
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    Brown dwarf companions in microlensing binaries detected during the 2016-2018 seasons
    (EDP Sciences on behalf of the European Southern Observatory, 2022-11-08) Han C; Ryu Y-H; Shin I-G; Jung YK; Kim D; Hirao Y; Bozza V; Albrow MD; Zang W; Udalski A; Bond IA; Chung S-J; Gould A; Hwang K-H; Shvartzvald Y; Yang H; Cha S-M; Kim D-J; Kim H-W; Kim S-L; Lee C-U; Lee D-J; Yee JC; Lee Y; Park B-G; Pogge RW; Mróz P; Szymański 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; 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; Itow Y
    Aims. With the aim of finding microlensing binaries containing brown dwarf (BD) companions, we investigate the microlensing survey data collected during the 2016 2018 seasons. Methods. For this purpose, we first modeled lensing events with light curves exhibiting anomaly features that are likely to be produced by binary lenses. We then sorted out BD companion binary-lens events by applying the criterion that the companion-to-primary mass ratio is q 0.1. With this procedure, we identify six binaries with candidate BD companions: OGLE-2016-BLG-0890L, MOA-2017-BLG-477L, OGLE-2017-BLG-0614L, KMT-2018-BLG-0357L, OGLE-2018-BLG-1489L, and OGLE-2018-BLG-0360L. Results. We estimated the masses of the binary companions by conducting Bayesian analyses using the observables of the individual lensing events. According to the Bayesian estimation of the lens masses, the probabilities for the lens companions of the events OGLE-2016-BLG-0890, OGLE-2017-BLG-0614, OGLE-2018-BLG-1489, and OGLE-2018-BLG-0360 to be in the BD mass regime are very high with PBD > 80%. For MOA-2017-BLG-477 and KMT-2018-BLG-0357, the probabilities are relatively low with PBD = 61% and 69%, respectively.
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    Comparative study on the rheological properties of myofibrillar proteins from different kinds of meat
    (Elsevier Ltd, 2022-01) Wang H; Yang Z; Yang H; Xue J; Li Y; Wang S; Ge L; Shen Q; Zhang M
    In this study, the gel properties of myofibrillar proteins (MPs) from four meat sources (fish, beef, sheep, and pork) were compared. Oscillatory rheology measurements including temperature sweep, frequency sweep, and strain sweep were conducted to characterise the small and large deformation rheological properties of the MPs. In addition, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and scanning electron microscopy (SEM) were used to evaluate differences in the molecular weight distribution as well as the microstructures in gel among different MPs. Frequency sweep measurements showed that all MP gels were weak gels. MPs extracted from pork exhibited the highest gel strength and most compact gel structure, whereas those from fish exhibited the lowest gel strength and loosest gel structure. In addition, the MP extracted from pork (PSM) had the highest content of myosin heavy chain (MHC) and actin. In conclusion, the MPs extracted from fish source and mammalian sources varied significantly in terms of rheological properties and microstructural characteristics. These results provided useful information for developing mixed gel products with different gel strengths.
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    Dual-network hydrogel capsules for controlled molecular transport via pH and temperature responsiveness
    (Elsevier Inc, 2025-01) Yang H; Whitby CP; Travas-Sejdic J
    We have developed innovative core-shell hydrogel capsules with a dual-network shell structure designed for precise control of molecular transport in response to external stimuli such as pH and temperature. The capsules were fabricated using a combination of microfluidic electrospray techniques and water-in-water (w/w) core-shell droplets templating. The primary network of the shell, calcium alginate (Ca-Alg), with a pKa around 3.4, exhibits sensitivity to pH. The secondary network of the shell, poly(ethylene glycol) methyl ether methacrylate (PEGMA), undergoes a volume phase transition near 60 °C. These properties enable precise molecular transport control in/out of the capsules by modulating the surface charges through varying pH and modifying pore size through temperature changes. Moreover, the dual-network shell structure not only significantly enhances the mechanical strength of the capsules but also improves their stability under external stimulus, ensuring structural integrity during the transport of molecules. This research lays the groundwork for further investigations into the multimodal stimuli-responsive hydrogel systems to control molecular transport, important in applications such as sensors and reactors for chemical cascade reactions.
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    Four microlensing giant planets detected through signals produced by minor-image perturbations
    (EDP Sciences on behalf of The European Southern Observatory, 2024-07) Han C; Bond IA; Lee C-U; Gould A; Albrow MD; Chung S-J; Hwang K-H; Jung YK; Ryu Y-H; Shvartzvald Y; Shin I-G; Yee JC; Yang H; Zang W; Cha S-M; Kim D; Kim D-J; Kim S-L; Lee D-J; Lee Y; Park B-G; Pogge RW; Abe F; Bando K; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hamada R; Hamada S; Hamasaki N; Hirao Y; Silva SI; Itow Y; Kirikawa R; Koshimoto N; Matsubara Y; Miyazaki S; Muraki Y; Nagai T; Nunota K; Olmschenk G; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Tomoyoshi M; Tristram PJ; Vandorou A; Yama H; Yamashita K; Bachelet E; Rota P; Bozza V; Zielinski P; Street RA; Tsapras Y; Hundertmark M; Wambsganss J; Wyrzykowski Ł; Jaimes RF; Cassan A; Dominik M; Rybicki KA; Rabus M
    Aims. We investigated the nature of the anomalies appearing in four microlensing events KMT-2020-BLG-0757, KMT-2022-BLG-0732, KMT-2022-BLG-1787, and KMT-2022-BLG-1852. The light curves of these events commonly exhibit initial bumps followed by subsequent troughs that extend across a substantial portion of the light curves. Methods. We performed thorough modeling of the anomalies to elucidate their characteristics. Despite their prolonged durations, which differ from the usual brief anomalies observed in typical planetary events, our analysis revealed that each anomaly in these events originated from a planetary companion located within the Einstein ring of the primary star. It was found that the initial bump arouse when the source star crossed one of the planetary caustics, while the subsequent trough feature occurred as the source traversed the region of minor image perturbations lying between the pair of planetary caustics. Results. The estimated masses of the host and planet, their mass ratios, and the distance to the discovered planetary systems are (Mhost/M☉, Mplanet/MJ, q/10−3, DL/kpc) = (0.58−+00.3033, 10.71−+56.6117, 17.61 ± 2.25, 6.67+−01.9330) for KMT-2020-BLG-0757, (0.53+−00.3131, 1.12+−00.6565, 2.01 ± 0.07, 6.66+−11.1984) for KMT-2022-BLG-0732, (0.42−+00.2332, 6.64−+43.9864, 15.07 ± 0.86, 7.55+−01.8930) for KMT-2022-BLG-1787, and (0.32+−00.3419, 4.98+−52.4294, 8.74 ± 0.49, 6.27+−01.9015) for KMT-2022-BLG-1852. These parameters indicate that all the planets are giants with masses exceeding the mass of Jupiter in our solar system and the hosts are low-mass stars with masses substantially less massive than the Sun.
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    Genomic insights into the secondary aquatic transition of penguins
    (Springer Nature Limited, 2022-07-19) Cole TL; Zhou C; Fang M; Pan H; Ksepka DT; Fiddaman SR; Emerling CA; Thomas DB; Bi X; Fang Q; Ellegaard MR; Feng S; Smith AL; Heath TA; Tennyson AJD; Borboroglu PG; Wood JR; Hadden PW; Grosser S; Bost C-A; Cherel Y; Mattern T; Hart T; Sinding M-HS; Shepherd LD; Phillips RA; Quillfeldt P; Masello JF; Bouzat JL; Ryan PG; Thompson DR; Ellenberg U; Dann P; Miller G; Dee Boersma P; Zhao R; Gilbert MTP; Yang H; Zhang D-X; Zhang G
    Penguins lost the ability to fly more than 60 million years ago, subsequently evolving a hyper-specialized marine body plan. Within the framework of a genome-scale, fossil-inclusive phylogeny, we identify key geological events that shaped penguin diversification and genomic signatures consistent with widespread refugia/recolonization during major climate oscillations. We further identify a suite of genes potentially underpinning adaptations related to thermoregulation, oxygenation, diving, vision, diet, immunity and body size, which might have facilitated their remarkable secondary transition to an aquatic ecology. Our analyses indicate that penguins and their sister group (Procellariiformes) have the lowest evolutionary rates yet detected in birds. Together, these findings help improve our understanding of how penguins have transitioned to the marine environment, successfully colonizing some of the most extreme environments on Earth.
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    How Reproducible are Surface Areas Calculated from the BET Equation?
    (Wiley-VCH GmbH, 2022-05-23) Osterrieth JWM; Rampersad J; Madden D; Rampal N; Skoric L; Connolly B; Allendorf MD; Stavila V; Snider JL; Ameloot R; Marreiros J; Ania C; Azevedo D; Vilarrasa-Garcia E; Santos BF; Bu X-H; Chang Z; Bunzen H; Champness NR; Griffin SL; Chen B; Lin R-B; Coasne B; Cohen S; Moreton JC; Colón YJ; Chen L; Clowes R; Coudert F-X; Cui Y; Hou B; D'Alessandro DM; Doheny PW; Dincă M; Sun C; Doonan C; Huxley MT; Evans JD; Falcaro P; Ricco R; Farha O; Idrees KB; Islamoglu T; Feng P; Yang H; Forgan RS; Bara D; Furukawa S; Sanchez E; Gascon J; Telalović S; Ghosh SK; Mukherjee S; Hill MR; Sadiq MM; Horcajada P; Salcedo-Abraira P; Kaneko K; Kukobat R; Kenvin J; Keskin S; Kitagawa S; Otake K-I; Lively RP; DeWitt SJA; Llewellyn P; Lotsch BV; Emmerling ST; Pütz AM; Martí-Gastaldo C; Padial NM; García-Martínez J; Linares N; Maspoch D; Suárez Del Pino JA; Moghadam P; Oktavian R; Morris RE; Wheatley PS; Navarro J; Petit C; Danaci D; Rosseinsky MJ; Katsoulidis AP; Schröder M; Han X; Yang S; Serre C; Mouchaham G; Sholl DS; Thyagarajan R; Siderius D; Snurr RQ; Goncalves RB; Telfer S; Lee SJ; Ting VP; Rowlandson JL; Uemura T; Iiyuka T; van der Veen MA; Rega D; Van Speybroeck V; Rogge SMJ; Lamaire A; Walton KS; Bingel LW; Wuttke S; Andreo J; Yaghi O; Zhang B; Yavuz CT; Nguyen TS; Zamora F; Montoro C; Zhou H; Kirchon A; Fairen-Jimenez D
    Porosity and surface area analysis play a prominent role in modern materials science. At the heart of this sits the Brunauer-Emmett-Teller (BET) theory, which has been a remarkably successful contribution to the field of materials science. The BET method was developed in the 1930s for open surfaces but is now the most widely used metric for the estimation of surface areas of micro- and mesoporous materials. Despite its widespread use, the calculation of BET surface areas causes a spread in reported areas, resulting in reproducibility problems in both academia and industry. To prove this, for this analysis, 18 already-measured raw adsorption isotherms were provided to sixty-one labs, who were asked to calculate the corresponding BET areas. This round-robin exercise resulted in a wide range of values. Here, the reproducibility of BET area determination from identical isotherms is demonstrated to be a largely ignored issue, raising critical concerns over the reliability of reported BET areas. To solve this major issue, a new computational approach to accurately and systematically determine the BET area of nanoporous materials is developed. The software, called "BET surface identification" (BETSI), expands on the well-known Rouquerol criteria and makes an unambiguous BET area assignment possible.
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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-0284, KMT-2022-BLG-2480, and KMT-2024-BLG-0412: Three microlensing events involving two lens masses and two source stars
    (EDP Sciences for The European Southern Observatory, 2024-12) Han C; Udalski A; Bond IA; Lee C-U; Gould A; Albrow MD; Chung S-J; Hwang K-H; Jung YK; Ryu Y-H; Shvartzvald Y; Shin I-G; Yee JC; Yang H; Zang W; Cha S-M; Kim D; Kim D-J; Kim S-L; Lee D-J; Lee Y; Park B-G; Pogge RW; Mróz P; Szymanski MK; Skowron J; Poleski R; Soszynski I; Pietrukowicz P; Kozłowski S; Rybicki KA; Iwanek P; Ulaczyk K; Wrona M; Gromadzki M; Mróz MJ; Abe F; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hamada R; Hirao Y; Ishitani Silva S; Itow Y; Kirikawa R; 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 carried out a project involving the systematic analysis of microlensing data from the Korea Microlensing Telescope Network survey. The aim of this project is to identify lensing events with complex anomaly features that are difficult to explain using standard binary-lens or binary-source models. Methods. Our investigation reveals that the light curves of microlensing events KMT-2021-BLG-0284, KMT-2022-BLG-2480, and KMT-2024BLG-0412 display highly complex patterns with three or more anomaly features. These features cannot be adequately explained by a binary-lens (2L1S) model alone. However, the 2L1S model can effectively describe certain segments of the light curve. By incorporating an additional source into the modeling, we identified a comprehensive model that accounts for all the observed anomaly features. Results. Bayesian analysis, based on constraints provided by lensing observables, indicates that the lenses of KMT-2021-BLG-0284 and KMT-2024-BLG-0412 are binary systems composed of M dwarfs. For KMT-2022-BLG-2480, the primary lens is an early K-type main-sequence star with an M dwarf companion. The lenses of KMT-2021-BLG-0284 and KMT-2024-BLG-0412 are likely located in the bulge, whereas the lens of KMT-2022-BLG-2480 is more likely situated in the disk. In all events, the binary stars of the sources have similar magnitudes due to a detection bias favoring binary source events with a relatively bright secondary source star, which increases detection efficiency.
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    KMT-2021-BLG-1150Lb: Microlensing planet detected through a densely covered planetary-caustic signal
    (EDP Sciences, France, 2023-07) Han CH; Jung YK; Bond IA; Gould A; Chung S-J; Albrow MD; Hwang K-H; Ryu Y-H; Shin I-G; Shvartzvald Y; Yang H; Yee JC; Zang W; Cha S-M; Kim D; Kim D-J; Kim S-L; Lee C-U; Lee D-J; Lee Y; Park B-G; Pogge RW; 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; Matsumoto S; Miyazaki S; Muraki Y; Okamura A; Olmschenk G; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Toda T; Tomoyoshi M; Tristram PJ; Vandorou A; Yama H; Yamashita K
    Aims. Recently, there have been reports of various types of degeneracies in the interpretation of planetary signals induced by planetary caustics. In this work we check whether such degeneracies persist in the case of well-covered signals by analyzing the lensing event KMT-2021-BLG-1150, the light curve of which exhibits a densely and continuously covered short-term anomaly. Methods. In order to identify degenerate solutions, we thoroughly investigated the parameter space by conducting dense grid searches for the lensing parameters. We then checked the severity of the degeneracy among the identified solutions. Results. We identify a pair of planetary solutions resulting from the well-known inner-outer degeneracy, and find that interpreting the anomaly is not subject to any degeneracy other than the inner-outer degeneracy. The measured parameters of the planet separation (normalized to the Einstein radius) and mass ratio between the lens components are (s, q)in ∼ (1.297, 1.10 - 10-3) for the inner solution and (s, q)out ∼ (1.242, 1.15 - 10-3) for the outer solution. According to a Bayesian estimation, the lens is a planetary system consisting of a planet with a mass Mp = 0.88-0.36+0.38 Mj and its host with a mass Mh = 0.73-0.30+0.32 M· lying toward the Galactic center at a distance DL = 3.8-1.2+1.3 kpc. By conducting analyses using mock data sets prepared to mimic those obtained with data gaps and under various observational cadences, we find that gaps in data can result in various degenerate solutions, while the observational cadence does not pose a serious degeneracy problem as long as the anomaly feature can be delineated.
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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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    KMT-2022-BLG-0475Lb and KMT-2022-BLG-1480Lb: Microlensing ice giants detected via the non-caustic-crossing channel
    (EDP Sciences, France, 2023-08) Han C; Lee C-U; Bond IA; Zang W; Chung S-J; Albrow MD; Gould A; Hwang K-H; Jung YK; Ryu Y-H; Shin I-G; Shvartzvald Y; Yang H; Yee JC; Cha S-M; Kim D; Kim D-J; Kim S-L; Lee D-J; Lee Y; Park B-G; Pogge RW; Mao S; 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; Toda T; Tomoyoshi M; Tristram PJ; Vandorou A; Yama H; Yamashita K
    Aims. We investigate the microlensing data collected in the 2022 season from high-cadence microlensing surveys in order to find weak signals produced by planetary companions to lenses. Methods. From these searches, we find that two lensing events, KMT-2022-BLG-0475 and KMT-2022-BLG-1480, exhibit weak short-term anomalies. From a detailed modeling of the lensing light curves, we determine that the anomalies are produced by planetary companions with a mass ratio to the primary of q 1.8 A-104 for KMT-2022-BLG-0475L and q 4.3 A-104 for KMT-2022-BLG-1480L. Results. We estimate that the host and planet masses and the projected planet-host separation are (Mh/M, Mp/MU, a/au) = (0.430.23+0.35, 1.730.92+1.42, 2.030.38+0.25) for KMT-2022-BLG-0475L and (0.180.09+0.16, 1.820.92+1.60, 1.220.14+0.15) for KMT-2022-BLG-1480L, where MU denotes the mass of Uranus. The two planetary systems have some characteristics in common: the primaries of the lenses are early-mid M dwarfs that lie in the Galactic bulge, and the companions are ice giants that lie beyond the snow lines of the planetary systems.
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    KMT-2023-BLG-1866Lb: Microlensing super-Earth around an M dwarf host
    (EDP Sciences for The European Southern Observatory, 2024-07) Han C; Bond IA; Udalski A; Lee C-U; Gould A; Albrow MD; Chung S-J; Hwang K-H; Jung YK; Ryu Y-H; Shvartzvald Y; Shin I-G; Yee JC; Yang H; Zang W; Cha S-M; Kim D; Kim D-J; Kim S-L; Lee D-J; Lee Y; Park B-G; Pogge RW; Abe F; Bando K; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hamada R; Hamada S; Hamasaki N; Hirao Y; Ishitani Silva S; Itow Y; Kirikawa R; Koshimoto N; Matsubara Y; Miyazaki S; Muraki Y; Nagai T; Nunota K; Olmschenk G; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Tomoyoshi M; Tristram PJ; Vandorou A; Yama H; Yamashita K; Mróz P; Szymański MK; Skowron J; Poleski RA; Soszyński I; Pietrukowicz P; Kozłowski S; Rybicki KA; Iwanek P; Ulaczyk K; Wrona M; Gromadzki M; Mróz MJ
    Aims. We aim to investigate the nature of the short-term anomaly that appears in the lensing light curve of KMT-2023-BLG-1866. The anomaly was only partly covered due to its short duration of less than a day, coupled with cloudy weather conditions and a restricted nighttime duration. Methods. Considering the intricacy of interpreting partially covered signals, we thoroughly explored all potential degenerate solutions. Through this process, we identified three planetary scenarios that account for the observed anomaly equally well. These scenarios are characterized by the specific planetary parameters: (s, q)inner = [0.9740 ± 0.0083, (2.46 ± 1.07) × 10-5], (s, q)intermediate = [0.9779 ± 0.0017, (1.56 ± 0.25) × 10-5], and (s, q)outer = [0.9894 ± 0.0107, (2.31 ± 1.29) × 10-5], where s and q denote the projected separation (scaled to the Einstein radius) and mass ratio between the planet and its host, respectively. We identify that the ambiguity between the inner and outer solutions stems from the inner-outer degeneracy, while the similarity between the intermediate solution and the others is due to an accidental degeneracy caused by incomplete anomaly coverage. Results. Through Bayesian analysis utilizing the constraints derived from measured lensing observables and blending flux, our estimation indicates that the lens system comprises a very-low-mass planet orbiting an early M-type star situated approximately (6.2-6.5) kpc from Earth in terms of median posterior values for the different solutions. The median mass of the planet host is in the range of (0.48-0.51) M⊙, and that of the planet's mass spans a range of (2.6-4.0) ME, varying across different solutions. The detection of KMT-2023-BLG-1866Lb signifies the extension of the lensing surveys to very-low-mass planets that have been difficult to detect in earlier surveys.
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    Large-scale synthesis of N-doped carbon capsules supporting atomically dispersed iron for efficient oxygen reduction reaction electrocatalysis
    (Elsevier B.V. on behalf of Nankai University, 2022-05-17) Yang H; Liu Y; Liu X; Wang X; Tian H; Waterhouse GIN; Kruger PE; Telfer SG; Ma S
    The large-scale synthesis of platinum-free electrocatalysts for the oxygen reduction reaction (ORR) remains a grand challenge. We report the large-scale production of stable and active ORR electrocatalysts based on iron, an earth-abundant element. A core–shell zeolitic imidazolate framework–tannic acid coordination polymer composite (ZIF-8@K-TA) was utilized as the catalyst precursor, which was transformed into iron atoms dispersed in hollow porous nitrogen-doped carbon capsules (H-Fe-Nx-C) through ion exchange and pyrolysis. H-Fe-Nx-C features site-isolated single-atom iron centers coordinated to nitrogen in graphitic layers, high levels of nitrogen doping, and high permeability to incoming gases. Benefiting from these characteristics, H-Fe-Nx-C demonstrated efficient electrocatalytic activity (E1/2 ​= ​0.92 ​V, vs. RHE) and stability towards the ORR in both alkaline and acidic media. In ORR performance, it surpassed the majority of recently reported Fe-N-C catalysts and the standard Pt/C catalyst. In addition, H-Fe-Nx-C showed outstanding tolerance to methanol.
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    Mass Production of 2021 KMTNet Microlensing Planets. III. Analysis of Three Giant Planets
    (American Astronomical Society, 2022-12-07) Shin IG; Yee JC; Gould A; Hwang K-H; Yang H; Bond IA; Albrow MD; Chung S-J; Han C; Jung YK; Ryu Y-H; Shvartzvald Y; Zang W; Cha S-M; Kim D-J; Kim S-L; Lee C-U; Lee D-J; Lee Y; Park B-G; Pogge RW; Abe F; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hirao Y; Ishitani Silva S; Itow Y; 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
    We present the analysis of three more planets from the KMTNet 2021 microlensing season. KMT-2021-BLG-0119Lb is a ∼6M Jup planet orbiting an early M dwarf or a K dwarf, KMT-2021-BLG-0192Lb is a ∼2M Nep planet orbiting an M dwarf, and KMT-2021-BLG-2294Lb is a ∼1.25M Nep planet orbiting a very-low-mass M dwarf or a brown dwarf. These by-eye planet detections provide an important comparison sample to the sample selected with the AnomalyFinder algorithm, and in particular, KMT-2021-BLG-2294 is a case of a planet detected by eye but not by algorithm. KMT-2021-BLG-2294Lb is part of a population of microlensing planets around very-low-mass host stars that spans the full range of planet masses, in contrast to the planet population at ≲0.1 au, which shows a strong preference for small planets.
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    Microlensing brown-dwarf companions in binaries detected during the 2022 and 2023 seasons
    (EDP Sciences for The European Southern Observatory, 2024-11) Han C; Bond IA; Udalski A; Lee C-U; Gould A; Albrow MD; Chung S-J; Hwang K-H; Jung YK; Ryu Y-H; Shvartzvald Y; Shin I-G; Yee JC; Yang H; Zang W; Cha S-M; Kim D; Kim D-J; Kim S-L; Lee D-J; Lee Y; Park B-G; Pogge RW; Abe F; Bando K; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hamada R; Hamada S; Hamasaki N; Hirao Y; Ishitani Silva S; Itow Y; Kirikawa R; Koshimoto N; Matsubara Y; Miyazaki S; Muraki Y; Nagai T; Nunota K; Olmschenk G; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Tomoyoshi M; Tristram PJ; Vandorou A; Yama H; Yamashita K; Mróz P; Szymański MK; Skowron J; Poleski R; Soszyński I; Pietrukowicz P; Kozlowski S; Rybicki KA; Iwanek P; Ulaczyk K; Wrona M; Gromadzki M; Mróz MJ
    Aims. Building on previous works to construct a homogeneous sample of brown dwarfs in binary systems, we investigate microlensing events detected by the Korea Microlensing Telescope Network (KMTNet) survey during the 2022 and 2023 seasons. Methods. Given the difficulty in distinguishing brown-dwarf events from those produced by binary lenses with nearly equal-mass components, we analyze all lensing events detected during the seasons that exhibit anomalies characteristic of binary-lens systems. Results. Using the same criteria consistently applied in previous studies, we identify six additional brown dwarf candidates through the analysis of lensing events KMT-2022-BLG-0412, KMT-2022-BLG-2286, KMT-2023-BLG-0201, KMT-2023-BLG-0601, KMT-2023-BLG-1684, and KMT-2023-BLG-1743. An examination of the mass posteriors shows that the median mass of the lens companions ranges from 0.02 M⊙ to 0.05 M⊙, indicating that these companions fall within the brown-dwarf mass range. The mass of the primary lenses ranges from 0.11 M⊙ to 0.68 M⊙, indicating that they are low-mass stars with substantially lower masses compared to the Sun.
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    MOA-2022-BLG-033Lb, KMT-2023-BLG-0119Lb, and KMT-2023-BLG-1896Lb: Three low mass-ratio microlensing planets detected through dip signals
    (The European Southern Observatory (ESO), 2025-02-04) Han C; Bond IA; Jung YK; Albrow MD; Chung S-J; Gould A; Hwang K-H; Lee C-U; Ryu Y-H; Shvartzvald Y; Shin I-G; Yee JC; Yang H; Zang W; Cha S-M; Kim D; Kim D-J; Kim S-L; Lee D-J; Lee Y; Park B-G; Pogge RW; Abe F; Barry R; Bennett DP; Bhattacharya A; Fujii H; Fukui A; Hamada R; Hirao Y; Silva SI; Itow Y; Kirikawa R; 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 examined the anomalies in the light curves of the lensing events MOA-2022-BLG-033, KMT-2023-BLG-0119, and KMT- 2023-BLG-1896. These anomalies share similar traits: they occur near the peak of moderately to highly magnified events and display a distinct short-term dip feature. Methods. We conducted detailed modeling of the light curves to uncover the nature of the anomalies. This modeling revealed that all signals originated from planetary companions to the primary lens. The planet-to-host mass ratios are very low: q ∼ 7.5 × 10-5 for MOA-2022-BLG-033, q ∼ 3.6 × 10-4 for KMT-2023-BLG-0119, and q ∼ 6.9 × 10-5 for KMT-2023-BLG-1896. The anomalies occurred as the source passed through the negative deviation region behind the central caustic along the planet-host axis. The solutions are subject to a common inner-outer degeneracy, which results in varying estimations of the projected planet-host separation. For KMT-2023-BLG-1896, although the planetary scenario provides the best explanation for the anomaly, the binary companion scenario is possible. Results. We estimated the physical parameters of the planetary systems through Bayesian analyses based on the lensing observables. While the event timescale was measured for all events, the angular Einstein radius was not measured for any. Additionally, the microlens parallax was measured for MOA-2022-BLG-033. The analysis identifies MOA-2022-BLG-033L as a planetary system with an ice giant with a mass of approximately 12 times that of Earth orbiting an early M dwarf star. The companion of KMT-2023-BLG-1896L is also an ice giant, with a mass of around 16 Earth masses, orbiting a mid-K-type main-sequence star. The companion of KMT-2023-BLG- 0119L, which has a mass around that of Saturn, orbits a mid-K-type dwarf star. The lens for MOA-2022-BLG-033 is highly likely to be located in the disk, whereas for the other events the probabilities of the lens being in the disk or the bulge are roughly equal.
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    MOA-2022-BLG-249Lb: Nearby microlensing super-Earth planet detected from high-cadence surveys
    (EDP Sciences for The European Southern Observatory, 2023-06) Han C; Gould A; Jung YK; Bond IA; Zang W; Chung S-J; Albrow MD; 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; Mao S; 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; Matsumoto S; Miyazaki S; Muraki Y; Okamura A; Olmschenk G; Ranc C; Rattenbury NJ; Satoh Y; Sumi T; Suzuki D; Toda T; Tomoyoshi M; Tristram PJ; Vandorou A; Yama H; Yamashita K
    Aims. We investigate the data collected by the high-cadence microlensing surveys during the 2022 season in search of planetary signals appearing in the light curves of microlensing events. From this search, we find that the lensing event MOA-2022-BLG-249 exhibits a brief positive anomaly that lasted for about one day, with a maximum deviatio Methods. We analyzed the light curve under the two interpretations of the anomaly: one originated by a low-mass companion to the lens (planetary model) and the other originated by a faint companion to the source (binary-source model). Results. We find that the anomaly is better explained by the planetary model than the binary-source model. We identified two solutions rooted in the inner-outer degeneracy and for both of them, the estimated planet-To-host mass ratio, q ~ 8 A-10' 5, is very small. With the constraints provided by the microlens parallax and the lower limit on the Einstein radius, as well as the blend-flux constraint, we find that the lens is a planetary system, in which a super-Earth planet, with a mass of (4.83 ± 1.44) M·, orbits a low-mass host star, with a mass of (0.18 ± 0.05) M·, lying in the Galactic disk at a distance of (2.00 ± 0.42) kpc. The planet detection demonstrates the elevated microlensing sensitivity of the current high-cadence lensing surveys to low-mass planets.