ORCID Profile
0000-0002-1206-6803
Current Organisation
Korea Polar Research Institute
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Publisher: Springer Science and Business Media LLC
Date: 14-03-2023
Publisher: Springer Science and Business Media LLC
Date: 10-07-2023
Publisher: American Association for the Advancement of Science (AAAS)
Date: 14-07-2023
Abstract: Preliminary analyses of asteroid Ryugu s les show kinship to aqueously altered CI (Ivuna-type) chondrites, suggesting similar origins. We report identification of C-rich, particularly primitive clasts in Ryugu s les that contain preserved presolar silicate grains and exceptional abundances of presolar SiC and isotopically anomalous organic matter. The high presolar silicate abundance (104 ppm) indicates that the clast escaped extensive alteration. The 5 to 10 times higher abundances of presolar SiC (~235 ppm), N-rich organic matter, organics with N isotopic anomalies (1.2%), and organics with C isotopic anomalies (0.2%) in the primitive clasts compared to bulk Ryugu suggest that the clasts formed in a unique part of the protoplanetary disk enriched in presolar materials. These clasts likely represent previously uns led outer solar system material that accreted onto Ryugu after aqueous alteration ceased, consistent with Ryugu’s rubble pile origin.
Publisher: European Association of Geochemistry
Date: 10-2022
Publisher: American Association for the Advancement of Science (AAAS)
Date: 18-11-2022
Abstract: Little is known about the origin of the spectral ersity of asteroids and what it says about conditions in the protoplanetary disk. Here, we show that s les returned from Cb-type asteroid Ryugu have Fe isotopic anomalies indistinguishable from Ivuna-type (CI) chondrites, which are distinct from all other carbonaceous chondrites. Iron isotopes, therefore, demonstrate that Ryugu and CI chondrites formed in a reservoir that was different from the source regions of other carbonaceous asteroids. Growth and migration of the giant planets destabilized nearby planetesimals and ejected some inward to be implanted into the Main Belt. In this framework, most carbonaceous chondrites may have originated from regions around the birthplaces of Jupiter and Saturn, while the distinct isotopic composition of CI chondrites and Ryugu may reflect their formation further away in the disk, owing their presence in the inner Solar System to excitation by Uranus and Neptune.
Publisher: Springer Science and Business Media LLC
Date: 12-12-2022
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-12-2022
Abstract: The extraterrestrial materials returned from asteroid (162173) Ryugu consist predominantly of low-temperature aqueously formed secondary minerals and are chemically and mineralogically similar to CI (Ivuna-type) carbonaceous chondrites. Here, we show that high-temperature anhydrous primary minerals in Ryugu and CI chondrites exhibit a bimodal distribution of oxygen isotopic compositions: 16 O-rich (associated with refractory inclusions) and 16 O-poor (associated with chondrules). Both the 16 O-rich and 16 O-poor minerals probably formed in the inner solar protoplanetary disk and were subsequently transported outward. The abundance ratios of the 16 O-rich to 16 O-poor minerals in Ryugu and CI chondrites are higher than in other carbonaceous chondrite groups but are similar to that of comet 81P/Wild2, suggesting that Ryugu and CI chondrites accreted in the outer Solar System closer to the accretion region of comets.
Publisher: American Astronomical Society
Date: 08-2023
DOI: 10.3847/PSJ/ACEA62
Abstract: We present oxygen isotopic analyses of fragments of the near-Earth C b -type asteroid Ryugu returned by the Hayabusa2 spacecraft that reinforce the close correspondence between Ryugu and CI chondrites. Small differences between Ryugu s les and CI chondrites in Δ ′ 17 O can be explained at least in part by contamination of the latter by terrestrial water. The discovery that a randomly s led C-complex asteroid is composed of CI-chondrite-like rock, combined with thermal models for formation prior to significant decay of the short-lived radioisotope 26 Al, suggests that if lithified at the time of alteration, the parent body was small (≪50 km radius). If the parent planetesimal was large ( km in radius), it was likely composed of high-permeability, poorly lithified sediment rather than consolidated rock.
Publisher: Wiley
Date: 28-06-2023
DOI: 10.1111/NPH.19109
Abstract: Carotenoids are photoprotectant pigments and precursors of hormones such as strigolactones (SL). Carotenoids are produced in plastids from geranylgeranyl diphosphate (GGPP), which is erted to the carotenoid pathway by phytoene synthase (PSY). In tomato ( Solanum lycopersicum ), three genes encode plastid‐targeted GGPP synthases ( SlG1 to SlG3 ) and three genes encode PSY isoforms ( PSY1 to PSY3 ). Here, we investigated the function of SlG1 by generating loss‐of‐function lines and combining their metabolic and physiological phenotyping with gene co‐expression and co‐immunoprecipitation analyses. Leaves and fruits of slg1 lines showed a wild‐type phenotype in terms of carotenoid accumulation, photosynthesis, and development under normal growth conditions. In response to bacterial infection, however, slg1 leaves produced lower levels of defensive GGPP‐derived diterpenoids. In roots, SlG1 was co‐expressed with PSY3 and other genes involved in SL production, and slg1 lines grown under phosphate starvation exuded less SLs. However, slg1 plants did not display the branched shoot phenotype observed in other SL‐defective mutants. At the protein level, SlG1 physically interacted with the root‐specific PSY3 isoform but not with PSY1 and PSY2. Our results confirm specific roles for SlG1 in producing GGPP for defensive diterpenoids in leaves and carotenoid‐derived SLs (in combination with PSY3) in roots.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 26-08-2011
Abstract: Laboratory analysis of s les returned from an asteroid establishes a direct link between asteroids and meteorites and provides clues to the complex history of the asteroid and its surface.
Publisher: American Astronomical Society
Date: 08-2022
Abstract: We have conducted a NanoSIMS-based search for presolar material in s les recently returned from C-type asteroid Ryugu as part of JAXA's Hayabusa2 mission. We report the detection of all major presolar grain types with O- and C-anomalous isotopic compositions typically identified in carbonaceous chondrite meteorites: 1 silicate, 1 oxide, 1 O-anomalous supernova grain of ambiguous phase, 38 SiC, and 16 carbonaceous grains. At least two of the carbonaceous grains are presolar graphites, whereas several grains with moderate C isotopic anomalies are probably organics. The presolar silicate was located in a clast with a less altered lithology than the typical extensively aqueously altered Ryugu matrix. The matrix-normalized presolar grain abundances in Ryugu are 4.8 − 2.6 + 4.7 ppm for O-anomalous grains, 25 − 5 + 6 ppm for SiC grains, and 11 − 3 + 5 ppm for carbonaceous grains. Ryugu is isotopically and petrologically similar to carbonaceous Ivuna-type (CI) chondrites. To compare the in situ presolar grain abundances of Ryugu with CI chondrites, we also mapped Ivuna and Orgueil s les and found a total of 15 SiC grains and 6 carbonaceous grains. No O-anomalous grains were detected. The matrix-normalized presolar grain abundances in the CI chondrites are similar to those in Ryugu: 23 − 6 + 7 ppm SiC and 9.0 − 3.6 + 5.4 ppm carbonaceous grains. Thus, our results provide further evidence in support of the Ryugu–CI connection. They also reveal intriguing hints of small-scale heterogeneities in the Ryugu s les, such as locally distinct degrees of alteration that allowed the preservation of delicate presolar material.
Publisher: American Astronomical Society
Date: 04-2023
Abstract: Rock fragments of the Cb-type asteroid Ryugu returned to Earth by the JAXA Hayabusa2 mission share mineralogical, chemical, and isotopic properties with the Ivuna-type (CI) carbonaceous chondrites. Similar to CI chondrites, these fragments underwent extensive aqueous alteration and consist predominantly of hydrous minerals likely formed in the presence of liquid water on the Ryugu parent asteroid. Here we present an in situ analytical survey performed by secondary ion mass spectrometry from which we have estimated the D/H ratio of Ryugu’s hydrous minerals, D/H Ryugu , to be [165 ± 19] × 10 −6 , which corresponds to δ D Ryugu = +59 ± 121‰ (2 σ ). The hydrous mineral D/H Ryugu ’s values for the two s ling sites on Ryugu are similar they are also similar to the estimated D/H ratio of hydrous minerals in the CI chondrites Orgueil and Alais. This result reinforces a link between Ryugu and CI chondrites and an inference that Ryugu’s s les, which avoided terrestrial contamination, are our best proxy to estimate the composition of water at the origin of hydrous minerals in CI-like material. Based on this data and recent literature studies, the contribution of CI chondrites to the hydrogen of Earth’s surficial reservoirs is evaluated to be ∼3%. We conclude that the water responsible for the alteration of Ryugu’s rocks was derived from water ice precursors inherited from the interstellar medium the ice partially re-equilibrated its hydrogen with the nebular H 2 before being accreted on the Ryugu’s parent asteroid.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 24-02-2023
Abstract: Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. S les of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measured the mineralogy and bulk chemical and isotopic compositions of Ryugu s les. The s les are mainly composed of materials similar to those of carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The s les consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37° ± 10°C, about 5.2 − 0.7 + 0.8 million (statistical) or 5.2 − 2.1 + 1.6 million (systematic) years after the formation of the first solids in the Solar System. After aqueous alteration, the Ryugu s les were likely never heated above ~100°C. The s les have a chemical composition that more closely resembles that of the Sun’s photosphere than other natural s les do.
No related grants have been discovered for Changkun Park.