Author
Hikaru Yabuta
Other affiliations: Osaka University, Carnegie Institution for Science
Bio: Hikaru Yabuta is an academic researcher from Hiroshima University. The author has contributed to research in topics: Asteroid & Chondrite. The author has an hindex of 22, co-authored 91 publications receiving 3645 citations. Previous affiliations of Hikaru Yabuta include Osaka University & Carnegie Institution for Science.
Topics: Asteroid, Chondrite, Astrobiology, Meteorite, Medicine
Papers published on a yearly basis
Papers
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Donald E. Brownlee1, Peter Tsou2, Jérôme Aléon3, Conel M. O'd. Alexander4 +182 more•Institutions (57)
TL;DR: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study, and preliminary examination shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin.
Abstract: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.
886 citations
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Ames Research Center1, Lawrence Livermore National Laboratory2, Carnegie Institution for Science3, North Carolina State University4, University of Paris-Sud5, University of Washington6, University of Kent7, University of California, Berkeley8, Goddard Space Flight Center9, Stony Brook University10, University at Albany, SUNY11, Open University12, Lawrence Berkeley National Laboratory13, University of Münster14, California Institute of Technology15, Parthenope University of Naples16, Stanford University17, Washington University in St. Louis18
TL;DR: The presence of deuterium and nitrogen-15 excesses suggest that some organics have an interstellar/protostellar heritage and a diverse suite of organic compounds is present and identifiable within the returned samples.
Abstract: Organics found in comet 81P/Wild 2 samples show a heterogeneous and unequilibrated distribution in abundance and composition. Some organics are similar, but not identical, to those in interplanetary dust particles and carbonaceous meteorites. A class of aromatic-poor organic material is also present. The organics are rich in oxygen and nitrogen compared with meteoritic organics. Aromatic compounds are present, but the samples tend to be relatively poorer in aromatics than are meteorites and interplanetary dust particles. The presence of deuterium and nitrogen-15 excesses suggest that some organics have an interstellar/protostellar heritage. Although the variable extent of modification of these materials by impact capture is not yet fully constrained, a diverse suite of organic compounds is present and identifiable within the returned samples.
547 citations
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TL;DR: In a survey of the elemental and isotopic compositions of insoluble organic matter (IOM) from 75 carbonaceous, ordinary and enstatite chondrites, this article found dramatic variations within and between chondrite classes.
496 citations
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Japan Aerospace Exploration Agency1, Nagoya University2, Auburn University3, University of Aizu4, Kobe University5, University of Tokyo6, Graduate University for Advanced Studies7, Hiroshima University8, Tohoku University9, Chiba Institute of Technology10, Kindai University11, National Institute of Advanced Industrial Science and Technology12, Kōchi University13, Rikkyo University14, National Institute of Information and Communications Technology15, Seoul National University16, Planetary Science Institute17, Johns Hopkins University Applied Physics Laboratory18, Centre national de la recherche scientifique19, University of Colorado Boulder20, Meiji University21, German Aerospace Center22, Centre National D'Etudes Spatiales23
TL;DR: The Hayabusa2 spacecraft measured the mass, size, shape, density, and spin rate of asteroid Ryugu, showing that it is a porous rubble pile, and observations of Ryugu's shape, mass, and geomorphology suggest that Ryugu was reshaped by centrifugally induced deformation during a period of rapid rotation.
Abstract: The Hayabusa2 spacecraft arrived at the near-Earth carbonaceous asteroid 162173 Ryugu in 2018. We present Hayabusa2 observations of Ryugu’s shape, mass, and geomorphology. Ryugu has an oblate “spinning top” shape, with a prominent circular equatorial ridge. Its bulk density, 1.19 ± 0.02 grams per cubic centimeter, indicates a high-porosity (>50%) interior. Large surface boulders suggest a rubble-pile structure. Surface slope analysis shows Ryugu’s shape may have been produced from having once spun at twice the current rate. Coupled with the observed global material homogeneity, this suggests that Ryugu was reshaped by centrifugally induced deformation during a period of rapid rotation. From these remote-sensing investigations, we identified a suitable sample collection site on the equatorial ridge.
402 citations
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Chiba Institute of Technology1, University of Tokyo2, Kōchi University3, Nagoya University4, Rikkyo University5, Japan Aerospace Exploration Agency6, University of Aizu7, National Institute of Advanced Industrial Science and Technology8, Kobe University9, Meiji University10, Graduate University for Advanced Studies11, Planetary Science Institute12, Auburn University13, Tohoku University14, Brown University15, Kindai University16, Centre national de la recherche scientifique17, University of Arizona18, Johns Hopkins University Applied Physics Laboratory19, German Aerospace Center20, Hokkaido University of Education21, Max Planck Society22, University of Stirling23, Nihon University24, Osaka University25, Hitotsubashi University26, Hiroshima University27, Seoul National University28, Paris Diderot University29
TL;DR: Spectral observations and a principal components analysis suggest that Ryugu originates from the Eulalia or Polana asteroid family in the inner main belt, possibly via more than one generation of parent bodies.
Abstract: Additional co-authors: N Namiki, S Tanaka, Y Iijima, K Yoshioka, M Hayakawa, Y Cho, M Matsuoka, N Hirata, N Hirata, H Miyamoto, D Domingue, M Hirabayashi, T Nakamura, T Hiroi, T Michikami, P Michel, R-L Ballouz, O S Barnouin, C M Ernst, S E Schroder, H Kikuchi, R Hemmi, G Komatsu, T Fukuhara, M Taguchi, T Arai, H Senshu, H Demura, Y Ogawa, Y Shimaki, T Sekiguchi, T G Muller, T Mizuno, H Noda, K Matsumoto, R Yamada, Y Ishihara, H Ikeda, H Araki, K Yamamoto, S Abe, F Yoshida, A Higuchi, S Sasaki, S Oshigami, S Tsuruta, K Asari, S Tazawa, M Shizugami, J Kimura, T Otsubo, H Yabuta, S Hasegawa, M Ishiguro, S Tachibana, E Palmer, R Gaskell, L Le Corre, R Jaumann, K Otto, N Schmitz, P A Abell, M A Barucci, M E Zolensky, F Vilas, F Thuillet, C Sugimoto, N Takaki, Y Suzuki, H Kamiyoshihara, M Okada, K Nagata, M Fujimoto, M Yoshikawa, Y Yamamoto, K Shirai, R Noguchi, N Ogawa, F Terui, S Kikuchi, T Yamaguchi, Y Oki, Y Takao, H Takeuchi, G Ono, Y Mimasu, K Yoshikawa, T Takahashi, Y Takei, A Fujii, C Hirose, S Nakazawa, S Hosoda, O Mori, T Shimada, S Soldini, T Iwata, M Abe, H Yano, R Tsukizaki, M Ozaki, K Nishiyama, T Saiki, S Watanabe, Y Tsuda
325 citations
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TL;DR: Simulation of the early Solar System shows how the inward migration of Jupiter to 1.5 au, and its subsequent outward migration, lead to a planetesimal disk truncated at 1’au; the terrestrial planets then form from this disk over the next 30–50 million years, with an Earth/Mars mass ratio consistent with observations.
Abstract: Jupiter and Saturn formed in a few million years from a gas-dominated protoplanetary disk, and were susceptible to gas-driven migration of their orbits on timescales of only approximately 100,000 years. Hydrodynamic simulations show that these giant planets can undergo a two-stage, inward-then-outward, migration. The terrestrial planets finished accreting much later and their characteristics, including Mars' small mass, are best reproduced by starting from a planetesimal disk with an outer edge at about one astronomical unit from the Sun (1 AU is the Earth-Sun distance). Here we report simulations of the early Solar System that show how the inward migration of Jupiter to 1.5 AU, and its subsequent outward migration, lead to a planetesimal disk truncated at 1 AU; the terrestrial planets then form from this disk over the next 30-50 million years, with an Earth/Mars mass ratio consistent with observations. Scattering by Jupiter initially empties but then repopulates the asteroid belt, with inner-belt bodies originating between 1 and 3 AU and outer-belt bodies originating between and beyond the giant planets. This explains the significant compositional differences across the asteroid belt. The key aspect missing from previous models of terrestrial planet formation is the substantial radial migration of the giant planets, which suggests that their behaviour is more similar to that inferred for extrasolar planets than previously thought.
1,174 citations
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TL;DR: In this article, a review examines the experimental achievements and puts them into the context of the dust processes in protoplanetary disks, concluding that the formation of planetesimals starts with the growth of fractal dust aggregates, followed by compaction processes.
Abstract: The formation of planetesimals, the kilometer-sized planetary precursors, is still a puzzling process. Considerable progress has been made over the past years in the physical description of the first stages of planetesimal formation, owing to extensive laboratory work. This review examines the experimental achievements and puts them into the context of the dust processes in protoplanetary disks. It has become clear that planetesimal formation starts with the growth of fractal dust aggregates, followed by compaction processes. As the dust-aggregate sizes increase, the mean collision velocity also increases, leading to the stalling of the growth and possibly to fragmentation, once the dust aggregates have reached decimeter sizes. A multitude of hypotheses for the further growth have been proposed, such as very sticky materials, secondary collision processes, enhanced growth at the snow line, or cumulative dust effects with gravitational instability. We will also critically review these ideas.
892 citations
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Donald E. Brownlee1, Peter Tsou2, Jérôme Aléon3, Conel M. O'd. Alexander4 +182 more•Institutions (57)
TL;DR: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study, and preliminary examination shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin.
Abstract: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.
886 citations
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TL;DR: U-corrected Pb-Pb dating from primitive meteorites indicates that chondrule formation started contemporaneously with CAIs and lasted ~3 million years, suggesting that the formation ofCAIs and chondrules reflects a process intrinsically linked to the secular evolution of accretionary disks.
Abstract: Transient heating events that formed calcium-aluminum–rich inclusions (CAIs) and chondrules are fundamental processes in the evolution of the solar protoplanetary disk, but their chronology is not understood. Using U-corrected Pb-Pb dating, we determined absolute ages of individual CAIs and chondrules from primitive meteorites. CAIs define a brief formation interval corresponding to an age of 4567.30 ± 0.16 million years (My), whereas chondrule ages range from 4567.32 ± 0.42 to 4564.71 ± 0.30 My. These data refute the long-held view of an age gap between CAIs and chondrules and, instead, indicate that chondrule formation started contemporaneously with CAIs and lasted ~3 My. This time scale is similar to disk lifetimes inferred from astronomical observations, suggesting that the formation of CAIs and chondrules reflects a process intrinsically linked to the secular evolution of accretionary disks.
724 citations