Faculty Profiles - WATANABE, Sei-ichiro

Papers - WATANABE, Sei-ichiro

Division display 61 - 80 of about 244 ／ All the affair displays >>

SPH simulations for shape deformation of rubble-pile asteroids through spinup: The challenge for making top-shaped asteroids Ryugu and Bennu Reviewed Open Access

Keisuke Sugiura, Hiroshi Kobayashi, Sei-ichiro Watanabe, Hidenori Genda, Ryuki Hyodo, Shu-ichiro Inutsuka

ICARUS Vol. 365 page： 114505 2021.9

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

Asteroid 162173 Ryugu and asteroid 101955 Bennu, which were recently visited by spacecraft Hayabusa2 and OSIRIS-REx, respectively, are spinning top-shaped rubble piles. Other axisymmetric top-shaped near-Earth asteroids have been observed with ground-based radar, most of which rotate near breakup rotation periods of similar to 3 h. This suggests that rotation-induced deformation of asteroids through rotational spinup produces top shapes. Although some previous simulations using the Discrete Element Method showed that spinup of rubble piles may produce oblate top shapes, it is still unclear what kinds of conditions such as friction angles of constituent materials and spinup timescales are required for top-shape formation. Here we show, through Smoothed Particle Hydrodynamics simulations of granular bodies spinning-up at different rates, that the rotation-induced deformation of spherical rubble piles before breakup can be classified into three modes according to the friction angle phi(d) : quasi-static and internal deformation for phi(d) <= 40 degrees, dynamical and internal deformation for 50 degrees <= phi(d) <= 60 degrees , and a set of surface landslides for phi(d) >= 70 degrees. Note that these apparent large values of friction angle can be acceptable if we consider the effect of cohesion among blocks of a rubble pile under weak gravity. Bodies with phi(d) <= 60 degrees evolve into oblate spheroids through internal deformation, but never form pronounced equators defining a top shape. In contrast, bodies with phi(d) >= 70 degrees deform into axisymmetric top shapes through an axisymmetric set of surface landslides if spinup timescales are less than or similar to a few days. In addition, through slow spinups with timescales greater than or similar to 1 month, bodies with phi(d) >= 70 degrees deform into non-axisymmetric shapes via localized sets of landslides. We suggest that rapid spinup mechanisms are preferable for the formation of axisymmetric top shapes.

DOI： 10.1016/j.icarus.2021.114505

Open Access

Web of Science

Anomalously porous boulders on (162173) Ryugu as primordial materials from its parent body Reviewed International coauthorship

N. Sakatani, S. Tanaka, T. Okada, T. Fukuhara, L. Riu, S. Sugita, R. Honda, T. Morota, S. Kameda, Y. Yokota, E. Tatsumi, K. Yumoto, N. Hirata, A. Miura, T. Kouyama, H. Senshu, Y. Shimaki, T. Arai, J. Takita, H. Demura, T. Sekiguchi, T. G. Müller, A. Hagermann, J. Biele, M. Grott, M. Hamm, M. Delbo, W. Neumann, M. Taguchi, Y. Ogawa, T. Matsunaga, T. Wada, S. Hasegawa, J. Helbert, N. Hirata, R. Noguchi, M. Yamada, H. Suzuki, C. Honda, K. Ogawa, M. Hayakawa, K. Yoshioka, M. Matsuoka, Y. Cho, H. Sawada, K. Kitazato, T. Iwata, M. Abe, M. Ohtake, S. Matsuura, K. Matsumoto, H. Noda, Y. Ishihara, K. Yamamoto, A. Higuchi, N. Namiki, G. Ono, T. Saiki, H. Imamura, Y. Takagi, H. Yano, K. Shirai, C. Okamoto, S. Nakazawa, Y. Iijima, M. Arakawa, K. Wada, T. Kadono, K. Ishibashi, F. Terui, S. Kikuchi, T. Yamaguchi, N. Ogawa, Y. Mimasu, K. Yoshikawa, T. Takahashi, Y. Takei, A. Fujii, H. Takeuchi, Y. Yamamoto, C. Hirose, S. Hosoda, O. Mori, T. Shimada, S. Soldini, R. Tsukizaki, M. Ozaki, S. Tachibana, H. Ikeda, M. Ishiguro, H. Yabuta, M. Yoshikawa, S. Watanabe, Y. Tsuda

Nature Astronomy Vol. 5 ( 8 ) page： 766 - + 2021.8

Language：English Publishing type：Research paper (scientific journal)

Planetesimals—the initial stage of the planetary formation process—are considered to be initially very porous aggregates of dusts1,2, and subsequent thermal and compaction processes reduce their porosity3. The Hayabusa2 spacecraft found that boulders on the surface of asteroid (162173) Ryugu have an average porosity of 30–50% (refs. 4–6), higher than meteorites but lower than cometary nuclei7, which are considered to be remnants of the original planetesimals8. Here, using high-resolution thermal and optical imaging of Ryugu’s surface, we discovered, on the floor of fresh small craters (<20 m in diameter), boulders with reflectance (~0.015) lower than the Ryugu average6 and porosity >70%, which is as high as in cometary bodies. The artificial crater formed by Hayabusa2’s impact experiment9 is similar to these craters in size but does not have such high-porosity boulders. Thus, we argue that the observed high porosity is intrinsic and not created by subsequent impact comminution and/or cracking. We propose that these boulders are the least processed material on Ryugu and represent remnants of porous planetesimals that did not undergo a high degree of heating and compaction3. Our multi-instrumental analysis suggests that fragments of the highly porous boulders are mixed within the surface regolith globally, implying that they might be captured within collected samples by touch-down operations10,11.

DOI： 10.1038/s41550-021-01371-7

Web of Science

Scopus

Thermally altered subsurface material of asteroid (162173) Ryugu Reviewed International coauthorship

K. Kitazato, R. E. Milliken, T. Iwata, M. Abe, M. Ohtake, S. Matsuura, Y. Takagi, T. Nakamura, T. Hiroi, M. Matsuoka, L. Riu, Y. Nakauchi, K. Tsumura, T. Arai, H. Senshu, N. Hirata, M. A. Barucci, R. Brunetto, C. Pilorget, F. Poulet, J.-P. Bibring, D. L. Domingue, F. Vilas, D. Takir, E. Palomba, A. Galiano, D. Perna, T. Osawa, M. Komatsu, A. Nakato, T. Arai, N. Takato, T. Matsunaga, M. Arakawa, T. Saiki, K. Wada, T. Kadono, H. Imamura, H. Yano, K. Shirai, M. Hayakawa, C. Okamoto, H. Sawada, K. Ogawa, Y. Iijima, S. Sugita, R. Honda, T. Morota, S. Kameda, E. Tatsumi, Y. Cho, K. Yoshioka, Y. Yokota, N. Sakatani, M. Yamada, T. Kouyama, H. Suzuki, C. Honda, N. Namiki, T. Mizuno, K. Matsumoto, H. Noda, Y. Ishihara, R. Yamada, K. Yamamoto, F. Yoshida, S. Abe, A. Higuchi, Y. Yamamoto, T. Okada, Y. Shimaki, R. Noguchi, A. Miura, N. Hirata, S. Tachibana, H. Yabuta, M. Ishiguro, H. Ikeda, H. Takeuchi, T. Shimada, O. Mori, S. Hosoda, R. Tsukizaki, S. Soldini, M. Ozaki, F. Terui, N. Ogawa, Y. Mimasu, G. Ono, K. Yoshikawa, C. Hirose, A. Fujii, T. Takahashi, S. Kikuchi, Y. Takei, T. Yamaguchi, S. Nakazawa, S. Tanaka, M. Yoshikawa, S. Watanabe, Y. Tsuda

Nature Astronomy Vol. 5 ( 3 ) page： 246 - + 2021.3

Alignment determination of the Hayabusa2 laser altimeter (LIDAR) Reviewed International journal Open Access

Noda, H; Senshu, H; Matsumoto, K; Namiki, N; Mizuno, T; Sugita, S; Abe, S; Araki, H; Asari, K; Cho, Y; Fujii, A; Hayakawa, M; Higuchi, A; Hirata, N; Hirata, N; Honda, C; Honda, R; Ishihara, Y; Kameda, S; Kikuchi, S; Kouyama, T; Matsuoka, M; Mimasu, Y; Morota, T; Nakazawa, S; Ogawa, K; Ogawa, N; Ono, G; Oshigami, S; Saiki, T; Sakatani, N; Sasaki, S; Sawada, H; Shizugami, M; Suzuki, H; Takahashi, T; Takei, Y; Tanaka, S; Tatsumi, E; Terui, F; Tsuda, Y; Tsuruta, S; Watanabe, S; Yamada, M; Yamada, R; Yamaguchi, T; Yamamoto, K; Yokota, Y; Yoshida, F; Yoshikawa, K; Yoshikawa, M; Yoshioka, K

EARTH PLANETS AND SPACE Vol. 73 ( 1 ) 2021.1

Characterization of D-Type Spectra Based on Hyperspectral Remote Sensing of the Lunar Surface Reviewed

Yamamoto Satoru, Watanabe Sei-ichiro

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Vol. 126 ( 1 ) 2021.1

Sample collection from asteroid (162173) Ryugu by Hayabusa2: Implications for surface evolution Reviewed International coauthorship Open Access

T. Morota, S. Sugita, Y. Cho, M. Kanamaru, E. Tatsumi, N. Sakatani, R. Honda, N. Hirata, H. Kikuchi, M. Yamada, Y. Yokota, S. Kameda, M. Matsuoka, H. Sawada, C. Honda, T. Kouyama, K. Ogawa, H. Suzuki, K. Yoshioka, M. Hayakawa, N. Hirata, M. Hirabayashi, H. Miyamoto, T. Michikami, T. Hiroi, R. Hemmi, O. S. Barnouin, C. M. Ernst, K. Kitazato, T. Nakamura, L. Riu, H. Senshu, H. Kobayashi, S. Sasaki, G. Komatsu, N. Tanabe, Y. Fujii, T. Irie, M. Suemitsu, N. Takaki, C. Sugimoto, K. Yumoto, M. Ishida, H. Kato, K. Moroi, D. Domingue, P. Michel, C. Pilorget, T. Iwata, M. Abe, M. Ohtake, Y. Nakauchi, K. Tsumura, H. Yabuta, Y. Ishihara, R. Noguchi, K. Matsumoto, A. Miura, N. Namiki, S. Tachibana, M. Arakawa, H. Ikeda, K. Wada, T. Mizuno, C. Hirose, S. Hosoda, O. Mori, T. Shimada, S. Soldini, R. Tsukizaki, H. Yano, M. Ozaki, H. Takeuchi, Y. Yamamoto, T. Okada, Y. Shimaki, K. Shirai, Y. Iijima, H. Noda, S. Kikuchi, T. Yamaguchi, N. Ogawa, G. Ono, Y. Mimasu, K. Yoshikawa, T. Takahashi, Y. Takei, A. Fujii, S. Nakazawa, F. Terui, S. Tanaka, M. Yoshikawa, T. Saiki, S. Watanabe, Y. Tsuda

Science Vol. 368 ( 6491 ) page： 654 - + 2020.5

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

© 2020 American Association for the Advancement of Science. All rights reserved. The near-Earth asteroid (162173) Ryugu is thought to be a primitive carbonaceous object that contains hydrated minerals and organic molecules. We report sample collection from Ryugu’s surface by the Hayabusa2 spacecraft on 21 February 2019. Touchdown images and global observations of surface colors are used to investigate the stratigraphy of the surface around the sample location and across Ryugu. Latitudinal color variations suggest the reddening of exposed surface material by solar heating and/or space weathering. Immediately after touchdown, Hayabusa2’s thrusters disturbed dark, fine grains that originate from the redder materials. The stratigraphic relationship between identified craters and the redder material indicates that surface reddening occurred over a short period of time. We suggest that Ryugu previously experienced an orbital excursion near the Sun.

DOI： 10.1126/science.aaz6306

Web of Science

Scopus

PubMed

An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime Reviewed International journal Open Access

Arakawa M, Saiki T, Wada K, Ogawa K, Kadono T, Shirai K, Sawada H, Ishibashi K, Honda R, Sakatani N, Iijima Y, Okamoto C, Yano H, Takagi Y, Hayakawa M, Michel P, Jutzi M, Shimaki Y, Kimura S, Mimasu Y, Toda T, Imamura H, Nakazawa S, Hayakawa H, Sugita S, Morota T, Kameda S, Tatsumi E, Cho Y, Yoshioka K, Yokota Y, Matsuoka M, Yamada M, Kouyama T, Honda C, Tsuda Y, Watanabe S, Yoshikawa M, Tanaka S, Terui F, Kikuchi S, Yamaguchi T, Ogawa N, Ono G, Yoshik

SCIENCE Vol. 368 ( 6486 ) page： 67 - + 2020.4

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

Blowing a crater in asteroid Ryugu

The Hayabusa2 spacecraft was designed to collect samples from the nearby asteroid (162173) Ryugu and return them to Earth for laboratory analysis. Arakawa et al. describe how the spacecraft's Small Carry-on Impactor was fired into the asteroid's surface, producing an artificial impact crater. Analysis of the resulting plume of ejecta, recorded by a remote camera, sets an upper limit on the strength of the rubble-pile surface. The crater has a semicircular shape, probably due to a large boulder buried close to the impact location. The crater exposed material from Ryugu's subsurface, which has not been subjected to space weathering, that is suitable for collection by Hayabusa2.

Science , this issue p. 67

DOI： 10.1126/science.aaz1701

Web of Science

Highly porous nature of a primitive asteroid revealed by thermal imaging Reviewed International coauthorship Open Access

Tatsuaki Okada, Tetsuya Fukuhara, Satoshi Tanaka, Makoto Taguchi, Takehiko Arai, Hiroki Senshu, Naoya Sakatani, Yuri Shimaki, Hirohide Demura, Yoshiko Ogawa, Kentaro Suko, Tomohiko Sekiguchi, Toru Kouyama, Jun Takita, Tsuneo Matsunaga, Takeshi Imamura, Takehiko Wada, Sunao Hasegawa, Joern Helbert, Thomas G. Mueller, Axel Hagermann, Jens Biele, Matthias Grott, Maximilian Hamm, Marco Delbo, Naru Hirata, Naoyuki Hirata, Yukio Yamamoto, Seiji Sugita, Noriyuki Namiki, Kohei Kitazato, Masahiko Arakawa, Shogo Tachibana, Hitoshi Ikeda, Masateru Ishiguro, Koji Wada, Chikatoshi Honda, Rie Honda, Yoshiaki Ishihara, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Akira Miura, Tomokatsu Morota, Hirotomo Noda, Rina Noguchi, Kazunori Ogawa, Kei Shirai, Eri Tatsumi, Hikaru Yabuta, Yasuhiro Yokota, Manabu Yamada, Masanao Abe, Masahiko Hayakawa, Takahiro Iwata, Masanobu Ozaki, Hajime Yano, Satoshi Hosoda, Osamu Mori, Hirotaka Sawada, Takanobu Shimada, Hiroshi Takeuchi, Ryudo Tsukizaki, Atsushi Fujii, Chikako Hirose, Shota Kikuchi, Yuya Mimasu, Naoko Ogawa, Go Ono, Tadateru Takahashi, Yuto Takei, Tomohiro Yamaguchi, Kent Yoshikawa, Fuyuto Terui, Takanao Saiki, Satoru Nakazawa, Makoto Yoshikawa, Seiichiro Watanabe, Yuichi Tsuda

NATURE Vol. 579 ( 7800 ) page： 518 - 522 2020.3

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Carbonaceous (C-type) asteroids(1) are relics of the early Solar System that have preserved primitive materials since their formation approximately 4.6 billion years ago. They are probably analogues of carbonaceous chondrites(2,3) and are essential for understanding planetary formation processes. However, their physical properties remain poorly known because carbonaceous chondrite meteoroids tend not to survive entry to Earth's atmosphere. Here we report on global one-rotation thermographic images of the C-type asteroid 162173 Ryugu, taken by the thermal infrared imager (TIR)(4) onboard the spacecraft Hayabusa2(5), indicating that the asteroid's boulders and their surroundings have similar temperatures, with a derived thermal inertia of about 300 J m(-2) s(-0.5) K-1 (300 tiu). Contrary to predictions that the surface consists of regolith and dense boulders, this low thermal inertia suggests that the boulders are more porous than typical carbonaceous chondrites(6) and that their surroundings are covered with porous fragments more than 10 centimetres in diameter. Close-up thermal images confirm the presence of such porous fragments and the flat diurnal temperature profiles suggest a strong surface roughness effect(7,8). We also observed in the close-up thermal images boulders that are colder during the day, with thermal inertia exceeding 600 tiu, corresponding to dense boulders similar to typical carbonaceous chondrites(6). These results constrain the formation history of Ryugu: the asteroid must be a rubble pile formed from impact fragments of a parent body with microporosity(9) of approximately 30 to 50 per cent that experienced a low degree of consolidation. The dense boulders might have originated from the consolidated innermost region or they may have an exogenic origin. This high-porosity asteroid may link cosmic fluffy dust to dense celestial bodies(10).Thermal imaging data obtained from the spacecraft Hayabusa2 reveal that the carbonaceous asteroid 162173 Ryugu is an object of unusually high porosity.

DOI： 10.1038/s41586-020-2102-6

Web of Science

Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu-A spinning top-shaped rubble pile. Reviewed International coauthorship International journal Open Access

S Watanabe, M Hirabayashi, N Hirata, Na Hirata, R Noguchi, Y Shimaki, H Ikeda, E Tatsumi, M Yoshikawa, S Kikuchi, H Yabuta, T Nakamura, S Tachibana, Y Ishihara, T Morota, K Kitazato, N Sakatani, K Matsumoto, K Wada, H Senshu, C Honda, T Michikami, H Takeuchi, T Kouyama, R Honda, S Kameda, T Fuse, H Miyamoto, G Komatsu, S Sugita, T Okada, N Namiki, M Arakawa, M Ishiguro, M Abe, R Gaskell, E Palmer, O S Barnouin, P Michel, A S French, J W McMahon, D J Scheeres, P A Abell, Y Yamamoto, S Tanaka, K Shirai, M Matsuoka, M Yamada, Y Yokota, H Suzuki, K Yoshioka, Y Cho, S Tanaka, N Nishikawa, T Sugiyama, H Kikuchi, R Hemmi, T Yamaguchi, N Ogawa, G Ono, Y Mimasu, K Yoshikawa, T Takahashi, Y Takei, A Fujii, C Hirose, T Iwata, M Hayakawa, S Hosoda, O Mori, H Sawada, T Shimada, S Soldini, H Yano, R Tsukizaki, M Ozaki, Y Iijima, K Ogawa, M Fujimoto, T-M Ho, A Moussi, R Jaumann, J-P Bibring, C Krause, F Terui, T Saiki, S Nakazawa, Y Tsuda

Science (New York, N.Y.) Vol. 364 ( 6437 ) page： 268 - 272 2019.4

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

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.

DOI： 10.1126/science.aav8032

Web of Science

PubMed

The surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy Reviewed International coauthorship Open Access

K. Kitazato, R. E. Milliken, T. Iwata, M. Abe, M. Ohtake, S. Matsuura, T. Arai, Y. Nakauchi, T. Nakamura, M. Matsuoka, H. Senshu, N. Hirata, T. Hiroi, C. Pilorget, R. Brunetto, F. Poulet, L. Riu, J.-P. Bibring, D. Takir, D. L. Domingue, F. Vilas, M. A. Barucci, D. Perna, E. Palomba, A. Galiano, K. Tsumura, T. Osawa, M. Komatsu, A. Nakato, T. Arai, N. Takato, T. Matsunaga, Y. Takagi, K. Matsumoto, T. Kouyama, Y. Yokota, E. Tatsumi, N. Sakatani, Y. Yamamoto, T. Okada, S. Sugita, R. Honda, T. Morota, S. Kameda, H. Sawada, C. Honda, M. Yamada, H. Suzuki, K. Yoshioka, M. Hayakawa, K. Ogawa, Y. Cho, K. Shirai, Y. Shimaki, N. Hirata, A. Yamaguchi, N. Ogawa, F. Terui, T. Yamaguchi, Y. Takei, T. Saiki, S. Nakazawa, S. Tanaka, M. Yoshikawa, S. Watanabe, Y. Tsuda

Science Vol. 364 ( 6437 ) page： 272 - + 2019.4

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is thought to be a primitive carbonaceous object. We report reflectance spectra of Ryugu’s surface acquired with the Near Infrared Spectrometer (NIRS3) on Hayabusa2, to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 μm was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object, generated from impact fragments of an undifferentiated aqueously altered parent body.

DOI： 10.1126/science.aav7432

Web of Science

The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes Reviewed International coauthorship Open Access

S. Sugita, R. Honda, T. Morota, S. Kameda, H. Sawada, E. Tatsumi, M. Yamada, C. Honda, Y. Yokota, T. Kouyama, N. Sakatani, K. Ogawa, H. Suzuki, T. Okada, 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. Schröder, H. Kikuchi, R. Hemmi, G. Komatsu, T. Fukuhara, M. Taguchi, T. Arai, H. Senshu, H. Demura, Y. Ogawa, Y. Shimaki, T. Sekiguchi, T. G. Müller, A. Hagermann, 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

Science Vol. 364 ( 6437 ) page： 252 - + 2019.4

Space-weathered anorthosite as spectral D-type material on the Martian satellites Reviewed

S. Yamamoto, S. Watanabe, T. Matsunaga

Geophysical Research Letters Vol. 45 ( 3 ) page： 1305-1312 2018.2

Hayabusa2 Mission Overview Reviewed Open Access

S. Watanabe, Y. Tsuda, M. Yoshikawa, S. Tanaka, T. Saiki, S. Nakazawa

Space Science Reviews Vol. 208 page： 3-16 2017.7

Thermal waves in irradiated protoplanetary disks Reviewed International coauthorship Open Access

Sei-ichiro Watanabe, D. N. C. Lin

The Astrophysical Journal Vol. 672 ( 2 ) page： 1183 - 1195 2008.1

Phyllosilicates with embedded Fe-based nanophases in Ryugu and Orgueil Reviewed International coauthorship International journal Open Access

Leroux, H; Le Guillou, C; Marinova, M; Laforet, S; Viennet, JC; Mouloud, BE; Teurtrie, A; de la Peña, F; Jacob, D; Hallatt, D; Fernandez, MP; Troadec, D; Noguchi, T; Matsumoto, T; Miyake, A; Igami, Y; Haruta, M; Saito, H; Hata, S; Seto, Y; Miyahara, M; Tomioka, N; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Langenhorst, F; Harries, D; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, SI; Tsuda, Y

METEORITICS & PLANETARY SCIENCE Vol. 59 ( 8 ) page： 1947 - 1965 2024.8

Quantification of bulk elemental composition for C-type asteroid Ryugu samples with nondestructive elemental analysis using muon beam Reviewed International coauthorship International journal

Ninomiya, K; Osawa, T; Terada, K; Wada, T; Nagasawa, S; Chiu, IH; Nakamura, T; Takahashi, T; Miyake, Y; Kubo, MK; Takeshita, S; Taniguchi, A; Umegaki, I; Watanabe, S; Azuma, T; Katsuragawa, M; Minami, T; Mizumoto, K; Shimomura, K; Takeda, S; Morita, T; Kikuiri, M; Amano, K; Kagawa, E; Furukawa, Y; Yurimoto, H; Noguchi, T; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE Vol. 59 ( 8 ) page： 2044 - 2057 2024.8

IR SPECTRA OF RYUGU'S ANHYDROUS INGREDIENTS COMPARED WITH PRIMITIVE DUST FROM THE OUTER SOLAR SYSTEM Reviewed International coauthorship International journal

Brunetto, R; Nakamura, T; Lantz, C; Fukuda, Y; Aléon-Toppani, A; Dionnet, Z; Baklouti, D; Borondics, F; Djouadi, Z; Rubino, S; Amano, K; Matsumoto, M; Fujioka, Y; Morita, T; Kikuiri, M; Kagawa, E; Milliken, R; Matsuoka, M; Yurimoto, H; Noguchi, T; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE Vol. 59 page： A46 - A46 2024.8

Soluble organic matter Molecular atlas of Ryugu reveals cold hydrothermalism on C-type asteroid parent body Reviewed International coauthorship International journal Open Access

Schmitt-Kopplin, P; Hertkorn, N; Harir, M; Moritz, F; Lucio, M; Bonal, L; Quirico, E; Takano, Y; Dworkin, JP; Naraoka, H; Tachibana, S; Nakamura, T; Noguchi, T; Okazaki, R; Yabuta, H; Yurimoto, H; Sakamoto, K; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Okada, T; Watanabe, SI; Tsuda, Y

NATURE COMMUNICATIONS Vol. 14 ( 1 ) 2023.10

Chemical evolution of primordial salts and organic sulfur molecules in the asteroid 162173 Ryugu. Reviewed International journal Open Access

Toshihiro Yoshimura, Yoshinori Takano, Hiroshi Naraoka, Toshiki Koga, Daisuke Araoka, Nanako O Ogawa, Philippe Schmitt-Kopplin, Norbert Hertkorn, Yasuhiro Oba, Jason P Dworkin, José C Aponte, Takaaki Yoshikawa, Satoru Tanaka, Naohiko Ohkouchi, Minako Hashiguchi, Hannah McLain, Eric T Parker, Saburo Sakai, Mihoko Yamaguchi, Takahiro Suzuki, Tetsuya Yokoyama, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-Ichiro Watanabe, Yuichi Tsuda, Shogo Tachibana

Nature communications Vol. 14 ( 1 ) page： 5284 - 5284 2023.9

Language：English Publishing type：Research paper (scientific journal)

Samples from the carbonaceous asteroid (162173) Ryugu provide information on the chemical evolution of organic molecules in the early solar system. Here we show the element partitioning of the major component ions by sequential extractions of salts, carbonates, and phyllosilicate-bearing fractions to reveal primordial brine composition of the primitive asteroid. Sodium is the dominant electrolyte of the salt fraction extract. Anions and NH4+ are more abundant in the salt fraction than in the carbonate and phyllosilicate fractions, with molar concentrations in the order SO42- > Cl- > S2O32- > NO3- > NH4+. The salt fraction extracts contain anionic soluble sulfur-bearing species such as Sn-polythionic acids (n < 6), Cn-alkylsulfonates, alkylthiosulfonates, hydroxyalkylsulfonates, and hydroxyalkylthiosulfonates (n < 7). The sulfur-bearing soluble compounds may have driven the molecular evolution of prebiotic organic material transforming simple organic molecules into hydrophilic, amphiphilic, and refractory S allotropes.

DOI： 10.1038/s41467-023-40871-0

Open Access

Web of Science

PubMed

Visualization of nanoscale magnetic domain states in the asteroid Ryugu Reviewed International coauthorship International journal Open Access

Yuki Kimura, Takeharu Kato, Toshiaki Tanigaki, Tetsuya Akashi, Hiroto Kasai, Satoshi Anada, Ryuji Yoshida, Kazuo Yamamoto, Tomoki Nakamura, Masahiko Sato, Kana Amano, Mizuha Kikuiri, Tomoyo Morita, Eiichi Kagawa, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Sei-ichiro Watanabe, Yuichi Tsuda, Shogo Tachibana

Scientific Reports Vol. 13 ( 1 ) 2023.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

In the samples collected from the asteroid Ryugu, magnetite displays natural remanent magnetization due to nebular magnetic field, whereas contemporaneously grown iron sulfide does not display stable remanent magnetization. To clarify this counterintuitive feature, we observed their nanoscale magnetic domain structures using electron holography and found that framboidal magnetites have an external magnetic field of 300 A m<sup>−1</sup>, similar to the bulk value, and its magnetic stability was enhanced by interactions with neighboring magnetites, permitting a disk magnetic field to be recorded. Micrometer-sized pyrrhotite showed a multidomain magnetic structure that was unable to retain natural remanent magnetization over a long time due to short relaxation time of magnetic-domain-wall movement, whereas submicron-sized sulfides formed a nonmagnetic phase. These results show that both magnetite and sulfide could have formed simultaneously during the aqueous alteration in the parent body of the asteroid Ryugu.

DOI： 10.1038/s41598-023-41242-x

Open Access

Web of Science

PubMed

Other Link： https://www.nature.com/articles/s41598-023-41242-x

　 PREV - NEXT 　

<WATANABE, Sei-ichiro>

Papers - WATANABE, Sei-ichiro