Updated on 2025/08/15

写真a

 
genda hidenori
 
Organization
Institute of Future Science Earth-Life Science Institute Professor
Title
Professor
External link

News & Topics
  • Hayabusa2 samples reveal the formation and evolution of asteroid Ryugu

    2022/11/02

    Languages: English

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    A team of scientists determined the origin and evolution of carbonaceous asteroid Ryugu through sample analysis and computer simulations. The analysis of 17 particles included the third largest sample

  • Large moons may be a clue for habitable planets

    2022/03/23

    Languages: English

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    Earth's moon is vitally important in making Earth the planet we know today: the moon controls the length of the day and ocean tides, which affect the

  • 小天体衝突による火星から衛星への物質輸送、従来見積もりの10倍以上 火星衛星サンプルリターンで火星の全歴史の解明が可能

    2020/01/14

    Languages: Japanese

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    要点-火星上で起きた小天体の衝突によって、火星表層物質が吹き飛ばされ、その一部が火星衛星フォボスに降り積もっている。-最新の数値計算によって、フォボスには従来の見積もりの10~100倍の火星表層物質が混入していることが明らかになった。-日本が進める

  • Japan’s MMX Martian Moon Probe is Unlikely to Bring Back Dangerous Martian Microbes A Japanese research team has assessed the probability that Martian microbes that might have contaminated Mars’ moons would be returned to Earth by JAXA's Martian Moons eXploration (MMX) sample return mission.

    2019/11/07

    Languages: English

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    Japan's Aerospace Exploration Agency (JAXA) plans to send the Martian Moons eXploration (MMX) mission to Mars' moons Phobos and Deimos. MMX would return samples to Earth in 2029, but before sendin

  • 火星衛星探査に向けた国際的な惑星保護方針への貢献について 日本の研究チームが火星衛星微生物汚染評価に関する科学的研究成果を発表・国際ルール設定へ主導的な役割

    2019/09/06

    Languages: Japanese

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    東京工業大学地球生命研究所の玄田英典准教授および兵頭龍樹日本学術振興会特別研究員は、国立研究開発法人宇宙航空研究開発機構(JAXA)宇宙科学研究所の藤田和央教授、千葉工業大学惑星探査研究センターの黒澤耕介上席研究員、東京大学、東京薬科大学と共同で、火星衛星の微生物汚染評価に関する科学的研

  • Tokyo Tech-led study shows how icy outer solar system satellites may have formed: Scientists use sophisticated computer simulations and observations of Trans-Neptunian Objects to understand the formation of the solar system

    2019/06/26

    Languages: English

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    Using sophisticated computer simulations and observations, a team led by researchers from the Earth-Life Science Institute (ELSI) at Tokyo Institute of Technology has shown how the so-called trans-Neptunian Objects (or TNOs) may have formed.

  • 冥王星を含む太陽系外縁天体の衛星、太陽系初期の巨大天体衝突で形成された可能性

    2019/06/25

    Languages: Japanese

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    太陽系外縁天体のうち、冥王星をはじめとする直径1,000 km以上の天体はすべて大きな衛星を持つが、その衛星の形成機構と形成時期は謎であった 太陽系外縁天体の大きな衛星が巨大天体衝突によって形成された可能性が高いことを、数値シミュレーションで示した 衛星形成後の一定期間は天体が溶融していたと考えると、現在の衛星の公転周期や離心率をうまく説明できる 太陽系外縁天体の衛星は太陽系初期に形成されたと考えられる

  • 隕石の記憶は容易に消去される 天体衝突時の加熱過程における物質強度の効果を解明

    2018/01/26

    Languages: Japanese

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    隕石に記録された放射壊変年代(アルゴン年代)は、初期太陽系で起きた出来事を紐解く上で重要である。隕石のふるさとである小惑星帯での典型的な衝突(およそ5 km/s)ではアルゴン年代はリセットされない、と推定されてきた。岩石の強度を考慮した数値衝突計算を実施し、衝撃圧縮状態からの減圧中に摩擦や塑性変形に伴う加熱が起こり、低速度衝突(2 km/s)でもアルゴン年代がリセットされることを示した。初期太陽系の姿は従来推定されていたよりも穏やかであった可能性が高い。

  • Meteorites from Mars suffer a velocity boost due to the material pileup

    2017/12/18

    Languages: English

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    Researchers have performed numerical simulations to explore the launch mechanism of the Martian meteorites. According to the knowledge of shock physics, a strong shock compression higher than 50 GPa is required to accelerate martian materials up to the escape velocity of Mars (5 km/s). In contrast, detailed analysis of martian meteorites shows that they suffer only 30?50 GPa during the ejection. The researchers found that a material pileup in an excavation flow causes a significant velocity boost of materials near the surface without strong compression. This newly descovered late-stage acceleration could play an important role not only in the launch of martian meteorites, but also in the context of the (Litho-)Panspermia.

  • 天体衝突による火星隕石の放出メカニズムを解明 ―心太式加速による惑星間物質輸送―

    2017/12/11

    Languages: Japanese

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    火星隕石は天体衝突によって火星から飛び出し、地球に飛来したと考えられている。衝撃物理学の知見では、火星からの放出速度(秒速5 km以上)と火星隕石が経験した衝撃圧力(30~50万気圧)を同時に説明できていなかった。詳細な天体衝突の数値解析により、深部の岩石が、浅部の低衝撃圧力しか受けていない岩石を心太(ところてん)式に押し出すというメカニズムで火星隕石が放出されることを発見。天体間の物質輸送が従来考えられていたよりも容易に起こることを示唆。

  • 火星衛星に火星マントル物質の存在を予言 ―JAXA火星衛星サンプルリターン計画での実証に高まる期待―

    2017/08/31

    Languages: Japanese

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    巨大衝突起源説で火星衛星の反射スペクトルの特徴が説明可能 火星衛星は衝突当時の火星本体の地殻物質とマントル物質を多く含有 JAXAの火星衛星サンプルリターン計画で火星本体の物質採取に期待

  • The smoking gun of the giant impact on Pluto

    2017/02/07

    Languages: English

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    Researchers revealed that the dark and reddish elongated regions along Pluto's equator were formed by the Charon-forming giant impact.

  • 冥王星のクジラ模様は衛星カロンを作ったジャイアント・インパクトの痕跡だった

    2017/01/31

    Languages: Japanese

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    発表のポイント 冥王星とその巨大な衛星カロンは、地球と月の形成と同様に、原始惑星のジャイアント・インパクト[用語1]によってできた。そのジャイアント・インパクトの痕跡が、冥王星の赤道域に広がる褐色のクジラ模様、通称「クトゥルフ領域[用語2]」だと考えられる。地球形成領域から太陽系外縁部までにわたって、原始惑星同士が頻繁に衝突・合体する大変動を経て、現在の太陽系ができあがったことを示唆。

  • Mystery solved behind birth of Saturn's rings

    2016/11/15

    Languages: English

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    A team of researchers has presented a new model for the origin of Saturn's rings based on results of computer simulations. The results of the simulations are also applicable to rings of other giant planets and explain the compositional differences between the rings of Saturn and Uranus. The findings were published on October 6 in the online version of Icarus.

  • 土星の輪、誕生の謎を解明

    2016/10/21

    Languages: Japanese

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    神戸大学 大学院理学研究科の兵頭龍樹研究員、大槻圭史教授、東京工業大学 地球生命研究所の玄田英典特任准教授、パリ地球物理研究所/パリ・ディドゥロ大学のシャノーズ教授の研究グループは、コンピュータ・シミュレーションを用いた研究に基づき、土星リング形成に関する新たなモデルを発表しました。本研究の結果は他の巨大惑星にも適用でき、土星と天王星のリング組成の違いも説明可能です。この研究成果は10月6日に米国の国際学術雑誌 Icarusにオンライン掲載されました。

  • ケンタウルス族小天体のリングの起源を解明

    2016/09/08

    Languages: Japanese

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    神戸大学 大学院理学研究科 惑星学専攻の大学院生・兵頭龍樹さん、大槻圭史教授、東京工業大学 地球生命研究所の玄田英典特任准教授、パリ地球物理研究所/パリ・ディドゥロ大学のシャノーズ教授の研究グループは、ケンタウルス族と呼ばれる小天体がもつリングの起源を明らかにしました。本研究の結果は他にもリングをもつケンタウルス族天体が存在することを示唆しており、今後のさらなる観測による発見が期待されます。この研究成果は、8月29日に、Astrophysical Journal Lettersにオンライン掲載されました。また、アメリカ天文学会発行学術雑誌のResearch Highlightsのページで紹介されました。

  • Formation of Martian Satellites via a Giant Impact

    2016/07/06

    Languages: English

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    Researchers found that two small satellites (Phobos and Deimos) orbiting around Mars can be also formed by a giant impact like the origin of our Moon.

  • 火星衛星フォボスとディモスの形成過程を解明―JAXA火星衛星サンプルリターン計画への期待高まる―

    2016/07/05

    Languages: Japanese

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    要点 火星衛星は地球の月の起源と同様に巨大天体衝突により誕生 火星にかつて存在した巨大衛星がフォボスとディモスの形成に重要な役割 JAXAの火星衛星サンプルリターン計画で火星物質の持ち帰りに期待

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News & Media

Degree

  • 博士(理学) ( 東京大学 )

Research Interests

  • 水惑星学

  • SPH法

  • 天体衝突

  • 惑星科学

  • 惑星進化学

  • 比較惑星学

  • アストロバイオロジー

Research Areas

  • Natural Science / Solid earth sciences

  • Natural Science / Astronomy

  • Natural Science / Space and planetary sciences

  • Informatics / Computational science

Education

  • 東京大学大学院   理学系研究科   地球惑星科学専攻

    2001.4 - 2004.3

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  • 東京大学大学院   理学系研究科   地球惑星物理学専攻

    1999.4 - 2001.3

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  • Keio University   Faculty of Science and Technology   Department of Physics

    1995.4 - 1999.3

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Research History

  • Tokyo Institute of Technology   Earth-Life Science Institute   Professor

    2022.7

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  • Tokyo Institute of Technology   Earth-Life Science Institute   Associate Professor

    2018.4 - 2022.6

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  • Tokyo Institute of Technology   Earth-Life Science Institute

    2013.4 - 2018.3

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  • The University of Tokyo

    2009.10 - 2013.3

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  • Tokyo Institute of Technology

    2009.4 - 2009.9

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  • Tokyo Institute of Technology

    2008.4 - 2009.3

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  • Tokyo Institute of Technology   Researcher

    2007.4 - 2008.3

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  • 日本学術振興会   特別研究員(PD)

    2004.4 - 2007.3

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  • 日本学術振興会   特別研究員(DC1)

    2001.4 - 2004.3

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Professional Memberships

Committee Memberships

  • 日本惑星科学会   行事部会 委員長  

    2021.1   

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    Committee type:Academic society

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  • 日本惑星科学会   運営委員  

    2019.1   

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    Committee type:Academic society

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  • 日本惑星科学会   欧文誌専門委員会 委員長  

    2019.1 - 2020.12   

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    Committee type:Academic society

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  • 東京工業大学   高性能コンピュータシステム専門委員会  

    2017.4   

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    Committee type:Academic society

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  • 日本惑星科学会   学会賞選考委員  

    2016.4 - 2018.3   

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    Committee type:Academic society

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  • 日本地球惑星科学連合   プログラム委員  

    2012.4 - 2013.3   

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    Committee type:Academic society

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Papers

  • Mixing model of Phobos’ bulk elemental composition for the determination of its origin: Multivariate analysis of MMX/MEGANE data

    Kaori Hirata, Tomohiro Usui, Ryuki Hyodo, Hidenori Genda, Ryota Fukai, David J. Lawrence, Nancy L. Chabot, Patrick N. Peplowski, Hiroki Kusano

    Icarus   410   2024.3

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.icarus.2023.115891

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  • Curation protocol of Phobos sample returned by Martian Moons eXploration

    Ryota Fukai, Tomohiro Usui, Wataru Fujiya, Yoshinori Takano, Ken‐ichi Bajo, Andrew Beck, Enrica Bonato, Nancy L. Chabot, Yoshihiro Furukawa, Hidenori Genda, Yuki Hibiya, Fred Jourdan, Thorsten Kleine, Mizuho Koike, Moe Matsuoka, Yayoi N. Miura, Frédéric Moynier, Ryuji Okazaki, Sara S. Russell, Hirochika Sumino, Michael E. Zolensky, Haruna Sugahara, Shogo Tachibana, Kanako Sakamoto, Masanao Abe, Yuichiro Cho, Kiyoshi Kuramoto

    Meteoritics & Planetary Science   2024.1

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    Publishing type:Research paper (scientific journal)   Publisher:Wiley  

    Abstract

    Japan Aerospace Exploration Agency's Martian Moons eXploration (MMX) mission will launch a spacecraft in 2024 to return samples from Phobos in 2029. Curatorial work for the returned Phobos samples is critical for the sample allocation without degrading the sample integrity and subsequent sample analysis that will provide new constraints on the origin of Phobos and the evolution of the circum‐Mars environment. The Sample Analysis Working Team of the MMX is designing the sample curation protocol. The curation protocol consists of three phases: (1) quick analysis (extraction and mass spectrometry for gases), (2) pre‐basic characterization (bulk‐scale observation), and (3) basic characterization (grain‐by‐grain observation and allocation of the sample aliquots). Nondestructive analyses within the clean chamber (e.g., visible and near‐infrared spectral imaging) and outside the chamber (e.g., gas mass spectrometry) are incorporated into the curation flow in coordination with the MMX mission instrument teams for ground‐truthing the remote‐sensing data sets. The MMX curation/sample analysis flow enables the seamless integration between the sample and remote‐sensing data sets to maximize the scientific value of the collected Phobos samples.

    DOI: 10.1111/maps.14121

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  • Experimental Evidence for Shear‐Induced Melting and Generation of Stishovite in Granite at Low (<18 GPa) Shock Pressure

    Christopher Hamann, Kosuke Kurosawa, Haruka Ono, Toshihiro Tada, Falko Langenhorst, Kilian Pollok, Hidenori Genda, Takafumi Niihara, Takaya Okamoto, Takafumi Matsui

    Journal of Geophysical Research: Planets   128 ( 6 )   2023.5

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    Publishing type:Research paper (scientific journal)   Publisher:American Geophysical Union (AGU)  

    DOI: 10.1029/2023je007742

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  • Early Water Delivery to Terrestrial Planet Regions during the Stages of Jupiter’s Formation and Migration in the Grand Tack Model

    Masahiro Ogihara, Hidenori Genda, Yasuhito Sekine

    The Planetary Science Journal   4 ( 2 )   32 - 32   2023.2

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    Publishing type:Research paper (scientific journal)   Publisher:American Astronomical Society  

    Abstract

    The formation and subsequent migration of gas giants could significantly affect the material mixing in the solar system. In this study, we use N-body simulations to investigate how much water is transported into the region of the terrestrial planet formation during the growth and migration phases of Jupiter in the Grand Tack model. We found that Jupiter’s growth was accompanied by significant mass transport and that a substantial amount of water (about 10 times Earth’s ocean mass for the initial planetesimal distribution based on the minimum-mass solar nebula) was transported into the terrestrial planet region. The total amount delivered increased further during Jupiter’s migration phase (totaling about 10–40 times Earth’s ocean mass), which was less dependent on simulation parameters. In addition, at these stages, terrestrial planets were not fully grown. Therefore, water supplied during these early stages could interact with metallic iron during the core formation of protoplanets and/or growing Earth. Since hydrogen in water molecules can dissolve into their cores, this could explain the density deficit observed in the current Earth core. Notably, Jupiter could play an important role as a “barrier” in explaining the dichotomy of the isotopic compositions between noncarbonaceous (NC) and carbonaceous (CC) meteorites. This study’s results show that Jupiter’s growth necessitates some mixing of NC and CC materials.

    DOI: 10.3847/psj/acb64b

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    Other Link: https://iopscience.iop.org/article/10.3847/PSJ/acb64b/pdf

  • Experimentally Shock‐Induced Melt Veins in Basalt: Improving the Shock Classification of Eucrites

    Haruka Ono, Kosuke Kurosawa, Takafumi Niihara, Takashi Mikouchi, Naotaka Tomioka, Junko Isa, Hiroyuki Kagi, Takuya Matsuzaki, Hiroshi Sakuma, Hidenori Genda, Tatsuhiro Sakaiya, Tadashi Kondo, Masahiro Kayama, Mizuho Koike, Yuji Sano, Masafumi Murayama, Wataru Satake, Takafumi Matsui

    Geophysical Research Letters   50 ( 1 )   2023.1

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    Publishing type:Research paper (scientific journal)   Publisher:American Geophysical Union (AGU)  

    Abstract

    Basaltic rocks occur widely on the terrestrial planets and differentiated asteroids, including the asteroid 4 Vesta. We conducted a shock recovery experiment with decaying compressive pulses on a terrestrial basalt at the Chiba Institute of Technology, Japan. The sample recorded a range of pressures, and shock physics modeling was conducted to add a pressure scale to the observed shock features. The shocked sample was examined by optical and electron microscopy, electron back‐scattered diffractometry, and Raman spectroscopy. We found that localized melting occurs at a lower pressure (∼10 GPa) than previously thought (>20 GPa). The shocked basalt near the epicenter represents “shock degree C” of a recently proposed classification scheme for basaltic eucrites and, as such, our results provide a pressure scale for the classification scheme. Finally, we estimated the total fraction of the basaltic eucrites classified as shock degree C to be ∼15% by assuming the impact velocity distribution onto Vesta.

    DOI: 10.1029/2022gl101009

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    Other Link: https://onlinelibrary.wiley.com/doi/full-xml/10.1029/2022GL101009

  • Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples

    T. Nakamura, M. Matsumoto, K. Amano, Y. Enokido, M. E. Zolensky, T. Mikouchi, H. Genda, S. Tanaka, M. Y. Zolotov, K. Kurosawa, S. Wakita, R. Hyodo, H. Nagano, D. Nakashima, Y. Takahashi, Y. Fujioka, M. Kikuiri, E. Kagawa, M. Matsuoka, A. J. Brearley, A. Tsuchiyama, M. Uesugi, J. Matsuno, Y. Kimura, M. Sato, R. E. Milliken, E. Tatsumi, S. Sugita, T. Hiroi, K. Kitazato, D. Brownlee, D. J. Joswiak, M. Takahashi, K. Ninomiya, T. Takahashi, T. Osawa, K. Terada, F. E. Brenker, B. J. Tkalcec, L. Vincze, R. Brunetto, A. Aléon-Toppani, Q. H. S. Chan, M. Roskosz, J.-C. Viennet, P. Beck, E. E. Alp, T. Michikami, Y. Nagaashi, T. Tsuji, Y. Ino, J. Martinez, J. Han, A. Dolocan, R. J. Bodnar, M. Tanaka, H. Yoshida, K. Sugiyama, A. J. King, K. Fukushi, H. Suga, S. Yamashita, T. Kawai, K. Inoue, A. Nakato, T. Noguchi, F. Vilas, A. R. Hendrix, C. Jaramillo-Correa, D. L. Domingue, G. Dominguez, Z. Gainsforth, C. Engrand, J. Duprat, S. S. Russell, E. Bonato, C. Ma, T. Kawamoto, T. Wada, S. Watanabe, R. Endo, S. Enju, L. Riu, S. Rubino, P. Tack, S. Takeshita, Y. Takeichi, A. Takeuchi, A. Takigawa, D. Takir, T. Tanigaki, A. Taniguchi, K. Tsukamoto, T. Yagi, S. Yamada, K. Yamamoto, Y. Yamashita, M. Yasutake, K. Uesugi, I. Umegaki, I. Chiu, T. Ishizaki, S. Okumura, E. Palomba, C. Pilorget, S. M. Potin, A. Alasli, S. Anada, Y. Araki, N. Sakatani, C. Schultz, O. Sekizawa, S. D. Sitzman, K. Sugiura, M. Sun, E. Dartois, E. De Pauw, Z. Dionnet, Z. Djouadi, G. Falkenberg, R. Fujita, T. Fukuma, I. R. Gearba, K. Hagiya, M. Y. Hu, T. Kato, T. Kawamura, M. Kimura, M. K. Kubo, F. Langenhorst, C. Lantz, B. Lavina, M. Lindner, J. Zhao, B. Vekemans, D. Baklouti, B. Bazi, F. Borondics, S. Nagasawa, G. Nishiyama, K. Nitta, J. Mathurin, T. Matsumoto, I. Mitsukawa, H. Miura, A. Miyake, Y. Miyake, H. Yurimoto, R. Okazaki, H. Yabuta, H. Naraoka, K. Sakamoto, S. Tachibana, H. C. Connolly, D. S. Lauretta, M. Yoshitake, M. Yoshikawa, K. Yoshikawa, K. Yoshihara, Y. Yokota, K. Yogata, H. Yano, Y. Yamamoto, D. Yamamoto, M. Yamada, T. Yamada, T. Yada, K. Wada, T. Usui, R. Tsukizaki, F. Terui, H. Takeuchi, Y. Takei, A. Iwamae, H. Soejima, K. Shirai, Y. Shimaki, H. Senshu, H. Sawada, T. Saiki, M. Ozaki, G. Ono, T. Okada, N. Ogawa, K. Ogawa, R. Noguchi, H. Noda, M. Nishimura, N. Namiki, S. Nakazawa, T. Morota, A. Miyazaki, A. Miura, Y. Mimasu, K. Matsumoto, K. Kumagai, T. Kouyama, S. Kikuchi, K. Kawahara, S. Kameda, T. Iwata, Y. Ishihara, M. Ishiguro, H. Ikeda, S. Hosoda, R. Honda, C. Honda, Y. Hitomi, N. Hirata, N. Hirata, T. Hayashi, M. Hayakawa, K. Hatakeda, S. Furuya, R. Fukai, A. Fujii, Y. Cho, M. Arakawa, M. Abe, S. Watanabe, Y. Tsuda

    Science   379 ( 6634 )   2022.9

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    Publishing type:Research paper (scientific journal)   Publisher:American Association for the Advancement of Science (AAAS)  

    Samples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed seventeen Ryugu samples measuring 1-8 mm. CO 2 -bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu’s parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and Ca, Al-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed by aqueous alteration reactions at low temperature, high pH, and water/rock ratios < 1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate Ryugu’s parent body formed ~ 2 million years after the beginning of Solar System formation.

    DOI: 10.1126/science.abn8671

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  • Effect of Impact Velocity and Angle on Deformational Heating and Postimpact Temperature Reviewed

    S. Wakita, H. Genda, K. Kurosawa, T. M. Davison, B. C. Johnson

    Journal of Geophysical Research: Planets   127 ( 8 )   2022.8

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    DOI: 10.1029/2022je007266

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  • Shock Recovery With Decaying Compressive Pulses: Shock Effects in Calcite (CaCO 3 ) Around the Hugoniot Elastic Limit Reviewed

    Kosuke Kurosawa, Haruka Ono, Takafumi Niihara, Tatsuhiro Sakaiya, Tadashi Kondo, Naotaka Tomioka, Takashi Mikouchi, Hidenori Genda, Takuya Matsuzaki, Masahiro Kayama, Mizuho Koike, Yuji Sano, Masafumi Murayama, Wataru Satake, Takafumi Matsui

    Journal of Geophysical Research: Planets   127 ( 6 )   2022.6

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    Shock metamorphism of minerals in meteorites provides insights into the ancient Solar System. Calcite is an abundant aqueous alteration mineral in carbonaceous chondrites. Return samples from the asteroids Ryugu and Bennu are expected to contain calcite‐group minerals. Although shock metamorphism in silicates has been well studied, such data for aqueous alteration minerals are limited. Here, we investigated the shock effects in calcite with marble using impact experiments at the Planetary Exploration Research Center of Chiba Institute of Technology. We produced decaying compressive pulses with a smaller projectile than the target. A metal container facilitates recovery of a sample that retains its pre‐impact stratigraphy. We estimated the peak pressure distributions in the samples with the iSALE shock physics code. The capability of this method to produce shocked grains that have experienced different degrees of metamorphism from a single experiment is an advantage over conventional uniaxial shock recovery experiments. The shocked samples were investigated by polarizing microscopy and X‐ray diffraction analysis. We found that more than half of calcite grains exhibit undulatory extinction when peak pressure exceeds 3 GPa. This shock pressure is one order of magnitude higher than the Hugoniot elastic limit (HEL) of marble, but it is close to the HEL of a calcite crystal, suggesting that the undulatory extinction records dislocation‐induced plastic deformation in the crystal. Finally, we propose a strategy to re‐construct the maximum depth of calcite grains in a meteorite parent body, if shocked calcite grains are identified in chondrites and/or return samples from Ryugu and Bennu.

    DOI: 10.1029/2021je007133

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  • Giant impact onto a Vesta-like asteroid and formation of mesosiderites through mixing of metallic core and surface crust Reviewed

    Keisuke Sugiura, Makiko K. Haba, Hidenori Genda

    Icarus   114949 - 114949   2022.2

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    DOI: 10.1016/j.icarus.2022.114949

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  • Martian moons exploration MMX: sample return mission to Phobos elucidating formation processes of habitable planets Reviewed

    Kiyoshi Kuramoto, Yasuhiro Kawakatsu, Masaki Fujimoto, Akito Araya, Maria Antonietta Barucci, Hidenori Genda, Naru Hirata, Hitoshi Ikeda, Takeshi Imamura, Jörn Helbert, Shingo Kameda, Masanori Kobayashi, Hiroki Kusano, David J. Lawrence, Koji Matsumoto, Patrick Michel, Hideaki Miyamoto, Tomokatsu Morota, Hiromu Nakagawa, Tomoki Nakamura, Kazunori Ogawa, Hisashi Otake, Masanobu Ozaki, Sara Russell, Sho Sasaki, Hirotaka Sawada, Hiroki Senshu, Shogo Tachibana, Naoki Terada, Stephan Ulamec, Tomohiro Usui, Koji Wada, Sei-ichiro Watanabe, Shoichiro Yokota

    Earth, Planets and Space   74 ( 1 )   12   2022.1

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    DOI: 10.1186/s40623-021-01545-7

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  • Tidal Evolution of the Eccentric Moon around Dwarf Planet (225088) Gonggong Reviewed

    Sota Arakawa, Ryuki Hyodo, Daigo Shoji, Hidenori Genda

    ASTRONOMICAL JOURNAL   162 ( 6 )   2021.12

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  • MIRS: an imaging spectrometer for the MMX mission Reviewed

    Maria Antonietta Barucci, Jean Michel Reess, Pernelle Bernardi, Alain Doressoundiram, Sonia Fornasier, Michel Le Du, Takahiro Iwata, Hiromu Nakagawa, Tomoki Nakamura, Yves André, Shohei Aoki, Takehiko Arai, Elisa Baldit, Pierre Beck, Jean Tristan Buey, Elisabet Canalias, Matthieu Castelnau, Sebastien Charnoz, Marc Chaussidon, Fréderic Chapron, Valerie Ciarletti, Marco Delbo, Bruno Dubois, Stephane Gauffre, Thomas Gautier, Hidenori Genda, Rafik Hassen-Khodja, Gilles Hervet, Ryuki Hyodo, Christian Imbert, Takeshi Imamura, Laurent Jorda, Shingo Kameda, Driss Kouach, Toru Kouyama, Takeshi Kuroda, Hiroyuki Kurokawa, Laurent Lapaw, Jeremie Lasue, Laetitia Le Deit, Aurélien Ledot, Cedric Leyrat, Bertrand Le Ruyet, Moe Matsuoka, Frederic Merlin, Hideaki Miyamoto, Frederic Moynier, Napoleon Nguyen Tuong, Kazunori Ogohara, Takahito Osawa, Jérôme Parisot, Laurie Pistre, Benjamin Quertier, Sean N. Raymond, Francis Rocard, Takeshi Sakanoi, Takao M. Sato, Eric Sawyer, Fériel Tache, Sylvain Trémolières, Fuminori Tsuchiya, Pierre Vernazza, Didier Zeganadin

    Earth, Planets and Space   73 ( 1 )   2021.12

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    DOI: 10.1186/s40623-021-01423-2

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  • The Onset of a Globally Ice‐Covered State for a Land Planet Reviewed

    T. Kodama, H. Genda, J. Leconte, A. Abe‐Ouchi

    Journal of Geophysical Research: Planets   126 ( 12 )   2021.12

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    DOI: 10.1029/2021JE006975

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  • Numerous chondritic impactors and oxidized magma ocean set Earth’s volatile depletion Reviewed

    Haruka Sakuraba, Hiroyuki Kurokawa, Hidenori Genda, Kenji Ohta

    Scientific Reports   11 ( 20894 )   2021.10

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    Abstract

    Earth’s surface environment is largely influenced by its budget of major volatile elements: carbon (C), nitrogen (N), and hydrogen (H). Although the volatiles on Earth are thought to have been delivered by chondritic materials, the elemental composition of the bulk silicate Earth (BSE) shows depletion in the order of N, C, and H. Previous studies have concluded that non-chondritic materials are needed for this depletion pattern. Here, we model the evolution of the volatile abundances in the atmosphere, oceans, crust, mantle, and core through the accretion history by considering elemental partitioning and impact erosion. We show that the BSE depletion pattern can be reproduced from continuous accretion of chondritic bodies by the partitioning of C into the core and H storage in the magma ocean in the main accretion stage and atmospheric erosion of N in the late accretion stage. This scenario requires a relatively oxidized magma ocean ($$\log _{10} f_{ { \mathrm{O } }_2}$$$$\gtrsim$$$${\mathrm{IW } }$$$$-2$$, where $$f_{ { \mathrm{O } }_2}$$ is the oxygen fugacity, $$\mathrm{IW}$$ is $$\log _{10} f_{ { \mathrm{O } }_2}^{\mathrm{IW } }$$, and $$f_{ { \mathrm{O } }_2}^{\mathrm{IW } }$$ is $$f_{ { \mathrm{O } }_2}$$ at the iron-wüstite buffer), the dominance of small impactors in the late accretion, and the storage of H and C in oceanic water and carbonate rocks in the late accretion stage, all of which are naturally expected from the formation of an Earth-sized planet in the habitable zone.

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

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

    ICARUS   365   2021.9

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    DOI: 10.1016/j.icarus.2021.114505

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  • Erosion and Accretion by Cratering Impacts on Rocky and Icy Bodies Reviewed

    Ryuki Hyodo, Hidenori Genda

    ASTROPHYSICAL JOURNAL   913 ( 2 )   2021.6

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    DOI: 10.3847/1538-4357/abf6d8

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  • The Role of Post‐Shock Heating by Plastic Deformation During Impact Devolatilization of Calcite (CaCO 3 ) Reviewed

    Kosuke Kurosawa, Hidenori Genda, Shintaro Azuma, Keishi Okazaki

    Geophysical Research Letters   48 ( 7 )   2021.4

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    DOI: 10.1029/2020gl091130

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  • Modification of the composition and density of Mercury from late accretion Reviewed

    Ryuki Hyodo, Hidenori Genda, Ramon Brasser

    Icarus   354   114064 - 114064   2021.1

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    DOI: 10.1016/j.icarus.2020.114064

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  • Escape and Accretion by Cratering Impacts: Formulation of Scaling Relations for High-speed Ejecta

    Ryuki Hyodo, Hidenori Genda

    Astrophysical Journal   898 ( 1 )   2020.7

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    DOI: 10.3847/1538-4357/ab9897

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  • The Formation of the Martian Moons Reviewed

    Pascal Rosenblatt, Ryuki Hyodo, Francesco Pignatale, Antony Trinh, Sebastien Charnoz, Kevin Dunseath, Mariko Dunseath-Terao, Hidenori Genda

    Oxford Research Encyclopedia of Planetary Science   2020.3

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    <p>The origin of the natural satellites or moons of the solar system is as challenging to unravel as the formation of the planets. Before the start of the space probe exploration era, this topic of planetary science was restricted to telescopic observations, which limited the possibility of testing different formation scenarios. This era has considerably boosted this topic of research, particularly after the Apollo missions returned samples from the Moon’s surface to Earth. Observations from subsequent deep space missions such as Viking 1 and 2 Orbiters, Voyager 1 and 2, Phobos-2, Galileo, Cassini-Huygens, and the most recent Mars orbiters such as Mars Express, as well as from the Hubble space telescope, have served to intensify research in this area.</p>
    <p>Each moon system has its own specificities, with different origins and histories. It is widely accepted that the Earth’s Moon formed after a giant collision between the proto-Earth and a body similar in size to Mars. The Galilean moons of Jupiter, on the other hand, appear to have formed by accretion in a circum-Jovian disk, while smaller, irregularly shaped satellites were probably captured by the giant planet. The small and medium-sized Saturnian moons may have formed from the rings encircling the planet. Among the terrestrial planets, Mercury and Venus have no moons, the Earth has a single large moon, and Mars has two very small satellites. This raises some challenging questions: What processes can lead to moon formation around terrestrial planets and what parameters determine the possible outcomes, such as the number and size of moons? The answer to such fundamental questions necessarily entails a thorough understanding of the formation of the Martian system and may have relevance to the possible existence of (exo)moons orbiting exoplanets. The formation of such exomoons is of great importance as they could influence conditions for habitability or for maintaining life over long periods of time on the surface of Earth-like exoplanets, for example by limiting the variations of the orientation of the planet’s rotation axis and thus preventing frequent changes of its climate.</p>
    <p>Our current knowledge concerning the origin of Phobos and Deimos has been acquired from observational data as well as theoretical work. Early observations led to the idea that the two satellites were captured asteroids but this created difficulties in reconciling the current orbits of Phobos and Deimos with those of captured bodies, hence suggesting the need for an alternative theory. A giant-impact scenario provides a description of how moons similar to Phobos and Deimos can be formed in orbits similar to those observed today. This scenario also restricts the range of possible composition of the two moons, providing a motivation for future missions that aim for the first time to bring material from the Martian system back to Earth.</p>

    DOI: 10.1093/acrefore/9780190647926.013.24

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  • Impact Ejecta Near the Impact Point Observed Using Ultra-high-Speed Imaging and SPH Simulations and a Comparison of the Two Methods

    Okamoto, T., Kurosawa, K., Genda, H., Matsui, T.

    Journal of Geophysical Research: Planets   125 ( 4 )   2020

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    DOI: 10.1029/2019JE005943

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  • 太陽系外縁天体の衛星形成と潮汐進化 Reviewed

    荒川 創太, 兵頭 龍樹, 庄司 大悟, 玄田 英典

    遊星人(日本惑星科学会誌)   29   104 - 114   2020

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    DOI: 10.14909/yuseijin.29.3_104

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  • Enhancement of impact heating in pressure-strengthened rocks in oblique impacts Reviewed

    Wakita, S, H. Genda, K. Kurosawa, T. M. Davison

    Geophysical Research Letters   46 ( 23 )   2019.12

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    DOI: 10.1029/2019GL085174

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  • Transport of impact ejecta from Mars to its moons as a means to reveal Martian history Reviewed

    Ryuki Hyodo, Kosuke Kurosawa, Hidenori Genda, Tomohiro Usui, Kazuhisa Fujita

    SCIENTIFIC REPORTS   9   2019.12

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    DOI: 10.1038/s41598-019-56139-x

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  • Assessment of the probability of microbial contamination for sample return from Martian moons I: Departure of microbes from Martian surface Reviewed International journal

    Kazuhisa Fujita, Kosuke Kurosawa, Hidenori Genda, Ryuki Hyodo, Shingo Matsuyama, Akihiko Yamagishi, Takashi Mikouchi, Takafumi Niihara

    Life Sciences in Space Research   23   73 - 84   2019.11

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    Potential microbial contamination of Martian moons, Phobos and Deimos, which can be brought about by transportation of Mars ejecta produced by meteoroid impacts on the Martian surface, has been comprehensively assessed in a statistical approach, based on the most probable history of recent major gigantic meteoroid collisions on the Martian surface. This article is the first part of our study to assess potential microbial density in Mars ejecta departing from the Martian atmosphere, as a source of the second part (Kurosawa et al., 2019) where statistical analysis of microbial contamination probability is conducted. Potential microbial density on the Martian surface as the source of microorganisms was estimated by analogy to the terrestrial areas having the similar arid and cold environments, from which a probabilistic function was deduced as the asymptotic limit. Microbial survival rate during hypervelocity meteoroid collisions was estimated by numerical analysis of impact phenomena with and without taking internal friction and plastic deformation of the colliding meteoroid and the target ground into consideration. Trajectory calculations of departing ejecta through the Martian atmosphere were conducted with taking account of aerodynamic deceleration and heating by the aid of computational fluid dynamic analysis. It is found that Mars ejecta smaller than 0.03 m in diameter hardly reach the Phobos orbit due to aerodynamic deceleration, or mostly sterilized due to significant aerodynamic heating even though they can reach the Phobos orbit and beyond. Finally, the baseline dataset of microbial density in Mars ejecta departing for Martian moons has been presented for the second part of our study.

    DOI: 10.1016/j.lssr.2019.07.009

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  • Assessment of the probability of microbial contamination for sample return from Martian moons II: The fate of microbes on Martian moons Reviewed International journal

    Kosuke Kurosawa, Hidenori Genda, Ryuki Hyodo, Akihiko Yamagishi, Takashi Mikouchi, Takafumi Niihara, Shingo Matsuyama, Kazuhisa Fujita

    Life Sciences in Space Research   23   85 - 100   2019.11

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    This paper presents a case study of microbe transportation in the Mars-satellites system. We examined the spatial distribution of potential impact-transported microbes on the Martian moons using impact physics by following a companion study (Fujita et al., in this issue). We used sterilization data from the precede studies (Patel et al., 2018; Summers, 2017). We considered that the microbes came mainly from the Zunil crater on Mars, which was formed during 1.0-0.1 Ma. We found that 70-80% of the microbes are likely to be dispersed all over the moon surface and are rapidly sterilized due to solar and galactic cosmic radiation except for those microbes within a thick ejecta deposit produced by natural meteoroids. The other 20-30% might be shielded from radiation by thick regolith layers that formed at collapsed layers in craters produced by Mars rock impacts. The total number of potentially surviving microbes at the thick ejecta deposits is estimated to be 3-4 orders of magnitude lower than at the Mars rock craters. The microbe concentration is irregular in the horizontal direction due to Mars rock bombardment and is largely depth-dependent due to the radiation sterilization. The surviving fraction of transported microbes would be only ∼1 ppm on Phobos and ∼100 ppm on Deimos, suggesting that the transport processes and radiation severely affect microbe survival. The microbe sampling probability from the Martian moons was also investigatesd. We suggest that sample return missions from the Martian moons are classified into Unrestricted Earth-Return missions for 30 g samples and 10 cm depth sampling, even in our conservative scenario. We also conducted a full statistical analysis pertaining to sampling the regolith of Phobos to include the effects of uncertainties in input parameters on the sampling probability. The most likely probability of microbial contamination for return samples is estimated to be two orders of magnitude lower than the 10-6 criterion defined by the planetary protection policy of the Committee on Space Research (COSPAR).

    DOI: 10.1016/j.lssr.2019.07.006

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  • Inner Edge of Habitable Zones for Earth‐Sized Planets With Various Surface Water Distributions Reviewed

    T. Kodama, H. Genda, R. O'ishi, A. Abe‐Ouchi, Y. Abe

    Journal of Geophysical Research: Planets   124 ( 8 )   2306 - 2324   2019.8

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    DOI: 10.1029/2019JE006037

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  • Fates of hydrous materials during planetesimal collisions

    Shigeru Wakita, Hidenori Genda

    Icarus   328   58 - 68   2019.8

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    DOI: 10.1016/j.icarus.2019.03.008

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  • Early formation of moons around large trans-Neptunian objects via giant impacts Reviewed

    Arakawa, Sota, Hyodo, Ryuki, Genda, Hidenori

    Nature Astronomy   2019.6

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    Recent studies1,2 have revealed that all large (over 1,000 km in diameter) trans-Neptunian objects (TNOs) form satellite systems. Although the largest Plutonian satellite, Charon, is thought to be an intact fragment of an impactor directly formed via a giant impact3, whether giant impacts can explain the variations in secondary-to-primary mass ratios (the ratio between the body and its main satellite) and spin/orbital periods among all large TNOs remains to be determined. Here we find that hydrodynamic simulations of giant impacts can reproduce the secondary-to-primary mass ratio of the satellite systems of large TNOs when the impact velocity is approximately the same as the escape velocity. We also reveal that the satellite systems' current distribution of spin/orbital periods and small eccentricity can be most easily explained when their spins and orbits tidally evolve, initially as fluid-like bodies and finally as rigid bodies. The preferred duration of fluid-like behaviour is approximately 104-106 yr, and it depends on the secondary-to-primary mass ratio and the initial orbital elements. These results suggest that all satellites of large TNOs were formed via giant impacts before the outward migration of Neptune4 and that they were fully or partially molten during the giant impact era. <P />...

    DOI: 10.1038/s41550-019-0797-9

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  • Hydrogen Limits Carbon in Liquid Iron Reviewed

    Kei Hirose, Shoh Tagawa, Yasuhiro Kuwayama, Ryosuke Sinmyo, Guillaume Morard, Yasuo Ohishi, Hidenori Genda

    Geophysical Research Letters   46 ( 10 )   5190 - 5197   2019.5

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    DOI: 10.1029/2019gl082591

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  • Impact degassing and atmospheric erosion on Venus, Earth, and Mars during the late accretion Reviewed

    Haruka Sakuraba, Hiroyuki Kurokawa, Hidenori Genda

    Icarus   317   48 - 58   2019.1

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    DOI: 10.1016/j.icarus.2018.05.035

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  • Collisional disruption of planetesimals in the gravity regime with iSALE code: Comparison with SPH code for purely hydrodynamic bodies Reviewed

    Ryo Suetsugu, Hidekazu Tanaka, Hiroshi Kobayashi, Hidenori Genda

    Icarus   314   121 - 132   2018.11

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    DOI: 10.1016/j.icarus.2018.05.027

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  • The launch of Martian meteorites Reviewed

    Kurosawa K., Genda H., Okamoto T., Matsui T.

    Planetary People - The Japanese Society for Planetary Sciences   27 ( 3 )   197 - 206   2018.9

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    DOI: 10.14909/yuseijin.27.3_197

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  • On the Impact Origin of Phobos and Deimos. IV. Volatile Depletion Reviewed

    Hyodo Ryuki, Genda Hidenori, Charnoz Sebastien, Pignatale Francesco, Rosenblatt Pascal

    ASTROPHYSICAL JOURNAL   860 ( 2 )   2018.6

  • Implantation of martian materials in the inner solar system by a mega impact on mars Reviewed

    Ryuki Hyodo, Hidenori Genda

    Astrophysical Journal Letters   856 ( 2 )   2018.4

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    DOI: 10.3847/2041-8213/aab7f0

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  • Dependence of the Onset of the Runaway Greenhouse Effect on the Latitudinal Surface Water Distribution of Earth-Like Planets Reviewed

    T. Kodama, A. Nitta, H. Genda, Y. Takao, R. O'ishi, A. Abe-Ouchi, Y. Abe

    Journal of Geophysical Research: Planets   123 ( 2 )   559 - 574   2018.2

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    DOI: 10.1002/2017JE005383

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  • Hydrocode modeling of the spallation process during hypervelocity impacts: Implications for the ejection of Martian meteorites Reviewed

    Kosuke Kurosawa, Takaya Okamoto, Hidenori Genda

    ICARUS   301   219 - 234   2018.2

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    DOI: 10.1016/j.icarus.2017.09.015

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  • On the Impact Origin of Phobos and Deimos. III. Resulting Composition from Different Impactors Reviewed

    Francesco C. Pignatale, Sébastien Charnoz, Pascal Rosenblatt, Ryuki Hyodo, Tomoki Nakamura, Hidenori Genda

    The Astrophysical Journal   853 ( 2 )   118 - 118   2018.1

  • Effects of Friction and Plastic Deformation in Shock-Comminuted Damaged Rocks on Impact Heating Reviewed

    Kosuke Kurosawa, Hidenori Genda

    Geophysical Research Letters   45 ( 2 )   620 - 626   2018.1

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    DOI: 10.1002/2017GL076285

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  • Martian Moons eXploration MMX elucidating the formation of habitable planets in the solar system Reviewed

    Kuramoto K., Morota T., Nagaoka H., Nakagawa H., Nakamura T., Ogawa K., Otake H., Ozaki M., Sasaki S., Senshu H., Tachibana S., Kawakatsu Y., Terada N., Usui T., Wada K., Watanabe S., MMX study team, Fujimoto M., Genda H., Hirata N., Imamura T., Kameda S., Matsumoto K., Miyamoto H.

    Planetary People - The Japanese Society for Planetary Sciences   27 ( 3 )   207 - 215   2018

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    &lt;p&gt;火星衛星Phobosからのサンプルリターンに挑む火星衛星探査計画 (Martian Moons eXploration: MMX) は,現在,宇宙航空研究開発機構 (JAXA) プリプロジェクトとして,2024年の打ち上げと5年の往還期間を設定し,精力的な検討・初期開発が進められている.MMXは,サンプル分析,Deimosを加えた火星衛星の近接観測,そして火星大気および火星圏のモニタリング観測を組み合わせることにより,惑星に寄りそう衛星という切り口と視座から,太陽系における大気と水を湛えたハビタブル惑星の形成と進化の解明に迫ろうとしている.&lt;/p&gt;

    DOI: 10.14909/yuseijin.27.3_207

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  • The terrestrial late veneer from core disruption of a lunar-sized impactor Reviewed

    H. Genda, R. Brasser, S. J. Mojzsis

    EARTH AND PLANETARY SCIENCE LETTERS   480   25 - 32   2017.12

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    DOI: 10.1016/j.epsl.2017.09.041

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  • On the Impact Origin of Phobos and Deimos. II. True Polar Wander and Disk Evolution Reviewed

    Ryuki Hyodo, Pascal Rosenblatt, Hidenori Genda, Sebastien Charnoz

    ASTROPHYSICAL JOURNAL   851 ( 2 )   2017.12

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  • Impact erosion model for gravity-dominated planetesimals Reviewed

    Hidenori Genda, Tomoaki Fujita, Hiroshi Kobayashi, Hidekazu Tanaka, Ryo Suetsugu, Yutaka Abe

    ICARUS   294   234 - 246   2017.9

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    DOI: 10.1016/j.icarus.2017.03.009

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  • On the Impact Origin of Phobos and Deimos. I. Thermodynamic and Physical Aspects Reviewed

    Ryuki Hyodo, Hidenori Genda, Sebastien Charnoz, Pascal Rosenblatt

    ASTROPHYSICAL JOURNAL   845 ( 2 )   2017.8

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    DOI: 10.3847/1538-4357/aa81c4

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  • Ejection of iron-bearing giant-impact fragments and the dynamical and geochemical influence of the fragment re-accretion Reviewed

    Hidenori Genda, Tsuyoshi Iizuka, Takanori Sasaki, Yuichiro Ueno, Masahiro Ikoma

    EARTH AND PLANETARY SCIENCE LETTERS   470   87 - 95   2017.7

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    DOI: 10.1016/j.epsl.2017.04.035

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  • The Charon-forming giant impact as a source of Pluto's dark equatorial regions Reviewed

    Yasuhito Sekine, Hidenori Genda, Shunichi Kamata, Taro Funatsu

    NATURE ASTRONOMY   1 ( 2 )   2017.2

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    DOI: 10.1038/s41550-016-0031

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  • Ring formation around giant planets by tidal disruption of a single passing large Kuiper belt object Reviewed

    Ryuki Hyodo, Sebastien Charnoz, Keiji Ohtsuki, Hidenori Genda

    ICARUS   282   195 - 213   2017.1

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    DOI: 10.1016/j.icarus.2016.09.012

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  • Diverse ring systems around giant planets Reviewed

    Hyodo Ryuki, Charnoz Sébastien, Ohtsuki Keiji, Genda Hidenori

    Planetary People - The Japanese Society for Planetary Sciences   26 ( 3 )   82 - 91   2017

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    DOI: 10.14909/yuseijin.26.3_82

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  • Formation and Evolution of Protoatmospheres Reviewed

    H. Massol, K. Hamano, F. Tian, M. Ikoma, Y. Abe, E. Chassefiere, A. Davaille, H. Genda, M. Guedel, Y. Hori, F. Leblanc, E. Marcq, P. Sarda, V. I. Shematovich, A. Stoekl, H. Lammer

    SPACE SCIENCE REVIEWS   205 ( 1-4 )   153 - 211   2016.12

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  • FORMATION OF CENTAURS' RINGS THROUGH THEIR PARTIAL TIDAL DISRUPTION DURING PLANETARY ENCOUNTERS Reviewed

    Ryuki Hyodo, Sebastien Charnoz, Hidenori Genda, Keiji Ohtsuki

    ASTROPHYSICAL JOURNAL LETTERS   828 ( 1 )   2016.9

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    DOI: 10.3847/2041-8205/828/1/L8

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  • Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons Reviewed

    Pascal Rosenblatt, Sebastien Charnoz, Kevin M. Dunseath, Mariko Terao-Dunseath, Antony Trinh, Ryuki Hyodo, Hidenori Genda, Steven Toupin

    NATURE GEOSCIENCE   9 ( 8 )   581 - +   2016.8

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    DOI: 10.1038/NGEO2742

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  • The giant impact simulations with density independent smoothed particle hydrodynamics Reviewed

    Natsuki Hosono, Takayuki R. Saitoh, Junichiro Makino, Hidenori Genda, Shigeru Ida

    ICARUS   271   131 - 157   2016.6

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    DOI: 10.1016/j.icarus.2016.01.036

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  • Origin of Earth's oceans: An assessment of the total amount, history and supply of water Reviewed

    Hidenori Genda

    GEOCHEMICAL JOURNAL   50 ( 1 )   27 - 42   2016

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    DOI: 10.2343/geochemj.2.0398

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  • Resolution dependence of disruptive collisions between planetesimals in the gravity regime Reviewed

    Hidenori Genda, Tomoaki Fujita, Hiroshi Kobayashi, Hidekazu Tanaka, Yutaka Abe

    ICARUS   262   58 - 66   2015.12

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    DOI: 10.1016/j.icarus.2015.08.029

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  • RAPID WATER LOSS CAN EXTEND THE LIFETIME OF PLANETARY HABITABILITY Reviewed

    Takanori Kodama, Hidenori Genda, Yutaka Abe, Kevin J. Zahnle

    ASTROPHYSICAL JOURNAL   812 ( 2 )   2015.10

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    DOI: 10.1088/0004-637X/812/2/165

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  • WARM DEBRIS DISKS PRODUCED BY GIANT IMPACTS DURING TERRESTRIAL PLANET FORMATION Reviewed

    H. Genda, H. Kobayashi, E. Kokubo

    ASTROPHYSICAL JOURNAL   810 ( 2 )   2015.9

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    DOI: 10.1088/0004-637X/810/2/136

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  • Formation of Phobos and Deimos via a giant impact Reviewed

    Robert I. Citron, Hidenori Genda, Shigeru Ida

    ICARUS   252   334 - 338   2015.5

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    DOI: 10.1016/j.icarus.2015.02.011

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  • Impact chemistry of methanol: Implications for volatile evolution on icy satellites and dwarf planets, and cometary delivery to the Moon Reviewed

    Yasuhito Sekine, Hidenori Genda, Yuta Muto, Seiji Stigita, Toshihiko Kadono, Takafumi Matsui

    ICARUS   243   39 - 47   2014.11

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    DOI: 10.1016/j.icarus.2014.08.034

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  • Infrared Doppler instrument (IRD) for the Subaru telescope to search for Earth-like planets around nearby M-dwarfs Reviewed

    Takayuki Kotani, Motohide Tamura, Hiroshi Suto, Jun Nishikawa, Bun'ei Sato, Wak Aoki, Tomonori Usuda, Takashi Kurokawa, Ken Kashiwagi, Shogo Nishiyama, Yuji Ikeda, Donald B. Hall, Klaus W. Hodapp, Shane Jacobson, Jun Hashimoto, Jun-Ichi Morino, Yasushi Okuyama, Yoichi Tanaka, Shota Suzuki, Sadahiro Inoue, Jungmi Kwon, Takuya Suenaga, Dehyun Oh, Haruka Baba, Norio Narita, Eiichiro Kokubo, Yutaka Hayano, Hideyuki Izumiura, Eiji Kambe, Tomoyuki Kudo, Nobuhiko Kusakabe, Masahiro Ikoma, Yasunori Hori, Masashi Omiya, Hidenori Genda, Akihiko Fukui, Yuka Fujii, Olivier Guyon, Hiroki Harakawa, Masahiko Hayashi, Masahide Hidai, Teruyuki Hirano, Masayuki Kuzuhara, Masahiro Machida, Taro Matsuo, Tetsuya Nagata, Hirohi Onuki, Masahiro Ogihara, Hideki Takami, Naruhisa Takato, Yasuhiro H. Takahashi, Chihiro Tachinami, Hiroshi Terada, Hajime Kawahara, Tomoyasu Yamamuro

    GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V   9147   2014

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    DOI: 10.1117/12.2055075

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  • Emergence of two types of terrestrial planet on solidification of magma ocean Reviewed

    Keiko Hamano, Yutaka Abe, Hidenori Genda

    NATURE   497 ( 7451 )   607 - +   2013.5

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    DOI: 10.1038/nature12163

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  • The naked planet Earth: Most essential pre-requisite for the origin and evolution of life Reviewed

    S. Maruyama, M. Ikoma, H. Genda, K. Hirose, T. Yokoyama, M. Santosh

    Geoscience Frontiers   4 ( 2 )   141 - 165   2013.3

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    DOI: 10.1016/j.gsf.2012.11.001

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  • Giant impacts in the Saturnian system: A possible origin of diversity in the inner mid-sized satellites Reviewed

    Yasuhito Sekine, Hidenori Genda

    PLANETARY AND SPACE SCIENCE   63-64   133 - 138   2012.4

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    DOI: 10.1016/j.pss.2011.05.015

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  • MERGING CRITERIA FOR GIANT IMPACTS OF PROTOPLANETS Reviewed

    H. Genda, E. Kokubo, S. Ida

    ASTROPHYSICAL JOURNAL   744 ( 2 )   2012.1

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    DOI: 10.1088/0004-637X/744/2/137

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  • Re-evaluation of the inner edge of habitable zone Reviewed

    Takanori Kodama, Hidenori Genda, Yutaka Abe, Kevin Zahnle

    Proceedings of the International Astronomical Union   8 ( 293 )   323 - 325   2012

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    DOI: 10.1017/S1743921313013082

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  • Giant impacts and debris disks Reviewed

    H. Genda, H. Kobayashi, E. Kokubo

    Proceedings of the International Astronomical Union   8 ( 293 )   270 - 272   2012

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    DOI: 10.1017/S1743921313012969

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  • The complete evaporation limit of land planets Reviewed

    Yuya Takao, Hidenori Genda, Miyuki Wakida, Yutaka Abe

    Proceedings of the International Astronomical Union   8 ( 293 )   336 - 338   2012

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    DOI: 10.1017/S1743921313013124

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  • Infrared Doppler Instrument for the Subaru Telescope (IRD) Reviewed

    M. Tamura, H. Suto, J. Nishikawa, T. Kotani, B. Sato, W. Aoki, T. Usuda, T. Kurokawa, K. Kashiwagi, S. Nishiyama, Y. Ikeda, D. Hall, K. Hodapp, J. Hashimoto, J. Morino, S. Inoue, Y. Mizuno, Y. Washizaki, Y. Tanaka, S. Suzuki, J. Kwon, T. Suenaga, D. Oh, N. Narita, E. Kokubo, Y. Hayano, H. Izumiura, E. Kambe, T. Kudo, N. Kusakabe, M. Ikoma, Y. Hori, M. Omiya, H. Genda, A. Fukui, Y. Fujii, O. Guyon, H. Harakawa, M. Hayashi, M. Hidai, T. Hirano, M. Kuzuhara, M. Machida, T. Matsuo, T. Nagata, Y. Ohnuki, M. Ogihara, S. Oshino, R. Suzuki, H. Takami, N. Takato, Y. Takahashi, C. Tachinami, H. Terada

    GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY IV   8446   2012

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    DOI: 10.1117/12.925885

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  • A ground-based observation of the LCROSS impact events using the Subaru Telescope Reviewed

    Peng K. Hong, Seiji Sugita, Natsuko Okamura, Yasuhito Sekine, Hiroshi Terada, Naruhisa Takatoh, Yutaka Hayano, Tetsuharu Fuse, Tae-Soo Pyo, Hideyo Kawakita, Diane H. Wooden, Eliot F. Young, Paul G. Lucey, Kosuke Kurosawa, Hidenori Genda, Junichi Haruyama, Reiko Furusho, Toshihiko Kadono, Ryosuke Nakamura, Shunichi Kamata, Taiga Hamura, Tomohiko Sekiguchi, Mitsuru Soma, Hirotomo Noda, Jun-ichi Watanabe

    ICARUS   214 ( 1 )   21 - 29   2011.7

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    DOI: 10.1016/j.icarus.2011.05.008

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  • Replacement and late formation of atmospheric N-2 on undifferentiated Titan by impacts Reviewed

    Yasuhito Sekine, Hidenori Genda, Seiji Sugita, Toshihiko Kadono, Takafumi Matsui

    NATURE GEOSCIENCE   4 ( 6 )   359 - 362   2011.6

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    DOI: 10.1038/NGEO1147

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  • Impact-induced N-2 production from ammonium sulfate: Implications for the origin and evolution of N-2 in Titan's atmosphere Reviewed

    Sho Fukuzaki, Yasuhito Sekine, Hidenori Genda, Seiji Sugita, Toshihiko Kadono, Takafumi Matsui

    ICARUS   209 ( 2 )   715 - 722   2010.10

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    DOI: 10.1016/j.icarus.2010.04.015

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  • FORMATION OF TERRESTRIAL PLANETS FROM PROTOPLANETS UNDER A REALISTIC ACCRETION CONDITION Reviewed

    Eiichiro Kokubo, Hidenori Genda

    ASTROPHYSICAL JOURNAL LETTERS   714 ( 1 )   L21 - L25   2010.5

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    DOI: 10.1088/2041-8205/714/1/L21

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  • Giant impacts and terrestrial planet formation Reviewed

    Hidenori Genda, Eiichiro Kokubo, Sigeru Ida

    EXOPLANETS AND DISKS: THEIR FORMATION AND DIVERSITY   1158   243 - +   2009

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  • A Numerical Study of Collisions of Icy Bodies Using the SPH Method Reviewed

    Miki Nakajima, Hidenori Genda, Shigeru Ida

    EXOPLANETS AND DISKS: THEIR FORMATION AND DIVERSITY   1158   257 - 258   2009

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  • Origin of the ocean on the Earth: Early evolution of water D/H in a hydrogen-rich atmosphere Reviewed

    Hidenori Genda, Masahiro Ikoma

    ICARUS   194 ( 1 )   42 - 52   2008.3

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    DOI: 10.1016/j.icarus.2007.09.007

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  • Formation of heavy element rich giant planets by giant impacts Reviewed

    H. Genda, M. Ikoma, T. Guillot, S. Ida

    Proceedings of the International Astronomical Union   3 ( 249 )   267 - 270   2007.10

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    DOI: 10.1017/S1743921308016682

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  • Enigmas of the lunar thermal evolution Reviewed

    Kuramoto Kiyoshi, Genda Hidenori, Arai Tomoko, Okada Tatsuaki, Sugita Seiji

    Planetary People   16 ( 3 )   197 - 207   2007.9

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  • On the origin of HD 149026b Reviewed

    M. Ikoma, T. Guillot, H. Genda, T. Tanigawa, S. Ida

    ASTROPHYSICAL JOURNAL   650 ( 2 )   1150 - 1159   2006.10

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    DOI: 10.1086/507088

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  • Constraints on the mass of a habitable planet with water of nebular origin Reviewed

    Masahiro Ikoma, Hidenori Genda

    ASTROPHYSICAL JOURNAL   648 ( 1 )   696 - 706   2006.9

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    DOI: 10.1086/505780

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  • Enhanced atmospheric loss on protoplanets at the giant impact phase in the presence of oceans Reviewed

    H Genda, Y Abe

    NATURE   433 ( 7028 )   842 - 844   2005.2

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    DOI: 10.1038/nature03360

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  • Survival of a proto-atmosphere through the stage of giant impacts: the mechanical aspects Reviewed

    H Genda, Y Abe

    ICARUS   164 ( 1 )   149 - 162   2003.7

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    DOI: 10.1016/S0019-1035(03)00101-5

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  • Modification of a proto-lunar disk by hydrodynamic escape of silicate vapor Reviewed

    H Genda, Y Abe

    EARTH PLANETS AND SPACE   55 ( 1 )   53 - 57   2003

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    DOI: 10.1186/BF03352462

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    遊・星・人 = Planetary people : 日本惑星科学会誌   32 ( 3 )   226 - 235   2023.9

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  • Shock recovery of rocky materials with decaying compressive pulses: The conditions required for producing shock metamorphic features

    黒澤耕介, 大野遼, 新原隆史, 三河内岳, 富岡尚敬, 伊佐純子, 鍵裕之, 松崎琢也, 佐久間博, 玄田英典, 境家達弘, 近藤忠, 鹿山雅裕, 小池みずほ, 佐野有司, 村山雅史, 佐竹渉, 松井孝典, 松井孝典

    衝撃波シンポジウム講演論文集(CD-ROM)   2022   2023

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    Abstracts of Annual Meeting of the Geochemical Society of Japan   69   216   2022

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    DOI: 10.14862/geochemproc.69.0_216

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    日本地球惑星科学連合大会予稿集(Web)   2022   2022

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    日本地球惑星科学連合大会予稿集(Web)   2021   2021

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    日本鉱物科学会年会講演要旨(Web)   2020   2020

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    日本惑星科学会秋季講演会予稿集(Web)   2020   2020

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    ELEMENTS   15 ( 2 )   122 - 122   2019.4

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  • Impact heating in oblique impacts with rocks including material strength

    脇田茂, 玄田英典, 黒澤耕介, DAVISON Thomas M.

    日本惑星科学会秋季講演会予稿集(Web)   2019   2019

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    日本惑星科学会秋季講演会予稿集(Web)   2018   2018

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    日本惑星科学会秋季講演会予稿集(Web)   2018   2018

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    Abstracts of Annual Meeting of the Geochemical Society of Japan   64 ( 0 )   139 - 139   2017

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    日本惑星科学会秋期講演会予稿集   2014   "O5 - 06"   2014.9

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  • Numerical modeling of impact phenomena using iSALE shock physics code

    Kurosawa K, Takata T, Senshu H, Wada K, Mikami T, Hirata N, Kamata S, Ishihara Y, Genda H, Nakamura A. M

    Planetary People   23 ( 2 )   103 - 110   2014

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    Language:Japanese   Publisher:The Japanese Society for Planetary Sciences  

    iSALE shock physics codeは惑星科学者に対して公開されている汎用性の高い衝突計算コードである.我々は日本の衝突コミュニテイでもiSALEを自由に扱い,研究を進められる環境を整備するために「iSALE users group in Japan」というグループを立ち上げた.本稿ではiSALEについての簡単な解説を行い,幾つかの計算例を示す.衝突現象は惑星科学の至るところで重要になってくる素過程である.自らの手で数値衝突計算を行えるようになれば,研究の幅が大きく広がることが期待できる.本稿がiSALEでどんなことができるのか想像するための一助となれば幸いである.

    DOI: 10.14909/yuseijin.23.2_103

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  • S21-03P 土星系中型質量衛星における多様性の起源 : SPH流体コードを用いたジャイアントインパクトのシミュレーション(一般ポスターセッション1,ポスター発表)

    藤田 航, 玄田 英典, 関根 康人, 杉田 精司

    日本惑星科学会秋期講演会予稿集   2011   120 - 120   2011.10

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  • 地球の水は宇宙のどこからやって来たのか

    ABE Yutaka, GENDA Hidenori

    化学と工業 = Chemistry and chemical industry   64 ( 7 )   540 - 541   2011.7

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  • すばるIRDによるサイエンス:M型星での惑星系形成

    小久保英一郎, 押野翔一, 堀安範, 生駒大洋, 立浪千尋, 玄田英典, 藤井友香, 荻原正博

    日本天文学会年会講演予稿集   2011   2011

  • 313 タイタン大気の窒素の起源と進化 : 氷地殻からの衝突脱ガスの役割(オーラルセッション10 惑星気象・惑星大気)

    福崎 翔, 関根 康人, 玄田 英典, 杉田 精司, 門野 敏彦, 松井 孝典

    日本惑星科学会秋期講演会予稿集   2009   64 - 64   2009.9

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  • Origin of the Earth's Ocean : Overview and Early Evolution of D/H

    GENDA Hidenori, IKOMA Masahiro

    Planetary people   17 ( 4 )   238 - 243   2008.12

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  • Report : Frontier Seminar 2007

    GENDA Hidenori

    Planetary People   16 ( 3 )   237 - 238   2007.9

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    Language:Japanese   Publisher:The Japanese Society for Planetary Sciences  

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  • S-86 Upcoming global cooling

    Maruyama S., Ikoma S., Genda H.

    114   44 - 44   2007.9

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    Language:Japanese   Publisher:The Geological Society of Japan  

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  • Effects of hydrogen on limits of radiative emission from a planet with a saturated-water-vapor atmosphere

    Miki Nakajima, Masahiro Ikoma, Hidenori Genda, Shigeru Ida

    GEOCHIMICA ET COSMOCHIMICA ACTA   71 ( 15 )   A702 - A702   2007.8

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  • Imperfect accretion during the giant impact stage of terrestrial planet formation

    H. Genda, E. Kokubo, S. Ida

    GEOCHIMICA ET COSMOCHIMICA ACTA   71 ( 15 )   A316 - A316   2007.8

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  • Origins of Sea Water on the Earth

    Masahiro Ikoma, Hidenori Genda

    J. Geography   116 ( 1 )   196 - 210   2007

  • Effects of Giant Impacts on the Atmosphere Formation of Terrestrial Planets

    Genda Hidenori, Abe Yutaka

    Planetary People   13 ( 2 )   94 - 98   2004.6

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  • Effects of giant impacts on the atmosphere formation

    H Genda, Y Abe

    GEOCHIMICA ET COSMOCHIMICA ACTA   66 ( 15A )   A270 - A270   2002.8

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  • A mixed proto-atmosphere during the runaway accretion

    Y Abe, H Genda, K Nishikawa

    GEOCHIMICA ET COSMOCHIMICA ACTA   66 ( 15A )   A5 - A5   2002.8

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Awards

  • 東京工業大学 2021年度理学院教員教育賞

    2022.3   東京工業大学  

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  • Geochemical Journal 賞

    2017.8   日本地球化学会  

    玄田 英典

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  • 最優秀発表賞

    2003.10   日本惑星科学会  

    玄田 英典

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Research Projects

  • 原始惑星系円盤外縁部に存在した太陽系第三世界の初期状態の解明

    Grant number:24H00259  2024.4 - 2029.3

    日本学術振興会  科学研究費助成事業  基盤研究(A)

    中村 智樹, 牛久保 孝行, 上椙 真之, 藤谷 渉, 玄田 英典

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    Grant amount:\47190000 ( Direct Cost: \36300000 、 Indirect Cost:\10890000 )

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  • Understanding of the diversity of prebiotic chemistries and emergence of molecular systems in various planetary environments in the Solar System

    Grant number:22K21344  2022.12 - 2029.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Fund for the Promotion of Joint International Research (International Leading Research )

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    Grant amount:\689000000 ( Direct Cost: \530000000 、 Indirect Cost:\159000000 )

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  • Aquaplanetology

    Grant number:22H04900  2022.4 - 2023.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

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    Grant amount:\3900000 ( Direct Cost: \3000000 、 Indirect Cost:\900000 )

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  • To elucidate formation process of martian moons

    Grant number:21H04514  2021.4 - 2026.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)  Grant-in-Aid for Scientific Research (A)

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    Grant amount:\41730000 ( Direct Cost: \32100000 、 Indirect Cost:\9630000 )

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  • 岩石・氷・ガス惑星の衛星形成の総合的モデル:太陽系、系外惑星系

    Grant number:21H04512  2021.4 - 2026.3

    日本学術振興会  科学研究費助成事業 基盤研究(A)  基盤研究(A)

    井田 茂, 兵頭 龍樹, 佐々木 貴教, 玄田 英典

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    Grant amount:\41210000 ( Direct Cost: \31700000 、 Indirect Cost:\9510000 )

    円盤の化学組成と相状態: 惑星は一般に中心から鉄、岩石、氷、大気の層構造を持ち、天体衝突で飛び出す物質の組成や相状態は、惑星や衝突天体の組成や質量により大きく変わる。周惑星円盤の組成および各成分の蒸発率を統一的に求めるために、様々な化学組成、質量の惑星に対して、蒸発や凝縮といった現実的な相変化を組み込んだ高精度衝突数値計算を、パラメータを変えて系統的に実行した。その結果、氷成分を多く含む惑星同士の衝突で形成される周惑星円盤においては、大型の衛星の集積は極めて制限されることが定量的にわかった。このことは、天文観測サーベイがすでに始まっている、太陽系外の惑星のまわりをめぐる衛星を考える際には重要である。この結果の第一報は高インパクトファクターを持つ学術誌 Nature Communications に発表した。今後もさらに詳しい解析を続けたい。
    小天体の潮汐捕獲と円盤形成 : 小天体は惑星に近づくと潮汐変形でエネルギーを失って、惑星重力場に捕獲されると同時に破壊されて、破片円盤を作る可能性が高い。潮汐破壊時にも温度は上がり、放出された破片粒子は当初は楕円軌道を持つので、破片同士の衝突速度は大きく、その衝突でも加熱を受ける。このような加熱過程を詳しく調べるために、重力N体数値シミュレーションを行った。その結果、氷を主成分とする天体の破壊によって作られた氷粒子の破片円盤であっても、加熱は十分には強くなく、そこに含まれていた有機物の多くは残ることが示された。今後、この結果を詳しく解析していきたい。

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  • Japan-France joint research on the origin of Martian moons

    Grant number:20KK0080  2020.10 - 2026.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))  Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))

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    Grant amount:\18720000 ( Direct Cost: \14400000 、 Indirect Cost:\4320000 )

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  • 新しい時代の太陽系物質科学:マルチスケールで見た含水小惑星の形成進化過程

    Grant number:20H00188  2020.4 - 2024.3

    日本学術振興会  科学研究費助成事業 基盤研究(A)  基盤研究(A)

    中村 智樹, 牛久保 孝行, 上椙 真之, 玄田 英典, 臼井 文彦, 三宅 亮

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    Grant amount:\46280000 ( Direct Cost: \35600000 、 Indirect Cost:\10680000 )

    はやぶさ2探査機が回収する予定の小惑星リュウグウサンプルの初期分析を担当するため,その分析方法の開発と炭素質隕石サンプルを用いたリハーサル分析を行った.また,小惑星リュウグウは天体表面の分光観察により,加熱された可能性があるため,CIコンドライトを用いて加熱実験を行い,その加熱物を用いて一連の分析を行った.大気遮断状態でのサンプルのハンドリング,大気遮断状態での反射スペクトル測定,大気遮断での放射光X線回折分析,大気遮断での放射光XANES分析,大気暴露下での放射光CT分析,走査型,および透過型電子顕微鏡を用いた組織観察などをCIコンドライト,CMコンドライト,およびその加熱物に対して行った.その結果,小惑星リュウグウの反射スペクトルはCIコンドライトの粗粒(mmサイズ)粒子の300度程度に還元下で加熱したものと類似することが分かった.また,このとき,層状ケイ酸塩のFeの価数が3価に富んだ状態から2価に富んだ状態に還元されていることが分かった.一方,X線回折分析より300度の加熱では,層状ケイ酸塩(Saponite, serpentine)は分解していないことが分かった.一連の炭素質隕石を用いたリハーサルの結果と,実際のリュウグウ回収サンプルの分析結果を比較することで,小惑星リュウグウの形成進化史を解明することを目指す.

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  • 隕石に刻まれた初期太陽系衝突史の復元

    Grant number:19H00726  2019.4 - 2023.3

    日本学術振興会  科学研究費助成事業 基盤研究(A)  基盤研究(A)

    黒澤 耕介, 玄田 英典, 新原 隆史, 鹿山 雅裕, 小池 みずほ, 三河内 岳, 佐野 有司, 松井 孝典

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    Grant amount:\45370000 ( Direct Cost: \34900000 、 Indirect Cost:\10470000 )

    本研究課題の起点である岩石物質の「塑性変形加熱」の効果を実証した. 数値衝突計算で炭酸塩岩からの脱ガス量を計算し先行研究の実験結果と比較した. その結果, 完全流体モデルでは実験結果よりも系統的に少ない脱ガス量となり, 弾塑性体モデルで塑性変形加熱が顕著に起こる場合のみ実験結果を再現できることを確かめた.
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    2020年度より博士研究員を雇用し, 3次元衝撃回収実験手順を確立した.まずは地球上の典型的な堆積岩である炭酸塩岩(大理石), 火成岩である玄武岩を用いて衝撃回収実験を行った. 初期の層序を保ったまま衝撃を受けた試料を回収できるまで手順を最適化した. 衝突点に近づくほど衝撃後の変化が顕著になる様子が観察され, 狙い通りに天然衝突と同様の幾何条件で衝撃を受けた試料を回収することができた. 試料が経験した衝撃圧力を定量化するため数値衝突計算を実施した. その結果, 炭酸塩岩がおよそ3 GPaで波状消光と呼ばれる組織を示すようになり, 衝撃指標となり得ることを見出した. また玄武岩では~10 GPa程度の比較的低い衝撃圧で局所的に熔融脈が発生することを発見した. 数値衝突計算で温度上昇も調べたところ, 10 GPa程度では玄武岩の融点を超えることはなかった. 衝撃時の温度分布が従来の想定よりも著しく局在化する可能性を示唆する. このような低い衝撃圧力と熔融脈の存在が観られる組織はHED隕石中で実際に発見されている. この組織を読み解く圧力の尺度を定量的に与えたことになる.
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    実際の隕石分析でも成果が得られた. 高解像度二次イオン質量分析を用いて, 小惑星ベスタ由来の隕石に含まれる微小リン酸塩鉱物のU-Pb年代を測定し, 小惑星が経験した41.5億年以前の天体衝突の痕跡を発見した.

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  • Construction of Earth formation model by isotopic analysis of siderophile elements in meteorites and Archean igneous rocks

    Grant number:19H00715  2019.4 - 2023.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)  Grant-in-Aid for Scientific Research (A)

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    Grant amount:\45630000 ( Direct Cost: \35100000 、 Indirect Cost:\10530000 )

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  • Aqua planetology

    Grant number:17H06454  2017.6 - 2022.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)  Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

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    Grant amount:\103090000 ( Direct Cost: \79300000 、 Indirect Cost:\23790000 )

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  • Modeling of water and material circulations in the solar system objects

    Grant number:17H06457  2017.6 - 2022.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)  Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

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    Grant amount:\109200000 ( Direct Cost: \84000000 、 Indirect Cost:\25200000 )

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  • Study on impact spallation: Material transfer between planetary bodies by impacts

    Grant number:17H02990  2017.4 - 2020.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

    Genda Hidenori

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    Grant amount:\17680000 ( Direct Cost: \13600000 、 Indirect Cost:\4080000 )

    We performed impact simulations and experiments in order to reveal the details of the impact spallation process. We newly found "late-stage acceleration" mechanism, where the lightly shocked surface materials near the impact point are accelerated by the pressure gradient at the root of the ejecta curtain. We also confirmed this mechanism in our impact experiments. This new mechanism can explain the ejection of Martian meteorites, which experienced relatively low peak pressures, from the Martian surface. We applied the impact simulations for the material transfer from the Martian surface to Martian moons, and found that the transferred mass was more than 10 times than previously estimated.

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  • On the probability of moons formation

    Grant number:15K13562  2015.4 - 2017.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research  Grant-in-Aid for Challenging Exploratory Research

    GENDA Hidenori, CHARNOZ Sebastian, ROSENBLATT Pascal, HYODO Ryuki

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    Grant amount:\3770000 ( Direct Cost: \2900000 、 Indirect Cost:\870000 )

    We developed the new numerical code that includes the orbital evolution of protoplanets and collisional process of them. We carried out 10 simulations of terrestrial planet formation, and extracted the impact conditions for giant impacts. First we focused on the Martian moons, and discussed the possibility of their formation via a giant impact onto Mars. Next we showed that Pluto's satellite Charon can also be formed by a giant impact that happened in the outer solar system.

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  • Understanding of planetary diversity originated from coupled evolution of early atmosphere and magma ocean

    Grant number:26800242  2014.4 - 2018.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)  Grant-in-Aid for Young Scientists (B)

    Hamano Keiko, ABE Yutaka, GENDA Hidenori

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    Grant amount:\3900000 ( Direct Cost: \3000000 、 Indirect Cost:\900000 )

    We have developed a coupled model of H2-H2O atmospheres and magma oceans to investigate how initial redox state of atmospheres and magma oceans affects solidification time and the subsequent early climate. Our model includes blanketing effects by an H2-H2O atmosphere, escape of H2 into space, outgassing of H2 and H2O, and redox reaction between an atmosphere and a magma ocean. At the Earth’s orbit, amount of H2 has less affected the solidification time of a magma ocean, as long as the total H2 water-equivalent mass is less than several ocean mass of water. However, the initial composition of the atmosphere greatly affects the atmospheric composition after solidification. If several bars of H2 remains after the solidification, it can keep the surface temperature above the freezing point of water without other greenhouse gases. In the case with the larger H2 amount or at closer orbit to the young Sun, the solidification time becomes sensitive to the initial amount of H2 and H2O.

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  • Modelling of Collisional Disruption of Planetary Bodies via Large-scale Numerical Simulations

    Grant number:26287101  2014.4 - 2018.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

    Tanaka Hidekazu, SUETSUGU Ryo

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    Grant amount:\16900000 ( Direct Cost: \13000000 、 Indirect Cost:\3900000 )

    In this work, by performing a large-scale survey of numerical simulations, we constructed an accurate and unified model of collisional disruption, which is a key process in various studies of planetary sciences. As the numerical methods, we used three kinds of methods, i.e., a SPH code, a mesh (iSALE) code, and a DEM code, which enable us to obtain the total ejecta mass at various impacts for planetary bodies with a wide size range from km-size to 1000km-size.
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    Clarifying the resolution dependence of the collisional disruption, we developed the method to calculate the convergent value at high-resolution limit. From a survey of accurate numerical simulations applied this method to, we obtain a new scaling law of the total ejecta mass, which is valid for a wide range of parameters (sizes of colliding bodies, the impact velocity, and the angle) and succeeded in modelling the collisional disruption. We also applied this new model to Jovian planets formation and obtained constraints on it.

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  • Hydrogen Isotopic Evolution of Earth's Seawater

    Grant number:26287125  2014.4 - 2017.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

    Ueno Yuichiro, SHIBUYA Takazo, FORIEL Julien

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    Grant amount:\16770000 ( Direct Cost: \12900000 、 Indirect Cost:\3870000 )

    Hydrogen isotopic compositions of Archean basalts were determined by TCEA-IRMS technique. The analysis of more than 200 samples from 3.2 Ga Cleaverville Formation showed that dD values of hydrous minerals are clearly correlated with metamorphic grade which reflect ocean-floor metamorphism at that time based on metamorphic mineral assemblages. Also, the dD values are correlated with water content of the basaltic rocks as observed in modern seafloor basalts. These observations all indicate that hydrous minerals in the Cleaverville basalts preserve the isotopic composition of Archean seawater. The estimated dD value of the 3.2 billion-years-old seawater is -21±5‰, indicating deuterium content of Earth's seawater increased through the history of the Earth, potentially owing to hydrogen escape into space. Furthermore, we found igneous amphibole from the most D-depleted sample, suggesting not only Archean seawater but also Archean mantle was depleted in deuterium.

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  • Modelling and theoretical study for exoplanet atmospheres

    Grant number:23103003  2011.4 - 2016.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)  Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

    Kuramoto Kiyoshi, ISHIWATARI Masaki, GENDA Hidenori, TAKEHIRO Shinichi, SASAKI Yohei, NAKAJIMA Kensuke, HAMANO Keiko, ONISHI Masanori

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    Grant amount:\143000000 ( Direct Cost: \110000000 、 Indirect Cost:\33000000 )

    Evolution of steam atmospheres on earth-like planets after each final giant impact event is theoretically solved with an analysis of its observability. Two types of evolutionary tracks are found: one is the rapid formation of a water ocean and another is the long-term persistence of the magma ocean state. The secular loss of surface water due to atmospheric escape driven by stellar UV irradiation may rather stabilize surface liquid water than merely produce an arid surface environment. General circulation experiments provided with various boundary conditions reveal that a synchronously rotating planet and a land planet may have wider habitable zones than previously thought. Numerical models to solve cloud convection and radiative transfer in gas giant planets are also developed, revealing the mechanisms for the intermittencies observed for cloud convection in the solar system gas planets as well as roles of cloud layers on controlling the thermal emission from gas giant atmospheres.

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  • Development of Impact Simulation Code with GPU

    Grant number:22740291  2010 - 2012

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)  Grant-in-Aid for Young Scientists (B)

    GENDA Hidenori

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    Grant amount:\3380000 ( Direct Cost: \2600000 、 Indirect Cost:\780000 )

    We developed a GPU-based code for impact calculation from CPU-based code. We added some new components to our code in order to solve the equations quickly. Finally, calculation speed becomes 30 times faster than the previous CPU-based code. We applied our code to several problems. We performed very high-resolution simulation of the moon forming impact, and we found that the effect of angular momentum transport was week. We conducted cooperative research on impact simulation with experimental lab.

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  • Dependence of extrasolar planetary systems on host stars' metallicity

    Grant number:20244013  2008 - 2011

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)  Grant-in-Aid for Scientific Research (A)

    IDA Shigeru, SATO Bun' ei, WATANABE Junichi, KAWAI Nobuyuki, GENDA Hidenori

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    Grant amount:\46670000 ( Direct Cost: \35900000 、 Indirect Cost:\10770000 )

    More than 750 extrasolar planets have been discovered, as well as more than 2300 candidates by Kepler space telescope, which motivates statistical discussions of planets and planetary systems. Here we investigated dependence of planetary systems on metallicity of the host stars. N-body and fluid dynamical simulations for planet-planet scattering and collisions have been carried out. Combining these results, we also performed Monte Carlo simulations to find that in a metal-rich disk around a metal-rich star, multiple gas giants are formed and they undergo orbital stability to pump up orbital eccentricities. We also promoted radial velocity surveys and construct a transit follow-up network involving amateurs and students to study the problem both from theory and observation.

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  • Terrestrial planet formation including impact process

    Grant number:20740252  2007 - 2009

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)  Grant-in-Aid for Young Scientists (B)

    GENDA Hidenori

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    Grant amount:\3510000 ( Direct Cost: \2700000 、 Indirect Cost:\810000 )

    We have made the hybrid code including both the orbital evolution and impact process of the protoplanets. Such two processes are fundamental to the planet formation. Using this hybrid code for the giant impact stage, we systematically investigate the terrestrial planet formation, and derive the important statics such as the final number of the terrestrial planets, their mass, spin states, and so on. From these outcomes, we discuss the generality and specificity of the terrestrial planets.

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  • 地球型惑星の大気形成:惑星形成過程における混合大気の寄与

    Grant number:04J04281  2004 - 2006

    日本学術振興会  科学研究費助成事業 特別研究員奨励費  特別研究員奨励費

    玄田 英典

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    Grant amount:\3400000 ( Direct Cost: \3400000 )

    地球型惑星は原始太陽系星雲ガス(ネビュラガス)の中で形成した可能性が高いことが惑星形成理論および観測からわかっている。微惑星の衝突合体によって惑星が現在の月サイズよりも大きくなると、周囲のネビュラガスを重力的に捕獲し始める。また、微惑星に含まれている揮発性成分が脱ガスするのも惑星が月サイズ以上になってからである。脱ガスは地表面付近で起こるため、大気の混合を考慮しなければ、脱ガス成分の大気を下層、ネビュラガス成分の大気を上層とした2層大気が惑星の初期には形成されたはずである。原始太陽系星雲ガスが散逸するときに、上層のネビュラガス成分の大気は散逸し、下層の脱ガス成分の大気が生き残ることが定性的にわかるが、2層の混合によってネビュラガス成分が生き残ってしまう可能性もある。
    混合を考慮し、大気の構造を数値的に解くプログラムを作成した。その結果、惑星が火星サイズ程度の場合、対流は地表面付近で起こっており、その領域は薄く、脱ガス大気とネビュラ大気の混合があまり起こらないことがわかった。一方、惑星が地球サイズ程に成長すると、対流層が厚くなり、必然的に2層の混合が大規模に起こることがわかった。
    ネビュラガスには、大量の希ガスが含まれており、量的にも同位体組成的にも、現在の地球大気のものとは異なっている。そのため、地球サイズの惑星では、混合によって混ざってしまったネビュラガス成分が、何らかのメカニズムで失われる必要がある。そのメカニズムとして、太陽UVによる大気の散逸を考えた。惑星形成時の太陽EUVが現在の100倍程度強いことと、惑星大気が分子量の小さな水素大気を主体とすることから、大規模な水素大気の散逸が起こる。そして散逸する水素分子に引きずられて分子量の大きな希ガスも散逸し、現在の地球大気中の希ガス量まで減少させることが可能であることがわかった。

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  • 巨大天体衝突を考慮した惑星初期進化の研究

    Grant number:01J06173  2001 - 2003

    日本学術振興会  科学研究費助成事業 特別研究員奨励費  特別研究員奨励費

    玄田 英典

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    Grant amount:\3000000 ( Direct Cost: \3000000 )

    地球型惑星は、その形成末期に火星サイズの天体が複数回衝突したと考えられている。このような巨大天体衝突で解放されるエネルギーは極めて大きく、惑星表層には、ケイ酸塩が蒸発してできたケイ酸塩ガス大気と、もともと惑星が保持していた原始大気の混合大気が形成される。これら混合大気は極めて高温で(5000K以上)あるため、分子量の小さい水素は、熱的に散逸する可能性がある。本年度は、これら混合大気からの水素の熱的散逸について研究を行った。水素の大規模な散逸が起これば、水素散逸に引きずられて、その他の分子量の大きな気体も散逸し、その影響が残るはずである。このことは、惑星大気の起源と進化を考える上で重要である。
    数値計算を行った結果、惑星表面が高温時(4000K以上)の場合は、惑星表層に分子量の比較的大きなケイ酸塩ガスが大量に存在し、水素散逸が、ケイ酸塩ガスのドラッグによって抑制されることがわかった。この場合の水素散逸のタイムスケールは、100万年以上となることがわかった。また、惑星表面が低温時(4000K以下)の場合は、水素以外の分子量の大きな分子(H_2OやCO_2)が、水素散逸を抑制し、同様に水素散逸のタイムスケールが100万年以上となることがわかった。一方、惑星表層の冷却のタイムスケールは数万年と早く、事実上、巨大天体衝突後の大規模な熱的散逸は起こらないということがわかった。
    以上の研究は、地球惑星科学関連学会2003年合同大会、第36回月惑星シンポジウム、日本惑星科学会2003年秋季講演会で発表をした。また、3月に行われる35th Lunar and Planetary Science Conference (Houston, America)で発表予定である。

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Teaching Experience

  • Computational Planetary Science

    2019.4 Institution:Tokyo Institute of Technology

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  • 電子計算機論

    Institution:横浜市立大学

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  • 応用電子計算機論

    Institution:横浜市立大学

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  • 地球惑星物理学演習

    Institution:東京大学

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  • 地球の理解

    Institution:立教大学

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  • 地球科学概論II

    Institution:慶應義塾大学

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  • 地球惑星環境学基礎演習II

    Institution:東京大学

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  • 全学ゼミ

    Institution:東京大学

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  • 地球惑星科学特別講義

    Institution:京都大学

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