衝突蒸気雲内の炭素化合物反応過程の実験的研究-地球初期大気組成の解明に向けて-

• Project/Area Number: 17684028
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Geochemistry/Astrochemistry
• Research Institution: The University of Tokyo
• Principal Investigator: 杉田 精司 The University of Tokyo, 大学院・新領域創成科学研究科, 准教授 (80313203)
• Project Period (FY): 2005 – 2007
• Project Status: Completed (Fiscal Year 2007)
• Budget Amount: ¥29,900,000 (Direct Cost: ¥23,000,000、Indirect Cost: ¥6,900,000); Fiscal Year 2007: ¥5,330,000 (Direct Cost: ¥4,100,000、Indirect Cost: ¥1,230,000); Fiscal Year 2006: ¥8,190,000 (Direct Cost: ¥6,300,000、Indirect Cost: ¥1,890,000); Fiscal Year 2005: ¥16,380,000 (Direct Cost: ¥12,600,000、Indirect Cost: ¥3,780,000)
• Keywords: 高速衝突物理 / 高速化学反応 / 有機分析 / 衝突蒸気雲 / 地球初期大気 / 生命の起源 / 天体衝突 / 衝突閃光

Research Abstract

研究計画第3年度の本年度は、(1)熱的に非平衡状態にある可能性のあるCNやC_2,CHラジカルを定量的に分光計測するための新しい解析法を開発すること、(2)ビームサイズおよび照射強度を大きく変化させてレーザー照射による衝突模擬実験によるガス生成物の収量変化を計測することを実験目標とした。その結果、(A)振動状態に関して非平衡な2原子分子についても回転温度のみを取り出して計測する計測方法を確立することができた。この計測方法を使うことにより、レーザー照射によって作った高温蒸気雲が、どのような条件の天体衝突によって作られる衝突蒸気雲に対応するかを定量的に評価することができるようになった。この方法を実際に利用することにより、本研究で生成しているレーザー蒸気雲は、1-8km/sの速度で斜め衝突した際に発生する大気と光速衝突破片の間の空力加熱由来の高温蒸気をよく再現していることが分かった。(B)こうして得られた対応関係を踏まえ上記(2)の実験結果を解析したところ、高速衝突破片内の還元炭素が窒素大気と反応して単純有機物であるHCNに変換する効率φは、衝突速度νに強く依存せず(φ∝V<-0.5>)、宇宙速度(>11.2km/s)においてもHCNが生成される可能性を示す結果を得た。一方、衝突蒸気雲の半径γはφに大きな影響を与えうることが示された(φ∝γ<-1.75>)。これは、衝突天体が斜め衝突した際に、細粒に破砕され且つ速やかに空間的に分散すれはHCNが効率的に生成されることを示唆している。本研究で得たφの推定値は、直径1km以下の小型炭素質小惑星が地球に斜め衝突した際には数百km^2程度の面積にわたって、10mol/m^2という多量のHCNが供給されるということに対応し、天体衝突が生命の発生に大きな影響与えた可能性を強く示唆している。

Research Products

• [Journal Article] The role of organic haze in Tita's atmospheric chemistry I: Laboratory investigation on heterogeneous reaction of atomic hydrogen with Titan tholin (2008)
  • Author(s): Sekine, Y., H. Imanaka, T. Matsui, B. N. Khare, E. L. O. Bakes, C. P. McKay, and S. Sugita
  • Journal Title: Icarus 194 Pages: 186-200
  • Peer Reviewed
• [Journal Article] The role of organic haze in Tita's atmospheric chemistry II: Effect of heterogeneous reaction to the hydrogen budget and chemical composition of the atmosphere (2008)
  • Author(s): Sekine, Y., S. Lebonnois, H. Imanaka, T. Matsui, B. N. Khare, E. L. O. Bakes^5, C. P. McKay, and S. Sugita
  • Journal Title: Icarus 194 Pages: 201-211
  • Peer Reviewed
• [Journal Article] Hydrodynamical and Radiative Transfer Modeling of Meteoroid Impacts into Saturn's Rings (2008)
  • Author(s): Chambers, L. S., J. N. Cuzzi, E. Asphaug, J. Colwell and S. Sugita
  • Journal Title: Icarus 194 Pages: 623-635
  • Peer Reviewed
• [Journal Article] The chemical composition of the early terrestrial atmosphere: Formation of a reducing atmosphere from CI-like material (2007)
  • Author(s): Hashimoto, G., Y. Abe, and S. Sugita
  • Journal Title: Journal of Geophysical Research 112
  • Peer Reviewed
• [Journal Article] Thermal alternation of hydrated minerals during hypervelocity capture to silica aerogel at the flyby speed of Stardust (2007)
  • Author(s): Noguchi, T., T. Nakamura, K. Okudaira, H. Yano, S. Sugita, and M. J. Burchell
  • Journal Title: Meteoritics Planetary Science 42 Pages: 357-372
  • Peer Reviewed
• [Journal Article] Spectroscopic observation of thermal dissociation of SiO_2 in impact-induced vapor (2007)
  • Author(s): Fuyuki, M., S. Sugita, S. Hasegawa, T. Kadono, and T. Matsui
  • Journal Title: Earth Planets and Space 59 Pages: 437-451
  • Peer Reviewed
• [Journal Article] Thickness and formation age of surface layer on Comet 9P/Tempel 1 (2007)
  • Author(s): Kadono, T., S. Sugita, S. Sako, T. Ootsubo, M. Honda, H. Kawakita, T. Miyata, R. Furusho, and J. Watanabe
  • Journal Title: Astrophysical Journal (Letters) 661
  • Peer Reviewed
• [Journal Article] Non-intrusive measurements of crater growth (2007)
  • Author(s): Barnouin-Jha, O. S., S Yamamoto, T. Toriumi, S. Sugita, and T. Matsui
  • Journal Title: Icarus 188 Pages: 506-521
  • Peer Reviewed
• [Journal Article] Spectroscopic observation of thermal dissociation of SiO_2 in impact-induced vapor (2007)
  • Author(s): Fuyuki, M., S.Sugita, S.Hasegawa, T.Kadono, T.Matsui
  • Journal Title: Earth Planets and Space (印刷中)
• [Journal Article] The chemical composition of the early terrestrial atmosphere : Formation of a reducing atmosphere from CI-like material (2007)
  • Author(s): Hashimoto, G., Y.Abe, S.Sugita
  • Journal Title: Journal of Geophysical Research (印刷中)
• [Journal Article] Thickness and formation age of surface layer on Comet 9P/Tempel 1 (2007)
  • Author(s): Kadono, T., S.Sugita, S.Sako, T.Ootsubo, M.Honda, H.Kawakita, T.Miyata, R.Furusho, J.Watanabe
  • Journal Title: Astrophysical Journal (Letters) (印刷中)
• [Journal Article] An experimental study on Fischer-Tropsch catalysis : Implications for impact phenomena and nebular (2006)
  • Author(s): Sekine, Y., S.Sugita, T.Shido, T.Yamamoto, Y.Iwasawa, T.Kadono, T.Matsui
  • Journal Title: Meteoritics and Planetary Science 41 Pages: 715-729
• [Journal Article] The role of Fischer-Tropsch catalysis in jovian subnebula chemistry (2006)
  • Author(s): Mousis O., Y.Alibert, Y.Sekine, S.Sugita, T.Matsui
  • Journal Title: Astronomy and Astrophysics 459 Pages: 965-968
• [Journal Article] The role of ricochet impact on impact vaporization (2006)
  • Author(s): Schultz, P.H., S.Sugita, C.A.Eberhardy, C.M.Ernst
  • Journal Title: International Journal of Impact Engineering 33 Pages: 771-780
• [Journal Article] An experimental study on Fischer-Tropsch catalysis : Implications for impact phenomena and nebular (2006)
  • Author(s): Sekine, Y., S.Sugita, T.Shido, T.Yamamoto, Y.Iwasawa, T.Kadono, T.Matsui
  • Journal Title: Meteoritics and Planetary Science (印刷中)
• [Journal Article] Subaru Telescope Observations of Deep Impact (2005)
  • Author(s): S.Sugita, T.Ootsubo, T.Kadono, M.Honda, S.Sako, T.Miyata et al.
  • Journal Title: Science 310 Pages: 274-278
• [Journal Article] Deep Impact : Observations from a Worldwide Earth-Based Campaign (2005)
  • Author(s): Meech, K.Ageorges, N., A'Hearn, M.F., Arpigny, C., Ates, Aycock, J., Bagnulo, S., Bailey, J., Barber, R., Barrera et al.
  • Journal Title: Science 310 Pages: 265-269
• [Journal Article] The role of Fischer-Tropsch catalysis in the origin of methane-rich Titan (2005)
  • Author(s): Sekine, Y., S.Sugita, T.Shido, T.Yamamoto, Y.Iwasawa, T.Kadono, T.Matsui
  • Journal Title: Icarus 178 Pages: 154-164
• [Journal Article] Velocity distributions of high-velocity ejecta from regolith targets (2005)
  • Author(s): Yamamoto, S., T.Kadono, S.Sugita, T.Matsui
  • Journal Title: Icarus 178 Pages: 264-273
• [Presentation] An experimental study on HCN production in redox-neutral atmospheres by oblique impacts: size and velocity scaling (2008)
  • Author(s): Kurosawa, K., K. Ishibashi, S. Sugita, T. Kadono, S. Ohno, and T. Matsui
  • Organizer: 39th Lunar and Planetary Science Conference
  • Place of Presentation: League City, Texas, USA
  • Year and Date: 2008-03-12
• [Presentation] Acceleration of projectiles to>10 km/s with a laser gun: Toward silicate impact vaporization experiments (2008)
  • Author(s): Sugita, S., T. Kadono, K. Shigemori, S. Fujioka, K. Otani, T. Sano, Y. Sakawa, H. Azechi, N. Ozaki, T. Kimura, K. Miyanishi, T. Endo, M. Arakawa, A. M. Nakamura, and T. Matsui
  • Organizer: 39th Lunar and Planetary Science Conference
  • Place of Presentation: League City, Texas, USA
  • Year and Date: 2008-03-11
• [Presentation] The effects of target material properties on transient crater growth (2008)
  • Author(s): Yamamoto, S., S. Sugita, and T. Matsui
  • Organizer: 39th Lunar and Planetary Science Conference
  • Place of Presentation: League City, Texas, USA
  • Year and Date: 2008-03-11
• [Presentation] Constrants from laboratory experiments on crater excavation and formation of an uprange forbidden zone in an oblique impact (2008)
  • Author(s): Herrick, R. R., S. Yamamoto, O. S. Barnouin-Jha, S. Sugita, and T. Matsui
  • Organizer: 39th Lunar and Planetary Science Conference
  • Place of Presentation: League City, Texas, USA
  • Year and Date: 2008-03-11
• [Presentation] Impact devolatilization of calcite; Direct measurements using a laser gun (2008)
  • Author(s): Ohno, S. T. Kadono, K. Ishibashi, K. Kawaragi, S. Sugita, E. Nakamura, and T. Matsui
  • Organizer: 39th Lunar and Planetary Science Conference
  • Place of Presentation: League City, Texas, USA
  • Year and Date: 2008-03-11