| Project/Area Number |
02640305
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体地球物理学
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| Research Institution | Kyoto University |
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Principal Investigator |
FUJIWARA Akira Kyoto Univ. Fac. of Science Research Associate, 理学部, 助手 (70173482)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1991: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1990: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Hypervelocity impact / Disruption / Velocity distribution / Asteroid / Solar system / 惑星 / 高速衝突 |
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| Research Abstract |
Velocity distribution of the fragments is an especially fundamental quantity among many outcomes of the large scale catastrophic disruptions airong many small bodies during the formation the planets from planetesimals. In this study we made sirall scale high-velocity collsion experiments in the laboratory, and tried to obtain the velocty distribution of the produced fragments systematically. In the experiments, small nylon spheres (7mm in diameter)were accelerated by a two-stage light-gas gun at velocity 2 - 4km/s against spherical basalt and plaster targets. t4ovement of the fragments produced in the impact was recorded by a high-speed framiriq camera. and a strobe system. The velocities of the fragments of size larger than lmm were determined with the aid of an image-analyzer. The velocity of tl) ne fragments in this size range is less than about 100m/s, and proportional to -1/3 - -1/16 th power of the fragment size both for basalt and plaster tcirgets. To extrapolate other experimental results to the larger scale collisions, we made some considerations and experiments. First, dispersion of the orbital elements among asteroid families shows tliat family asteroids have been ejected from their parent asteroid at velocities of about a few hundred m/s. The apparent contradiction between this fact (larger fragments with higher velocity) and our experimental results (smaller fragments with lower velocity) should be attributed to the difference of rising' and falling time of the shock wave ; they become longer for large scale collision compared witti the laboratory scale. As the fragment velocity is closely related with the propagation of the shock wave and destruction' process, ; 4f-also studied on the mechanism of the cratering on curved surfaces. I'n the future, it is necessary to do impact experiments with varying projectile size to establish a scalitiq law for the velocity distribution which can be applicable for the larger scale impact disruption.
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