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arXiv 1912.08994astro-ph.EP
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通过超高速碰撞引起的喷出物粒子的相互碰撞形成环形山射线

Crater-ray formation through mutual collisions of hypervelocity-impact induced ejecta particles

Toshihiko Kadono, Ayako I. Suzuki, Rintaro Matsumura, Junta Naka, Ryo Suetsugu, Kosuke Kurosawa, Sunao Hasegawa

摘要:

我们研究了在超高速撞击(2-6 km/s)引起的喷射物幕中观察到的各种尺寸和形状的目标粒子的图案。我们用一个角度来描述图案的特征,该角度被定义为通过傅里叶变换获得的图案的特征长度与到撞击点的距离的比率。发现该角度几乎与先前研究中在较低冲击速度下通过重新分析模式获得的角度相同(Kadono等人,2015年,伊卡洛斯250,215-221),这是符合月球陨石坑射线系统。假设该图案是由开挖流中具有波动速度的颗粒相互碰撞形成的,我们评估了图案生长停止的角度,并表明该角度与波动速度和径向速度的比值在数量级上相同。实验和数值模拟的结果证实了这种关系。最后,我们讨论了图案的影响条件的依赖性。实验表明,角度对冲击速度没有依赖性。这表明开挖流中脉动速度分量与径向速度分量的比值与冲击速度无关。此外,颗粒尺寸和颗粒形状的独立性表明,表征图案结构的角度不依赖于cohesion内聚力。由于cohesion内聚力应该与颗粒的弹性性质有关,因此结构不依赖于弹性性质,尽管非弹性碰撞对于图案的持久性和对比度是重要的。

英文摘要:

We investigate the patterns observed in ejecta curtain induced by hypervelocity impact (2-6 km/s) with a variety of the size and shape of target particles. We characterize the patterns by an angle, defined as the ratio of the characteristic length of the pattern obtained by Fourier transformation to the distance from the impact point. This angle is found to be almost the same as that obtained by the reanalysis of the patterns in the previous study at lower impact velocities (Kadono et al., 2015, Icarus 250, 215-221), which are consistent with lunar crater-ray systems. Assuming that the pattern is formed by mutual collision of particles with fluctuation velocity in excavation flow, we evaluate an angle at which the pattern growth stops and show that this angle is the same in the order of magnitude as the ratio of the fluctuation velocity and the radial velocity. This relation is confirmed in the results of experiments and numerical simulations. Finally, we discuss the dependence of the patterns on impact conditions. The experiments show no dependence of the angle on impact velocity. This indicates that the ratio between the fluctuation and radial velocity components in excavation flow does not depend on impact velocity. Moreover, the independences on particle size and particle shape suggest that the angle characterizing the structure of the patterns does not depend on cohesive force. Since cohesive forces should be related with elastic properties of particles, the structure does not depend on elastic properties, though inelastic collisions are important for the persistence and contrast of the patterns.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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