Silicate Dust Size Distribution from Hypervelocity Collisions: Implications for Dust Production in Debris Disks

Fragments generated by high-velocity collisions between solid planetary bodies are one of the main sources of new interplanetary dust particles. However, only limited ranges of collision velocity, ejecta size, and target materials have been studied in previous laboratory experiments, and the collisi...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2011-06, Vol.733 (2), p.L39-jQuery1323917478301='48'
Main Authors: Takasawa, S, Nakamura, A. M, Kadono, T, Arakawa, M, Dohi, K, Ohno, S, Seto, Y, Maeda, M, Shigemori, K, Hironaka, Y, Sakaiya, T, Fujioka, S, Sano, T, Otani, K, Watari, T, Sangen, K, Setoh, M, Machii, N, Takeuchi, T
Format: Article
Language:English
Subjects:
ABLATION
ALUMINIUM
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
BASALT
COLLISIONS
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
DISTRIBUTION
DUSTS
ELEMENTS
GOLD
IGNEOUS ROCKS
LASERS
METALS
OXYGEN COMPOUNDS
PROTOPLANETS
ROCKS
SILICATES
SILICON COMPOUNDS
TRANSITION ELEMENTS
VOLCANIC ROCKS
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Summary:Fragments generated by high-velocity collisions between solid planetary bodies are one of the main sources of new interplanetary dust particles. However, only limited ranges of collision velocity, ejecta size, and target materials have been studied in previous laboratory experiments, and the collision condition that enables the production of dust-sized particles remains unclear. We conducted hypervelocity impact experiments on silicate rocks at relative velocities of 9 to 61 km s--1, which is beyond the upper limit of previous laboratory studies. Sub-millimeter-diameter aluminum and gold spheres were accelerated by laser ablation and were shot into dunite and basalt targets. We analyzed the surfaces of aerogel blocks deployed near the targets using an electron probe micro analyzer and counted the number of particles that contained the target material. The size distributions of ejecta ranged from five to tens of microns in diameter. The total cross-sectional area of dust-sized ejecta monotonically increased with the projectile kinetic energy, independent of impact velocity, projectile diameter, and projectile and target material compositions. The slopes of the cumulative ejecta-size distributions ranged from --2 to --5. Most of the slopes were steeper than the --2.5 or --2.7 that is expected for a collisional equilibrium distribution in a collision cascade with mass-independent or mass-dependent catastrophic disruption thresholds, respectively. This suggests that the steep dust size-distribution proposed for the debris disk around HD172555 (an A5V star) could be due to a hypervelocity collision.
ISSN:2041-8205
2041-8213
DOI:10.1088/2041-8205/733/2/L39