http://arxiv.org/abs/1804.11039
About one quarter of asteroids in the main belt have irregular shapes with the ratios between the minor and major axis length less than a half. One of the mechanisms to create such shapes is the collisions between asteroids. The relationship between shapes of collisional outcomes and impact conditions such as impact velocities may provide information on the collisional environments and its evolutionary stages when those asteroids are created. In this study, we perform numerical simulations of collisional destruction of asteroids with radii 50 km and subsequent gravitational reaccumulation using Smoothed Particle Hydrodynamics for elastic dynamics with self-gravity, a model of fracture of rock, and a model of friction of completely damaged rock. We systematically vary the impact velocity from 50 m/s to 400 m/s and the impact angle from 5 degrees to 45 degrees. We investigate shapes of the largest remnants resulting from collisional simulations. As a result, various shapes (bilobed, spherical, flat, elongated, and hemispherical shapes) are formed through equal-mass and low-velocity (50 – 400 m/s) impacts. We clarify a range of the impact angle and velocity to form each shape. Our results indicate that irregular shapes, especially flat shapes, of asteroids with diameters larger than 10 km are likely to be formed through similar-mass and low-velocity impacts, which are likely to occur in primordial environment prior to the formation of Jupiter.
K. Sugiura, H. Kobayashi and S. Inutsuka
Tue, 1 May 18
65/78
Comments: 11 pages, 15 figures, submitted to Astronomy and Astrophysics
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