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Angular momentum drain: A mechanism for despinning asteroids |
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| Authors: | Anthony R Dobrovolskis Joseph A Burns |
| Institution: | Jet Propulsion Laboratory, 264-664, California Institute of Technology, Pasadena, California 91109, USA;Department of Theoretical & Applied Mechanics, Cornell University, Ithaca, New York 14853, USA |
| Abstract: | It is proposed that a new mechanism—angular momentum drain—helps account for the relatively slow rotation rates of intermediate-sized asteroids. Impact ejecta on a spinning body preferentially escape in the direction of rotation. This material systematically drains away spin angular momentum, leading to the counterintuitive result that collisions can reduce the spin of midsized objects. For an asteroid of mass M spinning at frequency ω, a mass loss δM correspond to an average decrease in rotation rate . A. W. Harris' (1979), Icarus40, 145–153) theory for the collisional evolution of asteroidal spins is significantly altered by inlusion of this effect. While the modified theory is still somewhat artificial, comparison of its predictions with the data of S. F. Dermott, A. W. Harris, and C. D. Murray (1984, Icarus57, 14–34) suggests that angular momentum drain is essential for understanding the statistics of asteroidal rotations. |
| Keywords: | To whom correspondence should be addressed |
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