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C. W. Hergenrother, R. J. Whiteley (University of Arizona)
The smallest asteroids exibit rotational properties that are distinct from more typical larger bodies. While all but two asteroids larger than absolute magnitude (H) = 21.5 have rotation periods greater than 2.2 hours, the opposite is true for bodies smaller than H = 21.5. Of the 50+ small asteroids with measured rotation periods, over 90% have periods shorter than 2.2 hours. The periods range from 78 seconds (2000 DO8 and 2000 WH10) to greater than 6 hours for 2002 EC. A small but significant fraction of this population are non-principal axis rotators.
The rapid rotation of small asteroids suggests that they are coherent objects with intrinsic strength and not strength-less rubble piles. Recent theoretical work has shed doubt on this interpretation and argues that there is no evidence for rubble pile structure among the asteroids (Holsappe, K. A. 2005. Proc. Lunar Planet. Conf. 36th, abstract 2329). We will show whether the objects in our dataset are limited by strength-determined spin rates or rubble pile-determined spin rates. The question of regolith retention on such rapidly rotating asteroids will also be addressed.
Funding for this research has been provided through a grant from the NASA Near-Earth Object Observation program.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.