Obliquities of "Top-Shaped" Asteroids May Not Imply Reshaping by YORP Spin-up
arXiv:1411.0638 · doi:10.1016/j.icarus.2014.10.050
Abstract
The timescales over which the YORP effect alters the rotation period and the obliquity of a small asteroid can be very different, because the corresponding torques couple to different aspects of the object's shape. For nearly axisymmetric, "top-shaped" near-Earth asteroids such as 101955 Bennu, spin timescales are an order of magnitude or more longer than obliquity timescales, which are of order 10^5 to 10^6 yr. The observed low obliquities (near 0 or 180 degrees) of top-shaped asteroids do not constitute evidence that they acquired their present shapes and spins through YORP spin-up, because low obliquities are expected regardless of the spin-up or reshaping mechanism.
10 pages, 2 figures, Icarus in press. 2 typos corrected, 1 arXiv reference added
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Cited by in corpus (5)
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- Spin-driven evolution of asteroids' top-shapes at fast and slow spins seen from (101955) Bennu and (162173) Ryugu
- A Contact Binary Satellite of the Asteroid (152830) Dinkinesh
- The Surface Roughness of (433) Eros as Measured by Thermal-Infrared Beaming
- A pre-flyby view on the origin of asteroid Donaldjohanson, a target of the NASA Lucy mission