The vector alignments of asteroid spins by thermal torques
- 1 September 2003
- journal article
- research article
- Published by Springer Science and Business Media LLC in Nature
- Vol. 425 (6954), 147-151
- https://doi.org/10.1038/nature01948
Abstract
Collisions have been thought to be the dominant process altering asteroid rotations, but recent observations of the Koronis family of asteroids suggest that this may be incorrect. This group of asteroids was formed in a catastrophic collision several billion years ago; in the intervening period their rotational axes should have become nearly random because of subsequent collisions, with spin rates that follow a maxwellian distribution. What is seen, however, is that the observed family members with prograde spins have nearly identical periods (7.5–9.5 h) and obliquities between 42 and 50 degrees, while those with retrograde spins have obliquities between 154 and 169 degrees with periods either 13 h. Here we show that these non-random orientations and spin rates can be explained by ‘thermal torques’ (arising from differential solar heating), which modify the spin states over time. In some cases, the asteroids become trapped in spin-orbit resonances. Our results suggest that thermal torques may be more important than collisions in changing the spin states (and possibly shapes) of asteroids with diameters <40 km.This publication has 30 references indexed in Scilit:
- Impact cratering on porous asteroidsIcarus, 2003
- Is asteroid 951 Gaspra in a resonant obliquity state with its spin increasing due to YORP?Journal of Geophysical Research, 2002
- Origin of asteroid rotation rates in catastrophic impactsNature, 1997
- The Discovery and Orbit of 1993 (243)1 DactylIcarus, 1996
- The Direction of the North Pole and the Control Network of Asteroid 243 IdaIcarus, 1996
- Collisional Evolution of Asteroid FamiliesIcarus, 1995
- First Images of Asteroid 243 IdaScience, 1994
- The chaotic obliquity of the planetsNature, 1993
- Collisional evolution in the Eos and Koronis asteroid families: Observational and numerical resultsIcarus, 1988
- Colombo's topCelestial Mechanics and Dynamical Astronomy, 1987