## Abstract

We present both a review of earlier data and new results on non-principal axis rotators (tumblers) among asteroids. Among new tumblers found, the best data we have are for 2002 TD_{60}, 2000 WL_{107}, and (54789) 2001 MZ_{7}-each of them shows a lightcurve with two frequencies (full terms with linear combinations of the two frequencies are present in the lightcurve). For 2002 TD_{60}, we have constructed a physical model of the NPA rotation. Other recent objects which have been found to be likely tumblers based on their lightcurves that do not fit with a single periodicity are 2002 NY_{40}, (16067) 1999 RH_{27}, and (5645) 1990 SP. We have done a statistical analysis of the present sample of the population of NPA rotators. It appears that most asteroids larger than ∼ 0.4 km with estimated damping timescales (Harris, 1994, Icarus 107, 209) of 4.5 byr and longer are NPA rotators. The statistic of two short-period tumblers (D and 0.4 km) with non-zero tensile strength suggests that for them the quantity μ Q/T, where μ is the mechanical rigidity, Q is the elastic dissipation factor, and T is a spin excitation age (i.e., a time elapsed since the last significant spin excitation event), is greater by two to four orders of magnitude than the larger, likely rubble-pile tumblers. Among observational conditions and selection effects affecting detections of NPA rotations, there is a bias against detection of low-amplitude (small elongation) tumblers.

Original language | English (US) |
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Pages (from-to) | 108-131 |

Number of pages | 24 |

Journal | Icarus |

Volume | 173 |

Issue number | 1 |

DOIs | |

State | Published - Jan 2005 |

Externally published | Yes |

## Keywords

- Asteroids
- Excited rotation
- Photometry

## ASJC Scopus subject areas

- Astronomy and Astrophysics
- Space and Planetary Science