[X] My Assistant

[Guest_AlexBlackwell_*]

Nesvorny et al. have a Brevia article in the June 9, 2006, issue of Science entitled "The Breakup of a Main-Belt Asteroid 450 Thousand Years Ago." Click here for the abstract.

I found their methodology interesting:

"To determine the age of the Datura cluster, [t(age)], we numerically tracked the present orbits of four Datura cluster members backward in time. We did not use (89309) 2001VN36, which is strongly chaotic due to effects of the 9:16 orbital resonance with Mars, nor did we use 2003 SQ168 and 2003 UD112, which have large orbital uncertainties. A total of 840 alternative orbit histories were produced for each of the four asteroids that differed by the starting orbit (chosen randomly within the orbit uncertainty range for each asteroid) and magnitude of Yarkovsky thermal drag...The range of plausible [t(age)] values was determined from 10^7 trials. The result shows that the Datura cluster is 450 ± 50 thousand years (ky) old, considerably younger than other known asteroid families." (References omitted)

[SigurRosFan]

Which are the four cluster members?

[Tom Ames]

From the paper, the Datura cluster comprises:
Datura
1999UZ6
2001VN36
2003CL5

as well as these asteroids excluded from the final analysis:
2001WY35
2003SQ168
2003UD112