Abstract
In order to fully understand the shapes of asteroids families in the 3-dimensional space of the proper elements (a(p),e(p), sin I-p) it is necessary to compare observed asteroids with N-body simulations. To this point, we describe a rigorous yet simple method which allows for a selection of the observed asteroids, assures the same size-frequency distribution of synthetic asteroids, accounts for a background population, and computes a chi(2 )metric.
We study the Eos family as an example, and we are able to fully explain its non-isotropic features, including the distribution of pole latitudes beta. We confirm its age t = (1.3 +/- 0.3) Gyr; while this value still scales with the bulk density, it is verified by a Monte-Carlo collisional model.
The method can be applied to other populous families (Flora, Eunomia, Hygiea, Koronis, Themis, Vesta, etc.).