A frequency approach to identifying asteroid families

Abstract

Context. Secular resonances usually have a complicated three-dimensional structure in a - e - i (or a - e - sin(i)) space, which is not easily represented in a two-dimensional projection. As a consequence, the classic approach to identifying asteroid families fails in some cases to identify objects that have migrated in such resonances because of the Yarkovsky effect. Aims. We propose an alternative approach by identifying asteroid families in the proper frequency domain (n, g, g + s) rather than in the proper element domain (a, e, sin(i)). Methods. We applied the HCM method in the proper frequency domain (n, g, g + s) to identify four of the largest asteroid families: Vesta, Eunomia, Eos, and Koronis. We compared our results with those obtained with the classical method. In addition, we applied the extended metrics in the domain of asteroid colors in both proper element and frequency domains. Results. The frequency approach to determining families is an excellent tool for (i) more easily identifying the effect of nonlinear secular resonances on families and (ii) connecting to the family of origin objects that have migrated via the interplay of the Yarkovsky effect and nonlinear secular resonances. © ESO 2007.