ASTEROID DYNAMIC FAMILIES - A RELIABILITY TEST FOR 2 IDENTIFICATION METHODS

Since a couple of years the asteroid families are under the light of a renewed interest. This is due to the simultaneous improvement of the techniques of proper elements computation and of the methods of classi fication. Recently, two different cluster analysis methods (Zappala et al. 1990, Bendjoya et al. 1991) have provided two very similar lists of asteroid families. This has brought a renewed confidence on the rel iability of asteroid families classification. Since a new set of impro ved proper elements is now available (Milani & Knezevic 1992), the ide a of the present work is to test the two identification methods by mea ns of artificially generated families in order to gain an insight into their limitations and to possibly develop improved strategies for fut ure analyses. Different cases have been envisaged in order to study th e effectiveness of the methods as a function of increasing background densities and of the spread of the families. The ability of the method s to detect peculiar features such as filaments or to separate two clo se families has also been tested. The number of interlopers has been d etermined in each case in order to evaluate their relative amount. Whi le some improvements to the adopted procedures are suggested by the nu merical tests, the results presented in the present paper are encourag ing and allow us to be confident about the reliability of our previous family lists, as well as about the expected performances of the metho ds in future applications.