Asteroid “one-sided” families: Identifying footprints of YORP effect and estimating the age

In a previous paper (Icarus 274, 314 (2016)) we have developed a new method to estimate the ages of asteroid families, based on an analysis of some expected consequence of the YORP effect acting on family members. The method is based on the identification of what we called the YORP eye, namely a region of depletion of the domain occupied by family members in the absolute magnitude - orbital semi-major axis plane. In this paper we develop a technique (“Mirroring tool”) to apply the same age determination method also in cases of strongly asymmetric families, for which it is difficult to assess the existence and location of a YORP eye. At the same time, we also apply some modifications to the procedure described in the previous paper. The results indicate that the mirroring tool can, in some cases, be satisfactorily effective, whereas in some other cases the results we obtain are more ambiguous. A necessary next step of this analysis will be to develop a better calibration of this method against the results obtained by means of other techniques, including primarily the age determination techniques based on analyses of the Yarkovsky-driven spreading in the semi-major axis of family members of different sizes.