Yarkovsky Drift Fidelity: Unveiling Dynamical Boundaries in Asteroid Family Dispersal and Implications for Spin Evolution

Abstract: To quantify the cumulative impact of asteroid spin evolution on asteroid family dispersal, we introduced the Yarkovsky Drift Fidelity Index (YDFI). Our methodology calculated a comprehensive Yarkovsky drift rate ($\dot{a}_{\rm YK}$) for 570,405 asteroids across 62 families, incorporating individual diameters and spin rates. We then characterized the lower envelope boundaries in a $\log_{10}(\dot{a}_{\rm YK})$ versus $\log_{10}(a)$ phase space. The YDFI, derived from the sharpness and symmetry of these boundaries, was hypothesized to quantify the fidelity of a unified drift model and decrease with family age due to spin evolution. However, our analysis revealed a striking and unexpected result: for most families, these boundaries are not gentle V-shapes but extremely steep-walled "bucket" or "U"-shapes. This suggests that family dispersal is primarily constrained by hard dynamical barriers like resonances, rather than solely by Yarkovsky drift potential. Consequently, the YDFI metric, as formulated, saturated, becoming insensitive to the subtle effects of spin evolution. Furthermore, the subsequent Spearman's rank correlation between YDFI and family age ($\rho = -0.0004$, p = 0.989) was critically invalidated by a severe data merging error. Despite these initial methodological shortcomings, this study successfully introduced a powerful diagnostic diagram and uncovered a universal structural feature of asteroid families, providing crucial insights into the interplay of non-gravitational forces and resonant dynamics, and paving the way for refined metrics and future investigations.

Subjects:	astro-ph.EP; physics.space-ph
Cite as:	PX:2508.00065