Unraveling Asteroid Family Evolution: Deconstructing Yarkovsky V-Shapes through Comparative Analysis with YORP-Evolved Distributions

Abstract: Asteroid families, remnants of ancient collisions, are dynamically shaped by non-gravitational forces, notably the Yarkovsky effect, which disperses members based on their spin and size, often forming characteristic "V-shapes" in semi-major axis versus spin period space. However, the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, which alters asteroid spin states over time, complicates this evolution, making it challenging to fully disentangle the complex interplay of these forces through empirical V-shape characterization alone. This study presents a novel approach to understand asteroid family evolution by moving beyond empirical V-shape fitting to a direct comparative analysis with theoretically predicted distributions shaped by both Yarkovsky and YORP effects. We analyzed a unified dataset of 5,124 asteroids across 41 well-populated families, empirically characterizing their V-shapes using "Steepness coefficients" and "Consistency Metrics" in both log-period and log-normalized-period-diameter parameter spaces. Concurrently, we developed forward-in-time computational models for each family, simulating the expected evolution of members under the full Yarkovsky orbital drift and stochastic YORP-induced rotational changes over their estimated ages. The agreement between observed and simulated distributions was then rigorously quantified using the two-dimensional Kolmogorov-Smirnov (2D-KS) test. Our empirical analysis revealed that while V-shapes are prevalent (68% "Well-defined" in log-period space), a significant subset exhibited unexpected positive slopes, challenging simple Yarkovsky approximations, and that incorporating diameter did not systematically improve clarity. The quantitative comparison with our Yarkovsky-YORP simulations showed varying degrees of agreement, with observed discrepancies linked to factors such as family age, member count, and the potential for YORP-induced spin evolution to blur these patterns. This work provides unprecedented insights into the relative importance and complex manifestation of Yarkovsky and YORP effects in shaping asteroid family structures, demonstrating that a combined empirical and simulation-based approach is crucial for a comprehensive understanding of their long-term dynamical evolution.

Subjects:	astro-ph.EP; physics.space-ph
Cite as:	PX:2508.00062