Identifying Anomalous Asteroids via Predictive Modeling of Physical and Spin Properties based on Orbit and Age

Abstract: Understanding the diverse evolutionary paths of asteroids and identifying objects that deviate from typical trends is crucial for planetary science. Physical and spin properties, such as diameter, spin period, and obliquity, are shaped by complex processes including collisions, thermal radiation forces like the YORP effect, and internal structure, which are not fully determined by current orbital elements and age alone. This study presents an anomaly detection framework to identify asteroids whose observed properties deviate significantly from expected values predicted by their orbit and age. We utilized a large dataset of asteroid properties, including orbital elements (semimajor axis, eccentricity, inclination), estimated age, diameter, spin period, and obliquity. After extensive data preprocessing to handle sparsity, apply logarithmic transformations, and scale features, we trained both Gaussian Process Regression and Neural Network models to predict diameter, spin period, and obliquity from the orbital elements and age. Anomalies were identified by calculating standardized residuals from the GPR models and z-scores of residuals from the NN models, flagging objects whose absolute scores exceeded a predefined threshold. Applying this method identified over 1,100 unique anomalous asteroids. Characterization of this population revealed that these outliers are predominantly larger bodies located on remarkably stable, low-inclination, low-eccentricity orbits within the main belt, and frequently exhibit extreme spin periods that defy typical predictions. These findings suggest that the identified anomalous asteroids likely constitute a physically distinct population, potentially representing primordial planetesimals or objects whose evolution has been governed by unusual events or internal structures, providing valuable targets for further investigation into Solar System formation and evolution.

Subjects:	astro-ph.EP; physics.space-ph
Cite as:	PX:2508.00056