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Near-Earth asteroids destroyed by tidal forces during close encounters with terrestrial planets

Presentation #321.05 in the session Asteroids: Origins (Oral Presentation)

Published onOct 23, 2023
Near-Earth asteroids destroyed by tidal forces during close encounters with terrestrial planets

Numerical modeling has long suggested that gravitationally-bound near-Earth asteroids (NEAs) can be destroyed by tidal forces during close and slow encounters with terrestrial planets. However, there has so far been hardly any undisputable evidence of tidal disruptions actually occuring in the innermost regions of the Solar System. We present population-level evidence for the tidal disruption of NEAs during close encounters with the Earth and Venus. A comparison between observations and model distributions for NEA orbits and absolute magnitudes shows that the models underpredict the number of NEAs with perihelion distance coinciding with the semimajor axes of Venus and the Earth. A detailed analysis of the excess NEAs shows that their characteristics agree with the prediction for tidal disruptions, and they cannot be explained by observational selection effects or orbital dynamics. Accounting for tidal disruptions in evolutionary models of the NEA population, that are calibrated with detection statistics from ongoing and planned NEA surveys, will eventually allow us to place useful constraints on asteroid interior structure, one of the main knowledge gaps in contemporary planetary science. Tidal disruptions also partly solve the long-standing puzzle of bolide-detection networks predicting more decameter-scale Earth impactors than telescopic asteroid surveys.

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