A Numerical Study of Near-Earth Asteroid Family Orbital Dispersion

ABSTRACT We have studied the evolution of near-Earth asteroid (NEA) families and pairs to inform future searches. To do so, we integrated clusters of simulated NEAs with different initial conditions, namely the orbital inclination, ejection speed, and the effects of mean-motion resonances on the parent body prior to breakup while also varying the orbit, mass, and number of perturbing planetary bodies. We studied the orbital element dispersion rates of NEA family members and found a power-law increase in those families whose orbits brought them close to a planet. This allowed us to conclude that family dispersion is significantly affected by the Kozai–Lidov effect due to oscillations in the eccentricity, and that the rate of dispersion is slowest at high inclination relatively far from the nearest planet. In most cases, the ejection speed of the initial breakup does not affect the dispersion, except within weaker mean-motion resonances where more violent breakups will result in the ejection of a fraction of the asteroids, causing a large increase in dispersion. Within mean-motion resonances, where Kozai–Lidov oscillations are slowed, increases in the dispersion of a family are delayed, leading them to be identifiable for longer.