Minimum perihelion distances and associated dwell times for near-Earth asteroids

TL;DR

This study probabilistically assesses the minimum perihelion distances and dwell times of near-Earth asteroids, providing insights into their orbital evolution, potential disruption, and implications for meteorite origins.

Contribution

It introduces a method to estimate the past minimum perihelion distances and dwell times of NEAs, aiding understanding of their evolution and disruption processes.

Findings

Carbonaceous chondrites have short dwell times at small q.

Ordinary chondrites' dwell times range from 10,000 to 500,000 years.

Dearth of meteorites with long dwell times at small q suggests asteroid disruption at small perihelion.

Abstract

The observed near-Earth asteroid population contains very few objects with small perihelion distances, say, q<=0.2 au. NEAs that currently have orbits with larger q might be hiding a past evolution during which they have approached closer to the Sun. We present a probabilistic assessment of the minimum q that an asteroid has reached during its orbital history. At the same time, we offer an estimate of the dwell time, that is, the time q has been in a specific range. We have re-analyzed orbital integrations of test asteroids from the moment they enter the near-Earth region until they either collide with a major body or are thrown out from the inner Solar System. We considered a total disruption of asteroids at certain q as a function of absolute magnitude (H). We calculated the probability that an asteroid with given orbital elements and H has reached a q smaller than a given threshold value and its respective dwell time in that range. We have constructed a look-up table that can be used to study the past orbital and thermal evolution of asteroids as well as meteorite falls and their possible parent bodies. An application to 25 meteorite falls shows that carbonaceous chondrites typically have short dwell times at small q, whereas for ordinary chondrites it ranges from 10,000 to 500,000 years. A dearth of meteorite falls with long dwell times and small minimum q supports a super-catastrophic disruption of asteroids at small q.