Dormant Comets Among the Near-Earth Object Population: A Meteor-Based Survey

TL;DR

This study uses meteor radar data to identify dormant comets among near-Earth objects by detecting associated meteor showers, revealing a low dormancy rate and supporting the idea that many JFCs are disrupted or removed.

Contribution

It introduces a novel meteor-based survey method to estimate dormant comet prevalence in the NEO population, providing new statistical insights.

Findings

Detected 5 meteor showers likely linked to dormant comets.

Estimated dormant comet fraction in NEOs is approximately 2%.

Confirmed low dormancy rate supports the disruption hypothesis for JFCs.

Abstract

Dormant comets in the near-Earth object (NEO) population are thought to be involved in the terrestrial accretion of water and organic materials. Identification of dormant comets is difficult as they are observationally indistinguishable from their asteroidal counterparts, however they may have produced dust during their final active stages which potentially are detectable today as weak meteor showers at the Earth. Here we present the result of a reconnaissance survey looking for dormant comets using 13~567~542 meteor orbits measured by the Canadian Meteor Orbit Radar (CMOR). We simulate the dynamical evolution of the hypothetical meteoroid streams originated from 407 near-Earth asteroids in cometary orbits (NEACOs) that resemble orbital characteristics of Jupiter-family comets (JFCs). Out of the 44 hypothetical showers that are predicted to be detectable by CMOR, we identify 5 positive detections that are statistically unlikely to be chance associations, including 3 previously known associations. This translates to a lower limit to the dormant comet fraction of $2.0\pm1.7\%$ in the NEO population and a dormancy rate of $\sim 10^{-5}~\mathrm{yr^{-1}}$ per comet. The low dormancy rate confirms disruption and dynamical removal as the dominant end state for near-Earth JFCs. We also predict the existence of a significant number of meteoroid streams whose parents have already been disrupted or dynamically removed.