Dynamics of Dust Particles Released from Oort Cloud Comets and Their Contribution to Radar Meteors

TL;DR

This study investigates the fate of dust particles from Oort Cloud Comets and their potential contribution to radar-detected meteors, revealing size-dependent dynamics and matching model predictions with observations.

Contribution

It provides a detailed analysis of dust particle sizes from OCC disruptions and links their orbital evolution to observed meteor radar data, addressing a longstanding meteor science problem.

Findings

Particles with D<10 um are blown out by radiation pressure.

Particles with D>1 um have low impact probability.

Approximately 1% of 100 um particles reach Earth orbit and produce apex meteors.

Abstract

The Oort Cloud Comets (OCCs), exemplified by the Great Comet of 1997 (Hale-Bopp), are occasional visitors from the heatless periphery of the solar system. Previous works hypothesized that a great majority of OCCs must physically disrupt after one or two passages through the inner solar system, where strong thermal gradients can cause phase transitions or volatile pressure buildup. Here we study the fate of small debris particles produced by OCC disruptions to determine whether the imprints of a hypothetical population of OCC meteoroids can be found in the existing meteor radar data. We find that OCC particles with diameters D<10 um are blown out from the solar system by radiation pressure, while those with D>1 um have a very low Earth-impact probability. The intermediate particle sizes, D=100 um, represent a sweet spot. About 1% of these particles orbitally evolve by Poynting-Robertson drag to reach orbits with semimajor axis a=1 AU. They are expected to produce meteors with radiants near the apex of the Earth's orbital motion. We find that the model distributions of their impact speeds and orbits provide a good match to radar observations of apex meteors, except for the eccentricity distribution, which is more skewed toward e=1 in our model. Finally, we propose an explanation for the long-standing problem in meteor science related to the relative strength of apex and helion/antihelion sources. As we show in detail, the observed trend, with the apex meteors being more prominent in observations of highly sensitive radars, can be related to orbital dynamics of particles released on the long-period orbits.