Capture and evolution of dust in planetary mean-motion resonances: a fast, semi-analytic method for generating resonantly trapped disk images

TL;DR

The paper introduces a fast semi-analytic method to model dust grain capture and evolution in planetary resonances, aiding the interpretation of disk images and planet detection.

Contribution

A novel semi-analytic approach that significantly speeds up modeling of dust resonance trapping compared to traditional N-body simulations.

Findings

Model agrees well with N-body simulations for various planetary masses and grain parameters.

Resonantly trapped asteroid dust explains the zodiacal trailing blob structure.

Most of the zodiacal cloud's brightness requires cometary grains, not captured asteroid grains.

Abstract

Dust grains migrating under Poynting-Robertson drag may be trapped in mean-motion resonances with planets. Such resonantly trapped grains are observed in the solar system. In extrasolar systems, the exozodiacal light produced by dust grains is expected to be a major obstacle to future missions attempting to directly image terrestrial planets. The patterns made by resonantly trapped dust, however, can be used to infer the presence of planets, and the properties of those planets, if the capture and evolution of the grains can be modelled. This has been done with N-body methods, but such methods are computationally expensive, limiting their usefulness when considering large, slowly evolving grains, and for extrasolar systems with unknown planets and parent bodies, where the possible parameter space for investigation is large. In this work, we present a semi-analytic method for calculating the capture and evolution of dust grains in resonance, which can be orders of magnitude faster than N-body methods. We calibrate the model against N-body simulations, finding excellent agreement for Earth to Neptune mass planets, for a variety of grain sizes, initial eccentricities, and initial semimajor axes. We then apply the model to observations of dust resonantly trapped by the Earth. We find that resonantly trapped, asteroidally produced grains naturally produce the `trailing blob' structure in the zodiacal cloud, while to match the intensity of the blob, most of the cloud must be composed of cometary grains, which owing to their high eccentricity are not captured, but produce a smooth disk.