Observational constraints to the dynamics of dust particles in the coma of comet 67P/Churyumov-Gerasimenko

TL;DR

This study uses high-resolution images from the Rosetta mission to analyze dust particle trajectories, sizes, and rotation in comet 67P's coma, providing data to improve theoretical models of cometary dust dynamics.

Contribution

It offers the first detailed statistical analysis of individual dust particles' motion, size, and rotation close to the comet nucleus, aiding the development of more accurate 3D coma models.

Findings

Particles move highly radially relative to the nucleus.

Particles are slow rotators with frequencies below 3.6 Hz.

Particle sizes range from millimeters to centimeters.

Abstract

In this work we aim to characterise the dust motion in the inner coma of comet 67P/Churyumov- Gerasimenko to provide constraints for theoretical 3D coma models. The OSIRIS camera onboard the Rosetta mission was able for the first time to acquire images of single dust particles from inside the cometary coma, very close to the nucleus. We analyse a large number of particles, performing a significant statistic of their behaviour during the post perihelion period, when the spacecraft covered distances from the nucleus ranging between 80 and 400 km. We describe the particle trajectories, investigating their orientation and finding highly radial motion with respect to the nucleus. Then, from the particle brightness profiles, we derive a particle rotational frequency of v < 3.6 Hz, revealing that they are slow rotators and do not undergo fragmentation. We use scattering models to compare the observed spectral radiance of the particles with the simulated ones in order to estimate their size, finding values that range from millimetres up to centimetres. The statistics performed in this paper provide useful parameters to constrain the cometary coma dynamical models.