Dust and gas emission from cometary nuclei: the case of comet 67P/Churyumov-Gerasimenko

TL;DR

This paper investigates the dust and gas emissions from comet 67P/Churyumov-Gerasimenko, linking jet-like structures to the comet's complex shape through a detailed gas-dust interaction model.

Contribution

It introduces a novel gas-dust model incorporating the comet's shape and rotation to explain jet formation and dust dynamics.

Findings

Jet-like structures are linked to the comet's concave topography.

Dust velocity influences the bending of jet structures.

Homogeneous surface emission can produce collimated jets.

Abstract

Comets display with decreasing solar distance an increased emission of gas and dust particles, leading to the formation of the coma and tail. Spacecraft missions provide insight in the temporal and spatial variations of the dust and gas sources located on the cometary nucleus. For the case of comet 67P/Churyumov-Gerasimenko (67P/C-G), the long-term observations from the Rosetta mission point to a homogeneous dust emission across the entire illuminated surface. Despite the homogeneous initial distribution, a collimation in jet-like structures becomes visible. We propose that this observation is linked directly to the complex shape of the nucleus and projects concave topographical features into the dust coma. To test this hypothesis, we put forward a gas-dust description of 67P/C-G, where gravitational and gas forces are accurately determined from the surface mesh and the rotation of the nucleus is fully incorporated. The emerging jet-like structures persist for a wide range of gas-dust interactions and show a dust velocity dependent bending.