Triboelectrification of KCl and ZnS particles in approximated exoplanet environments

TL;DR

This study investigates how potassium chloride and zinc sulfide particles in exoplanet atmospheres can become electrified through triboelectrification, potentially leading to lightning and atmospheric chemical processes on distant worlds.

Contribution

It demonstrates that mineral particles like KCl and ZnS can easily acquire charge in exoplanet cloud conditions, suggesting electrification is common in such extraterrestrial environments.

Findings

Particles attain charge densities similar to volcanic ash.

Electrification likely leads to lightning or corona discharge.

Mineral clouds in exoplanets can be electrically active.

Abstract

When mobilized, granular materials become charged as grains undergo collisions and frictional interactions. On Earth, this process, known as triboelectrification, has been recognized in volcanic plumes and sandstorms. Yet, frictional charging almost certainly exists on other worlds, both in our own Solar System (such as Mars, the Moon, and Venus) and exosolar planets. Indeed, observations suggest that numerous planets in the galaxy are enshrouded by optically-thick clouds or hazes. Triboelectric charging within these clouds may contribute to global electric circuits of these worlds, providing mechanisms to generate lightning, drive chemical processes in the atmospheres, and, perhaps, influence habitability. In this work, we explore the frictional electrification of potassium chloride and zinc sulfide, two substances proposed to make up the clouds of giant exo-planets with >50x solar metallicities, including the widely-studied super-Earth GJ 1214b, super-earth HD 97658b, Neptune-sized GJ 436b, and hot- Jupiter WASP-31b. We find that both materials become readily electrified when mobilized, attaining charge densities similar to those found on volcanic ash particles. Thus, if these worlds do indeed host collections of mineral particles in their atmospheres, these clouds are likely electrified and may be capable of producing lightning or corona discharge.