The dust that floats between the stars seems almost insignificant. Yet it contains some of the chemical ingredients that preceded the formation of planets. In Sydney, a team has succeeded in creating an analogue in the laboratory to better understand its history.
The experiment recreates certain extreme conditions encountered around aging stars, supernovae, or in vast interstellar clouds. This is where many carbon-rich particles form.
Carbonaceous cosmic dust forms when small molecules gradually assemble, then aggregate into particles. The process varies depending on distance from the star, temperature, and ion bombardment.
The researchers first removed most of the air from a glass tube. They then introduced nitrogen, carbon dioxide, and acetylene. A high electrical voltage transformed this gas mixture into a plasma.
Within this plasma, molecules break apart and then recombine. Gradually, they form more complex structures that deposit as fine particles. The result resembles a carbonaceous dust, similar to that observed in space.
This material contains carbon, hydrogen, oxygen, and nitrogen. These four elements, often referred to by the acronym CHON, are part of the composition of many organic molecules. They do not constitute life itself but represent important chemical building blocks.
The most interesting point lies in the infrared light. Each material has a particular signature in this invisible part of the light spectrum. The dust created in the laboratory produces signals close to those detected around certain stars.
This similarity gives astronomers a valuable tool. Instead of waiting for a meteorite to arrive or for a space mission to return, they can test hypotheses directly on Earth.
The work does not yet allow them to trace the origin of every grain found in a meteorite. However, it should help distinguish the effects of temperature and energetic particles. These two factors shape dust throughout its cosmic journey.