The rocket that will carry out microgravity experiments is being launched by the Swedish Space Corporation. Credit: Swedish Space Corporation
Exploring interstellar gas dust grains might be of benefit to astronomers, as well as materials scientists in developing useful nanoparticles.
Through laboratory and rocket-borne investigations, Hokkaido University researchers and their colleagues from Japan and Germany have discovered new information about the origins of interstellar dust grains. The findings, published in the journal Science Advances, could help scientists better understand the formation process and develop more environmentally friendly nanoparticles.
Meteorites that fall to Earth have these 'presolar' grains, thus allowing laboratory investigations to reveal possible routes for their formation.
The characteristics of presolar grains in meteorites limit the environments in which they might have formed, according to Yuki Kimura of the Hokkaido team. Despite this, it has been difficult to pin down the probable conditions for the formation of grains composed of a titanium carbide core and a surrounding graphitic carbon mantle.
Yuki Kimura with the rocket used for microgravity experiments in the research. Credit: Yuki Kimura
To be aware of the interstellar environment in general, it's crucial to study its evolution. Materials around them are the foundations for planets.
The structure of the grains suggests that the grains' titanium carbide core was first formed and was then coated in a thick layer of carbon in distant regions of gas outflow from stars that formed before the Sun.
In laboratory modelling experiments based on theoretical research on grain nucleation – the formation of grains from tiny original specks – the group explored the possibilities for sub-orbital rocket flights.
The grain design from the study has been developed using a transmission electron micrograph. Credit: Yuki Kimura
The findings reveal some surprising things. They suggest that grains most likely evolved through a non-classical nucleation pathway, which is composed of three distinct steps that are unpredictable by conventional wisdom. First, carbon forms tiny, homogenous nuclei; then titanium deposits on these nuclei to form carbon particles containing titanium carbide; finally, thousands of these fine particles fuse to form the grain.
Kimura concludes that other presolar and solar grains that emerged at later stages in the solar system might be accurately explained by considering non-classical nucleation pathways, such as those suggested by our research.
The implications of studying tiny grains in meteorites may extend from Earth's future industries to as far away as we can imagine.
Yuki Kimura, Kyoko K. Tanaka, Coskun Aktas, and Jürgen Blum, "Nucleation experiments on a titanium-carbon system imply nonclassical formation of presolar grains," published on the 13th of January 2023, Science Advances. DOI: 10.126/sciadv.add8295