An organic molecule made of nine atoms has been detected inside the planet-forming disk of a young star. The substance is dimethyl ether and it is the largest molecule yet to be found in such an environment.

The findings, reported in the journal Astronomy & Astrophysics, concern the young star IRS 48. Dimethyl ether has been observed in star-forming clouds, so astronomers knew it was out there, but not in the regions where planets form. The observations tell us about the small building blocks of planets and the organic molecules that led to life on Earth.

"From these results, we can learn more about the origin of life on our planet and therefore get a better idea of the potential for life in other planetary systems. It is very exciting to see how these findings fit into the bigger picture," lead author Nashanty Brunken, a Master's student at Leiden Observatory, part of Leiden University, said in a statement.

Complex chemistry in space tends to combine dust grains covered in ice. There, simple molecules, such as carbon monoxide, can undergo chemical reactions that lead to more complex molecules such as dimethyl ether. As the light of the stars heats these dust grains and makes the ice that covers them sublimate, these larger molecules become detectable.

"It is really exciting to finally detect these larger molecules in discs. For a while we thought it might not be possible to observe them,” added co-author Alice Booth, also a researcher at Leiden Observatory. “What makes this even more exciting is that we now know these larger complex molecules are available to feed forming planets in the disc. This was not known before as in most systems these molecules are hidden in the ice.”

The observations were possible thanks to the Atacama Large Millimeter/submillimeter Array (ALMA). Molecules such as dimethyl ether are key to making molecules that are very important for life such as amino acids, the building blocks of proteins.

“We are incredibly pleased that we can now start to follow the entire journey of these complex molecules from the clouds that form stars, to planet-forming discs, and to comets. Hopefully with more observations we can get a step closer to understanding the origin of prebiotic molecules in our own Solar System,” co-author Nienke van der Marel, also at Leiden Observatory said.

The team hopes to follow up with observations using the Extremely Large Telescope, currently under construction, which will be able to zoom into the region in the planet-forming disk where Earth-sized planets might be forming.