An international team led by astronomers from Leiden University used the Webb telescope to reveal the presence of several molecules in ice form in the darkest and coldest spots of a large star-forming cloud. The results show that the chemical ingredients for making larger and complex molecules are already present long before a new star is born. The researchers published their findings in Nature Astronomy. Under the right conditions, important building blocks for life, such as sugars and amino acids, can form from simple molecules on icy dust particles. Later in the star formation process, these substances end up on new planets and in their atmospheres. With this research, the team demonstrated that the ingredients for the formation of sugars and amino acids are widely available even in the darkest and coldest places in a large interstellar cloud. The astronomers found ice from water, carbon monoxide, carbon dioxide, methane, cyanate, carbonyl sulfide and methanol. They also saw signs that may indicate the presence of larger frozen organic molecules. Chameleon The cloud in question is located in Chamaeleon I, a star-forming area some 500 light years from the Earth, near the southern Chameleon constellation. Hundreds of young stars are forming in the area. This process involves chemical reactions in which increasingly complex molecules form on icy dust particles. Ultraviolet light normally plays an important role in these reactions. However, if there is a lot of gas and dust, this light cannot pierce through. ICE AGE The Webb telescope allowed the researchers to examine very dark areas in the cloud. It will still take millions of years for stars to form in these areas. “It turns out that there are many ice particles, and also many different types of ice particles available,” says Melissa McClure, Assistant Professor at Leiden University and leader of the ICE AGE team that was one of the first in the world to make measurements with the Webb telescope. “Our observations allow us to gain a better understanding of how simple and complex molecules, which are in turn the building blocks for life, form in such places. We know from laboratory work on Earth, that in places where UV light cannot reach, free atoms play an important role in ice chemistry.” Herma Cuppen, Professor of Computational Chemistry at Radboud University, contributed to the chemical interpretation of the results. “It’s fascinating to see how even under these very dark and cold conditions, reasonably complex molecules can still form. Until a few years ago, we thought that this process required light, but the experiments conducted at the Leiden Laboratory for Astrophysics by Harold Linnartz, co-project leader of ICE AGE, and the simulations we performed in my Nijmegen group, show that light is not required. This is confirmed by these new observations.” Tip of the iceberg In future, the researchers hope to discover even more molecules in the cold dark cloud. They have now examined in detail two areas in the cloud. There are dozens more to come. The team plans to systematically explore the different stages of star and planet formation in the cloud: from dark cloud to protoplanetary system. The differences between the successive stages are particularly important in order to be able to follow the evolution of the ice. MIRI This research was made possible thanks to MIRI, one of the four instruments on board of the Webb telescope. This instrument was designed and built in the Netherlands and co-funded by NOVA, the Netherlands Research School for Astronomy. MIRI can capture very precisely the colours of infrared light absorbed by ice. Photo: ESA/Webb/McClure et al.