Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, astronomers from the Netherlands’ Leiden Observatory discovered dimethyl ether in a planet-forming disc for the first time. This is the biggest molecule discovered in such a disc to yet, with nine atoms. It is also a precursor to bigger organic compounds, which may result in the birth of life.
“We may learn more about the origins of life on our planet from these findings, and hence get a greater understanding of the possibilities for life in other planetary systems. It would be fascinating to see how these discoveries fit into the larger picture “Nashanty Brunken, a Master’s student at Leiden Observatory and principal author of the research published today in Astronomy & Astrophysics, comments
Dimethyl ether is a common chemical compound found in star-forming clouds, but it has never been seen in a planet-forming disc previously. The researchers also achieved a preliminary discovery of methyl formate, a complex chemical akin to dimethyl ether that may be used to generate even bigger organic compounds.
“It’s incredibly amazing to see these bigger molecules in discs for the first time. We believed for a long that we wouldn’t be able to see them “Alice Booth, a researcher at Leiden Observatory, is one of the co-authors.
The molecules were discovered using ALMA, an observatory co-owned by the European Southern Observatory, in the planet-forming disc surrounding the young star IRS 48 (also known as Oph-IRS 48). (ESO). IRS 48, situated 444 light-years distant in the constellation Ophiuchus, has been the topic of multiple research due to the presence of an asymmetric, cashew-nut-shaped “dust trap” on its disc. This region, which most likely formed as a result of a newly formed planet or small companion star located between the star and the dust trap, retains a large number of millimetre-sized dust grains that can collide and grow into kilometre-sized objects such as comets, asteroids, and possibly planets.
Many complex chemical compounds, such as dimethyl ether, are predicted to develop in star-forming clouds prior to the birth of the stars themselves. Atoms and basic molecules like carbon monoxide adhere to dust grains in these freezing conditions, generating an ice coating and performing chemical processes that result in more complex molecules. Researchers have revealed that the IRS 48 disc’s dust trap is actually an ice reservoir, with dust grains encased in this ice rich in complex compounds. ALMA has recently discovered evidence of the dimethyl ether molecule in this area of the disc: when heating from IRS 48 sublimates the ice into gas, the trapped molecules inherited from the cold clouds become free and observable.
“What makes this more more intriguing is that we now know these bigger complex chemicals are accessible to feed planets developing in the disc,” Booth says. “This was previously unknown since in most settings, these molecules are concealed under the ice.”
The finding of dimethyl ether hints that many additional complex compounds seen in star-forming regions may also be hidden atop frozen structures in planet-forming discs. These compounds are the antecedents of prebiotic chemicals like amino acids and carbohydrates, which are some of the fundamental building blocks of life.
Researchers can acquire a better grasp of how prebiotic chemicals end up on worlds like ours by examining their origin and development. “We are overjoyed that we can now begin to track the complete course of these complicated chemicals from star-forming clouds to planet-forming discs and comets. With further data, we should be able to come a little closer to understanding the origins of prebiotic chemicals in our own Solar System “Nienke van der Marel, a Leiden Observatory researcher who also took part in the study, agrees.
Future investigations of IRS 48 using ESO’s Extremely Large Telescope (ELT), which is now being built in Chile and is scheduled to begin operations later this decade, will enable the researchers to explore the chemistry of the disc’s most inner regions, where planets like Earth may be forming.
