Using the ALMA (Large Millimeter/Small Millimeter Atacama) antenna system in Chile, a research team at the Leiden Observatory (Netherlands) has detected for the first time dimethyl ether in a planetary disk. With nine atoms, this molecule is the largest molecule identified in such a disk. At the same time, he is a pioneer of larger organic molecules that may even give rise to life.
“The result will help us gain a better understanding of the emergence of life on our planet, providing a better starting point for examining similar processes in other planetary systems. It is very exciting to see how these discoveries paint a bigger picture,” concludes Nashanti Bronkin, student at Leiden University, lead author For a study published today in Astronomy & Astrophysics.
Dimethyl ether is an organic molecule that is often discovered in stellar regions but has not yet been identified in a planetary disk. The researchers also found a trace of another organic molecule similar to dimethyl ether, methyl formate, which is also a building block for larger organic molecules.
“It’s really exciting that we were finally able to detect these larger particles in planetary disks as well. We’ve thought for a long time that this might not be possible,” adds Alice Booth, one of the article’s co-authors and a researcher at the Leiden Observatory.
The particles were found in a planetary orbit around the young star classified as IRS 48 (or Oph-IRS 48) with the ALMA antenna system owned by the European Southern Observatory. Located 48, 444 light-years away, in the direction of the constellation Ophiuchus, the IRS was already the subject of an asymmetric cashew-shaped “dust trap” in its disk. The region formed by the companion star stores large amounts of millimeters of large-sized dust particles that would be able to gather into larger kilometer-sized objects, comets, asteroids, and possibly even planets.
Most organic molecules, including dimethyl ether, are believed to form in the clouds of star-forming regions before the stars themselves are born. In a low-temperature environment, simple atoms and molecules, such as carbon monoxide, stick to dust particles and form chemical reactions on them, resulting in more complex molecules. The cartilage trap of IRS 48 has also recently been shown to be an ice reservoir in which dust particles are covered by a layer of ice rich in complex particles. Now ALMA has also found traces of dimethyl ether in this part of the disk: radiation from IRS 48 lifts the ice, releasing particles inherited from the cold cloud trapped in the ice and becoming detectable.
“What makes it even more exciting is that we now know that these larger organic molecules could be the raw materials for planetary formation in the disk,” Booth explains.
The discovery of dimethyl ether suggests that many other complex molecules commonly observed in stellar regions may also linger in planetary disks under icy shields. The precursors of these molecules are the so-called prebiotic molecules such as amino acids or polysaccharides.
Studying their origin and evolution could help researchers better understand the prebiotic molecules that will eventually become on planets, including our own. “We are incredibly excited to be able to trace the full path of these complex particles from star-forming clouds all the way to the disks of planets to comets. We hope that further observations will bring us closer to understanding the origins of prebiotic particles in the solar system,” says another researcher, Nienke van der Marel, also a member of the Leiden Observatory.
The ESO Extremely Large Telescope (ELT), currently under construction in Chile and scheduled to be operational by the end of the decade, will also allow the research team to study the chemistry of the innermost part of the IRS 48 disk, where planets like Earth are located. may form.
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