Mit dem Atacama Large Millimeter/submillimeter Array ([{” attribute=””>ALMA) in Chile, researchers at Leiden Observatory in the Netherlands have for the first time detected dimethyl ether in a planet-forming disc. With nine atoms, this is the largest molecule identified in such a disc to date. It is also a precursor of larger organic molecules that can lead to the emergence of life.
“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,” says Nashanty Brunken, a Master’s student at Leiden Observatory, part of Leiden University, and lead author of the study published on March 8, 2022, in Astronomy & Astrophysics.
Wie kommen die Zutaten für das Leben auf die Planeten? Die Entdeckung des größten Moleküls, das jemals in einer planetenbildenden Scheibe gefunden wurde, liefert Hinweise. Kredit:[{” attribute=””>ESO
Dimethyl ether is an organic molecule commonly seen in star-forming clouds, but had never before been found in a planet-forming disc. The researchers also made a tentative detection of methyl formate, a complex molecule similar to dimethyl ether that is also a building block for even larger organic molecules.
“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,” says co-author Alice Booth, also a researcher at Leiden Observatory.
The molecules were found in the planet-forming disc around the young star IRS 48 (also known as Oph-IRS 48) with the help of ALMA, an observatory co-owned by the European Southern Observatory (ESO). IRS 48, located 444 light-years away in the constellation Ophiuchus, has been the subject of numerous studies because its disc contains an asymmetric, cashew-nut-shaped “dust trap.” This region, which likely formed as a result of a newly born planet or small companion star located between the star and the dust trap, retains large numbers of millimeter-sized dust grains that can come together and grow into kilometer-sized objects like comets, asteroids and potentially even planets.
Many complex organic molecules, such as dimethyl ether, are thought to arise in star-forming clouds, even before the stars themselves are born. In these cold environments, atoms and simple molecules like carbon monoxide stick to dust grains, forming an ice layer and undergoing chemical reactions, which result in more complex molecules. Researchers recently discovered that the dust trap in the IRS 48 disc is also an ice reservoir, harboring dust grains covered with this ice rich in complex molecules. It was in this region of the disc that ALMA has now spotted signs of the dimethyl ether molecule: as heating from IRS 48 sublimates the ice into gas, the trapped molecules inherited from the cold clouds are freed and become detectable.
Dieses Video vergrößert das System Oph-IRS 48, einen Stern, der von einer planetenbildenden Scheibe umgeben ist, die eine Staubfalle enthält. Diese Falle lässt Staubpartikel wachsen und größere Körper hervorbringen.
„Was die Sache noch spannender macht, ist, dass wir jetzt wissen, dass diese größeren komplexen Moleküle verfügbar sind, um Planeten in der Scheibe zu bilden“, erklärt Booth. „Das war vorher nicht bekannt, da diese Moleküle in den meisten Systemen im Eis verborgen sind.“
Die Entdeckung von Dimethylether deutet darauf hin, dass viele andere komplexe Moleküle, die häufig in Sternentstehungsregionen nachgewiesen werden, möglicherweise auch auf Eisstrukturen in planetenbildenden Scheiben lauern. Diese Moleküle sind die Vorläufer von präbiotischen Molekülen wie z[{” attribute=””>amino acids and sugars, which are some of the basic building blocks of life.
By studying their formation and evolution, researchers can therefore gain a better understanding of how prebiotic molecules end up on planets, including our own. “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,” says Nienke van der Marel, a Leiden Observatory researcher who also participated in the study.
Dieses Video vergrößert das System Oph-IRS 48, einen Stern, der von einer planetenbildenden Scheibe umgeben ist, die eine Staubfalle enthält. Diese Falle lässt Staubpartikel wachsen und größere Körper hervorbringen.
Zukünftige Studien von IRS 48 mit dem Extremely Large Telescope (ELT) der ESO, das sich derzeit in Chile im Bau befindet und noch in diesem Jahrzehnt in Betrieb gehen soll, werden es dem Team ermöglichen, die Chemie der sehr inneren Regionen der Scheibe zu untersuchen, wo Planeten wie die Erde sein könnten bilden.
Referenz: „Eine große asymmetrische Eisfalle in einer planetenbildenden Scheibe: III. First Detection of Dimethyl Ether“ von Nashanty GC Brunken, Alice S. Booth, Margot Leemker, Pooneh Nazari, Nienke van der Marel und Ewine F. van Dishoeck, 8. März 2022, Astronomie und Astrophysik.
DOI: 10.1051/0004-6361/202142981
Diese Veröffentlichung wurde am Internationalen Frauentag 2022 veröffentlicht und enthält Forschungsergebnisse von sechs Forscherinnen, die sich als Frauen identifizieren.
Das Team besteht aus Nashanty GC Brunken (Observatorium Leiden, Universität Leiden, Niederlande [Leiden]), Alice S. Booth (Leiden), Margot Leemker (Leiden), Pooneh Nazari (Leiden), Nienke van der Marel (Leiden), Ewine F. van Dishoeck (Leiden Observatory, Max-Planck-Institut für Extraterrestrische Physik, Garching, Deuschland)