Biggest building block in the chemistry of life discovered in a protoplanetary disk

Almost eleven years ago and already, using the network of radio telescope Alma (Atacama Large Millimeter/submillimeter Array) in Chile, astrophysicists brought to the fore the protoplanetary disk of the star Oph-IRS 48 located at about 444 light years from Sun in the constellation of Ophiuchus. “Oph” refers to the serpent-bearer constellation Ophiuchus, and IRS stands for source infrared as Futura explained in an article from which we partly reproduce the content today. Observations, made using the VLT (Very Large Telescope) of the’ESOhad shown before Alma that we were in the presence of a disc pierced by a central hole probably created by an invisible planet whose mass was estimated to be ten times that of Jupiterunless it is another star.

Alma’s subsequent observations then revealed instead of the ring that radio astronomers expected to see a cashew nut which it quickly became clear was most likely the observational evidence so far lacking in a model put forward in 1995 by Pierre Barge then stationed at the Laboratory ofAstrophysics from Marseille (lam) and by his colleague Joel Sommeria then from the Laboratory of Geophysical and Industrial Flows in Grenoble (Legi). This model suggests that whirlwinds giant gases are responsible for capturing and containing the dust contained in the disc of gas which surrounds the star, this with such efficiency that the formation of comets and even planets would become possible. It assumes the existence of anticyclonic vortices, the only ones capable of surviving without being torn apart by the rotation of the disc.

Futura had asked Pierre Barge at that time to talk to us in more detail about the model he had proposed with Joël Sommeria and the problems he was supposed to solve by cosmogony planetary, which he had done in an interview exposed in of them items .

Oph-IRS 48 and exobiology

Today is rather exobiology which is affected by new observations made with Alma and therefore again Oph-IRS 48. As explained in an Eso press release, and as evidenced by the accompanying article published in Astronomy and Astrophysicsit was mainly researchers from the Leiden Observatory in the Netherlands who were behind the new discovery, the detection of the largest molecule identified in a protoplanetary disk and, in addition, organic since it is methoxymethane with the formula CH₃OCH₃.

However, it turns out that this molecule is a precursor allowing the appearance in chemical reactions of prebiotic molecules larger sizes that can be used for the appearance of Life. We already knew of the existence of this molecule and others relating toexobiology in clouds molecules where we know that stars are born surrounded by protoplanetary discs. But this is the first time that it has been shown that this molecule can also be found in such a disc and therefore potentially also on exoplanets capable of giving birth to and developing life forms similar to those we know on Earth.

” Thanks to these results, we can learn more about the origin of life on our planet and therefore have a better idea of ​​the potential for life in other planetary systems. It is very interesting to see how these results fit into the bigger picture. “, explains moreover in this regard, in the Eso press release, Nashanty Brunken, master’s student at the Leiden Observatory and main author of the published study.

In fact, it is expected in the coming years that the commissioning of theELT (Extremely Large Telescope), in Korean construction in Chile, allow us to go even further in the astrochemical studies of the disc around Oph-IRS 48 and more precisely in its internal regions, where exoterres could appear.

Prebiotic molecules in ice

Decades ago, the study of the astrochemistry of molecular and dusty clouds by radio astronomers proved startling. In addition to hydrogen molecules and silicate and carbonaceous dust, more than 120 simple organic molecules have been discovered there. The modelization of this astrochemistry and the observational data suggest that the dust is surrounded by a gangue of water ice in which these simple molecules, such as carbon monoxide (Collar’ammonia (NH₃), methane (CH₄), methanol (CH₃Oh), the formaldehyde (H₂CO) or theacid formic acid (HCOOH), form and react with each other under the action of photons ultraviolet young stars born in these clouds.

We know that carbonaceous meteorites contain organic molecules that can be considered as bricks of lifefrom sugars and amino acids especially. But meteorites were formed from dust in molecular clouds. So there is a whole chemistry prebiotic that can condition the appearance of life on rocky exoplanets that ranges from molecular clouds to the protoplanetary disks that form from these clouds.

However, recently, it had been shown that the dust trap previously discovered in Oph-IRS 48 by Alma contained precisely dust surrounded by ice and it is in this region that Alma’s observations revealed the presence of the molecule of methoxymethane .

We therefore understand the statements of Alice Booth, also a researcher at the Leiden Observatory and co-author of the published article: “ What makes this finding even more exciting is that we now know that these larger, complex molecules are available to power planets forming in the disk. This was not known before because in most systems these molecules are hidden in ice “.

We also understand that of his colleague Nienke van der Marel: “ We are extremely happy to be able to begin to follow the complete path of these complex molecules, from the clouds that form stars to comets, passing through planet-forming disks. We hope that with further observations we can get closer to understanding the origin of molecules prebiotics in our own solar system “.