Will we ever understand life’s origins? Will we ever be able to put our finger on the exact moment and circumstances that lead to living matter? Will we ever pinpoint the spark? Who knows.
But what we can do is find out how widespread the conditions for life are and how widespread the molecular constituents for life are.
If a moment comes when we can point and say, “Look! Behold the Origins of Life!” it would be amazing. But scientific truth tends to come at us like clues along a winding path. Right now, we’re walking that path and finding the building blocks of life in more and more places.
We think peptides, the precursors to amino acids, can form on icy grains in space. According to one study, asteroid impacts can create chemical building blocks to life. On a comet, we’ve found phosphorous, one of the raw elements necessary for life, and we know that comets also host the amino acid glycine.
A new study expands our understanding of how widespread life’s building blocks are. The researchers found a large, complex, organic molecule in a protoplanetary disk. The molecule is called dimethyl ether, and while it’s not a building block for life on its own, it’s a precursor to even larger molecules that can lead to life.
Researchers at Leiden Observatory in the Netherlands discovered the molecule using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. They published their findings in a paper titled “A major asymmetric ice trap in a planet-forming disk III. First detection of dimethyl ether.” The paper is published in the journal Astronomy and Astrophysics, and the lead author is Nashanty Brunken, a Master’s student at Leiden Observatory.
Dimethyl ether has the formula CH3OCH3, simplified to C2H6O. It’s the simplest ether and a precursor to other organic molecules. Image Credit: By Benjah-bmm27 – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=2117395
Ethers are common in organic chemistry and are widespread in biochemistry. Dimethyl ether is also called DME or methoxymethane. Astronomers have found it in star-forming molecular clouds but never in a planet-forming disk. “This work confirms the presence of oxygen-bearing molecules more complex than CH3OH (methanol) in protoplanetary disks for the first time,” the authors write in the paper. “It also shows that it is indeed possible to trace the full interstellar journey of complex organic molecules (COMs) across the different evolutionary stages of star, disk, and planet formation.”
“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.”
Nienke van der Marel, Leiden Observatory.
“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,” lead author Brunken said in a press release.
The disk is around the star Oph-IRS 48, about 400 light-years from Earth. Astronomers are very interested in the disk because the gas (traced by CO molecules) and small dust grains follow a complete disk ring structure around the star, but dust particles are gathered in a crescent shape. The unusual ring is an example of dust trapping and explains how dust particles can grow by clumping together, eventually forming planets, comets, and other bodies.
“It is really exciting to finally detect these larger molecules in discs,” explained co-author Alice Booth, also a researcher at Leiden Observatory. “For a while, we thought it might not be possible to observe them.”
If this new study is accurate, then any rocky bodies that form around Oph-IRS 48 may form with some biological molecules on them.
“What makes this even more exciting is that we now know these larger complex molecules are available to feed forming planets in the disc,” said Booth. “This was not known before as in most systems, these molecules are hidden in the ice.”