In a new study, published Wednesday in Nature, astronomers have found the first signs that carbon-based molecules, which make life possible on Earth, also exist in a protoplanetary disk – a rotating disk of dense gas surrounding a newly-formed star – 455 light-years away in the Taurus star-forming region.
These findings, obtained courtesy of the Atacama Large Millimetre/Submillimetre Array (ALMA) confirm that the conditions which gave birth to the Earth and Sun are not unique in the Universe.
The new ALMA observations have shown that the protoplanetary disk surrounding the young star MWC 480 contains large amounts of a complex carbon-based molecule called methyl cyanide (CH3CN) – the amount is so massive it would be enough to fill up all of the Earth’s oceans with.
Without cyanides that are known to contain carbon-nitrogen bonds there would be no proteins and, therefore, no organic life: “We know when our own solar system was very young, it was rich in water and complex organics. We know that from observing comets,” said study lead author Karin Öberg, an astronomer at the Harvard-Smithsonian Centre for Astrophysics in Cambridge, USA.
Comets retain a pristine record of the early chemistry of the Solar System from the period of planet formation. The planetesimals (solid objects made up of dust, rock and other materials), comets and asteroids, found in the cold outer reaches of the Kuiper Belt, located beyond Neptune, are thought to have seeded the young Earth with organic molecules that led to the emergence of primordial life.
But before now, we have never had evidence that similar processes take place elsewhere in the known Universe: “We’re finding that we’re not that special,” Öberg said. “Other young solar systems in the making are also rich in the same volatiles, and in similar proportions.”
“From the study of exoplanets, we know the Solar System isn’t unique in its number of planets or abundance of water,” explained Öberg. “Now we know we’re not unique in organic chemistry. Once more, we have learnt that we’re not special. From a life in the Universe point of view, this is great news.”
The complex organics were spotted around 15 billion kilometres from the star itself, thought to be right in the middle of the comet-forming region. This means that the compounds could get locked away in comets, which would then seed the future planets.
Although scientists haven’t been able to detect any clear signs of planet formation yet, higher resolution observations may eventually reveal structures like that of the HL Tauri – a similar early-stage star system.
“It was kind of a chance discovery, because we weren’t targeting this specific molecule,” said Öberg. She and her team now plans to try and look for star systems that are more similar to our own, as MWC 480 is twice the size of the Sun.
“We of course want to know whether this is a really common thing or if we just lucked out in this one.”