Two teams of astronomers said Thursday they have for the first time detected a key chemical building block of life swirling around infant stars that resemble our Sun before its planets formed.
The molecule, methyl isocyanate, "plays an essential role in the formation of proteins, which are basic ingredients for life," said Victor Rivilla, a scientist at the Astrophysics Observatory in Florence, Italy, and co-author of a study published in Monthly Notices of the Royal Astronomical Society.
The findings could offer clues on how chemicals sparked into living matter on Earth several billion years ago.
At the very least, they show that elements crucial for the emergence of life "were very likely already available at the earliest stage of solar system formation," said Niels Ligterink, a researcher at Leiden Observatory in The Netherlands, and lead author of a second study in the same journal.
Scientists spotted the organic compound in a dense envelope of interstellar dust and gas circling three young stars some 400 lightyears from Earth in the constellation Ophiuchus, better known as the Serpent Bearer.
Using the Atacama array of radiotelescopes in the northern desert of Chile, the two teams independently isolated the chemical signature of methyl isocyanate, and then followed up with computer modelling and laboratory experiments to probe the molecule's origins.
"Thanks to the amazing capabilities of current telescopes, we are discovering more and more complex organic molecules around the birthplaces of stars and planets," Rivilla told AFP.
Life-giving but toxic
Scientists also recently detected sugars in space, including a compound called glycolaldehyde, which plays a role in the formation of DNA structure.
Methyl isocyanate beyond our atmosphere was first discovered two years ago, but in a very different context: near complex, high-mass stars many times bigger than the Sun. These are not environments that can yield planetary systems like our own.
Earth and the other planets in our Solar System formed some 4.5 billion years ago out of matter left over from the Sun.
At this very early stage of evolution, the material feeding the formation of the three-star system described Thursday -- known prosaically as IRAS 16293-2422 -- is rotating in a disk around each star.
Some of the gas and dust will fall to the stars, and the rest will make up the planets.
Paradoxically, methyl isocyanate -- and other chemical precursors to life -- are highly toxic, potentially lethal, to humans and other animals.
"This makes laboratory work challenging," Ligterink noted dryly by email.
Indeed, methyl isocyanate (CH3NCO) was the main poison in the 1984 Bhopal disaster in India, in which a leak from a pesticide factory on the night of December 2 killed more than 3,700 people.
But in combination with other molecules, such as water, it transforms and can eventually lead to life-bearing compounds.
One of the new studies contained a note in memory of the Bhopal victims....