New laboratory research by Hokkaido University scientists opens the curtain of this mystery. Professor Masashi Tsuge and his colleagues have recreated the conditions of interstellar clouds in the laboratory. The vital role played by ice grains.

How are complex organic molecules formed?

The vast majority of known organic molecules are based on chains of linked carbon atoms. The chemical properties of carbon allow it to form much larger molecules than other elements. But in the voids of star-forming clouds, atoms are so dispersed that they rarely come into contact with each other. It is believed that ice grains can act as a kind of “attachment” that joins carbon molecules together, but for this to work, the carbon must be able to move across the surface of the particles.

In experiments, we were able to detect that weakly bonded carbon atoms spread on the surface of ice grains react and produce C molecules.₂,
– says Tsuge.

Experimentally, it has been found that diffusion can occur at temperatures above -243 degrees Celsius. The energy required for carbon atoms to diffuse through the ice is so small that, in theory, even -251 degrees should be sufficient. However, it is still hotter than parts of space far from the stars.

Zuge states that large protoplanetary disks around very young stars have reached the required temperatures. Even if such stars have not yet reached their maximum brightness, Looks like a little heat and all it needs is carbon.

It can take 100,000 to 10 million years for two carbon atoms to move across ice a hundred nanometers and meet, but on the scale of the universe, atoms have that long and much longer. Once a carbon bond is formed, more atoms are added by the same process, gradually creating larger carbon skeletons that are easier for other atoms to bond to.

The team notes that most carbon atoms in the cloud will not follow this path. Instead, they will combine with hydrogen or oxygen atoms to form methane or carbon monoxide. Even those that fall onto the surface of ice grains alone often form only formaldehyde (CH).₂HE). But it turns out that even a relatively small number of atoms is enough to form long carbon chains.