Why are planets more complex than stars

Complex molecules survive planet formation

The first building blocks of life, such as amino acids and proteins, are created in space and can even survive the hot phase of planet formation. This is now shown by the detection of methanol in the protoplanetary disk around a young star, in which gas and dust condense into ever denser objects and finally into planets. According to the scientists in the journal "Nature Astronomy", the decisive steps for the formation of these prebiotic molecules, which made biological evolution possible on earth, already take place in cosmic clouds of gas and dust.

Astrobiologists assume that the first building blocks for the creation of life - complex molecules based on carbon and hydrogen - are brought to the surface of young planets by comets, among other things. In search of the origin of such organic molecules, researchers try to detect methanol. Because the chemical compound plays an important role in the development of the building blocks of life. In fact, astronomers have already detected numerous prebiotic molecules in the great clouds of gas and dust. But since methanol is only produced in relatively cool environments, it was previously unclear whether the molecules could also survive in the heated disks of matter around young stars during planet formation.

With the ALMA radio telescope system in Chile, Alice Booth from the University of Leiden in the Netherlands and her colleagues surprisingly succeeded in detecting methanol in the protoplanetary disk around the 5.8 million year old star HD 100546. The star, which is 360 light years away, has about the twice the mass of our sun and is therefore much more luminous and hotter. Correspondingly, its protoplanetary disk also heats up more strongly than the sun did in the time the planets formed.

According to the researchers, methanol cannot be produced at the temperatures prevailing there. The chemical compound must have formed earlier in the still cool cloud of gas and dust, from which the star HD 100546 emerged. "This gives us a strong indication that at least some of the interstellar organic material can survive the formation of the protoplanetary disk," said Booth and her colleagues. "And so these substances are then available for the planets, moons and comets that are forming." The first step in the creation of life takes place in space.