How is gold created in the universe?

Where does the gold of the universe come from? Cosmic phenomena such as collisions of neutron stars or the collapse of massive black holes could explain the presence of this precious metal, as well as other chemical elements scattered throughout the universe.

We all admire the wonderful gold or platinum jewellery, the precious metals that shine on our fingers or the earrings that many women wear. Another "hard" chemical element, a jewel of nuclear power plants, is uranium, whose fission is the basis of nuclear power produced by nuclear reactors.

But where do these chemical elements come from? They were not born after the Big Bang; Later they were formed in processes based on stars with a mass greater than that of the Sun.
The iron-to-iron elements are formed by nuclear fusion in the stars, these processes take place with the release of energy. In practice, part of the mass of the nuclei that join the fusion process is transformed into energy. However, from the iron upwards, because the nuclei come together to give rise to heavy chemical elements such as gold, platinum or uranium, energy needs to be supplied. So, how is this fusion in the universe carried out? What is the alchemy underlying the existence of gold?

There are two hypotheses: one that the heavy elements are born from the process of joining two neutron stars that orbit each other through the emission of gravitational waves. After a long period of time, the two stars probably merge into a black hole, part of the material of the star, as a result of the so-called rapid process, when the neutrons are absorbed by the nuclei, heavier nuclei than, after the disintegration, they give rise to heavier chemical elements such as gold, platinum or uranium.

But as the union of neutron stars takes a long time, it remains to explain the presence of gold in the early history of the universe. Practically, the heavy elements existed just after the first stars and galaxies were born.

A group of researchers proposed a mechanism, called collapse, that would generate much of the heavy chemical elements in the universe. These are massive stars with a much larger mass than the sun, which, when they die, that is, they have consumed the nuclear fuel inside, explode in the form of a type-A supernova. This results in a black hole as a result of the gravitational collapse of the central part of the star, but also of a substantial amount of matter rich in chemical elements such as oxygen, carbon or iron, and in neutrons, which revolve around it. The black hole, reaching very high speeds. Neutrons are captured by the nuclei and, just after the r-process, ultimately generate heavy chemical elements. The result of this study, a computer simulation of the entire collapse process, was recently published in the journal Nature.

It is believed that practically 80% of heavy chemical elements originate in collapses, with only 20% formed in neutron star collisions.

At present, however, it is not clear if these collapses can still explain the large amounts of gold that exist in the universe, even if a collapse could generate a quantity of gold a hundred times greater than that of our planet.

Astronomers will have to carry out new studies on massive stars that give rise to type A supernovae, with the hope that they will better understand the r-type processes. The same is done in terrestrial laboratories where r processes are studied in detail.

The gold in our jewels is, therefore, created by some great cosmic processes: collisions or explosions of stars, being ourselves children of the stars since the chemical elements of our body arose in the hearts of the stars after the nuclear fusion.

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