Gold is primarily formed through a process called nucleosynthesis that occurs in the cores of stars during their life cycle. The journey begins with the fusion of lighter elements like hydrogen and helium. In the intense heat and pressure at the stellar core, these elements undergo nuclear fusion reactions, converting them into heavier elements.
As a star ages, it goes through different stages of fusion, creating progressively heavier elements. In the later stages, when a star has exhausted its hydrogen fuel, it may undergo a series of fusion reactions, including helium fusion, carbon fusion, and so on, until it reaches iron.
Unlike lighter elements, the fusion of iron is not energetically favorable, and it absorbs more energy than it releases. This marks a critical point in a star's life. The star can no longer sustain itself against gravitational collapse, leading to a dramatic event known as a supernova.
During a supernova explosion, the outer layers of the star are expelled into space, and the intense energy and pressure generated in the explosion can trigger rapid neutron capture, a process known as the r-process. This is where gold formation comes into play.
In the r-process, heavy elements like gold are formed by quickly capturing neutrons onto existing nuclei. This rapid neutron capture creates unstable isotopes, which subsequently decay into more stable forms, ultimately producing elements like gold.
The dispersed material from the supernova, enriched with these newly formed elements, contributes to the formation of future stellar systems, planets, and even our solar system. So, gold, along with other heavy elements, owes its existence to the explosive death throes of massive stars in the cosmos.
- Published in Science & Technology