Our Sun, an average star that can fit up to 1.3 million Earths, emits light due to a continuous reaction called nuclear fusion – the bonding of 4 hydrogen nuclei to make a helium nucleus by means of the proton-proton chain in its core and is the source of about 99 per cent of the star’s energy. This emanates heaps of energy and photons – which are electromagnetic bundles of energy that carry light and are massless. A side effect of this process is the spawning of neutrinos, which are subatomic particles that are almost massless. They have a fractional spin and rarely ever react with the matter. Solar neutrinos – neutrinos emitted from the sun – have provided physicists with an invaluable tool to study how the sun works and what it’s made of. Studying the sun – a star – would give insight into how stars across the universe work.
Scientists have long expected a CNO (carbon-nitrogen-oxygen) cycle to be present in the sun. if the process didn’t occur, it would mean that there is an inadequate amount of these elements in the sun, which act as catalysts to fuel the conversion of hydrogen to helium. Fortunately, a laboratory in Italy announced the first-ever detection of neutrinos from this less-common fusion process. This establishes the fact that we have now completely unravelled the 2main processes that power the sun.
These CNO neutrinos and their ratio to the most abundant element in the universe – hydrogen – is important to determine the sun’s, and in turn the rest of the stars and planets in our observable universe’s, metallicity. This is crucial to evaluate how they live, die, what types of planets form, and even how readily life might arise on other worlds.
Writer: Ariya Gupta
30/06/2020
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