European Space Observatory’s Very Large Telescope finds what’s left of the universe’s first stars

Astronomers have discovered the remains of the very first stars in the universe.

The European Space Observatory’s Very Large Telescope was used to pick out a distant trio of gas clouds, with a chemical composition matching what is believed to have made up star-killing explosions known as supernovae.

The leftovers are from ancient stars that first appeared 13.5 billion years ago – and while they were up to hundreds of times larger than our galaxy’s sun, they contained nothing but hydrogen and helium.

But when they died, the blasts released additional elements such as magnesium, carbon and oxygen, enriching the surrounding gas from where later generations of stars would be born.

These later generation stars in turn ejected heavier elements when they died.

The explosions that killed the first stars, however, were not powerful enough to expel heavier elements like iron, contained at the very core of a star – and this point of difference gave astronomers useful criteria for searching for their remains.

To search for the telltale sign of these very first stars, they looked for distant gas clouds poor in iron but rich in other elements like carbon and oxygen.

This is what led to the discovery of the three faraway clouds using data from the observatory’s telescope in Chile.

Astronomers used light beacons known as quasars to study them – incredibly bright sources of light powered by supermassive black holes at the centres of faraway galaxies.

As light from a quasar travels through the universe, it passes through gas clouds and the chemical elements within leave different imprints – letting researchers see what the composition is.

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‘Our discovery opens new avenues’

University of Florence associate professor Stefania Salvadori, who co-authored a study on the findings in the Astrophysical Journal, said the remains allowed the long dead stars to be “studied indirectly”.

She added: “Our discovery opens new avenues to indirectly study the nature of the first stars, fully complementing studies of stars in our galaxy.”

It is hoped the remains will help uncover more secrets about how the first stars were formed after the Big Bang.