Astronomers have discovered the earliest stellar remnants in the universe.
The European Space Observatory’s Very Large Telescope was used to identify a distant triple cloud of gas whose chemical composition matches that thought to make up the star-killing supernova explosion.
These remnants come from ancient stars that first appeared 13.5 billion years ago — and while they’re hundreds of times larger than our Milky Way’s sun, they contain only hydrogen and helium.
But when they die, the explosion releases additional elements such as magnesium, carbon and oxygen, enriching the surrounding gas from which future generations of stars are born.
These descendant stars eject heavier elements as they die.
However, the explosions that killed the first stars were not powerful enough to expel heavier elements such as iron from their cores—a difference that provides useful criteria for astronomers looking for their remains.
Looking for signs of these earliest stars, they looked for distant clouds of gas that were poor in iron but rich in other elements like carbon and oxygen.
That’s what led to the discovery of these three distant clouds using data from the Chilean Observatory’s telescope.
Astronomers study them using light beacons known as quasars—extremely bright sources of light powered by supermassive black holes at the centers of distant galaxies.
As light from a quasar travels through the universe, it travels through clouds of gas where the chemical elements leave a distinct imprint — giving researchers an idea of its composition.
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This diagram illustrates how the quasar’s light is used as a beacon to analyze the chemical composition of the gas cloud. Image: ESO/L.Calcada
“Our discovery opens up new avenues”
Stefania Salvadori, an associate professor at the University of Florence who co-authored a study published in the Astrophysical Journal, said the remnants allowed long-dead stars to ” indirect research”.
She added: “Our findings open up new avenues to indirectly study the properties of the first stars, completely complementing the study of the stars in our own Milky Way galaxy.”
It is hoped that these remains will help to uncover more mysteries about how the first stars formed after the Big Bang.