Unusual death of massive ancient stars


This image is a slice through the interior of a supermassive star of 55,500 solar masses along the axis of symmetry. It shows the inner helium core in which nuclear burning is converting helium to oxygen, powering various fluid instabilities (swirling lines). This "snapshot" from a computer simulation shows one moment a day after the onset of the explosion, when the radius of the outer circle would be slightly larger than that of the orbit of the Earth around the sun.
Ken Chen, University of California at Santa Cruz

Astrophysicists believe that giant primordial stars – 55,000 times the mass of our Sun – may have died by exploding as supernovae and burning out completely, leaving no black hole behind.

Astrophysicists from the universities of California and Minnesota ran computer stimulations on the first-generation stars at the National Energy Research Scientific Computing Centre and the Minnesota Supercomputing Institute. Their results were published in Astrophysical Journal.

We found that there is a narrow window where supermassive stars could explode completely instead of becoming a supermassive black hole – no one has ever found this mechanism before, said Ke-Jung Chen, a postdoctoral researcher at the University of California and a lead author of the paper. Up until now it was believed that all supermassive stars ended their lives as black holes.

First-generation stars produced the first chemical elements other than hydrogen and helium. When they died, these chemicals were released into space, paving the way for the next generation of galaxies.

Chen and his colleagues found these giant primordial stars lived for about 1.69 million years before they become unstable and started to collapse. Heavy elements such as oxygen, neon, magnesium and silicon then started to synthesise, starting with helium in the stars core. This process caused a supernova – a massive explosion.

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