How some ancient stars met with an unusual death

In a first, researchers have discovered that certain primordial stars - those between 55,000 and 56,000 times the mass of our Sun - may have died unusually by exploding completely and leaving no remnant black hole behind.

The findings could provide new insights about how the Universe, as we know it today, came to be because in death these first generation stars sent their chemical creations into outer space, paving the way for subsequent generations of stars, solar systems and galaxies.

"We found that there is a narrow window where super-massive stars could explode completely instead of becoming a super-massive black hole - no one has ever found this mechanism before," said lead study author Ke-Jung Chen from the University of California, Santa Cruz (UCSC).

To model the life of a primordial super-massive star, the researchers used a one-dimensional stellar evolution code called KEPLER.

They found that the primordial stars live about 1.69 million years before collapse.

As the star collapses, it begins to rapidly synthesise heavy elements like oxygen, neon, magnesium and silicon - with helium in its core - which creates so much energy that it results in a supernova explosion.

Depending on the intensity of the supernovae, some super-massive stars could, when they explode, enrich their host galaxy and even some nearby galaxies with elements ranging from carbon to silicon.

To model the death mechanisms of these stars, the researchers used CASTRO - a multi-dimensional compressible astrophysics code developed at Berkeley Lab by scientists Ann Almgren and John Bell.

The findings were published in Astrophysical Journal.