Solar system collisions reveal secrets of alchemy

A British scientist revealed today the alchemist’s secret of turning base metal into gold.

All you need are two super-dense dead stars and a furnace heated to a billion degrees celsius.

It might be also be wise to stand back while the process takes place - or risk being sucked into a black hole.

Dr Stephen Rosswog used a new supercomputer at the University of Leicester to show how gold and platinum are hurled out into space by the most powerful explosions in the universe.

He and a team of colleagues at Leicester and the University of Basel in Switzerland were exploring the origin of heavy elements in violent collisions of super-dense neutron stars.

These bodies, the dead burned out cores of old stars, are only the size of London but weigh millions of times more than the Earth.

Many common elements, such as oxygen and carbon, are known to be made in stars and distributed through the universe when a star explodes.

But normal stars cannot make enough of heavy elements like gold and platinum, and their origin has been a mystery.

Dr Rosswog has shown that they are probably produced when neutron stars collide.

The supercomputer at the UK Astrophysical Fluids Facility, based in Leicester, carried out a huge number of complex calculations to work out what happens when paired neutron stars get too close to one another.

A single calculation representing just the final milliseconds in the life of the two stars took weeks to complete.

The simulation showed that the neutron stars spiral together and become torn apart by cataclysmic forces, releasing enough energy to outshine the entire universe for a split second.

Crushed out of existence by gravity, the stars collapse to form a black hole. But the computer showed that some of their material is thrown out into space.

The explosive ash is still extremely dense and, at a temperature of around a billion degrees, hot enough to trigger nuclear reactions.

This allows small seed nuclei, made of elements like iron, to collect neutrons and build themselves up into heavy elements such as gold.

Gradually, the gold and platinum-rich ash cools down and continues to fly out into deep space. It mixes with gas and dust and eventually collapses down to form new generations of stars.

The computer models showed that the relative amounts of elements formed by colliding neutron stars matched those seen in our Solar System.

Dr Rosswog, who reported his findings at the UK National Astronomy Meeting in Cambridge today, said: ‘‘This is an incredible result. It’s exciting to think that the gold in wedding rings was formed far away by colliding stars.’’