Gold produced when stars collide: Alchemists’ dream comes true 130m light years from Earth

Stars collidePA

Huge quantities of gold were created in the nuclear furnace lit by merging stars

Huge quantities of the precious metal and other heavy elements including platinum and uranium were created in the nuclear furnace lit by merging neutron stars, confirming theories about their origins.

The spectacular event also generated ripples in the fabric of the universe, leading to the fifth detection of gravitational waves on Earth – a major discovery in itself.

Scientists not only “heard” the phenomenon by measuring vibrations in space-time, they also used satellite and ground-based telescopes to see light and radiation pouring out of the stellar fireball, dubbed a “kilonova”.

Excited astronomers talked of opening a “new chapter in astrophysics” and unlocking a “treasure trove” of new science.

Every other gravitational wave detection has been traced to black holes crashing together in remote regions of the universe more than a billion light years away.

The new event – though still very distant – was much closer and completely different in nature. It was caused by colliding neutron stars – burned out remnants of giant stars so dense that a teaspoon of their material on Earth would weigh a billion tons.

The two objects, each about 12 miles in diameter, stretched and distorted space-time as they spiralled towards each other and finally collided.

Like ripples from a stone thrown in a pond, the gravitational waves fanned out across the universe at the speed of light.

They were picked up on Earth by two incredibly sensitive detectors in Washington and Louisiana in the US, operated by the Laser Interferometer Gravitational-Wave Observatory (Ligo).

It was here the first discovery of gravitational waves was made in September 2015, confirming a prediction made by Albert Einstein 100 years ago and earning three pioneers of the project a Nobel Prize.

Two seconds after the Ligo detection, a burst of gamma rays from the neutron star collision was captured by Nasa’s Fermi space telescope.

StarsPA

A collision of two super-dense stars which forged gold

Astronomers around the world quickly turned their telescopes and dishes towards a small patch in the southern sky and also saw the flash across the visible and invisible light spectrum.

Analysis of the light revealed something astonishing – the manufacture of gold on a cosmic scale, as well as other heavy elements.

A tight lid was kept on the findings until the publication of a series of papers in journals including Nature, Nature Astronomy, and Physical Review Letters.

The international researchers expect to spend many months trawling through the mountain of data.

One question already answered is the origin of short-duration gamma ray bursts. Gamma ray bursts (GRBs), marked by an eruption of gamma rays lasting milliseconds to several minutes, are the most powerful explosions known.

Scientists now know that one type of GRB is generated when neutron stars collide.

Dr Samantha Oates, also from the University of Warwick, said: “This discovery has answered three questions that astronomers have been puzzling for decades: what happens when neutron stars merge? What causes the short duration gamma-ray bursts? Where are the heavy elements, like gold, made?

“In the space of about a week all three of these mysteries were solved.”

Colleague Dr Danny Steeghs said: “This is a new chapter in astrophysics.”

StarsPA

The event also generated ripples in the fabric of the universe

British Ligo scientist Professor BS Sathyaprakash, from the University of Cardiff, described the new discovery as “truly a eureka moment”.

He added: “The 12 hours that followed are inarguably the most exciting hours of my scientific life. This event marks a turning point in observational astronomy and will lead to a treasure trove of scientific results.”

Professor Bernard Schutz, also from the University of Cardiff, told how his team used the gravitational wave detections to measure the expansion of the universe more accurately than had ever been achieved before.

“What has amazed me … is that with just this one measurement, we got a result right in the middle between the two rather different values that astronomers have measured recently,” he said.