Neutron stars in golden collision

Astronomers have observed one of the universe’s most cataclysmic events: the collision of a pair of neutron stars in deep space, 130 million years ago. It is the first time such a collision has been recorded, and provides compelling evidence for a long-held astronomical theory: that such cosmic collisions are what created the universe’s supply of gold and other heavy elements.

Neutron stars – the cores of massive stars that have collapsed and died – are the densest known objects in the universe, after black holes. Measuring around 12 miles across, they have a mass greater than that of Earth’s Sun, and are so dense, a teaspoon of their material on Earth would weigh a billion tons. Scientists have long believed that their explosive collisions, known as kilonovas, send immense clouds of radioactive material – including heavy elements such as gold, platinum and uranium – shooting across space.

Now, astronomers have actually seen these heavy elements being formed. The collision, which occurred in a region known as the Hydra constellation, was initially picked up in the form of gravitational waves – ripples in the fabric of space-time caused by massive objects moving through the universe that, until now, have only been detected from black holes. This triggered a global alert, and soon the world’s most powerful telescopes were trained on the sky. Hours later, a radiation flash brighter than a billion suns was observed from multiple locations. “I can’t think of a similar situation in my lifetime, where a single event provides so many staggering insights about our universe,” said Daniel Holz, an astrophysicist at the University of Chicago.