Colliding neutron stars may have created Earth’s heaviest elements — including those that form you

A violent cosmic event, billions of years ago, is the likely source of Earth’s heaviest elements — including those that became part of us.

If a comparable event happened today at a similar distance from the solar system, the ensuing radiation would outshine the entire night sky. ( Szabolcs Marka)

The violent collision of two neutron stars 4.6 billion years ago, was identified by astrophysicists Szabolcs Marka at Columbia University and Imre Bartos at the University of Florida as the likely source of some of Earth’s heaviest and rarest elements.

This single cosmic event — the merger of two neutron stars in a binary pairing, in close proximity to our solar system — gave birth to 0.3 per cent of the Earth’s heaviest elements — including gold, platinum and uranium — according to the two scientists.

Bartos says: “This means that in each of us we would find an eyelash worth of these elements, mostly in the form of iodine, which is essential to life.

“A wedding ring, which expresses a deep human connection, is also a connection to our cosmic past predating humanity and the formation of Earth itself, with about 10 milligrams of it likely having formed 4.6 billion years ago.”

Though neutron star mergers are fairly rare and their daughter products — isotopes with short half-lives — would have long faded in the solar system, some are preserved in high-temperature condensates found in meteorites — the pair report.

Bartos and Marka go on to explain that meteorites forged in the early solar system carry the traces of radioactive isotopes. As these isotopes decay, they act as clocks that can be used to reconstruct the time they were created.

To arrive at their conclusion, the team compared the composition of meteorites to numerical simulations of the Milky Way discovering that a single neutron-star collision could have occurred about 100 million years before the formation of Earth. This would have happened in our own neighbourhood — roughly 1000 light years from the gas cloud that eventually formed the Solar System.

This distance is roughly 1/100 of the total diameter of the Milky Way galaxy — 100,00 light years. Marka explains the significance of this with a modern day analogy: “If a comparable event happened today at a similar distance from the Solar System, the ensuing radiation could outshine the entire night sky.”

The researchers believe that their study — published in the journal Nature — provides insight into a uniquely consequential event in our history.

Bartos states: “It sheds a bright light on the processes involved in the origin and composition of our solar system, and will initiate a new type of quest within disciplines, such as chemistry, biology and geology, to solve the cosmic puzzle.”

Marka continues: “Our results address a fundamental quest of humanity: Where did we come from and where are we going? It is very difficult to describe the tremendous emotions we felt when realized what we had found and what it means for the future as we search for an explanation of our place in the universe.”

Original research: A nearby neutron-star merger explains the actinide abundances in the early Solar System, Bartos.I, Marka.S, 2019, Nature