Earth’s Gold Forged in Stellar Collisions

This artist’s illustration shows two neutron stars at the moment of collision. New observations confirm that colliding neutron stars produce short gamma-ray bursts. Such collisions produce rare heavy elements, including gold. All Earth’s gold likely came from colliding neutron stars.  Credit: Dana Berry, SkyWorks Digital, Inc.

Until today, astronomers believed that all the gold on Earth, and in the universe, was forged in ancient supernova explosions. But new evidence points to a far more violent birth for this most precious metal.

The new culprit is the cataclysmic collision of two neutron stars. The impact produces a titanic flash of intense but short-lived gamma ray bursts (GRB) along with a debris cloud filled with a complex cocktail of heavy elements, including copious amounts of gold. (Related Silver in Space: Metal Found to Form in Distinct Star Explosions)

Using NASA’s SWIFT gamma-ray hunting satellite, astronomers on June 3 detected just such a distant, high-energy explosion—dubbed GRB 130603B—some 3.9 billion light-years from Earth. The team of astronomers estimates that material (some of it gold) equal to about one-hundredth the mass of our sun, was ejected by the gamma-ray burst. (see also Ultrabright Gamma-ray Burst “Blinded” NASA Telescope)

Edo Berger, lead author of the new study and astrophysicist at the Harvard-Smithsonian Center for Astrophysics, and his team followed the resulting infrared glow from the burst for days until it faded out of sight. This glow can only be produced by the radioactive heavy elements rich in neutron stars, and the team believes it indicates that GRBs are a product of two neutron stars merging.

With several moons worth of gold being produced by just one GRB, and the many such blasts that are thought to have occurred  since the Big Bang nearly 14 billion years ago, Berger and his team suggest that neutron star collisions are the primary factories for gold in the cosmos.

“We estimate that the amount of gold produced and ejected during the merger of the two neutron stars may be as large as ten moon masses—quite a lot of bling!” said Berger in a press statement.

At today’s market rate, that amount of gold would be valued at ten octillion dollars—that’s a 1 with 28 zeros behind it, says Berger.

Unlike supernovae, where lighter elements like carbon and iron are born from the demise of a single star, GRBs are the universe’s most cataclysmic events and are powerful enough to forge precious metals.

“To paraphrase Carl Sagan, we are all star stuff, and our jewelry is colliding-star stuff,” said Berger.

The gold study has been submitted for publication in The Astrophysical Journal Letters and available online.

 

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Changing Planet

Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.