Gold on Earth Created by Colliding Dead Stars: Space Metal

Gold is worth quite a lot on Earth, and for a very good reason: It's rare. But gold isn't only rare on our planet, it's also rare in the universe. Unlike carbon or iron, it cannot be created within a star. Instead, it has to be born through a more cataclysmic event. Now, scientists are getting a closer look at how gold forms, and may have an explanation for the presence of gold on Earth.

Last month, scientists saw short gamma-ray burst (GRB). This phenomenon is a flash of high-energy light from a extremely energetic explosion. This particular incident was evidence of a collision of two neutron stars, the dead cores of stars that previously exploded as supernovae. After this collision, a unique glow persisted for days. This seemed to indicate that substantial amounts of heavy elements were created from the collision, including gold.

"We estimate that the amount of gold produced and ejected during the merger of the two neutron stars may be as large as 10 moon masses--quite a lot of bling!" said Edo Berger of the Harvard-Smithsonian Center for Astrophysics (CfA) in a news release.

The GRB was one of the closest to occur to Earth to date at a distance of only 3.9 billion light-years. Called GRB 130603B, the burst lasted for less than two-tenths of a second. While it didn't last long, though, it faded slowly in a glow dominated by infrared light. This particular glow didn't match typical "afterglow," which is created when a high-speed jet of particles slams into the surrounding environment.

So what explained this glow? The neutron-rich material ejected by colliding neutron stars can generate radioactive elements which then undergo radioactive decay, creating the glow.

By examining the data, the researchers determined about one-hundredth of the solar mass of material was ejected by the gamma-ray burst, some of which was gold. They then combined the estimated gold produced by a single short GRB with the number of similar explosions that have occurred over the years. In the end, they found that it was very likely that all of the gold in the universe might have been created through these gamma-ray bursts.

The findings show a little bit more about the origin of gold in the universe. In addition, it shows how these gamma-ray bursts are responsible for creating new materials that help form planets.

The findings will be published in The Astrophysical Journal Letters.