Share This Page

Scientists explain origins of gold

| Wednesday, July 17, 2013, 8:21 p.m.

The gold glinting on your wedding band was likely born in a cataclysmic merger of two exceedingly exotic stars, astronomers report Wednesday.

Dying stars billions of years ago cooked up most of the lighter elements in the universe, the oxygen in the air and calcium of our bones, and blasted it across the cosmos in their final explosive moments. We are stardust, as the singer Joni Mitchell put it.

But some of the heaviest atoms, including gold, defied this explanation, requiring an even more exotic origin.

A team led by Harvard astronomer Edo Berger now reports that gold is likely created as an effect of the collision of two “neutron” stars. Neutron stars are the collapsed remains of imploded stars, incredibly dense stellar objects that weigh at least 1.4 times as much as the sun but are thought to be less than 10 miles wide.

While ordinary stars explode about once every century in our galaxy, Berger says, explosive collisions of two neutron stars happen only about once every 100,000 years. And it appears they spew out gold and other heavy elements in the week after their merger.

“Call it the golden glow,” Berger says. “In this case, we were able to observe it for the first time and see how the merger seems to be producing (the) heavy elements.”

The team based its finding on observations of a high-energy flash of gamma rays, a “gamma ray burst” called GRB 130603B that was detected in June by NASA's Swift X-ray telescope satellite. The burst is seen as a signature of the explosive union of two neutron stars, in this case ones about 3.9 billion light-years away, the team reports in an Astrophysical Journal Letters report.

Observation of the cloudy aftereffects of the burst suggest that each merger of two neutron stars produces several moons worth of gold by weight. “At today's prices, that amount of gold would be worth 10 octillion dollars,” says Berger. (That's $10,000 trillion-trillion.) Overall about 1 percent of the mass of the two neutron stars was likely converted into exotic minerals by the merger, only a small part of it gold. Such are the likely origins for the gold that accumulated in Earth's crust some 4.54 billion years ago, swept up from space at the birth of the solar system.

TribLIVE commenting policy

You are solely responsible for your comments and by using TribLive.com you agree to our Terms of Service.

We moderate comments. Our goal is to provide substantive commentary for a general readership. By screening submissions, we provide a space where readers can share intelligent and informed commentary that enhances the quality of our news and information.

While most comments will be posted if they are on-topic and not abusive, moderating decisions are subjective. We will make them as carefully and consistently as we can. Because of the volume of reader comments, we cannot review individual moderation decisions with readers.

We value thoughtful comments representing a range of views that make their point quickly and politely. We make an effort to protect discussions from repeated comments either by the same reader or different readers

We follow the same standards for taste as the daily newspaper. A few things we won't tolerate: personal attacks, obscenity, vulgarity, profanity (including expletives and letters followed by dashes), commercial promotion, impersonations, incoherence, proselytizing and SHOUTING. Don't include URLs to Web sites.

We do not edit comments. They are either approved or deleted. We reserve the right to edit a comment that is quoted or excerpted in an article. In this case, we may fix spelling and punctuation.

We welcome strong opinions and criticism of our work, but we don't want comments to become bogged down with discussions of our policies and we will moderate accordingly.

We appreciate it when readers and people quoted in articles or blog posts point out errors of fact or emphasis and will investigate all assertions. But these suggestions should be sent via e-mail. To avoid distracting other readers, we won't publish comments that suggest a correction. Instead, corrections will be made in a blog post or in an article.