Gold on Earth formed in collision of exotic stars – by Dan Vergan (U.S.A. Today – July 17, 2013)

There’s gold in them thar neutron stars! That’s right, astronomers claim Earth’s gold, the stuff of wedding bands and pricey speaker wires, originated in cataclysmic collisions of exotic stars. 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 aftereffect of the collision of two “neutron” stars. Neutron stars are themselves the collapsed remains of imploded stars, incredibly dense stellar objects that weigh at least 1.4 times as much as the sun but which 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 10,000 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 bases 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 some 3.9 billion light-years away (one light year is about 5.9 trillion miles) the team reports in an Astrophysical Journal Letters report.

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