Thursday, July 18, 2013

All the Gold in the Universe Could Come From the Collisions of Neutron Stars



From smithsonianmag.com

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On June 3, 3.9 billion light-years away, two incredibly dense neutron stars— bodies that are each about 1.5 times the mass of the sun but just the size of mere cities—collided. Scientists studying the event say it solves an enduring mystery about the formation of elements in our universe.

“It's a very fast, catastrophic, extremely energetic type of explosion,” says Edo Berger, an astronomer at the Harvard-Smithsonian Center for Astrophysics. The massive collision released a powerful jet of gamma-rays across the universe. The flash, which lasted for only two-tenths of a second, was picked up by NASA’s Swift satellite and sent astronomers scrambling to collect data.

Over the next few days, telescopes in Chile and the Hubble Space Telescope turned their attention to that region of space. Today, Berger and colleagues announced at a press conference in Cambridge, Massachusetts, that their analysis reveals that neutron star collisions are responsible for the formation of virtually all the heavy elements in the universe—a list that includes gold, mercury, lead, platinum and more.

“This question of where elements like gold come from has been around for a long time,” Berger says. Though many scientists had long argued that supernova explosions were the source, he says his team—which includes Wen-fai Fong and Ryan Chornock of the Harvard astronomy department—have evidence that supernovas aren’t necessary. These neutron star collisions produce all elements heavier than iron, he says, “and they do it efficiently enough that they can account for all the gold that's been produced in the universe.”

Such collisions occur when both the stars in a binary system separately explode as supernovas, and then collapse into themselves, leaving behind a pair of tightly bound neutron stars. As they circle each other, the stars are gradually pulled together by gravitational forces, until they collide.

Read more: http://www.smithsonianmag.com/science-nature/All-the-Gold-in-the-Universe-Could-Come-from-the-Collisions-of-Neutron-Stars-215848391.html#ixzz2ZOtKNcVl
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