Exploding stars bring a rumble to Earth, and maybe gold, too – CNET

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Humans have long gazed at distant twinkling objects in the night sky. For the first time, scientists say they’ve felt them too.

An artist’s impression shows two tiny but very dense neutron stars at the point where they merge and explode as a kilonova. 

ESO/L. Calçada/M. Kornmesser

It’s as if we’ve been seeing flashes of lightning from across the universe for centuries, but have just now gained the capability to feel the rumbles of thunder that come with them.

A team of international scientists have picked up both gravitational waves and electromagnetic emissions, including visible light, from a powerful type of explosion that had been long theorized but never observed until now. The breakthrough marks the dawn of a new era that the scientists behind the discovery, as well as many not involved, are calling “multi-messenger astronomy.” 

The new, expanded approach to astronomy could help us measure and better understand some of the most violent and powerful events in the history of the universe and, perhaps, provide new insights into the forces that cause them. 

“This is a game changer for astrophysics,” said Andy Howell, who leads the supernova group at Las Cumbres Observatory in Goleta, California, and co-authored one of several studies about the discovery that were released Monday. “A hundred years after Einstein theorized gravitational waves, we’ve seen them and traced them back to their source to find an explosion with new physics of the kind we only dreamed about before.” 

A bonus: The new type of explosion could also be the super-heated cosmic source of some of the most precious metals found on Earth.

Here is how a collaboration of international observatories spotted the kilonova.

Las Cumbres Observatory

The story of how this blast was spotted and felt starts Aug. 17 when astronomers detected gravitational waves for just the fifth time ever. Each of the previous four times these ripples in the fabric of spacetime were picked up on Earth they were traced to distant, colliding black holes. But this time was different. The signal lasted for 100 seconds, compared with a fraction of a second for others, indicating the source was something new.

Data from the  Laser Interferometer Gravitational-Wave Observatory (LIGO) — which earlier this month was recognized in the 2017 Nobel Prize for physics — identified the source as coming from somewhere in a large section of the southern sky. At almost the same moment, NASA’s Fermi Gamma-ray telescope picked up a gamma-ray burst. A massive and unprecedented international effort then swung into action as every kind of telescope in and around the world was pointed in the same direction.

What they saw was an explosion called a “kilonova” caused by the collision of two neutron stars, which are the extremely dense, collapsed cores of high-mass stars left behind after going supernova.

“Thanks to knowing where to look and then having telescopes networked together all around the world, we were able to watch this new type of cosmic explosion rise and fade in real time,” said Curtis McCully of Las Cumbres Observatory, a co-author of one of the studies published Monday. “This is a remarkable story of the advent of gravitational-wave astronomy combined with robotic internet-based optical astronomy.”  

For weeks, multiple telescopes kept watch on what looked like a new star some 130 million light-years away, near the galaxy NGC 4993, as it brightened and then faded quickly, changing from blue to reddish in the span of just a few days.

An origin story for gold?

When scientists analyzed the spectra of the light coming from the new and rapidly changing object they found evidence that this new type of explosion could also be the source of some of the heavier elements on Earth, including gold and platinum.

“We see fingerprints of key elements that are heavier than iron,” said Ken Chambers, director of the Pan-STARRS Observatory at the University of Hawaii, adding that the result could be a change in our understanding of the origin of some of the heavier elements.

Frans Pretorius, a Princeton physics professor, said via email that the observation of a kilonova, both on the electromagnetic (light) spectrum and from gravitational waves, could help answer many outstanding questions and provide “clues to the nature of matter in the dense interiors of neutron stars.”

Added Janna Levin, a Columbia University physics and astronomy professor, “The outcome will be a more complete portrait of the most cataclysmic collisions in the universe.” 

Who knows? Perhaps someday soon a trip to the planetarium will include scientifically accurate haptic feedback on each seat that lets us feel the forces that forged the metal rings around our fingers.

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