The collision of 2 neutron stars gives space scientists a major breakthrough

Video This artist’s view shows the moments before and the nine days following a kilonova. Two neutron stars spiral inward creating gravitational waves. After the merger a jet produces gamma rays, while expanding radioactive debr

"Imagine that gravitational waves are like thunder", astronomer Philip Cowperthwaite, of the Harvard-Smithsonian Center for Astrophysics, said in a statement. A neutron star is the remnant of a larger star whose core has collapsed. "And it got approved". Their internal structure is not completely understood.

Three LIGO pioneers, Barry Barish, Kip Thorne and Rainer Weiss, were awarded the Nobel Physics Prize this month for the observation of gravitational waves, without which the latest discovery would not have been possible.

On August 18th, astronomers witnessed the remains of a neutron star mash-up, which traveled 130 million light years before it was seen by Earthly detectors.

"When the stars die, that creates new things", Smith said.

Typically about 20 kilometres (12 miles) in diameter, but with more mass than the Sun, they are highly radioactive and ultra-dense - a handful of material from one weighs as much as Mount Everest. The findings are "in excellent agreement with the models of binary-neutron-star formation", Berger said. They're also wondering why the gamma ray burst was only two seconds long. Once the neutron stars collided, light was visible on Earth for approximately two seconds, but other kinds of light were discovered days and weeks after the event. There was no way to directly check until now. Around the same time, the Gamma-ray Burst Monitor on NASA's Fermi space telescope had detected a burst of gamma rays.

Although astronomers have observed gravitational waves before, this marks the first time that an event of this nature was observed through gravitational waves and light.

Gamma-rays are high energy electromagnetic radiation, just like optical light but with 50,000 times more energy. The researchers believe that the GRB signal hitting Earth was weak only because the jet was pointing at an angle away from us. "It popped up within the first night of observing", said Smartt. The findings indicate that at least some GRBs come from colliding neutron stars, though it's too soon to say whether they all do. According to that thinking, the crash of neutron stars ejects matter in what's called a kilonova.

Neutron stars are the smallest, densest stars known to exist and are formed when massive stars explode in supernovae.

"This tells us that the heavy elements, like the gold or platinum in jewellery, are the cinders, forged in the billion degree remnants of a merging neutron star".

"The gravitational wave detectors let us "hear" the movies of black hole collisions but we couldn't see anything. We had hints of this before, but here we have a really nearby object with exquisite data, and there is no ambiguity". A single neutron star merger might produce an amount of gold comparable to the total mass of Earth. Mavalvala says it's hard to even speculate right now because the neutron star merger is the first such event ever observed. Scientists could identify the chirp source as objects that were much less massive than the black holes seen to date. And as the signals roll in, experts say the mergers will also serve as a precision tool for cosmologists. But before astronomers saw any visual evidence of this cataclysmic collision, their instruments picked up the movement of gravitational waves sending ripples through the fabric of space-time.

University of Sydney Associate Professor Tara Murphy, who leads the radio astronomy follow-up in Australia, says she was in the USA with colleague David Kaplan when they saw the gravitational wave announcement come through on the private email list of the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO).

Astronomers know the universe is expanding, and they use a figure called the Hubble Constant to describe how fast.

To improve the measurement, scientists will have to spot many more neutron-star mergers. But Smartt added that, by the time dusk fell in Paranal, the LIGO-Virgo collaboration had refined their localization of the GW signal, to the extent that searching for an electromagnetic counterpart became feasible. "It is clear that the rate of occurrence is somewhat higher than expected", he said. I expect it will be remembered as one of the most studied astrophysical events in history. "It will be tremendously exciting".



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