Astronomers have observed two collapsed stars of different masses locked in a "fiercely tight" orbit that are expected to collide about half a billion years from now. 

These highly massive astronomical objects called neutron stars are stellar remnants of a supernova--squeezing hundreds of times the Earth's mass into a vacuum that is the size of a city.

Once these stars collide, they'll be releasing vast quantities of energy in gravitational waves and light. The phenomenon may help shed light on some of the Universe's biggest mysteries.

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A rare sight

Scientists have observed these pulsars, and dead neutron stars trapped in binary systems, before. Named as GW170817, the spectacular phenomenon happened 130 million light-years from the Milky Way. Yet the scientists said it is rare to see such an unusual relationship with two neutron stars of different masses. 

The peculiar difference the scientists hope can be used to provide crucial information about some of the darkest, unresolved mysteries of the Universe. These give a better understanding of Hubble constant, Universe's expansion rate, and what the artifacts are made of.

"Such a disruption would allow astrophysicists to gain important new clues about the exotic matter that makes up the interiors of these extreme, dense objects," said study co-author Dr. Paulo Freire from Max Planck Institute for Radio Astronomy.

This matter remains a mystery, Freire added. Hence, scientists still don't know what it is actually made of. "These densities are far beyond what we can reproduce in Earth-based laboratories," the researcher said.

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The vast disparity between the two neutron stars is not something that scientists had hoped to discover until now.

When will it ever collide?

In a statement, lead researcher Dr. Robert Ferdman, from UEA's School of Physics, said most theories about this phenomenon claimed that neutron stars locked in binary systems are very similar in mass. The new discovery, however, changes these assumptions.

Dr. Ferdman and his team have uncovered a binary system containing two neutron stars with very different masses.

"These stars will collide and merge in around 470 million years, which seems like a long time, but it is only a small fraction of the age of the Universe," he claimed.

Dr. Ferdman said that because one of the stars is "significantly larger" than the other, its gravitational effects distort the form of its companion. The process would be stripping away vast quantities of matter just before they fully merge and eventually wrecking it, he added.

What will happen if these two collide?

Dr. Ferdman said the phenomenon will result in a far more powerful explosion than a collision of neutron stars with equal masses. He also added the results show there are many more of these structures out there that make up more than one in 10 merging double neutron star binaries.

The researchers claim neutron star mergers may help solve some of the biggest mysteries in astrophysics, including a more precise estimate of the expansion rate of the Universe, known as the Hubble constant.

Dr. Freire added such a disruption will allow astrophysicists to obtain important new information about the exotic matter that makes up the interiors of these large, dense objects.