Swapna Krishna

Mar 4th 2022

What Happens When Two Stars “Shake Hands” and a Kilonova Occurs?


Gravitational waves, cosmic distortions that occur when two massive objects collide, were first theorized by Albert Einstein in 1916. In 2016, scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected the first gravitational waves, as MIT News reported, confirming Einstein’s theory of relativity.

What’s even more remarkable is that scientists can trace them back to their source: in this case, the collision of two black holes. But that’s not the only source of these micro-distortions. In 2017, scientists at LIGO observed the collision of two neutron stars, or a kilonova, for the first time. A kilonova is a once-in-a-lifetime event, according to National Geographic.

The Effect of These Waves on Earth’s Atmosphere

Gravitational waves are ripples in the fabric of space-time, and they’re difficult to detect. When they pass through the universe, including through Earth’s atmosphere, they squeeze and stretch everything around them, as NASA explained.

According to the LIGO observatory, the three main causes of gravitational waves are a supernova, the collision between two black holes and the collision between two neutron stars. Scientists also theorize that some gravitational waves may still be leftover from the Big Bang.

The Source of Kilonovae: Neutron Stars

When a massive star runs out of fuel at the end of its life, it explodes in the most brilliant cosmic explosion we know of: a supernova. It’s worth noting that a star must be much more massive than our own sun to go supernova — it’s likely that our star will simply turn into a white dwarf at the end of its life.

These giant stars run out of fuel and then begin to cool. Because the nuclear reaction at its core is no longer occurring, the star collapses quickly, resulting in an explosion that can be seen across the cosmos. What’s left after the supernova fades, depending on the star’s size, is either a black hole or a neutron star, Penn State noted, which is the extremely dense collapsed core of a star. The most common neutron star is a pulsar.

A Kilonova Occurs When Two Neutron Stars Collide

When two extremely dense dead star cores collide, the result is a kilonova. This is a bright afterglow of the collision that’s made of decaying heavy elements.

For a long time, scientists thought precious metals and heavy elements were ejected out of supernovae. But that theory has been debunked over the past few years, as scientists have studied supernovae and witnessed that there isn’t enough density to justify the amount of these elements present in the universe. That led scientists to another theory: Kilonovae are actually responsible for seeding these heavier elements throughout the cosmos.

All the gold, platinum and other precious metals we see around us are a result of these cosmic explosions (scientists still believe that lighter metals, such as aluminum, come from supernovae). When LIGO detected the gravitational waves from this kilonova, scientists were able to point an infrared telescope at the location of the event and see the precious metals that were created as a result of the handshake between dead star cores. There was also more left behind that scientists haven’t yet been able to characterize, but it may become a black hole.

Your Bling Is Made of Star Stuff

Thanks to the observation of two neutron stars meeting, scientists have been able to determine that one kilonova is enough to seed the equivalent of 100 Earths with precious metals, according to

That means the gold you wear in your ears or the ring you wear on your finger is truly made of the most spectacular star stuff — the collision of two neutron stars deep in space may have produced the jewelry you’re wearing today. As we continue to study the stars, we can only hope to uncover more fascinating discoveries like this.

Interested in all things in outer space and exploration? We are, too. Take a look at open positions at Northrop Grumman and consider joining our team.