Many moons ago in a faraway galaxy there were two neutron stars that collided and gave everyone a magnificent light show. Then after spending billions of years circling one another, what was left of these two stars spiraled thousands more times around one another prior to one final collision that occurred a considerable fraction of speed of light, they in likelihood created a black hole.
Feeling a Massive Collision
This merging was so massive and violent that literally shook the entire universe. It emitted energy that was equivalent to the energy of about 200 million suns into the space-time fabric which is referred to as gravitational waves. These waves flowed away from this merger like a ripple within a pond, and eventually it would wash across the Earth—where it would be detected by the premiere gravitational-wave detectors which exist on our planet. One of these were built in the United States by LIGO, and the other was built in Europe by Virgo observatories.
However, these intense gravitational waves weren’t the only byproduct of the star merger. This major event emitted some electromagnetic radiation as well—in other word, light. This marked the very first time that astronomers successfully captured both gravitational waves as well as light from one solitary source. This first light detection from the star merger was actually a very brief, yet fabulous blast of gamma rays, along with a potential birth cry of a black hole that was detected by NASA’s Fermi Gamma-Ray Space Telescope. Hours after that, the astronomers used ground-based telescopes to pick up even more light from this star merger—which was called “kilonova”—that was created as debris from this intense merger continued to expand and cool. For several weeks, an astronomical global community observed this kilonova while it gradually disappeared faded from full view.
Kilonova Observed by the World
While the astronomers examined and evaluated the aftermath of the star merger in different light wavelengths, they observed signs of many heavy elements that had formed instantly. Astronomers had been predicting for a long time that a merging of neutron stars was most likely responsible for the forming of elements like titanium and gold , and other neutron-rich metals which aren’t known to originate in stars. Almost everything that they observed within the ever changing light of the star merger’s kilonova turned out to match their predictions, even though none of them definitively, observed this merger spitting out any gold nuggets.
Even though this event was visually witnessed across a separation of about 130 million light-years from Earth, the merger was still bright, big, and glorious. There is no doubt that neutron stars are rare by themselves—let alone seeing two of them about to merge—it is very unlikely that such an event will occur this close to Earth again anytime soon.
But let us imagine for a moment that if we could, and it were to occur in the Milky Way or even in one of its many satellite galaxies. Or perhaps if it were to occur in our own immediate space neighborhood, what would that be like and what exactly would we be able to see? Would our world survive such an event?
Although LIGO is able to actually hear mergers like this and other massive object collisions, astronomers were very fortunate to even detect this stellar event.