Astronomers have found compelling evidence that a black hole or neutron star spiraled its way into the core of one of the two stars and caused it to explode, triggering a chain reaction in the companion star. Scientists could observe such an event for the first time.
Experts from the California Institute of Technology began studying the unusual phenomenon in 2017. Then they found an object emitting radio waves, but not observed in earlier sky surveys, writes Phys.org.
After studying the intriguing object with a powerful telescope in Hawaii, scientists have determined that the bright radio emission is coming from the outskirts of a dwarf star-forming galaxy about 480 million light-years from Earth. Later, using an instrument aboard the International Space Station, they detected an X-ray burst emanating from the object in 2014.
All observations have allowed astronomers to piece together the fascinating story of the centuries-old "dance of death" between two massive stars. Like most stars that are much more massive than our Sun, these two stars were born as a double pair orbiting close to each other. One of them was more massive than the other, and developed faster through nuclear fusion.
The orbit of a black hole or neutron star steadily approached one of the two stars. About 300 years ago, a space object entered its atmosphere, starting the "dance of death". At this point, the interaction between the objects led to a massive release of gas into space. It spiraled and formed an expanding donut-shaped ring around a pair of stars.
Eventually, a black hole or neutron star made its way inward to the core of one star, disrupting nuclear fusion that keeps the core from collapsing under its own gravity. When the core collapsed, it briefly formed a disk of material that revolved around the intruder, and pushed a stream of material outward at a speed approaching the speed of light, punching its way through the second star.
“It was this 'jet' that produced the X-rays seen by the MAXI instrument aboard the International Space Station in 2014,” the scientists note. The collapse of the star's core caused the second to explode as a supernova, following an earlier explosion of its companion. Essentially, the remnants of the exploding star plunged into their companion, causing it to explode as well.
