Astronomers have observed a monumental collision between two neutron stars, resulting in the formation of the smallest black hole ever detected and the synthesis of precious metals like gold, silver, and uranium. This event took place 130 million light-years away in the galaxy NGC 4993.
The collision generated a kilonova, a powerful explosion that illuminated its surroundings with brightness equivalent to hundreds of millions of suns. A research team from the Cosmic DAWN Center at the Neils Bohr Institute utilized various instruments, including the Hubble Space Telescope, to capture this event, providing insights into the mergers of neutron stars and the origins of elements heavier than iron.
Rasmus Damgaard, a researcher at the Cosmic DAWN Center, noted, "We can now see the moment where atomic nuclei and electrons are uniting in the afterglow." This study marks the first observation of atom formation and the measurement of matter temperature in such a distant explosion.
Neutron stars form when massive stars exhaust their nuclear fuel, leading to supernova explosions that leave behind incredibly dense remnants. These remnants can weigh between 1 and 2 solar masses, compressed into a diameter of about 12 miles (20 kilometers).
The collision of neutron stars generates gravitational waves, which carry away angular momentum and tighten their orbit until they merge. This merger releases neutron-rich matter at temperatures billions of degrees, similar to conditions shortly after the Big Bang.
As the matter cools, the rapid neutron capture process (r-process) occurs, producing heavy elements. The team observed the afterglow of particles forming elements like strontium and yttrium, suggesting the creation of additional heavy elements during the event.
Albert Sneppen, the team leader, emphasized the importance of global collaboration among telescopes to capture the dynamic nature of the explosion. The findings were published on October 30 in the journal Astronomy & Astrophysics.