Witnessing the production of rare heavy elements in a collision between neutron stars.
Scientists observed the formation of uncommon, dense elements following a forceful crash between two neutron stars that had been expelled from their original galaxy located approximately 1 billion light years away.
The massive outburst caused by the explosion produced a release of gamma rays that were over 1 million times brighter than the Milky Way. This also resulted in the creation of rare elements such as tellurium, as well as actinides and lanthanides. It is believed that the elements iodine and thorium were also formed during this event.
This is the initial occasion that a cosmic event, called a kilonova, has been detected using the James Webb space telescope. This allowed scientists to determine the elements created in the collision based on their infrared characteristics.
The research, featured in the journal Nature, demonstrates that although numerous elements are created through the fusion of lighter elements within the cores of stars or in stellar explosions, certain heavier elements originate in the high-energy setting of neutron stars colliding with each other.
Andrew Levan, a professor of astrophysics at Radboud University in the Netherlands, stated that there is now proof of the creation of these specific elements during mergers.
“It has been 150 years since the creation of the periodic table, yet there are still several elements whose origins remain unknown. Our goal is to fill in these gaps.”
Neutron stars are incredibly dense and compact objects, as massive as the sun but as small as a city. Astronomers were alerted to the potential neutron-star collision in March when they detected an intense burst of gamma rays from deep space, the second brightest recorded in the past 50 years.
Using a combination of ground-based and space-based tools, scientists initially identified the origin of the 200-second burst of radiation and then directed the James Webb space telescope towards the aftermath.
During a span of multiple days, the color of the light emitted by the collision shifted from blue to red, which is a characteristic sign of a kilonova. The neutron stars were observed to have been displaced from a luminous galaxy seen in close proximity, before eventually merging 120,000 light years away – a distance equivalent to the width of our own Milky Way galaxy – hundreds of millions of years later.
The impact probably formed a fresh black hole, but during the combination, large quantities of neutrons and other matter were ejected into the universe. This resulted in the formation of heavier elements through a process known as rapid neutron capture. When atomic nuclei are bombarded by neutrons, they can become unstable and go through radioactive decay, changing into heavier elements.
Scientists have only observed one other event of its kind with enough information to determine what elements may have been produced in the explosion. Although elements like iron and nickel are typically formed in supernovae, it is believed that more intense collisions of neutron stars may be responsible for creating heavier elements.
Levan, along with a global team of astronomers, stated that approximately half of the elements that are heavier than iron are most likely produced during these occurrences. He expressed their anticipation to witness this phenomenon, but acknowledged the unpredictability of the outcome.