A growing body of evidence indicates that binary neutron-star mergers are the primary origin of heavy elements produced exclusively through rapid neutron capture. As neutron-star mergers occur infrequently, their deposition of radioactive isotopes into the pre-solar nebula could have been dominated by a few nearby events.
One such event occurs 4.6 billion years ago. In a new study, astrophysicists observed the event and suggested that the event is responsible for some of the most coveted matter on the Earth.
According to the study, this event is the origin of 0.3 percent of the Earth’s heaviest elements, including gold, platinum, and uranium.
Imre Bartos at the University of Florida said, “This means that in each of us we would find an eyelash worth of these elements, mostly in the form of iodine, which is essential to life. A wedding ring, which expresses a deep human connection, is also a connection to our cosmic past predating humanity and the formation of Earth itself, with about 10 milligrams of it likely having formed 4.6 billion years ago.”
“Meteorites forged in the early solar system carry the traces of radioactive isotopes.”
Szabolcs Marka at Columbia University said, “As these isotopes decay they act as clocks that can be used to reconstruct the time they were created.”
For the study, scientists compared the composition of meteorites to numerical simulations of the milky way. They found that a single neutron-star collision could have occurred about 100 million years before the formation of Earth, in our neighborhood, about 1000 light years from the gas cloud that eventually formed the Solar System.
Marka said, “The Milky Way galaxy itself is 100,000 light years in diameter or 100 times the distance of this cosmic event from the cradle of Earth. If a comparable event happened today at a similar distance from the Solar System, the ensuing radiation could outshine the entire night sky.”
Bartos said, “The researchers believe that their study provides insight into a uniquely consequential event in our history. It sheds a bright light on the processes involved in the origin and composition of our solar system and will initiate a new type of quests within disciplines, such as chemistry, biology, and geology, to solve the cosmic puzzle.”
Marka said, “Our results address a fundamental quest of humanity: Where did we come from and where are we going? It is very difficult to describe the tremendous emotions we felt when realized what we had found and what it means for the future as we search for an explanation of our place in the universe.”
The study is published in the journal Nature.