A team of international astronomers has found that a pair of stars that collided almost 350 years ago spilled radioactive molecules into space.
The researchers, from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, made the discovery when studying the remains of an explosive stellar merger which occurred (and was seen from Earth) in 1670, known as CK Vulpeculae, or CK Vul.
We are observing the guts of a star torn apart three centuries ago by a collision. How cool is that?
At that time, the merger appeared to observers as a bright, red "new star" and while initially visible with the naked eye, this burst of cosmic light quickly faded. It now requires powerful telescopes to see the remains of this merger: a dim central star surrounded by a halo of glowing material flowing away from it.
Using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Northern Extended Millimeter Array (NOEMA) radio telescopes, the research team, led by astronomer Tomasz Kamiński, found the clear and convincing signs of a radioactive version of aluminium bound with atoms of fluorine, forming 26-aluminum monofluoride (called 26AlF).
This is the first molecule bearing an unstable radioisotope detected outside of our solar system, the astronomers said.
Unstable isotopes have an excess of nuclear energy and eventually decay into a stable, less-radioactive form
"Unstable isotopes have an excess of nuclear energy and eventually decay into a stable, less-radioactive form. In this case, the 26-aluminum (26Al) decays to 26-magnesium," the researchers explained.
Kamiński added: "The first solid detection of this kind of radioactive molecule is an important milestone in our exploration of the cool molecular universe."
The researchers detected the unique spectral signature of these molecules in the debris surrounding CK Vul, which are approximately 2,000 light-years from Earth.
As these molecules spin and tumble through space, they found that they emit a distinctive fingerprint of millimetre-wavelength light, a process known as "rotational transition".
Deep, dense inner layers of a star, where heavy elements and radioactive isotopes are forged, can be churned up and cast into space
The astronomers considered this the "gold standard" for molecular detections and conclude that it provides fresh insights into the merger process that created CK Vul.
"It also demonstrates that the deep, dense inner layers of a star, where heavy elements and radioactive isotopes are forged, can be churned up and cast into space by stellar collisions," the researchers said.
"We are observing the guts of a star torn apart three centuries ago by a collision," added Kamiński. "How cool is that?"
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago