Nearby doomed stars spiraling toward a gigantic collision

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Nearby doomed stars spiraling toward a gigantic collision

A mere 150 light-years distant, two white dwarf stars are in a dance of death. Researchers at the University of Warwick in the U.K. said on April 4, 2025, that they’ve spotted two stars on a collision course, and the resulting supernova would be brighter than 10 full moons in our sky.

White dwarfs are the depleted but superdense remains of stars like our sun. The two stars the researchers found are in a compact binary system, meaning they orbit each other closely. And the more massive of the two white dwarfs is pulling material from the less massive star onto itself. Eventually, the star reaches a tipping point where it can’t sustain its gravity under all that mass, and it explodes in a powerful supernova. This scenario leads to what astronomers called a type 1a supernova.

The scientists published their study in the peer-reviewed journal Nature Astronomy on April 4, 2025.

An exciting discovery

Astronomers have long predicted that two orbiting white dwarfs were the source of most type 1a supernovas. But these white dwarfs mark the first discovery of such a system spiraling toward collision. As the two stars orbit in close proximity, one sucks in mass from the other until it reaches a critical point. This results in a supernova.

Lead author James Munday of the University of Warwick said:

For years a local and massive double white dwarf binary has been anticipated, so when I first spotted this system with a very high total mass on our galactic doorstep, I was immediately excited.

With an international team of astronomers, four based at The University of Warwick, we immediately chased this system on some of the biggest optical telescopes in the world to determine exactly how compact it is.

Discovering that the two stars are separated by just 1/60th of the Earth-sun distance, I quickly realized that we had discovered the first double white dwarf binary that will undoubtedly lead to a type 1a supernova on a timescale close to the age of the universe.

At last, we as a community can now account for a few percent of the rate of type 1a supernovae across the Milky Way with certainty.

A massive pair in a death spiral

This massive pair is the heaviest of its type yet confirmed. Together the two stars have a mass of 1.56 times that of our sun. The astronomers said this means the stars will eventually pass the threshold for the binary system. This will result in one erupting in a supernova and taking out its dance partner.

So what’s the timescale for this event? Currently, the stars orbit each other in approximately 14 hours. But over billions of years this dance will accelerate until the two swirl around each other in just 30 to 40 seconds. The explosion itself will take just a few seconds. But don’t expect to see it anytime soon. It will be some 23 billion years before the supernova occurs. And even if there were somehow still earthlings around to see it (despite our sun having just 5 billion years left), it’s too far away to damage Earth.

This animation shows 2 white dwarf stars colliding and then exploding in a supernova. Video via Dr. Ruediger Pakmor, Scientific Staff, Max Planck Institute for Astrophysics. Used with permission.

The doomed stars will have a quadruple detonation

When the star that’s been accumulating mass detonates, its first ignition point will be where that mass has accumulated, followed by the core exploding. Then the material will explode outward, falling upon the second star, which will follow with two explosions in the same manner as the first star.

Co-author Ingrid Pelisoli of The University of Warwick said:

This is very significant discovery. Finding such a system on our galactic doorstep is an indication that they must be relatively common, otherwise we would have needed to look much farther away, searching a larger volume of our galaxy, to encounter them.

Finding this system is not the end of the story though. Our survey searching for type 1a supernova progenitors is still ongoing and we expect more exciting discoveries in the future. Little by little we are getting closer to solving the mystery of the origin of type 1a explosions.

Bottom line: Astronomers at the University of Warwick in the U.K. said they’ve identified two nearby white dwarf stars that are on course to collide and create a supernova explosion, in about 23 billion years.

Source: A super-Chandrasekhar mass type Ia supernova progenitor at 49 pc set to detonate in 23 Gyr

Via University of Warwick