In the quiet vastness of the Milky Way, just 150 light-years from our cosmic doorstep, astronomers at the University of Warwick have made a discovery that feels like it belongs in the pages of science fiction. Nestled invisibly among the stars lies a compact binary system—two dead stars, white dwarfs, locked in a gravitational dance that will one day end in one of the most dramatic events the universe can offer: a type Ia supernova.
This isn’t just another distant cosmic curiosity. What makes this find extraordinary is its proximity, its mass, and its destiny. When these two stars collide, they won’t just vanish—they’ll ignite a titanic explosion visible across the galaxy, burning with a brilliance 10 times brighter than the full moon. And for the first time, scientists have not only identified such a system so close to Earth, but have confirmed with confidence that it is fated to explode.
The Fire Beneath the Ice: What Are White Dwarfs?
White dwarfs are the dense, cooling remnants of stars like our Sun. After exhausting their nuclear fuel, these stars shed their outer layers, leaving behind a hot, compact core. While they no longer shine with the intensity of their youth, they are far from dead—especially when they’re in pairs.
The newly discovered system contains two such stellar corpses, orbiting each other at a breathtakingly close distance—just 1/60th the space between Earth and the Sun. That’s roughly 2.5 million kilometers, or less than the width of our Sun.
James Munday, Ph.D. researcher at Warwick and lead author of the study, remembers the moment he realized what they had found: “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 the help of some of the largest optical telescopes on Earth, Munday and his international team of astronomers quickly confirmed the astonishing compactness and weight of the system.
Why This Star System Is a Big Deal
This is no ordinary binary pair. Combined, the two white dwarfs boast a mass 1.56 times that of our Sun. That figure may seem arbitrary—until you understand the physics of stellar death.
There’s a hard limit to how massive a white dwarf can become before gravity overwhelms its internal pressure. Called the Chandrasekhar limit, this cosmic tipping point is around 1.4 solar masses. Exceeding it leads to runaway nuclear reactions and a cataclysmic supernova.
In other words, the clock is ticking. These two stars are destined to collide and explode, no matter what. The question is not if, but when.
The answer? Not for another 23 billion years. So, no need to worry about doomsday headlines just yet.
Supernova: The Universe’s Most Dazzling Exit
Type Ia supernovae are among the brightest, most powerful explosions in the cosmos. And importantly, they all explode with a remarkably consistent brightness. This makes them vital tools for astronomers, who use them as “standard candles” to measure vast cosmic distances and map the expanding universe.
Yet for all their importance, the exact mechanism behind these explosions has remained a subject of mystery. One popular theory holds that they occur when two white dwarfs orbiting in close proximity eventually merge. The heavier of the two cannibalizes the other, siphoning off mass until the balance tips and nuclear ignition ensues.
This discovery marks the first time scientists have definitively found such a pair with enough mass to confirm that the process will, in time, lead to a supernova. And it’s right in our own galactic backyard.
Dr. Ingrid Pelisoli, Assistant Professor at Warwick and third author of the study, emphasized the importance of the find: “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 further away, searching a larger volume of our galaxy, to encounter them.”
A Symphony of Explosions: The Quadruple Detonation
When the time comes, this won’t be just any supernova. The event is expected to unfold in a complex and spectacular sequence known as a “quadruple detonation.”
Here’s how it works:
- Initial Surface Detonation: The mass-gaining white dwarf becomes unstable as material from its partner builds on its surface. This triggers a violent surface detonation.
- Core Detonation: The shockwave from the surface ignites the star’s core, initiating a second, far more powerful explosion.
- Collision-Triggered Detonation: The blast collides with the second white dwarf, transferring immense energy and triggering a third explosion.
- Final Detonation: The second star’s core then succumbs to pressure and heat, completing the cycle with a fourth, final detonation.
The result? Both stars are utterly obliterated in a cosmic spectacle of light and energy. The explosion will unleash energy a thousand trillion trillion times more powerful than the most devastating nuclear weapon ever imagined.
A Light in the Sky That Dwarfs the Moon
Billions of years from now, as the two stars spiral ever closer—speeding up their orbit from 14 hours to just 30–40 seconds before the final burst—our descendants, or perhaps alien civilizations, will witness a sky-shaking marvel.
For weeks, the night sky will feature a brilliant, unnatural star shining up to 10 times brighter than the full moon. It will rival the Sun in daytime visibility and cast sharp shadows on Earth at night. Compared to Jupiter, the largest and brightest of our night-time planets, this supernova will be 200,000 times more radiant.
Even though the event will be visually stunning, it will not threaten life on Earth. Its radiation and shockwaves will have dissipated over the 150-light-year journey to our solar system. All we’ll see is the light—and what a light it will be.
A Step Closer to Solving a Celestial Puzzle
This system not only confirms long-held theories about type Ia supernovae, but it also opens the door to a more accurate understanding of how often these events occur—and where to look for them.
“For decades, astronomers have been building models of how white dwarf binaries lead to type Ia supernovae,” said Munday. “This is the first time we’ve caught one with this much mass and this close to home. We now have direct evidence to account for a portion of the rate of these supernovae in our galaxy.”
The discovery was published in Nature Astronomy, one of the field’s most prestigious journals. Yet the journey is far from over. The Warwick team’s survey of the skies continues, with hopes of uncovering more such systems and further unraveling the mysterious origin of these cosmic explosions.
A Cosmic Love Story with a Violent Ending
At its core, this is a story of attraction. Two stars, once bright and full of life, now orbiting each other in a silent embrace for billions of years. Drawn ever inward by an invisible force—gravity—that binds them inescapably together.
They’re not in a hurry. They have time. Twenty-three billion years of it. But one day, their story will end in an explosion so grand, it will write itself across the night sky for all to see.
Until then, they remain hidden from the naked eye, circling one another in quiet anticipation, waiting for their final, fiery dance.
Reference: A super-Chandrasekhar mass type Ia supernova progenitor at 49 pc set to detonate in 23 Gyr, Nature Astronomy (2025). DOI: 10.1038/s41550-025-02528-4