This illustration shows the "Cow", the first example of a fast blue optical transient. It was discovered in 2018 and was 10 to 100 times brighter than a supernova explosion. Now, astronomers have found an even brighter one. Image Credit: Phil Drury, University of Sheffield
Have you ever wondered what happens when a star wanders too close to a black hole?
Welcome to FreeAstroScience, where we transform complex cosmic mysteries into stories you can understand over your morning coffee. Today, we're going to take you on a journey to witness one of the most violent, beautiful, and scientifically puzzling events ever recorded in our universe.
Imagine an explosion so bright it outshines 400 billion suns. Picture a cosmic crime scene 1.1 billion light-years away, where a star met its end in the gravitational jaws of a black hole. This isn't science fiction—it happened, astronomers caught it, and they've given it a name: Whippet.
Stick with us through this article. By the end, you'll understand not just what happened, but why events like this matter for our understanding of the cosmos. You'll also discover why astronomers around the world are scratching their heads—because even our best models can't fully explain what they've seen.
What Are These Mysterious "Fast Blue" Explosions?
Before we can appreciate Whippet, we need to understand the weird family it belongs to.
In astronomy, we call them Luminous Fast Blue Optical Transients—or LFBOTs for short. The name sounds technical, but it actually tells you everything you need to know :
- Luminous: They're incredibly bright, rivaling the most powerful supernovae
- Fast: They appear and disappear in just days or weeks (typical supernovae take months)
- Blue: They emit mostly blue light
- Optical Transients: They're temporary events we can see with telescopes
"The name basically tells you what they are, at least observationally," explained Daniel Perley, Associate Professor of Astrophysics at Liverpool John Moores University, during his presentation at the 247th Meeting of the American Astronomical Society. "They are as bright as a powerful supernova, but they play out much faster, appearing and disappearing on timescales of just a few days or weeks."
Here's what makes them strange: they shouldn't exist according to our standard models. A supernova gets its brightness from radioactive nickel-56 decaying inside the explosion. But LFBOTs are too bright and too fast for that explanation to work. The math simply doesn't add up .
The First One: A Cosmic "Cow"
We discovered our first LFBOT in 2018. Officially named AT2018cow, astronomers affectionately called it "the Cow." It appeared in a galaxy about 200 million light-years away and was 10 to 100 times brighter than a typical supernova .
The Cow showed us something unexpected: high temperatures (around 30,000 Kelvin) that persisted for weeks, velocities exceeding 10% the speed of light, and X-ray emissions that flickered and varied in ways we'd never seen before .
Since then, we've found a few more of these cosmic oddities. Each one has taught us something new—and raised even more questions.
How Did Scientists Discover Whippet?
The story of AT2024wpp—nicknamed Whippet—begins with automated sky surveys that never sleep.
The Zwicky Transient Facility (ZTF) at Palomar Observatory in California first spotted the event. This telescope scans the entire northern sky every two days, looking for anything that changes. When something new appears, algorithms flag it for human review .
What makes Whippet special is timing. Scientists caught it before it reached peak brightness—a first for any LFBOT. This meant they could watch the event unfold from the beginning, gathering data that previous discoveries missed .
Within hours of detection, astronomers around the world swung their instruments toward the source:
- The Liverpool Telescope in the Canary Islands captured optical and infrared images
- NASA's Swift satellite measured X-rays and ultraviolet light from space
- The Very Large Telescope in Chile obtained spectra
- The Karl G. Jansky Very Large Array in New Mexico recorded radio emissions
- ALMA in Chile captured millimeter-wavelength radiation
The location? A galaxy 1.1 billion light-years from Earth. When we see Whippet's light, we're looking at an event that happened when complex multicellular life on Earth was still hundreds of millions of years in the future .
Just How Bright Is 400 Billion Suns?
Let's put Whippet's peak brightness into perspective. Our brains struggle with astronomical numbers, so we'll build up to it.
| Object | Brightness Relative to the Sun |
|---|---|
| Full Moon | 0.00000005 × the Sun |
| Brightest star (Sirius) | ~25 × the Sun |
| Typical supernova | ~5 billion × the Sun |
| Superluminous supernova | ~100 billion × the Sun |
| Whippet (AT2024wpp) | 400 billion × the Sun |
"This was many times more energetic than any similar event and more than any known explosion powered by the collapse of a star," Perley said in a press release .
The technical measurement? Whippet's peak bolometric luminosity exceeded 1045 erg per second . That's scientific notation for "unimaginably enormous."
If you could somehow survive near Whippet during its peak, you would see a light brighter than the combined output of every star in four average galaxies. And all of that energy was released in just a few days.
What Caused This Extreme Event?
Here's where the detective work begins.
When massive stars die, they often explode as supernovae. Sometimes, after the explosion, a black hole forms from the collapsed core. Now, stars rarely live alone. About half of all stars have at least one companion in a binary system. So when one star becomes a black hole, its partner finds itself orbiting something dangerous .
The leading explanation for Whippet involves this exact scenario: a tidal disruption event (TDE).
How a Black Hole Shreds a Star
When a star passes too close to a black hole, the gravitational pull on the near side of the star is much stronger than on the far side. This difference—we call it tidal force—stretches the star like cosmic taffy.
If the star gets close enough, these forces overcome the star's own gravity holding it together. The star gets ripped apart. Some material escapes into space. The rest spirals inward, forming a swirling disk of superheated gas around the black hole.
This process releases enormous energy. Matter heats up to millions of degrees as it falls inward. X-rays blast outward. Powerful winds sweep through space.
"We discovered what we think is a black hole merging with a massive companion star, shredding it into a disk that feeds the black hole," Perley explained. "It's a rare and awe-inspiring phenomenon."
The Synchrotron Blast Wave
But the tidal disruption alone doesn't explain everything we saw.
The event also created what scientists call a synchrotron blast wave. Here's how it works:
- The violent disruption sends a shockwave racing outward through space
- This shockwave accelerates electrons to nearly the speed of light
- As these electrons travel through magnetic fields, they're forced to spiral
- Spiraling electrons emit radiation across the electromagnetic spectrum
This mechanism explains the bright optical emissions and the radio signals astronomers detected .
Hidden Chemical Fingerprints
One puzzle remained. For about a month after the explosion, astronomers couldn't detect any recognizable chemical signatures in the spectra. This was strange—stellar material should show distinct patterns of hydrogen, helium, and heavier elements.
The explanation? X-rays from the central engine were so intense that they ionized all the surrounding material, stripping away electrons and erasing the normal spectral lines .
Only later, as the event faded and the ionizing radiation weakened, did weak hydrogen and helium signatures appear. The helium was moving toward us at more than 6,000 kilometers per second—suggesting a dense cloud of material hurtling through space .
Why Can't Our Models Explain It?
Here's where things get humbling.
A team of researchers led by Conor Omand at Liverpool John Moores University tested every model they could think of against Whippet's data. They tried :
- Engine-driven supernovae: Where a magnetar or black hole powers the explosion
- Interaction-powered supernovae: Where ejected material slams into surrounding gas
- Shock cooling emission: Where shock-heated material radiates as it cools
- Tidal disruption events: Both from intermediate-mass black holes and stellar-mass black holes
- Wolf-Rayet/black hole mergers: Where a black hole consumes its massive stellar companion
The result? "We show that none of the multiwavelength light curve models can reasonably explain the data," the researchers wrote .
Let that sink in. We've observed something that doesn't fit any of our existing theories.
The Problem with the Photosphere
One specific problem stands out. The "photosphere" of an explosion is the visible surface—the boundary where light finally escapes. In normal explosions, this surface expands outward, then eventually recedes as the material thins.
For Whippet, the photosphere peaked at about 5 days. But spectral observations suggest the material remained optically thick (meaning light couldn't pass through easily) for at least 40 days .
That's mathematically inconsistent with material that's expanding outward in the way our supernova models predict. Something else must be happening—perhaps continuous injection of new material, or a geometry that's far from spherical.
What the Models Favor
Despite the difficulties, physical arguments point toward one scenario: a tidal disruption of a low-mass star by either a stellar-mass black hole or an intermediate-mass black hole, combined with a synchrotron blast wave .
The team couldn't definitively rule out other possibilities:
- A failed supernova where the star collapses directly into a black hole without exploding
- A reprocessing outflow where an accretion disk powers material that re-emits the energy
- Some exotic mechanism we haven't imagined yet
The honest truth is that Whippet has shown us the limits of our understanding.
The Growing Family of Cosmic Beasts
Whippet doesn't exist in isolation. Since we discovered the Cow in 2018, astronomers have found a small but growing family of these strange objects. Each one has been given an animal-themed nickname:
| Designation | Nickname | Discovery Year | Notable Feature |
|---|---|---|---|
| AT2018cow | The Cow | 2018 | First LFBOT discovered; closest to Earth |
| AT2018lug | The Koala | 2018 | Similar properties to the Cow |
| AT2020xnd | The Camel | 2020 | Well-studied with magnetar models |
| AT2022tsd | The Tasmanian Devil | 2022 | Showed giant optical flares |
| AT2023fhn | The Finch | 2023 | Extensive multiwavelength data |
| AT2024wpp | The Whippet | 2024 | Most luminous LFBOT ever; caught before peak |
These events are rare—less than 0.1% of the core-collapse supernova rate . They tend to occur in metal-poor, low-mass starburst galaxies, similar to where we find super-luminous supernovae and long gamma-ray bursts. This hints that they all might come from massive, low-metallicity stars .
The Tasmanian Devil showed something particularly wild: giant optical flares that varied on minute timescales . This kind of rapid flickering strongly suggests a central engine—either a newly formed neutron star with an incredibly strong magnetic field (a magnetar) or an accretion disk around a black hole.
Why Does This Discovery Matter?
You might be wondering: why should we care about an explosion that happened over a billion years ago?
Finding Hidden Black Holes
Black holes are notoriously hard to detect. They don't emit light on their own. We usually find them only when they're actively consuming material or when they pull on nearby objects.
LFBOTs like Whippet give us a new way to locate black holes. "Not only do these events help us identify black holes, they provide a new way to identify where black holes occur and how they form and grow, and the physics of how this happens," Perley noted .
This is especially important for intermediate-mass black holes—those between about 100 and 100,000 solar masses. We've confirmed the existence of stellar-mass black holes (from dead stars) and supermassive black holes (at galaxy centers). But the middle ground remains mysterious. LFBOTs might be our best tool for finding them.
Testing Physics at Extremes
The universe operates under the same physical laws everywhere. But we can only test those laws in our laboratories under limited conditions. Events like Whippet let us probe physics at extremes we can't recreate on Earth:
- Temperatures of millions of degrees
- Magnetic fields trillions of times stronger than Earth's
- Gravitational forces that can shred stars
- Particle acceleration to nearly light speed
Every time our models fail to explain an observation, we learn something. Whippet is telling us that our understanding of tidal disruptions, shock physics, or radiation processes is incomplete.
The Story of Stellar Death
Stars aren't immortal. Every star you see in the night sky will eventually die. Understanding how they die—and what they leave behind—helps us trace the cosmic cycle of matter.
The heavy elements in your body were forged inside stars and scattered by their deaths. Some of that scattering might have come from events like Whippet. The iron in your blood, the calcium in your bones, the oxygen you're breathing—all of it passed through stellar furnaces and violent endings.
The Search Continues
Astronomers will keep watching the location of Whippet for months and years to come. As the initial flash fades, they expect to see different kinds of emission emerge.
If a black hole truly formed there, it should settle into a steady accretion disk. That disk would glow in X-rays and ultraviolet light—a persistent signature we could detect with the Hubble Space Telescope or the Chandra X-ray Observatory .
Current upper limits from late-time observations already constrain what kind of black hole might be there. The data disfavor black holes more massive than about 100,000 solar masses. If the black hole is smaller—in the intermediate-mass range—the disk emission might be too faint to detect with current instruments .
We're also getting better at catching these events early. The Vera C. Rubin Observatory, set to begin operations soon, will survey the entire southern sky every few nights. It will find transients far fainter and faster than current surveys can detect. The LFBOT family is almost certainly larger than we know—we just haven't had the tools to find them all.
A Universe That Humbles Us
Here's what we find most beautiful about discoveries like Whippet.
For all our technology, for all our equations and computer models, the universe keeps surprising us. We point our telescopes at a distant galaxy and catch a cosmic event so extreme that it breaks our best theories.
That's not failure. That's science working exactly as it should.
Every observation that doesn't fit pushes us to think harder, to imagine new possibilities, to admit what we don't know. The Whippet—400 billion times brighter than our Sun, visible from over a billion light-years away, caused by forces that ripped a star to shreds—reminds us how much remains to discover.
Conclusion: Keep Your Mind Active
We've traveled together from the basics of fast blue transients to the bleeding edge of astrophysical research. Along the way, we've seen a black hole consume a star, witnessed energy releases that dwarf anything in our solar system, and confronted the honest truth that our models can't fully explain what we're seeing.
This is what we love about astronomy at FreeAstroScience. The universe doesn't care about our theories. It shows us what's real, and challenges us to understand.
Here's our invitation to you: Keep asking questions. Keep looking up. Keep reading. The sleep of reason breeds monsters—but the awakening of curiosity reveals wonders beyond imagination.
We'll be here, translating the cosmos into stories that make sense. Come back to FreeAstroScience.com whenever you're ready for your next cosmic journey. There's always more to explore, more to question, and more to understand.
The Whippet won't be the last surprise the universe sends our way. And we can't wait to tell you about the next one.
Sources
Gough, E. (2026, January 12). "Few Cosmic Events Can Rival The Brightness Of This Black Hole Shredding A Star Apart." Universe Today.
Omand, C. M. B., Sarin, N., Lamb, G. P., Perley, D. A., et al. (2026). "Multiwavelength Modeling of the Luminous Fast Blue Optical Transient AT2024wpp." Monthly Notices of the Royal Astronomical Society (preprint). arXiv:2601.03372v1.
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