Supermassive Black Hole Shreds a Huge Star in Record Flare

A colossal star met an unexpected fate when it drifted too close to a supermassive black hole 10 billion light-years away.

Instead of exploding as a supernova, the star was torn apart, creating the brightest and most distant black hole flare ever recorded—shining with the power of 10 trillion suns.

Star Meets Its Doom in a Cosmic Twist

The largest stars in the cosmos typically end their lives in spectacular fashion, exploding as supernova before collapsing into black holes. One enormous star, however, seems to have met a very different end. Instead of finishing its lifecycle with a brilliant blast, it drifted too close to a colossal black hole that tore it apart and consumed it piece by piece.

Researchers describe this scenario in a new Nature Astronomy study that details the most powerful and most distant flare of energy ever detected from a supermassive black hole. The outburst was first spotted in 2018 by the Zwicky Transient Facility (ZTF), a sky survey funded by the US National Science Foundation (NSF) and located at Caltech’s Palomar Observatory. The Caltech-led Catalina Real-Time Transient Survey, also supported by NSF, recorded it as well. The flare brightened dramatically, increasing its brightness by a factor of 40 within months, and ultimately became 30 times more luminous than any black hole flare previously seen. At its peak, it radiated the equivalent light of 10 trillion suns.

Peering Into the Distant Universe

The source of this powerful flash is an active galactic nucleus (AGN), a type of supermassive black hole that actively draws in surrounding material. Known as J2245+3743, it is estimated to have a mass 500 million times greater than the Sun and sits about 10 billion light-years from Earth. Because light takes time to travel across such vast distances, astronomers are viewing the event as it occurred billions of years ago, during an early era of the universe.

“The energetics show this object is very far away and very bright,” says study lead author Matthew Graham, research professor of astronomy at Caltech, as well as the project scientist for ZTF, and a co-principal investigator of the project. “This is unlike any AGN we’ve ever seen.”

Time Dilation and a Cosmic Slow-Motion Show

Although the flare is gradually fading, astronomers continue to observe it closely. The extreme distance affects not only how far back in time they are looking but also the rate at which the event appears to unfold. Time progresses more slowly at the black hole’s location relative to Earth.

Graham explains, “It’s a phenomenon called cosmological time dilation due to stretching of space and time. As the light travels across expanding space to reach us, its wavelength stretches as does time itself.”

This effect is one reason long-term sky surveys like ZTF and Catalina are so valuable. In this case, Graham notes that “seven years here is two years there. We are watching the event play back at quarter speed.”

A Star Torn Apart — The Tidal Disruption Event

To determine what could cause such a dramatic burst of light in the cosmos, the researchers thoroughly examined a list of possibilities, concluding that the most likely culprit is a tidal disruption event (TDE). This phenomenon occurs when a supermassive black hole’s gravity shears a star that comes too close, slowly consuming the star over time as it spirals into the black hole. The fact that the black hole flare J2245+3743 is still going indicates that we are witnessing a star not yet fully devoured but rather like “a fish only halfway down the whale’s gullet,” Graham says.

If the flare is from a TDE, the scientists estimate that the supermassive black hole gobbled a star with a mass at least 30 times greater than that of our Sun. The previous record holder for the largest candidate TDE, an event nicknamed Scary Barbie after its initial ZTF classification as ZTF20abrbeie, was not nearly as intense. That TDE, which is also thought to have originated from an AGN, was 30 times weaker than that of J2245+3743, and its doomed star is estimated to have been between three and 10 solar masses.

Stellar Snack Within a Black Hole’s Disk

Most of the roughly 100 TDEs seen to date do not take place around AGN—massive structures that consist of supermassive black holes surrounded by large, swirling disks of material that feed the central black hole. The AGN burble along, flaring up with their own feeding activity, which can mask TDE bursts and makes them harder to find. The recent jumbo flare J2245+3743, on the other hand, was so large that it was easier to see.

However, at first, J2245+3743 did not seem to be anything special. In 2018, after the object was first spotted, the researchers used the 200-inch Hale Telescope at Caltech’s Palomar Observatory to obtain a spectrum of the object’s light, but it did not reveal anything unusual. In 2023, the team noticed the flare was decaying slower than expected, so they obtained another spectrum from the W. M. Keck Observatory in Hawai‘i, which indicated the extreme brightness of this particular AGN.

Confirming the Unthinkable: A Star Devoured

“At first, it was important to establish that this extreme object was truly this bright,” explains co-author K. E. Saavik Ford, a professor at the City University of New York (CUNY) Graduate Center and Borough of Manhattan Community College and American Museum of Natural History (AMNH). It was possible, she says, that the object could have been beaming the light toward us rather than glowing in all directions, but data from NASA’s former Wide-field Infrared Survey Explorer (WISE) mission helped rule that out. In the end, after other scenarios were also ruled out, the researchers concluded that J2245+3743 was indeed the brightest black hole flare ever recorded.

“If you convert our entire Sun to energy, using Albert Einstein’s famous formula E = mc2, that’s how much energy has been pouring out from this flare since we began observing it,” Ford says.

Beyond Supernovae — A Rare Celestial Catastrophe

After confirming that the flare’s brightness surpassed anything previously recorded, the researchers turned to the question of what could create such an extreme burst of energy. One idea was a supernova, but that explanation was quickly dismissed.

“Supernovae are not bright enough to account for this,” Ford says. The team instead concluded that the most convincing cause is a supermassive black hole gradually tearing apart an enormous star.

“Stars this massive are rare,” Ford says, “but we think stars within the disk of an AGN can grow larger. The matter from the disk is dumped onto stars, causing them to grow in mass.”

A Window Into the Cosmic Past

Discovering a star this large being consumed by a black hole suggests that similar dramatic events may be happening elsewhere throughout the universe. The team plans to examine additional data from ZTF to search for more examples, and future observations from the NSF and Department of Energy’s Vera C. Rubin Observatory may reveal even larger tidal disruption events.

“We never would have found this rare event in the first place if it weren’t for ZTF,” Graham says. “We’ve been observing the sky with ZTF for seven years now, so when we see anything flare or change, we can see what it has done in the past and how it will evolve.”

Reference: “An extremely luminous flare recorded from a supermassive black hole” by Matthew J. Graham, Barry McKernan, K. E. Saavik Ford, Daniel Stern, Matteo Cantiello, Andrew J. Drake, Yuanze Ding, Mansi Kasliwal, Mike Koss, Raffaella Margutti, Sam Rose, Jean Somalwar, Phil Wiseman, S. G. Djorgovski, Patrik M. Veres, Eric C. Bellm, Tracy X. Chen, Steven L. Groom, Shrinivas R. Kulkarni and Ashish Mahabal, 4 November 2025, Nature Astronomy.
DOI: 10.1038/s41550-025-02699-0

The Nature Astronomy paper, titled “An Extremely Luminous Flare Recorded from a Supermassive Black Hole,” received support from the NSF, the Simons Foundation, NASA, and the German Research Foundation. The research team includes Caltech contributors Andrew Drake, Yuanze Ding (MS ’25), Mansi Kasliwal (PhD ’11), Sam Rose, Jean Somalwar (now a postdoc at UC Berkeley), George Djorgovski, Shri Kulkarni, and Ashish Mahabal. Tracy Chen and Steven Groom from Caltech’s IPAC astronomy center also took part, along with Daniel Stern of NASA’s Jet Propulsion Laboratory (which is managed by Caltech).

Additional collaborators include Barry McKernan of CUNY Graduate Center, Borough of Manhattan Community College, and AMNH; Matteo Cantiello of the Simons Foundation’s Flatiron Institute and Princeton University; Mike Koss of Eureka Scientific; Raffaella Margutti of UC Berkeley; Phil Wiseman of the University of Southampton, UK; Patrik Veres of Ruhr University in Bochum, Germany; and Eric Bellm of the University of Washington.

Caltech’s Zwicky Transient Facility (ZTF) is supported by the NSF and an international group of partners, with further funding from the Heising-Simons Foundation and Caltech. Data from ZTF are processed and stored by Caltech’s IPAC, and NASA contributes support for ZTF’s hunt for near-Earth objects through the Near-Earth Object Observations program.

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