Record-Breaking Black-Hole "Superflare" — Likely Caused by a 30-Solar-Mass Star Being Shredded

Brightest Black-Hole Flare Ever Detected

Astronomers have identified the most luminous burst of light ever recorded from a black hole — a superflare that, at its peak, shone more than 10 trillion times brighter than the Sun. New analysis suggests the outburst erupted when the black hole tidally shredded a very massive star, likely at least 30 times the mass of the Sun.

Discovery and follow-up observations

The source was first noticed in 2018 after it brightened, prompting observations with the Palomar Observatory's 200-inch Hale Telescope. The initial light curve appeared unremarkable, and the object was not immediately recognized as a dramatic event. When the team re-examined the source in 2023 they found it remained unusually luminous even five years after discovery.

Follow-up spectroscopy with the W. M. Keck Observatory in Hawaii placed the source at roughly 3 million kiloparsecs — about 10 billion light-years away. For an object at that distance to appear so bright, its jets must have been extraordinarily powerful; the researchers estimate this flare was roughly 30 times more luminous than any previously observed black-hole flare.

Ruling out alternative explanations

The authors considered other possibilities, including a nearby supernova or strong gravitational lensing that might artificially boost the apparent brightness. After comparing these scenarios to the full set of observations, they concluded that neither provided a satisfactory match to the data.

Leading interpretation: tidal disruption of a massive star

The preferred explanation is a tidal disruption event in which a very massive star wandered too close to the black hole and was torn apart by tidal forces. As the stellar debris fed the black hole, its jets brightened to roughly 40 times their previous intensity. Because the flare is still ongoing, the team suggests the star has not yet been fully consumed.

"It didn’t seem nearly as interesting as we thought it was," said Matthew Graham of Caltech, recalling the initial observations. "To appear so bright at such a great distance, the jets must have been particularly luminous."

What comes next

Scientists will continue monitoring the source to see whether the jets gradually fade or produce secondary brightenings as shock fronts interact with surrounding gas and dust. Joseph Michail of the Harvard–Smithsonian Center for Astrophysics says upcoming wide-field sky surveys may soon reveal many more such beacons.

Graham notes that the object's great distance slows our effective view of the event: roughly seven Earth years correspond to two years of the black hole's activity, so astronomers are watching the star's destruction at about one-quarter speed. Capturing the full evolution of these rare, extreme flares across a population will therefore be a long-term observational effort.

Publication: Results published 4 November 2025 in Nature Astronomy.

Reproduced with permission; originally published 4 November 2025.