Researchers from Tel Aviv University (TAU), together with international collaborators, have identified what may be the first confirmed case of a star surviving an encounter with a supermassive black hole-and returning.
The finding is based on a newly observed flare that closely resembles AT 2022dbl, another flare recorded from the same location about two years earlier, suggesting that both were caused by the same star making two separate passes near the black hole.
According to the research team, this discovery challenges existing assumptions about the fate of stars that wander too close to black holes and may reshape how astronomers interpret these rare and powerful events.
The study was conducted by Dr. Lydia Makrygianni, formaly a postdoctoral at Tel Aviv University and currently a researcher at Lancaster University in the UK. She led the research under the supervision of Prof. Iair Arcavi, a faculty member in the Astrophysics Department at TAU and Director of the Wise Observatory in Mitzpe Ramon.
Additional contributors included Prof. Ehud Nakar, Chair of TAU's Astrophysics Department, and students Sara Faris and Yael Dgany from Prof. Arcavi's research alongside multiple international collaborators. The results were published in the July 2025 issue of the Astrophysical Journal Letters.
Research team (Left to right): Sara Faris, Yael Dgany & Prof. Iair Arcavi
How Black Holes Reveal Themselves
At the center of nearly every large galaxy lies a supermassive black hole, with mass millions to billions of times greater than that of the sun. One such black hole is located at the center of our own Milky Way Galaxy, and its discovery was recognized with the 2020 Nobel Prize in physics.
Still, much remains unknown about how these black holes form and influence their surroundings. Because they do not emit light, their presence is difficult to detect. In our galaxy, they are identified by the movement of nearby stars. But in distant galaxies, astronomers rely on rare, high-energy events to uncover their existence.
Once every 10,000 to 100,000 years, a star may wander too close to the black hole at the center of its galaxy and get ripped to shreds by its immense gravitating pull. Roughly Half of the star's material is "swallowed" by the black hole, while the rest is ejected outward.
As the material falls in, it spirals in a circular motion, much like water going down a bathtub drain. Near the black hole, the rotating matter approaches the speed of light, heats up, and radiates intensely. For a few weeks to months, this flare "illuminates" the black hole, giving scientists a rare opportunity to observe its properties.
Yet strangely, many of these flares have not behaved as expected. Their brilliance and temperature have often been much lower than predicted, leaving researchers searching for explanations
Rethinking Stellar Disruption
According to the TAU-led team, the recently observed flare closely resembled AT 2022dbl, an earlier flare detected from the same location about two years prior.
This unusual repetition raises a new possibility: the first flare may have been caused by a partial disruption, in with the star was not fully destroyed and later returned for a second passage.
"The question now is whether we'll see a third flare after two more years, in early 2026" says Prof. Arcavi. "If we see a third flare", he continues, "it means that the second one was also the partial disruption of the star. So maybe all such flares, which we have been trying to understand for a decade now as full stellar disruptions, are not what we thought".
If no third flare is observed, the second event may have been a full disruption. Whether or not a third flare occurs, the findings suggests that partial and full stellar disruptions may appear nearly identical, a prediction previously proposed by Prof. Tsvi Piran and his team at the Hebrew University of Jerusalem. "Either way", adds Prof. Arcavi, "we'll have to re-write our interpretation of these flares and what they can teach us about the monsters lying in the centers of galaxies".
