In a galaxy 860 million light years away, a supermassive black hole is engaged in a cosmic feast like no other. Instead of consuming a nearby star in one cataclysmic event, the black hole has captured the star in a highly elliptical orbit, slowly devouring it over a series of dramatic encounters. This rare phenomenon, known as a “tidal disruption event” (TDE), offers astronomers a unique opportunity to study the extreme physics at play in the universe’s most violent environments.
Mysterious Case of AT2018fyk
The story began in 2018 when NASA’s Neutron star Interior Composition Explorer (NICER) detected an event named AT2018fyk. Initially, astronomers observed the characteristic bright flashes of X-ray and ultraviolet (UV) light that occur when a star is torn apart by a black hole’s immense gravitational forces. These intense emissions are typically the final death throes of a star as it is consumed by a black hole, with its matter heated to extreme temperatures as it spirals toward the event horizon.
In most cases, this would have marked the end of the star’s existence a brief, yet spectacular, flash followed by silence. However, something unusual happened two years later. In 2020, astronomers observed another spike in X-ray and UV emissions from the same black hole. This unexpected burst suggested that the star had not been completely destroyed in the first encounter. Instead, it had been captured in a perilous orbit, returning periodically to lose more of its mass to the black hole.
Star’s Prolonged Demise
This “slow-motion” devouring process is far less common than a typical TDE, where a star is swiftly consumed. Each time the star swings close to the black hole, it loses more of its material, resulting in a new burst of radiation. By studying these repeated TDEs, scientists can learn more about the dynamics of black holes and the interactions between these enigmatic objects and their stellar victims.
Astronomers hypothesize that the star was originally part of a binary system a pair of stars bound together by gravity. As the duo wandered too close to the black hole, the intense gravitational forces likely ejected one star from the system, sending it hurtling out of the galaxy at incredible speeds. The remaining star, however, was not so fortunate. It became trapped in a cycle of destruction, losing mass with each pass near the black hole.
Predicting the Next Act in the Cosmic Drama
The observations of AT2018fyk have allowed scientists to predict the next chapter in this celestial drama. The researchers calculated that the next significant emission event should occur between May and August of 2025. This upcoming interaction is expected to be less luminous than the previous ones, indicating that the star is running out of material to lose.
On August 14, 2023, the team observed a significant dimming of the emissions from the black hole, suggesting that the star might finally be nearing its end. However, it’s still unclear whether the star will survive for another close encounter or if it has already been completely torn apart.
Window into the Extreme Universe
This rare event provides a valuable opportunity to study the extreme physics of black holes. The system’s unusual characteristics, including the repeated TDEs and the potential origin as a binary star system, offer insights into the complex interactions between black holes and the stars that stray too close. These observations help scientists refine their understanding of black hole behavior and the life cycles of stars in such extreme environments.
As astronomers await the next possible flare from AT2018fyk, the anticipation builds. Will the star survive for another round? Or has it finally succumbed to the gravitational grip of its massive neighbor? Either way, this cosmic encounter offers a rare glimpse into the violent and fascinating processes that govern our universe’s most powerful objects.
With the next potential flare-up expected in 2025, the research team is preparing to request additional observational time from telescopes like Chandra to continue monitoring this extraordinary event. The results could provide unprecedented insights into the final moments of a star caught in the clutches of a supermassive black hole—a dance of destruction that may last for years to come.
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