Black holes are known for their destructive nature when it comes to stars in their proximity. The typical scenario involves a star being consumed by the black hole, resulting in a flash of light signaling its demise. However, in rare cases, a star may be captured in orbit around a black hole, leading to a much slower and potentially more excruciating death, if stars were capable of experiencing pain. A recent study utilizing X-ray data from Chandra and other instruments has shed light on a supermassive black hole in a distant galaxy that is currently devouring a star in its orbit. This unusual phenomenon could provide valuable insights into various physical processes of interest to astronomers.
The story of AT2018fyk began in 2018 with the detection of a “tidal disruption event” (TDE) involving a star being consumed by a black hole. Initial observations of AT2018fyk were conducted using NASA’s Neutron star Interior Composition Explorer (NICER), followed by follow-up studies with Chandra and XMM-Newton, ESA’s X-ray telescope. While the norm would have been for the star to be swallowed whole, emitting intense X-ray and UV radiation in the process, astronomers noticed a subsequent increase in emissions from the black hole two years later.
The second spike in luminosity was attributed to the star being partially devoured again during its elliptical orbit around the black hole. Periodically, the star’s close approach to the black hole results in more material being stripped away, triggering another TDE. Scientists predicted that this cycle would culminate in August 2023 and secured observational time on Chandra to monitor the event. As anticipated, on August 14th, 2023, a significant decrease in emissions from the black hole was observed, indicating that the star had either been completely disintegrated or had narrowly escaped to continue its celestial dance.
The star involved in the TDE, at the center of AT2018fyk, was believed to have originally been part of a binary star system. However, its companion star was likely ejected once the pair became ensnared in the black hole’s gravitational pull. The partner star is now moving away at a much higher velocity and may eventually exit the galaxy. The researchers speculate on whether the star at the heart of AT2018fyk has adequate material for a third round of luminous burnoff, with predictions suggesting a potential increase in brightness between May and August 2025.
The ongoing saga of AT2018fyk has captivated the scientific community due to its rare and intriguing nature, offering valuable insights into TDEs and astrophysical processes. The research team is poised to secure additional observational time in the coming years to monitor the evolution of this unique system. By studying the interactions between stars and black holes, astronomers hope to gain a deeper understanding of the universe’s most enigmatic phenomena.
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