By Jason Goodyer

Published: Friday, 13 January 2023 at 12:00 am


Just call it the Homer Simpson of black holes. Astronomers using NASA’s Hubble Space Telescope have observed a black hole twisting a nearby star into a doughnut shape before consuming it.

The violent cosmic occurrence is an example of a tidal disruption event – an astronomical phenomenon that occurs when a star strays close enough to a black hole to be ripped apart by the immense gravitational forces. After the star has been ripped apart, the black hole then devours the resulting gas and debris while belching out intense radiation.

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1. A normal star passes near a supermassive black hole in the centre of a galaxy. 2. The star’s outer gasses are pulled into the black hole’s gravitational field. 3. The star is shredded as tidal forces pull it apart. 4. The stellar remnants are pulled into a doughnut-shaped ring around the black hole, and will eventually fall into the black hole, unleashing a tremendous amount of light and high-energy radiation.
©NASA, ESA, Leah Hustak (STScI)

Named AT2022dsb, the event is occurring nearly 300 million light-years away from Earth at the centre of the galaxy ESO 583-G004. It was first spotted on 1 March 2022 by the All-Sky Automated Survey for Supernovae (ASAS-SN), a network of ground-based telescopes that scours the sky looking for violent events.

The team then used Hubble’s powerful ultraviolet imaging capabilities to study the cosmic chow down in fine detail as it unfolded.

“Typically, these events are hard to observe. You get maybe a few observations at the beginning of the disruption when it’s really bright. Our program is different in that it is designed to look at a few tidal events over a year to see what happens,” said co-researcher Peter Maksym of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

“We saw this early enough that we could observe it at these very intense black hole accretion stages. We saw the accretion rate drop as it turned to a trickle over time.”

After studying the Hubble data, the researchers concluded that the remains of the star have formed a doughnut-shaped ring of gas the size of the Solar System that is encircling the black hole as it is sucked in.

They hope that further studying the event, and others like it, will help them learn more about the lifecycle of black holes.

“We really are still getting our heads around the event. You shred the star and then it’s got this material that’s making its way into the black hole,” said Maksym.

“So, you’ve got models where you think you know what is going on, and then you’ve got what you actually see. This is an exciting place for scientists to be: right at the interface of the known and the unknown.”

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