These newly-spotted black holes consume stars over and over again

Is it possible that stars have more lives than previously believed?
Loukia Papadopoulos
A black hole eating a star again and again
A black hole eating a star again and again

ESA 

ESA’s XMM-Newton space telescope has helped two teams of astronomers make a rather unusual discovery, according to a press release by the space agency published on Thursday (Jan .12).

The scientists observed repeated outbursts of light from inactive black holes that partially destroy stars again and again. This phenomenon is unexpected, since outbursts of black holes usually appear only once when a black hole consumes a star

The studies, led by astronomers Thomas Wevers from the European Southern Observatory and Zhu Liu from the Max Planck Institute for Extraterrestrial Physics in Germany, could indicate that somehow part of the stars survive their first attack from the black holes. 

Not entirely consumed

This means that parts of the stars are not entirely eaten up and continue their orbit and encounter the disruptive black holes again, leading to recurring flares. The event is referred to as a partial tidal disruption event.

“The results from our first XMM-Newton observation were surprising. The black hole showed an unusually drastic dimming of X-ray light, compared to when it had been discovered two weeks previously by the eROSITA telescope," said Liu in the statement.

"Follow-up observations with XMM-Newton and other instruments confirmed our speculations that this behavior was being caused by a partial tidal disruption event.”

“At first, we were absolutely puzzled by what the rebrightening could mean. We had to go back to the drawing board to assess all the possible options to explain the observed behavior," added Wevers.

"It was a very exciting moment when we realized that the model for a repeating tidal disruption event could reproduce the observed data,” he said.

To monitor these changes, the researchers had to study over five days of XMM-Newton observations. In the end though they had an explanation for the results.

The influence of supermassive black holes

“These new observations are incredibly interesting for studying the influence of supermassive black holes. In typical tidal disruption events, we don’t expect to see a second flare for a few thousand years," said William Alston, ESA Research Fellow.

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"With the flares recurring so quickly, the orbit of the disrupted star must have been bound close to the supermassive black hole. These new studies suggest that the disrupted star is pulled into a close orbit after it is ripped away from a binary star system by the central supermassive black hole.”

These new events will now be monitored closely during the predicted periods of future re-brightening episodes to confirm the findings and make further discoveries.

Will the stars be swallowed whole in the ini flaring episode or will they survive to be ravaged again and again? Only time will tell as the hunt begins to find similar partial tidal disruption events.

The results of these studies are published in two papers in Astronomy & Astrophysics and The Astrophysical Journal Letters.