Black Hole Eating Star For A Decade; More Studies On Eddington Limit Urged


Black holes devouring stars is a common phenomenon. But a black hole eating up a star for more than 10 years is extraordinary.

This has baffled scientists as they have not come across such an instance and urged more research on the breaching of the Eddington limit by black holes.

This is because researchers are finding this phenomenon untenable as it is breaking some established principles of physics.

"We have witnessed a star's spectacular and prolonged demise," said lead researcher Dacheng Lin from the University of New Hampshire.

Tidal Disruption Event

The star-eating has been described as a tidal disruption event, or TDE. It happens when black holes with a massive gravitational force drag stars drifting into their vicinity and rip them apart.

The observations published in the journal Nature Astronomy calls the TDE as a long super-Eddington accretion process.

In a normal TDE, a black hole destroys the star, flings out part of the contents into space while eating up the rest, and starts spewing X-ray radiation as super hot flares.

Unlike the normal brevity of TDEs, the star meal noticed was seen extending beyond 10 years.

The lingering hunger of the black hole named as XJ1500+0154 was spotted in a tiny galaxy that was 1.8 billion light-years away from Earth.

While hunting for TDEs in 2005, a very bright flare by XJ1500+0154 caught the attention of satellites such as the Chandra X-ray observatory of NASA, Swift satellite, and the XMM-Newton of the ESA.

The decade-long tracking has shown the star-eating is entering the final stage.

The long-drawn star dinner broke the Eddington limit, which denotes the equilibrium that exists between the emitted hot gas radiation and inward gravitational pull exercised by the black hole.

The highest X-ray brightness from the black hole was recorded in mid-2008 and the glow has progressively reduced since then.

"For most of the time we've been looking at this object, it has been growing rapidly," said James Guillochon from the Harvard-Smithsonian Center for Astrophysics and a researcher.

According to the researcher, this translates to the conclusion the star being fed into the black hole must be double the size of the sun - evidence that black holes can eat massive stars. He said this calls for new studies on black holes.

If the findings are validated further, it can also explain why supermassive black holes are a billion times mightier than the sun.

Astronomers are also predicting that XJ1500+0154's X-ray brightness would start fading in the coming months and ultimately move away from the satellites' view.

Midsize Black Hole Discovered

Meanwhile, astronomers have reported about a new type of black hole, which falls between small and supermassive black holes.

Described as an "intermediate-mass black hole," the new type of black hole weighs an average 2,000 times the mass of the sun and was hidden behind a cluster of stars.

"We want to find intermediate-mass black holes because they are the missing link between stellar-mass and supermassive black holes," said Bulent Kiziltan from the Harvard-Smithsonian Center for Astrophysics and the lead researcher.

Kiziltan called midsize black holes the "primordial seeds" of today's monster black holes.

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