A international team of astronomers has detected a rare explosion of light coming from a star torn apart by a supermassive black hole, a phenomenon known as “tidal disruption” and which is the closest observed so far.
The observation was made possible with the telescopes of the European Southern Observatory (ESO) and other organizations around the world and the event happened just over 215 million light years from Earth.
“The idea of a black hole ‘sucking in’ a nearby star sounds like science fiction. But it is exactly what happens in a tidal disruption event,” said Matt Nicholl, professor and researcher at the Royal Astronomical Society at the University of Birmingham, UK, and lead author of the new study.
ESO said in a statement that these tidal disruption events, where a star experiences what is known as spaghetti when absorbed by a black hole, “are rare and are not always easy to study.”
In order to study in detail what happens when a star is eaten by such a monster, the research team pointed ESO’s VLT (Very Large Telescope) and NTT (New Technology Telescope) at a new flash of light that occurred last year near a supermassive black hole.
In theory astronomers know what should happen in such a situation; According to Thomas Wevers, another of the researchers who participated in the observation, “when an unfortunate star wanders too close to a supermassive black hole in the center of a galaxy, the extreme gravitational pull of the black hole rips apart the star, ripping out fine streams of material “.
As some of the fine strands of stellar matter fall into the black hole during this process, called spaghettiification, a bright flare of energy is released that astronomers can detect.
Although powerful and bright, astronomers have so far had trouble investigating these bursts of light that are often obscured by a curtain of dust and debris – they have now been able to shed light on the origin of this curtain.
“We discovered that, when a black hole devours a star, it can launch a powerful explosion of matter outward that obstructs our view,” explains Samantha Oates, from the University of Birmingham.
He adds that this happens because the energy released when the black hole feeds on the stellar material pushes the debris from the star outward.
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The discovery was made possible because the tidal disruption event the team studied, AT2019qiz, was detected shortly after the star was shattered.
“Actually, because we detected it early, we were able to see the curtain of dust and debris forming as the black hole launched a powerful jet of material with speeds of up to 10,000 kilometers per second,” explains Kate Alexander, postdoctoral researcher ( NASA Einstein Fellow) at Northwestern University (United States).
“This ‘look behind the scenes’ was our first opportunity to identify the origin of the obscuring material and to follow in real time how it envelops the black hole,” adds Alexander.
Over a period of 6 months, during which the flare grew in luminosity and then faded, the team carried out observations of AT2019qiz, located in a spiral galaxy, in the constellation Eridanus.
“Several soundings detected the emission of the new tidal disruption event very shortly after the star was shattered,” says Wevers, indicating that they immediately pointed to the array of ground and space telescopes in that direction to see how the star was produced. light.
In the following months, multiple observations of the event were carried out with other facilities; Celerity and extensive observations in ultraviolet light, optical range, X-rays and radio waves, revealed, for the first time, a direct connection between the material flowing from the star and the bright flash emitted as it is devoured by the hole black.
“Observations showed that the star was roughly the same mass as our own Sun and that the monstrous black hole, which is more than a million times more massive, had caused it to lose about half that mass,” according to Nicholl.
The team of astronomers believe that AT2019qiz could even act as a “Rosetta stone” to interpret future observations of tidal disruption events.
On the other hand, ESO’s ELT (Extremely Large Telescope), which is expected to begin operations this decade, will allow researchers to detect increasingly weak and rapidly evolving tidal disruption events in order to solve more mysteries of the physics of black holes.
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