Star-devouring black hole unleashes record-breaking energetic explosion.

Scientists have observed the most energetic explosion ever seen emanating from a black hole, according to a study published last Tuesday (4) in the journal Nature Astronomy . At its peak, it was 10 trillion times brighter than the Sun.

The black hole in question is estimated to be 300 million times the mass of the Sun. It is located in a galaxy about 11 billion light-years from Earth—a light-year is the distance light travels in one year, 9.5 trillion kilometers. It is believed that there is a black hole, dense objects with such strong gravitational pull that not even light can escape, at the center of most galaxies.

According to the study's authors, the most likely explanation for the flare is that a large star was pulled into the black hole. This process would result in an explosion of energy when the material from the doomed star reached the black hole's point of no return.

Researchers said they believe the star had at least 30 times—and perhaps even 200 times—the mass of the Sun. It may have been part of a population of stars in the vicinity of the black hole and somehow ended up getting very close to it after some interaction with another object.

"It seems reasonable that it was involved in a collision with another, more massive body in its original orbit around the black hole, which knocked it into it," said astronomer Matthew Graham, lead author of the new study.

"It was placed in a much more elliptical orbit, which brought it much closer to the black hole at its closest approach. Too close, as it turned out," added the researcher from Caltech (California Institute of Technology).

Supermassive black holes are surrounded by a disk of gas and dust, which is drawn into them after being captured by their gravitational force.

"However it happened, the star wandered close enough to the supermassive black hole," said astronomer and study co-author KE Saavik Ford, who compared the star to a strand of spaghetti. "It was stretched to become long and thin due to the black hole's gravity, which strengthens as it gets closer. This material then spiraled around the black hole as it fell into it."

The flare would be the result of gas from the shattered star heating up and glowing as it fades into oblivion. The star believed to be involved would have been exceptionally large.

"Stars like this are rare because smaller stars are born more frequently than larger ones, and because much larger stars have very short lifespans," Ford stated.

Researchers suspect that stars orbiting close to a supermassive black hole may increase in mass by attracting some of the material swirling around it, making them abnormally large.

The flare was observed using telescopes in California, Arizona, and Hawaii. Scientists considered other possible causes, such as a star exploding at the end of its lifespan, a jet of material flowing out of the black hole, or a phenomenon called gravitational lensing that could have made a weaker event appear more powerful. None of these scenarios fit the data.

Because of the time it takes for light to travel, when astronomers observe distant events like this, they are looking into the past, into an earlier era of the Universe.

The flare increased in brightness during observations, apparently as more and more material from the star fell into the black hole. It peaked in June 2018, when it was 30 times brighter than any previously observed black hole flare. It is still ongoing, but decreasing in luminosity, with the entire process expected to take 11 years to complete.

"The flash is still fading," Graham said.