LOS ANGELES -- For the first time, astronomers say they have borne witness to a supermassive black hole consuming a star.
Two papers released on Wednesday by the journal Nature describe powerful blasts of radiation whose brightness and behavior can be explained only by a sun-sized star's being torn apart by the gravitational forces of a black hole at the center of its galaxy, the authors say.
Scientists believe they have seen the aftermath of such stellar violence before, in the form of fading glows emanating from distant galaxies, in whose centers supermassive black holes usually reside. But they had never caught one in the act.
"This was the first time we saw one of these big black holes going from quiet and silent to very loud and noisy, producing a lot of light and radiation," said Davide Lazzati, an astrophysicist at North Carolina State University who was not involved in the study.
How did it happen⢠The team's theory is that a star about the same size as our sun ended up too close to the black hole. The black hole exerts a powerful gravitational pull -- it contains the mass of about a million suns -- and that caused the side of the star nearest the black hole to stretch toward it, in much the same way that the moon causes the tides on Earth.
Eventually, the gravitational forces shredded the star, and chunks of its plasma streamed toward the black hole. In the process, some of the material was expelled into a jet of high-energy radiation.
That jet was likely responsible for the mysterious burst astronomers picked up in March.
Pennsylvania State University astrophysicist David Burrows estimates that within a few months as much as one-fifth of the mangled star's mass might have been swallowed by the black hole. Burrows is the lead scientist for the X-ray telescope on the Earth-orbiting Swift observatory, which captured the event.
