A rare look at a star's demise in a supermassive black hole

Back when single-celled organisms ruled Earth, a gigantic black hole lurking quietly at the center of a distant galaxy dismantled and devoured a star.
On Wednesday, astronomers reported that they watched the whole thing unfold over a period of 15 months starting in 2010, the first time such an event had been witnessed in great detail from start to finish. “The star got so close that it was ripped apart by the gravitational force of the black hole,” said Johns Hopkins University astronomer Suvi Gezari, lead author of a paper about the observations that was published online by the journal Nature. Studying the radiation that escaped the catastrophe — signals that took about 2 billion years to reach Earth — Gezari and her colleagues were able to determine the size and composition of the ill-fated star and suss out the characteristics of the black hole that destroyed it. Estimated to occur only about once every 10,000 or so years in each galaxy, tidal disruptions are extremely difficult to spot. But astronomers seek them out because they make black holes visible, and therefore possible to study. Starved of fuel, most black holes normally lie dormant and invisible, said Michael Eracleous, an astronomer at Penn State University who was not involved in the research. But during a tidal disruption, energy produced by their interactions with stellar gases produces intense flares of radiation. “For a brief period of time the black hole lights up and makes itself known,” Eracleous said. Gezari and her colleagues used two telescopes — one in Hawaii that detected visible light and another perched in orbit that sensed ultraviolet radiation — to scan the sky for possible tidal disruptions, which appear as bright flashes that slowly fade away.