Computer-simulated image shows gas from a tidally shredded star falling into a black hole.

Nasa / Rex Features, Associated Press

Scientists watch as black hole rips apart a star

  • May 26, 2012 - 9:59 PM

Back when single-celled organisms ruled Earth, a gigantic black hole lurking at the center of a distant galaxy dismantled and devoured a star. Astronomers reported that they watched it all unfold over 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 astronomer Suvi Gezari, lead author of a paper published online by the journal Nature.

Studying the intense flares of radiation that escaped from the interaction -- 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 usually invisible black hole that destroyed it. Estimated to occur only about once every 10,000 or so years in each galaxy, these events -- called tidal disruptions -- are extremely difficult to spot. But when Gezari and her colleagues scanned the sky using two telescopes, they noticed a galaxy "that was just sitting there" quickly increase in brightness by a factor of hundreds, she said. Veering close to the black hole -- about the same distance as Mercury lies from the sun -- the star was torn asunder by the black hole's intense gravity. About 76 days after the star was ripped apart, the black hole began devouring its remains, taking at least a year to finish off the meal. The scientists calculated that the black hole's mass was 3 million times greater than that of the sun.


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