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"By observing how this cloud lit up and faded over 10 years, we could trace back the black hole's activity 300 years ago," said co-investigator Katsuji Koyama, also of Kyoto University. "The black hole was a million times brighter three centuries ago. It must have unleashed an incredibly powerful flare." Last year, a team of scientists headed by Michael Muno at the California Institute of Technology discovered a fainter but more recent outburst from Satittarius A-star, the Milky Way's black hole, which is between three and four million times as massive as our sun. During that outburst, which, like the new finding, was discovered by studying X-rays reflected off a gas cloud, a mass the size of the planet Mercury was devoured. If X-ray sensors had been around 50 years ago, the area around the black hole would have been 100,000 times brighter than it is today. "It has been 50 years or so since the black hole had its last decent meal," Muro said. Details of the black hole's feeding habits are unclear. One theory is that the black hole pulls in matter from the winds of nearby young stars. The burst 300 years ago could have been caused by a supernova explosion that blasted material toward the black hole. Related Links: |
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