Scientists have identified a young black hole formed from an exploding star witnessed 30 years ago.
The explosion of the star was first observed by an amateur astronomer in 1979, but it took decades of observation to confirm it had become a black hole.
The death of the star in supernova 1979C occurred some 50 million light years from earth, in what could be "the nearest example where the birth of a black hole has been observed," said Daniel Patnaude of Harvard, who led the study.
Scientists hope it will provide clues about the formation of the celestial objects and the death of stars.
"This may be the first time the common way of a making a black hole has been observed," Harvard University astronomer Abraham Loeb said.
Most black holes are believed to form when a star collapses, but run-of-the-mill black-hole creation is very difficult to observe. ... Scientists have been observing SN 1979C with the Chandra X-ray Observatory, NASA's Swift satellite, the Eruopean Space Agency's XMM-Newton spacecraft and the German ROSAT observatory. They have seen a bright source of X-rays that remained steady from 1995 to 2007 and is consistent with a black hole being fed by material falling into it from an exploding star or another nearby star. ...
via Astronomers find nearby baby black hole.
Is a black hole 50 million light years away dangerous? The nearest is at the center of our own galaxy.
The nearest black hole is believed to be a nearby object and is observed by observations of strong X-ray emissions from Cygnus X-1, located about 8000 light years away. But this all depends on the definition that you use to find your black hole. Another lies just 1,600 light-years from Earth on the way to the centre of the Milky Way in the direction of the constellation Sagittarius and is associated with a visible star called V 4641. It is being called a micro-quasar because it showed the brilliant behaviour associated with quasars. It sends out bursts of X-ray radiation and shoots out jets of plasma at some 90 percent the speed of light.
via WeirdWarp January 17, 2010
Why is the black hole at the center of our galaxy so tame?
One of the Milky Way's longstanding puzzles centers on the super-massive black hole at its core, in the constellation Sagittarius: Why is that monstrous black hole, known as Sag A*, so much less energetic that its counterparts in other galaxies?
The behemoth, with some 2.6 million times the sun's mass, is a cosmic dud at the moment. Something is starving it, depriving it of material that otherwise would plummet into it.
Roman Shcherbakov, a researcher at the Harvard-Smithsonian Center for Astrophysics, says he's figured out what that "something" is likely to be: heat.
As material from surrounding stars approaches the black hole and gets compressed by the monster's gravity, it heats up. Some of that heat gets conducted away from the black hole, setting up a source of pressure that sweeps material away from the voracious object.
In other words, heating around the black hole's event horizon – essentially the boundary within which material falls into oblivion – is in effect starving the black hole. ...
via CSmonitor January 7, 2010