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.
Astronomers have far more experience observing the spectacular but less common creation of black holes that create gamma ray bursts of energy during the collapse of the star.
Most black holes do not create gamma rays, but in order to verify that the death of a star has indeed created a black hole, scientists must make decades of X-ray observations, Loeb noted.
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.