Astronomers pick up a mayday call from a star being ripped apart by a black hole 3.8 billion light-years from Earth.
An unusual gamma-ray burst is believed to stem from a star's losing battle with a black hole.
Viewing geometry puts Earth looking down the barrel of a black hole jet.
The event was first detected in March and continues to stream gamma rays -- as well as X-ray and infrared light.
NASA launched the Swift gamma-ray telescope thinking it would give scientists a way to monitor the births of black holes. Now, a pair of new studies suggests it can watch them feed as well.
The evidence comes from an event called Sw1644+57, a bright flash of gamma rays detected by the Swift telescope on March 28 that came from the center of a small galaxy in the Draco constellation, located about 3.8 billion light-years from Earth.
Gamma ray bursts aren't all that uncommon. Swift has found more than 500 of them since it began tracking six years ago. These flashes are extremely powerful, but very short. They typically pack as much punch as all the energy put out by the sun over its entire lifetime into a few seconds.
Not so with Sw1644+57. An hour after it was found, it turned up again.
"This was the first the first indication that this was a highly unusual thing," astronomer Joshua Bloom, with the University of California at Berkeley, told Discovery News.
"Most gamma ray bursts last for only tens of milliseconds up to a few minutes. There's very few that last up to an hour," he said.
Longevity was just the beginning. Follow-up observations showed the light changing, and not just in gamma-ray wavelengths, but also in X-rays and infrared. Now, nearly three months after initial detection, it's still going strong.
Astronomers think Swift has a dead-on view of the digestive system of a black hole, which is blasting out a jet of energy as it rips apart a star trapped in its gravitational fist.
"This black hole not only was gobbling up mass, but actually launched off a jet of fast-moving material. We're looking down the barrel of that jet," Bloom said.
Black holes are regions of space so tightly packed with matter that not even light can escape their gravity wells. Watching how the prey succumbs, however, is giving astronomers new insight into how black holes operate.
"As black holes swallow matter, they just produce a huge amount of energy, which is believed to have an explosive effect on the environment," said astronomer Mitchell Begelman, with the University of Colorado at Boulder.
"This event and probably other events like it are happening all over the universe, they're just very uncommon," added Bloom. "We would have to look at 100 million galaxies a year just to find one of these events again.
The research appears in this week's Science.