Astronomers see a black hole destroy a star for the first time

Arp 299
The cosmic collision happened in a galaxy far, far away. Photo credit: Sophia Dagnello-NRAO-AUI-NSF-NASA-STScI.supplied

Astronomers for the first time have witnessed the destruction caused when a black hole rips apart a star.

Though the cosmic collision happened in a galaxy far, far away, it resulted in a jet of radio waves strong enough to be detected here on Earth.

"Never before have we been able to directly observe the formation and evolution of a jet from one of these events," said Spanish astronomer Miguel Perez-Torres, who led the team that discovered it.

In 2005, they detected a burst of infrared emissions from Arp 299, a pair of colliding galaxies 150 million light years away, in the constellation Ursa Major. At first they thought it was a supernova - a dying star going out in a blaze of glory.

Over the next decade they kept their instruments tuned to Arp 299, and found it was actually a supermassive black hole at the centre of one of the two galaxies, emitting a jet of radio waves at a quarter the speed of light.

"The combination of our infrared and radio observations, coupled with state-of-the-art simulations of radio jets and calculations of infrared emission from the dusty regions surrounding a supermassive black hole, left us with one plausible explanation - the infrared and the radio emission came from the disruption of a hapless star being devoured by the supermassive black hole when it passed too close to this cosmic monster," study co-lead author Seppo Mattila of the University of Turku told

The black hole has 20 million times the mass of the sun, and the jet of particles it fired out contains 125 billion times more energy than the sun emits in a year.

Jets are often seen coming from supermassive black holes - the Hubble Space Telescope once took a photo of the galaxy M87, in Virgo, which showed massive jets spewing from its central supermassive black hole, one of the biggest ever found.

M87. Photo credit: NASA

This is the first astronomers have found that was caused by the destruction of a star. It's taken so long to find one because it turns out they're not as bright in the visual spectrum as astronomers expected - interstellar dust and gas got in the way.

"How many similar events are we missing in dusty centres of galaxies that would only be detectable by infrared and radio observations but be completely invisible in the optical light?" Dr Mattila said.

The team's findings have been published in the journal Science.