For the first time, astrophysicists have observed a star being consumed by a supermassive black hole, ejecting a short-lived and high-speed thermal flare as it is swallowed up by a dense pocket of spacetime, according to research published this week in Science.
According to Sjoert van Velzen, a Hubble fellow at The Johns Hopkins University in Baltimore, and his colleagues, the star is approximately the same size as our sun and has been yanked from its customary path by the gravitational pull of the black hole. The flare it emitted moved at close to the speed of light, the team of 13 international scientists added in their report.
A black hole is a region of space that is so dense that its gravity prevents matter, gases, and even light from escaping, causing them to be essentially invisible and creating the appearance that there is a void in the very fabric of space. Astrophysicists predicted that a black hole that suddenly takes in large amounts of gas (say, the amount found in a whole star that is being consumed), a fast-moving jet of plasma could escape from the event horizon.
In a statement, van Velzen said that these events are “extremely rare.” In fact, he noted, this was “the first time we see everything from the stellar destruction followed by the launch of a conical outflow, also called a jet, and we watched it unfold over several months… Previous efforts to find evidence for these jets, including my own, were late to the game.”
Black hole’s close proximity made the observations possible
The supermassive black hole being observed by the Johns Hopkins-led team is about one million times the mass of our sun, meaning that it is on the lighter end of the spectrum. Nonetheless, the black hole is still more than strong enough to swallow a star whole, van Velzen’s team said.
A team at the Ohio State University, working with an optical telescope in Hawaii first witnessed the star being consumed and announced their discovery via social media in December 2014. Shortly thereafter, van Velzen and a team of astrophysicists from Oxford University used a radio telescope array to conduct follow up observations, hoping to catch the deed being done.
They were just in time, and were able to collect X-ray, radio and optical data from both satellites and ground-based observatories, providing what they called a “multi-wavelength” portrait of the phenomenon. Helping their cause was the fact that the galaxy was a mere 300 million light years from Earth, making it at least three times closer than other, similar supermassive black holes.
“The destruction of a star by a black hole is beautifully complicated, and far from understood,” said van Velzen, who studied supermassive black hole jets as a doctoral student at Radboud University. “From our observations, we learn the streams of stellar debris can organize and make a jet rather quickly, which is valuable input for constructing a complete theory of these events.”
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Image credit: Johns Hopkins/Artist’s Rendering
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