For the first time, scientists observed a star being swallowed up by a black hole, and then watched as some of the star’s matter was ejected back out as a flare of plasma moving at nearly the speed of light – a process likened to a cosmic ‘burp.’
Scientists have previously observed black holes swallowing stars and mysterious jets of matter blasting out, but until now, no one had been fast enough with their telescopes to link the two events, and they had never been able to witness them occurring in sequence.
“These events are extremely rare,” said lead researcher Sjoert van Velzen from Johns Hopkins University. “It’s 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.”
So, what’s the big deal about this observation? It confirms what astrophysicists predicted would happen when a black hole is force-fed a large amount of gas (in this case, an entire star): a fast-moving jet of plasma can escape from near the event horizon.
Until recently, it was assumed that black holes were so densely packed that nothing, not even light, could escape them. However, scientists such as Stephen Hawking and Gerard ‘t Hooft have demonstrated that energy can escape a black hole, and it now appears that matter can escape from near the event horizon too.
The unfortunate star that was devoured was roughly the size of our Sun, and the black hole in question was a relatively light one located at the center of a galaxy 300 million light-years away.
The first observation of the star being destroyed was made on Twitter in early December by a team from Ohio State University, who had spotted the event using an optical telescope in Hawaii.
Van Velzen and a group of international researchers jumped on the event right away, pointing a slew of radio telescopes in the direction of the galaxy in the hopes of catching the erupting plasma jet that they predicted would soon follow.
They arrived just in time to witness the event from a variety of satellites and telescopes, creating a picture of the event in X-ray, radio, and optical signals. Their findings were published in the journal Science.
The researchers ruled out the possibility that the light was coming from a ‘accretion disk,’ which forms when a black hole absorbs matter from the surrounding space, confirming the hypothesis that the jet was indeed coming from a sucked up star.
“The destruction of a star by a black hole is beautifully complicated, and far from understood,” said van Velzen. “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.”
We still have a lot to learn about how black holes work, but we’re getting closer, and that’s pretty cool.