Caught in the Act: ‘Black hole Swallows Star'
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An illustration shows a star torn up by a black hole’s strong gravity. The black hole is launching a powerful jet of matter into space. (NASA/Goddard Space Flight Center/Swift) |
Astronomers have caught black holes in the act of murdering stars before. But a study published Thursday in Science claims to have caught a step in the crime that has remained elusive until now.
In addition to catching evidence of the star's destruction -- an inevitable death caused by the massive, inescapable gravitational pull of a dense supermassive black hole -- the scientists saw a hot flare of matter escape from the scene of the crime.
In addition to catching evidence of the star's destruction -- an inevitable death caused by the massive, inescapable gravitational pull of a dense supermassive black hole -- the scientists saw a hot flare of matter escape from the scene of the crime.
You can basically think of it as a hot plasma burp.
This artist’s rendering illustrates new findings about a star shredded by a black hole. When a star wanders too close to a black hole, intense tidal forces rip the star apart. In these events, called “tidal disruptions,” some of the stellar debris is flung outward at high speed while the rest falls toward the black hole. This causes a distinct X-ray flare that can last for a few years. NASA’s Chandra X-ray Observatory, Swift Gamma-ray Burst Explorer, and ESA/NASA’s XMM-Newton collected different pieces of this astronomical puzzle in a tidal disruption event called ASASSN-14li, which was found in an optical search by the All-Sky Automated Survey for Supernovae (ASAS-SN) in November 2014. The event occurred near a supermassive black hole estimated to weigh a few million times the mass of the sun in the center of PGC 043234, a galaxy that lies about 290 million light-years away. Astronomers hope to find more events like ASASSN-14li to test theoretical models about how black holes affect their environments.During the tidal disruption event, filaments containing much of the star's mass fall toward the black hole. Eventually these gaseous filaments merge into a smooth, hot disk glowing brightly in X-rays. As the disk forms, its central region heats up tremendously, which drives a flow of material, called a wind, away from the disk.
The researchers say this is the first time anyone has successfully picked up the radio signal produced by this jet of escaping matter. These black hole jets have been seen before, but they’ve never been directly linked to a star being torn apart — and the phenomenon remains pretty mysterious.
"These events are extremely rare," study author Sjoert van Velzen, a Hubble fellow at Johns Hopkins University, said in a statement. “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."
The deceased star was quite similar to our own, but sat a staggering 300 million light years away. It was done in by the type of supermassive black hole thought to sit in the center of most galaxies -- including our own.
The deceased star was quite similar to our own, but sat a staggering 300 million light years away. It was done in by the type of supermassive black hole thought to sit in the center of most galaxies -- including our own.
Ohio State University scientists were the first to catch the murder in progress using an optical telescope, which they announced online in 2014. Along with researchers from the University of Oxford, van Velzen used different telescopes to gather optical, radio, and X-ray signals from the event as it unfolded. The researchers hope that they'll be able to catch more black hole burps in progress, so they can figure out the exact mechanism behind the purge.
We still have a lot to learn about black holes. Luckily, NASA has dubbed Nov. 27 “Black Hole Friday" -- so you can read up on all the latest black hole findings with just a few clicks.
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