09 May 2020
European astronomers say they have found the closest black hole to Earth ever discovered.
The black hole is believed to be at least 4.2 times the mass of the sun. It sits about 1,000 light years from Earth, or about 9.5 trillion kilometers away.
The discovery was made by researchers from the European Southern Observatory. They found the black hole using a telescope based in Chile. The research recently appeared in the publication Astronomy & Astrophysics.
Thomas Rivinius led the research for the European Southern Observatory. In an interview with Reuters news agency, he admitted the black hole is still very far from Earth. But he noted that in terms of the universe and the galaxy, we should consider the new find "just around the corner."
Rivinius said the next closest black hole to Earth is probably about three times further, about 3,200 light years away.
Black holes are extremely dense objects with gravitational pulls so powerful that not even light can escape. Some are huge, like the one at our galaxy's center 26,000 light years from Earth. That black hole is four million times the sun's mass.
The newly discovered black hole is gravitationally attached to two stars in a so-called triple system, the researchers said. It sits in the constellation Telescopium in the sky's Southern Hemisphere.
Astronomers theorize there are between 100 million to 1 billion of these small but dense objects in the Milky Way. But usually they cannot be seen. Scientists can only find them when they are eating away at parts of a partner star or something else falls into them. Astronomers think most black holes remain unseen because they do not have anything close enough to swallow up.
Astronomers found the new one because of the triple system formation. They say their telescope observations confirmed that there was an object about four times the mass of our sun pulling on the inner star. They decided it could only be a black hole.
Other astronomers say the theory makes sense. "It will motivate additional searches among bright, relatively nearby stars," said Ohio State University astronomer Todd Thompson. He was not part of the research.
Rivinius said these are young, hot stars compared to our 4.6 billion-year-old sun. They may be 140 million years old, but at 15,000 degrees Celsius, they are three times hotter than the sun. About 15 million years ago, one of the stars got too big and too hot and went supernova, turning into the black hole in a violent process, he added.
Rivinius said the two stars are far enough away from the black hole that it is not pulling material from them. But in a few million years the closer star is expected to grow as part of its life cycle.
Avi Loeb is director of Harvard's Black Hole Initiative. He was not part of the study. "It is most likely that there are black holes much closer than this one," he told the AP. "If you find an ant while scanning a tiny fraction of your kitchen, you know there must be many more out there."
I'm Bryan Lynn.
The Associated Press and Reuters reported on this story. Bryan Lynn adapted the reports for VOA Learning English. Hai Do was the editor.
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Words in This Story
around the corner – phr. very close or nearby
constellation – n. a group of stars
motivate – v. make someone behave in a particular way
supernova – n. a star that has exploded, strongly increasing its brightness
scan – v. to examine very closely
fraction – n. a small part of something