27 February 2021
A recent study found that the first black hole ever discovered is a lot bigger than scientists first thought.
Black holes are extremely massive space objects whose gravity is so powerful not even light escapes. The black hole, Cygnus X-1, was discovered in 1964. It is well-known for being the object of a friendly bet between two famous scientists.
Researchers found that new observations of Cygnus X-1 showed it is 21 times our sun's mass. That is about 50 percent more massive than scientists had believed.
While it is still one of the closest black holes known, the scientists found it is farther away than earlier estimates suggested. It is 7,200 light years away. A light year is the distance light travels in one year.
Some black holes, like the one at the center of the Milky Way Galaxy, are extremely large. These are called "supermassive" black holes. They can be millions of times more massive than the sun. Smaller black holes are called "stellar-mass" black holes. They have the mass of a single star.
Cygnus X-1 is the Milky Way's largest-known stellar-mass black hole. It is among the strongest X-ray sources seen from Earth, said James Miller-Jones of Curtin University and the International Centre for Radio Astronomy Research in Australia. Miller-Jones led the study that appeared in the publication Science.
Cygnus X-1 turns so quickly that it comes close to the highest rate predicted under physicist Albert Einstein's theory of general relativity, Miller-Jones added.
The black hole brings in material that comes from the surface of the star that it orbits. This star is a "blue supergiant," a very large star about 40 times our sun's mass.
Cygnus X-1 started to exist 4 million to 5 million years ago as a star up to 75 times more massive than the sun. But then it collapsed into a black hole a few tens of thousands of years ago.
The research included data from the Very Long Baseline Array radio telescope. It is made up of 10 observation stations in the United States.
After Cygnus X-1 was first identified as a possible black hole, a friendly bet was made between two physicists, Stephen Hawking and Kip Thorne. Hawking bet against the object being a black hole, while Thorne bet that it was one. Hawking eventually admitted that the evidence suggested Cygnus X-1 was a black hole.
Miller-Jones, the leader of the recent study said, "Indeed, I did not have any wagers riding on these findings."
I'm John Russell.
Will Dunham reported on this story for Reuters. John Russell adapted it for Learning English. Mario Ritter, Jr. was the editor. _____________________________________________________________
Words in This Story
bet – n. an agreement in which people try to guess what will happen and the person who guesses wrong has to give something (such as money) to the person who guesses right; a wager
source – n. the place where something starts from
wager – n. an agreement in which people try to guess what will happen and the person who guesses wrong has to give something (such as money) to the person who guesses right; a bet