In the sixth decade after its discovery, the first black hole discovered in history still caused astronomers to scratch their heads. It turns out that the cosmic behemoth at the core of the Cygnus X-1 system is 50% larger than previously thought, making it the heaviest stellar-mass black hole ever directly observed.
Based on new observations, an international research team estimates that black holes are 21 times the mass of our sun and spin faster than any other known black hole. The recalculated weight has caused scientists to reconsider how bright stars that become black holes evolve and how quickly they peel off before death.
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The mass of a black hole depends on the characteristics of its parent star, such as the mass of the star and its metallicity (how much of it is composed of elements heavier than it) helium). During the lifetime of a star, it will shed its outer layer through stellar wind bursts. Scientists believe that large stars rich in heavy elements release mass faster than smaller stars.
Studies have shown that: “stars lose their mass to the surrounding environment through the stellar wind blowing away from the surface. But to create a black hole that is so heavy and rotates so fast, we need to reduce the mass lost by bright stars during their lifetime.” Australia Mo Co-author of Nash University astrophysicist Ilya Mandel (Ilya Mandel) Said in the statement.
Distance is important
In this new study, the researchers used a tried-and-tested method to measure the mass of Cygnus X-1, which is used to measure the distance between the star and the Earth, called Parallax.As Earth Astronomers revolve around the sun, measure the visible motion of stars relative to the background of more distant stars, and use a little trigonometric function to calculate the distance between the star and the earth.
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In addition, the black hole of Cygnus X-1 slowly swallowed its bright blue companion star by sucking into the outer layer of the star, forming a bright disk rotating around the black hole. When matter falls into a black hole, it is heated to millions of degrees and emits bright X-ray radiation. Some of this material narrowly escaped the black hole, was ejected strongly, and emitted detectable radio waves on the earth.
The research team tracked these iconic bright jets using observations from the Very Long Baseline Array (VLBA), a continental-scale network of 10 radio telescopes throughout the United States, extending from Hawaii to the Virgin Islands. In six days, they tracked the complete orbit of the black hole around its companion star and determined the amount of movement of the black hole in space.
They found that Cygnus X-1 is about 7,200 Light years Exceeded the previous estimate of 6,000 light years. The updated distance shows that the blue supergiant companion star is brighter and heavier than previously thought, 40 times that of our sun. Taking into account the orbital period of the black hole, they were able to make a new estimate of the mass of the black hole-up to 21 solar masses.
“Using the updated measurements of the mass of the black hole and its distance from the Earth, we were able to confirm that Cygnus X-1 is rotating very fast, very close to the speed of light, and faster than any other black hole discovered so far, the author of the statement One is Gou Lijun, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences.
This discovery proves how the increased sensitivity and accuracy of telescopes can uncover mysteries even in some of the most studied parts of our universe.
The study’s co-author, NAOC researcher Xueshan Zhao said in a statement: “With the advent of the next generation of telescopes, their increased sensitivity reveals more and more details to people.” “Now I am an astronomer. good time.”
The researchers detailed their findings in the journal Science on February 18.
Originally published in “Life Science”.