Scientists Discover Unusual Black Hole
2022-07-22
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1Researchers have discovered a new kind of black hole - one that is not only dormant but also appears to have been born without the explosion of a dying star.
2Researchers said recently that the black hole is different from all other known black holes.
3It is "X-ray quiet" - meaning it does not release powerful X-ray radiation.
4The presence of x-rays would suggest the black hole was taking in nearby material with its strong gravitational pull.
5And this black hole was not born in a kind of explosion called a supernova.
6Black holes are dense objects with gravity so strong not even light can escape them.
7The newly discovered black hole has a mass at least nine times greater than our sun.
8It was discovered in the Tarantula Nebula, a huge gas cloud in the Large Magellanic Cloud galaxy.
9It is about 160,000 light years from Earth.
10A light year is the distance light travels in a year.
11A very bright and hot blue star with a mass 25 times that of the sun orbits with the black hole in a stellar marriage.
12This double system is named VFTS 243.
13The researchers believe the companion star will become a black hole and could join with the other one after a long period of time.
14Dormant black holes are thought to be relatively common.
15But they are hard to find because they have very little to do with their surroundings.
16Numerous proposed candidates have been ruled out with further study, including by members of the team that discovered this one.
17Tomer Shenar of Amsterdam University was the lead author of the study that was published in Nature Astronomy.
18Shenar described the difficulty of finding dormant black holes by saying, "We identified a needle in a haystack."
19Study co-writer Kareem El-Badry of the Harvard & Smithsonian Center for Astrophysics said: "It's the first object of its kind discovered after astronomers have been searching for decades."
20The researchers used six years of observations from the European Southern Observatory's Very Large Telescope based in Chile.
21Astronomers say there are different kinds of black holes.
22The smallest, like the newly discovered one, are called stellar-mass black holes.
23There also are intermediate-mass black holes as well as supermassive black holes believed to exist at the center of most galaxies.
24It is typically assumed that the collapse of massive stars into black holes is associated with a powerful supernova explosion.
25In this case, a star perhaps 20 times our sun's mass blew some of its material into space, then collapsed in on itself without an explosion.
26The shape of its orbit with its companion offers evidence for the lack of an explosion.
27"The orbit of the system is almost perfectly circular," Shenar said.
28Had a supernova taken place, the explosion's force would have pushed the newly formed black hole in a random direction and created an elliptical rather than a circular orbit, Shenar added.
29Study co-writer Julia Bodensteiner of the European Southern Observatory in Munich said that black holes can pull in large amounts of material if there is something close to them.
30"Usually, we detect them if they are receiving material from a companion star, a process we call accretion," Bodensteiner said.
31Shenar added, "In so-called dormant black hole systems, the companion is far enough away that the material does not accumulate around the black hole to heat up and emit X-rays. Instead, it is immediately swallowed by the black hole."
32I'm John Russell.
1Researchers have discovered a new kind of black hole - one that is not only dormant but also appears to have been born without the explosion of a dying star. 2Researchers said recently that the black hole is different from all other known black holes. It is "X-ray quiet" - meaning it does not release powerful X-ray radiation. The presence of x-rays would suggest the black hole was taking in nearby material with its strong gravitational pull. And this black hole was not born in a kind of explosion called a supernova. 3Black holes are dense objects with gravity so strong not even light can escape them. 4The newly discovered black hole has a mass at least nine times greater than our sun. It was discovered in the Tarantula Nebula, a huge gas cloud in the Large Magellanic Cloud galaxy. It is about 160,000 light years from Earth. A light year is the distance light travels in a year. 5A very bright and hot blue star with a mass 25 times that of the sun orbits with the black hole in a stellar marriage. This double system is named VFTS 243. The researchers believe the companion star will become a black hole and could join with the other one after a long period of time. 6Dormant black holes are thought to be relatively common. But they are hard to find because they have very little to do with their surroundings. Numerous proposed candidates have been ruled out with further study, including by members of the team that discovered this one. 7Tomer Shenar of Amsterdam University was the lead author of the study that was published in Nature Astronomy. 8Shenar described the difficulty of finding dormant black holes by saying, "We identified a needle in a haystack." 9Study co-writer Kareem El-Badry of the Harvard & Smithsonian Center for Astrophysics said: "It's the first object of its kind discovered after astronomers have been searching for decades." 10The researchers used six years of observations from the European Southern Observatory's Very Large Telescope based in Chile. 11Astronomers say there are different kinds of black holes. The smallest, like the newly discovered one, are called stellar-mass black holes. There also are intermediate-mass black holes as well as supermassive black holes believed to exist at the center of most galaxies. 12It is typically assumed that the collapse of massive stars into black holes is associated with a powerful supernova explosion. In this case, a star perhaps 20 times our sun's mass blew some of its material into space, then collapsed in on itself without an explosion. 13The shape of its orbit with its companion offers evidence for the lack of an explosion. 14"The orbit of the system is almost perfectly circular," Shenar said. 15Had a supernova taken place, the explosion's force would have pushed the newly formed black hole in a random direction and created an elliptical rather than a circular orbit, Shenar added. 16Study co-writer Julia Bodensteiner of the European Southern Observatory in Munich said that black holes can pull in large amounts of material if there is something close to them. 17"Usually, we detect them if they are receiving material from a companion star, a process we call accretion," Bodensteiner said. 18Shenar added, "In so-called dormant black hole systems, the companion is far enough away that the material does not accumulate around the black hole to heat up and emit X-rays. Instead, it is immediately swallowed by the black hole." 19I'm John Russell. 20Will Dunham reported on this story for Reuters. John Russell adapted it for VOA Learning English. 21______________________________________________________________________ 22Words in This Story 23dormant - adj. not doing anything at this time; not active but able to become active 24stellar - adj. of or relating to the stars 25companion - n. a person or animal you spend time with (sometimes used figuratively) 26a needle in a haystack - idiom something that is very difficult to find because it is hidden among many other things 27astronomer - n. a scientist who studies of stars, planets, and other objects in outer space 28random - adj. chosen or done without a plan or design 29elliptical - adj. shaped like a flattened circle