mercredi 27 novembre 2019

Discovery of a huge black hole













Astrophysics logo.

Nov. 27, 2019

Scientists have discovered a huge black hole in the Milky Way.


Image above: The Milky Way, of which our solar system is a part, contains some 100 million stellar black holes. (Photo: archive / photo illustration).

The black hole discovered by scientists is so important that it challenges existing theories of star evolution, according to the researchers.

The LB-1, a stellar black hole located 15'000 light-years from Earth, which the journal "Nature" describes for the first time, has a mass 70 times greater than that of the Sun.

"Black holes of such a mass should not even exist in our galaxy, according to most current theories of stellar evolution," said Liu Jifeng, a professor at the Chinese National Astronomical Observatory, head of the team of researchers who studied LB-1.

"We thought that very massive stars, whose chemical composition is typical of our galaxy, had to spill most of their gas into powerful stellar winds as they near the end of their lives," and therefore not leave behind they have such a massive black hole, said Liu Jifeng.

Abundance of black holes

While the Milky Way, of which our solar system is a part, contains some 100 million stellar black holes, LB-1 has a mass twice as large as scientists thought possible. "Now theorists will have to take up the challenge of explaining how it was formed," said Liu Jifeng in a statement.

Super massive black holes in the center of galaxies. (Illustration image)

For researcher David Reitze of the California Institute of Technology, who has not been involved in LB-1 work, astronomers "are just beginning to understand the abundance of black holes and the mechanisms of their formation." "In general, stellar black holes appear after supernova explosions, but according to current theories, they have a mass less than 50 to 60 times that of the sun," he said. The larger mass of LB-1 would therefore indicate that the black hole could not have been produced by a supernova.

"That means we're dealing with a new kind of black hole, created by another physical mechanism," insisted David Reitze.

"Nothing less than fantastic"

The LB-1 was discovered using the Chinese telescope LAMOST (Large Field Optical Fiber Spectroscopic Telescope) by an international team of Chinese, American and European scientists. Scientists first used this telescope to search for stars in orbit around invisible objects, a sign that the star could be orbiting a black hole.

Other images of the world's largest optical telescopes - the Spanish telescope Gran Telescopio Canarias and the Keck I telescope in the United States - have confirmed the size of the LB-1. The National Astronomical Observatory of China has described it in a statement of "nothing less than fantastic".

Related links:

Chinese telescope LAMOST: http://www.lamost.org/public/?locale=en

Gran Telescopio Canarias: http://www.gtc.iac.es/

W. M. Keck Observatory: http://www.keckobservatory.org/

Images, Text, Credits: ATS/LAMOST/Gran Telescopio Canarias/Keck Observatory/Orbiter.ch Aerospace/Roland Berga.

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