How It Works - UK (2020-02)

SPACE

Stellar black hole is

‘too big to exist’

Words by Yasemin Saplakoglu

A

gigantic stellar black hole 15,000 light

years from Earth is twice as massive as

what researchers thought was possible in

our own galaxy.

The black hole is 70 times more massive than the

Sun, the scientists wrote in a recent study.

Previously scientists thought the mass of a stellar

black hole, formed from the gravitational collapse

of massive stars, couldn’t exceed 30 times that of

the Sun.

“We thought that very massive stars with the

chemical composition typical of our galaxy must

shed most of their gas in powerful stellar winds as

they approach the end of their life,” lead study

author Jifeng Liu, deputy director-general of the

Chinese Academy of Sciences’ National

Astronomical Observatories, said in a statement.

“Therefore, they should not leave behind such a

massive remnant.”

It is thought that our Milky Way galaxy contains

some 100 million stellar black holes, yet scientists

havediscoveredonlyabouttwodozenofthem,

according to the statement. That’s because until a

couple of years ago, the only way scientists could

discover these giant beasts was by detecting the

X-rays they emitted while they chomped away at

their stellar companions. But most black holes in

our galaxy don’t have much of an appetite and

thus don’t release X-rays, the researchers

explained in the statement.

So Liu and his team turned to another method:

they scanned the skies with China’s Large Sky

Area Multi-Object Fiber Spectroscopic Telescope.

Using this telescope, they searched for stars that

orbit seemingly invisible objects, held on tight by

the object’s gravity. That’s how the researchers

came across one star 15,000 light years away that

was dancing around nothing – but was held in an

orbit by something that could only be a black hole,

they wrote.

The black hole “is twice as massive as what we

thought possible,” Liu said in the statement. “Now,

theorists will have to take up the challenge of

explainingitsformation.”

For more

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http://www.howitworksdaily.com livescience.com

The black hole is more than twice the

size that scientists thought possible

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