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Thursday, January 8, 1998 Published at 10:36 GMT



Sci/Tech

Massive black hole in galaxy, say scientists
image: [ Image of a black hole in the constellation Aquila overtaking a star (on left) ]
Image of a black hole in the constellation Aquila overtaking a star (on left)

Astronomers say they have the strongest evidence to date that a massive black hole exists at the centre of the galaxy, about 26,000 light years from the sun and the rest of the planets, including Earth.

Black holes are believed to be points of infinite density with such a strong gravitational pull that nothing can escape from them - including light.

Their existence has always been one of the most controversial issues in astronomy.

However, scientists from the Max Planck Institute in Germany say the fact that stars near the centre of the Milky Way are moving at more than 600 miles a second points to the existence of a black hole.


[ image: Andreas Eckart:
Andreas Eckart: "The only explanation is a black hole"
Andreas Eckart told a meeting of the American Astronomical Society that speed of the stars and the high mass of the object at the centre of the galaxy was the strongest evidence to date for the existence of black hole.

"This extraordinary mass concentration cannot be explained by the presence of a dense cluster of stars of stellar remnants," he said.

"The only plausible explanation is the presence of a massive black hole."

The black hole - which scientists have dubbed "Sagittarius A" - is believed to occupy an area the same size as our solar system.

Evidence gathered by US scientists appears to support the theory about the black hole.

Researchers at the Harvard-Smithsonian Centre for Astrophysics used radio telescopes to measure the sun's orbit of the centre of the galaxy and of the motion of Sagittarius A.

Two years of measurements showed that Sagittarius A was virtually motionless, while the sun was moving around it at half a million miles an hour.

Mark Reid of the Harvard-Smithsonian Centre said that if the object at the centre of the Milky Way was a black hole, then it would stay relatively still.

"This would be totally consistent with there being a supermassive black hole."

However, Mark Reid also said that while the burden of evidence pointed to the existence of a black hole, it could not yet be proved beyond a reasonable doubt.
 





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