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Friday, August 27, 1999 Published at 11:52 GMT 12:52 UK


Impressive debut for Chandra

The first images taken by the new Chandra X-ray observatory have just been released.

One of them shows a gigantic stellar explosion in such stunning detail that scientists think they can see evidence of what may be a neutron star or black hole at the centre of the blast.

The pictures are everything astronomers had hoped for from the $1.5bn observatory which was carried into an orbit around the Earth last month on board the shuttle Columbia.

After going through an extensive checkout and calibration procedure to see that all systems were working properly, Chandra last week opened its sunshade door and pointed its detection equipment at the cosmos.

[ image: The shuttle Columbia had to be modified to carry Chandra into orbit]
The shuttle Columbia had to be modified to carry Chandra into orbit
One of its first targets was the 320-year-old supernova remnant Cassiopeia A (top picture), which astronomers believe was produced by the explosion of a massive star that collapsed in on itself.

Material blasted into space from the explosion crashed into surrounding material at 16 million kilometres per hour. This collision caused violent shock waves, like massive sonic booms, creating a vast, 50-million degree bubble of X-ray emitting gas.

This is what Chandra was put in space to see: not the light that we can pick up with ordinary optical telescopes but the high-energy, invisible x-rays that are emitted from the hottest and most violent parts of the Universe.

"We were astounded by these images," said Harvey Tananbaum, Director of the Smithsonian Astrophysical Observatory's Chandra X-ray Center.

"We see the collision of the debris from the exploded star with the matter around it, we see shock waves rushing into interstellar space at millions of miles per hour, and, as a real bonus, we see for the first time a tantalising bright point near the centre of the remnant that could possibly be a collapsed star associated with the outburst."

10 trillion Suns

Another of the images is of Quasar PKS 0637-752. It is so distant that we see it as it was six billion years ago. It is a luminous quasar radiating the power of 10 trillion Suns from a region smaller than our Solar System.

The source of this enormous energy is believed to be a supermassive black hole. Chandra's X-ray image shows a powerful X-ray jet stretching across several hundred thousand light years, which is most likely the result of a beam of extremely high energy particles.

[ image: Quasar PKS 0637-752: As it was six billion years ago]
Quasar PKS 0637-752: As it was six billion years ago
Chandra will spend at least five years making these sorts of observations. Ten to 100 times more powerful than similar telescopes previously placed in orbit, it heralds a revolution in X-ray astronomy.

"When I saw the first image, I knew that the dream had been realised," said Dr Martin Weisskopf, Chandra Project Scientist at Nasa's Marshall Space Flight Center.

"This observatory is ready to take its place in the history of spectacular scientific achievements."

Named in honour of the late Nobel laureate Subrahmanyan Chandrasekhar, the observatory will help astronomers answer fundamental questions about the evolution of the Universe.

Nasa commentary of Chandra's deployment from Columbia
Its ability to precisely measure X-rays will allow us to investigate how exploding stars create and disperse the heavier elements on which life depends.

"Chandra will help to confirm one of the most fascinating theories of modern science - that we came from the stars," said Professor Robert Kirshner of Harvard University.

"Its ability to make X-ray images of comparable quality to optical images will have an impact on virtually every area of astronomy."

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