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Last Updated: Thursday, 4 November, 2004, 13:00 GMT
Supernova produces cosmic rays
Supernova 1987A   Nasa/P. Challis/r. Kirshner/B. Sugerman
Supernovae have long been thought to produce cosmic rays
Astronomers claim to have found the first firm evidence that cosmic rays can come from stars that have exploded, or supernova remnants.

Galactic cosmic rays are high energy particles that bombard Earth from space.

Researchers using a telescope array in Namibia found a stream of gamma radiation coming from a supernova remnant called RX J1713.7-3946.

The radiation is probably generated by the supernova remnant "accelerating" cosmic ray electrons, Nature reports.

If you had gamma-ray eyes and were in the Southern Hemisphere, you could see a large, brightly glowing ring in the sky every night
Dr Paula Chadwick, University of Durham
The mechanism through which the expanding remnants of supernovae accelerate particles has already been worked out in theory.

But unequivocal evidence for the production of high energy particles by these shattered stars has proven surprisingly hard to find.

RX J1713.7-3946 exploded some 1,000 years ago, leaving behind an expanding shell of debris which - when seen from Earth - is twice the diameter of the Moon.

New confirmation

Professor Ian Halliday is chief executive of the Particle Physics and Astronomy Research Council (PParc), which funds UK participation in the High Energy Stereoscopic System (Hess) telescope array.

He said: "These results provide the first unequivocal proof that supernovae are capable of producing large quantities of galactic cosmic rays - something we have long suspected, but never been able to confirm."

David Berge, of the Max Planck Institut für Kernphysik in Heidelberg, Germany, and an international team of researchers used Hess telescope array to detect very high energy gamma rays.

The researchers generated an image of the supernova using gamma rays showing that very high energy particles were being accelerated there.

A co-author on the Nature paper, Dr Paula Chadwick, of the University of Durham, UK, said: "This picture really is a big step forward for gamma-ray astronomy and the supernova remnant is a fascinating object.

"If you had gamma-ray eyes and were in the Southern Hemisphere, you could see a large, brightly glowing ring in the sky every night."

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16 Apr 03 |  Science/Nature
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19 Apr 00 |  Science/Nature

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