Riddle of a dying star

Scientists are hailing the photograph of a dust-cloaked star as one of the most dramatic pictures ever taken. The image from the Hubble Space Telescope shows the dying star 4,000 light years away being bombarded by hailstones.

However, astronomers are baffled by the vast butterflylike "wings" around the star.

These are dust clouds produced as the star dies. But scientists cannot work out how the so-called Butterfly Nebula formed its distinctive shape, as the star at its heart is actually round. Lars Christensen

of the European Space Agency, which operates the Hubble Space Telescope jointly with Nasa, said: "It's a big mystery to us all - how a round star like our own sun can create this effect, which is so symmetrical. It's amazing."

The image reveals huge walls of compressed gas and bubbling outflows. A massive ring of dark dust hiding the star also has experts baffled.

They do not understand how it formed or how long it can survive evaporation by the central star, which has become one of the universe's hottest objects at 250,000C.

Researchers at the University of Manchester Institute of Science and Technology, who led the astronomers analysing the Hubble data, revealed the picture today.