Star is a giant water sprinkler

June 28, 2002

Astronomers have found an ageing star that is spewing narrow, rotating streams of water molecules into space like a lawn sprinkler, writes Steve Farrar.

The discovery could betray the cosmic artistry behind one of the universe's most beautiful objects - planetary nebulae.

The Japanese-led international team used the Very Long Baseline Array radio telescope to capture images of a star called W43A.

This star, which is about 8,500 light years from Earth, is believed to be nearing the end of its life.

Astronomers believe it is on the brink of forming a so-called planetary nebula, a brightly glowing shell lit by the hot ember of the collapsed star.

This is formed from gas blown from a star's outer atmospheres as the nuclear fusion of hydrogen atoms in its core fizzles out.

Phillip Diamond, director of the Merlin radio observatory at Jodrell Bank and one of the collaborators who studied W43A, said it was a mystery why many of these nebulae were not spherical but instead had intricate shapes that had made them a favourite target for astronomers.

"The spinning jets of water we found coming from this star may be one mechanism for producing the structures seen in many planetary nebulae," he said.

Such jets had been hypothesised but had never been detected.

The VLBA radio telescope focused on regions of space close to W43A that were known to amplify radio emissions at a frequency connected to water.

The astronomers found these were strung out in two curved lines that were moving in opposite directions from the star at about 325,000 miles per hour.

Dr Diamond said: "The paths of the jets are curved like a corkscrew, as if whatever is squirting them out is slowly rotating."

How the star is producing the streams is not known.

The findings are published in the journal Nature .

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