Article Posted on : - Sep 06, 2010

ESA�s Herschel infrared space observatory has shown that the dying star IRC+10216 is surrounded by a large volume of high-temperature water vapour.

PARIS (BNS): Astronomers have revealed that ‘ultraviolet light’ is the secret ingredient for making water in space.

Astronomers had begun looking for the source of water when they discovered an unexpected cloud of water vapour around the old star IRC+10216 in 2001.

IRC+10216 is a red giant star, hundreds of times the sun’s size although only a few times its mass.

Initially the astronomers suspected the star’s heat must be evaporating comets or even dwarf planets to produce the water.

Now with the help of Herschel’s PACS and SPIRE instruments they have found that the secret ingredient for making water in space is ultraviolet light because the water is too hot to have come from the destruction of icy celestial bodies.

"The superb sensitivity of Herschel’s instruments has revealed that the water around IRC+10216 varies in temperature from about –200°C to 800°C, which indicates that it is being formed much closer to the star than comets can stably exist," ESA quoted  Leen Decin, the lead author of the paper, as saying.

According to the astronomers, ultraviolet light from surrounding stars can reach deep into the envelope between the clumps and break up molecules such as carbon monoxide and silicon monoxide, releasing oxygen atoms. The oxygen atoms then attach themselves to hydrogen molecules, forming water.

"This is the only mechanism that explains the full range of the water’s temperature,” said Decin from Katholieke Universiteit, Belgium. “The closer to the star the water is formed, the hotter it will be," he added.