Mystery of cosmic 'superwinds' solved?

April 11, 2012 at 6:56 PM
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MANCHESTER, England, April 11 (UPI) -- The mystery of a powerful solar "superwind" that plays a role in the death of stars may have been unraveled, Australian and European astronomers say.

Stars like the sun end their lives with a 'superwind," 100 million times stronger than the normal solar wind, that over a period of 10,000 years removes as much as half the mass of the star, leaving just a dying and fading remnant.

Research led by the University of Sydney in Australia, with scientists from the Universities of Manchester, Paris-Diderot, Oxford and Macquarie University, New South Wales, used new techniques that allowed astronomers to look into the atmospheres of distant, dying stars.

Scientists previously thought superwinds consisted of minute dust grains, which form in the star's atmosphere, absorbing light and being pushed away from the star.

But such minute grains would become too hot and evaporate before they could be pushed out as a superwind, the new research found.

However, using the Very Large Telescope in Chile operated by the European Southern Observatory, the researchers found the grains can grow to much larger sizes than previously thought, almost to a micrometer -- still small for dust but huge for stellar winds.

The large grains are driven out by the starlight at speeds of 20 thousand miles per hour in an effect similar to a sandstorm, they said.

"The dust and sand in the superwind will survive the star, and later become part of the clouds in space from which new stars form," University of Manchester astronomer Albert Zijlstra said in a released issued by the University of Manchester.

"The sand grains at that time become the building blocks of planets. Our own Earth has formed from stardust. We are now a big step further in understanding this cycle of life and death."

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