Nicky Phillips April 12, 2012
Dusted off ... an artist's impression of a red giant. Photo: Anna Mayall
POWERFUL winds may have howled through Sydney this week, but they're nothing compared with the winds that determine whether a star's life ends with a bang or a whimper.
Sydney scientists have used telescopes in northern Chile to discover what drives powerful stellar winds that whittle away a dying star.
A University of Sydney astronomer, Peter Tuthill, said the size of a star nearing the end of its life would determine whether it faded away or exploded as a supernova.
"These winds change the star in a fundamental way," he said.
His PhD student, Barnaby Norris, who led the research, said these cosmic gales were also responsible for distributing chemical elements necessary for building Earth-like planets throughout space.
"Even we are made up of stuff that came from ... these stars billions of years ago," he said.
But how stars release this material into the galaxy has puzzled astronomers until now.
Using a specialised telescope at the European Southern Observatory, Mr Norris and a team of international researchers pinpointed a halo of large, transparent dust particles being expelled from several dying stars, known as red giants.
"We were able to catch this dust in the act of being formed," he said.
The dust acted like tiny mirrors, reflecting the star's radiation instead of heating up and evaporating, said Professor Tuthill, whose findings are published in the journal Nature.
And the large size of the particles meant they could act like sails and harness the force of the star's radiation to drive a wind.
Astronomers had spent years trying to understand stellar winds, he said. "This is the first big crack in the case."
By understanding how the winds work, astronomers could predict which stars could defuse their supernova.