It's a death star, but that's life

This is an image taken with the Keck Telescope showing a plume of hot dust and gas flung out into a whirling spiral as the two stars at the centre of the system orbit one another every eight months.

Richard Macey
March 4, 2008

IT LOOKS like a catherine wheel in the sky, but its beauty may belie a lethal venom.

If Peter Tuthill's worst fears are right, it may one day blow Sydney's worries about interest rates, house prices and late-running trains clear off page one of the morning newspapers.

"If it happens," the University of Sydney astronomer said yesterday, "you would be lucky if there was a page one."

The spinning wheel is generated by two massive stars, 8000 light years away, circling each other every eight months. Gigantic clouds of gas streaming off the stars are being stretched by the stellar dance into a spiral, much as water spirals from a rotating garden sprinkler.

Eight years ago Dr Tuthill's team, using Hawaii's huge Keck telescope, discovered that one of the objects is a highly unstable beast called a Wolf-Rayet star. They inevitably die in huge explosions that may sometimes produce deadly gamma ray bursts.

Now Dr Tuthill's team has made another discovery. Overlapping 11 time-lapse images of the 30 billion-kilometre-long gas spiral, they have concluded that Earth is almost directly above one pole of the doomed star, dubbed WR 104. When Wolf-Rayet stars explode, much of their energy is blasted from the poles.

"From our vantage point," said Dr Tuthill, "we are looking right down the gun barrel. That's what's got us worried."

In 2003 a University Of Kansas astrophysicist, Adrian Melott, said a cosmic gamma ray burst from an exploding star triggered a mass extinction of life 443 million years ago. Dr Tuthill said it was impossible to say when WR 104 would explode. "It could be tomorrow, or in 100,000 years [but] it will definitely blow up. It's a ticking bomb."

Although the star was a possible candidate for a burst of gamma rays, "there are a lot of uncertainties". And more work was needed to establish the exact path of any radiation blast.

Dr Tuthill, whose findings have been published in the Astrophysical Journal, advised the public to stick to worrying about more earthly matters. "You might be able to do something about the trains not running on time. You can protest. If [WR 104] is a gamma ray burster, we may be in some degree of trouble, but there is nothing we can do."