|
Peter Calamai
Science Reporter
Toronto, July 2, 2004 - Canada's "Humble" space telescope has just shocked astronomers - by finding nothing when it focused for a month on the eighth brightest star in the winter night sky.
The $10-million MOST telescope tried to record faint light variations from Procyon, the tell-tale evidence of a suspected seismic pulse in this sun-like star.
But a report published yesterday says the scope's ultrasensitive light metre found nothing, even though astronomers have been recording signs of Procyon's seismic pulse with telescopes on Earth for two decades.
"This is forcing us to go back to the drawing board in our theories about how stars like our sun develop," said MOST chief scientist Jaymie Matthews, a University of British Columbia astronomy professor.
Unravelling the inner workings of sun-like stars is the prime mission of MOST, which stands for Microvariability and Oscillations of STars. Shot into orbit a year ago yesterday, the suitcase-sized satellite is considered a humble relation of the tractor-trailer- sized Hubble space telescope, which cost $2.2 billion (U.S.) when launched in 1990.
But unlike Hubble, MOST can keep its modest 15-centimetre telescope centred precisely on the same star for as long as two months even while orbiting the Earth every 100 minutes. This lets MOST detect variations in a star's brilliance as small as one part in one million.
Based on observing such changes in the sun's output, astronomers theorized that the similar oscillations would be found from other sun-like stars which make up 10 per cent of the Milky Way galaxy.
A leading candidate for confirming the theory was Procyon, a star twice the diameter of the sun and a mere 11 light-years away from Earth.
This star was known to the ancient Greeks, who named it Procyon, or "Before the Dog," because it rises immediately before Sirius, the Dog Star.
Beginning in 1986, astronomers using telescopes on Earth reported shifts in the colour of Procyon's light supposedly produced by seismic pulses in the star's outer surface.
But if Procyon was really ringing like a stellar bell, MOST should have detected pulsations in the output during its 32-day stakeout, says Matthews.
Since it didn't, astronomers are already busily rewriting the models of how the light from the inner atomic furnace battles its way to the surface of sun-like stars.
The MOST results, published yesterday in Nature, are expected to take centre stage at a mid-month meeting of solar experts at Yale University.
While the tiny telescope was built in Vancouver, the spacecraft was assembled at the University of Toronto's Institute for Aerospace Studies, which also provides mission control. Chief contractor is Dynacon Inc., a Toronto high-tech company specializing in automation and robotics.
|
