(jikun) Stellar 'baby boom' in early Universe

PureInsight | January 3, 2001

Stellar 'baby boom' in early Universe

The Australia Telescope will be replaced by better technology

The earliest stars in the Universe may be much older than previously thought following the discovery of what could be an entirely new kind of galaxy billions of light-years from Earth.

'Even the world's largest telescope can't collect enough light from this object to really pin down its distance

Professor Norris
Observations of several objects were undertaken by scientists using the Australia Telescope, run by the Commonwealth Scientific and Industrial Research Organisation (Csiro), and the Hubble Space Telescope.

'We think they are galaxies that are absolutely fizzing with star formation - a sort of huge stellar baby-boom,' said Csiro's Professor Ray Norris, leader of the Australia Telescope observing team.

'They seem to be a hundred times more active than even the most frenzied star-forming galaxy in today's Universe - the kind of galaxy we call starburst,' he said.

Many of these galaxies must be very faint. They might be very common, even outnumbering all the distant galaxies that astronomers had seen before. If that's the case, it pushes back the epoch of maximum star formation - when the Universe really got active - by a long way,' Professor Norris said.

Large structures

The discovery was made in a patch of the southern sky called Hubble Deep Field South, which contains many distant galaxies.

The radio telescope observations show that a faint red dot in the Hubble field, dubbed 'source c', is a very unusual object.

Red dot in the cross-hair could have been one of the first large structures in the Universe

The colours of its light suggest that it lies between five and 11 billion light-years away, which means we see it as it looked when the Universe was very young.

'That in itself is not remarkable,' said Professor Norris. 'But this galaxy is the most extreme example of a class of objects in the Hubble fields which are very faint in visible light but quite bright at radio wavelengths.

'If the strange source is an early starburst galaxy, then we now have solid evidence for what may have been a brief and furious burst of star formation, possibly the first really large structures that formed in the Universe,' said Dr Bob Williams, former director of the Space Telescope Science Institute, which oversees the Hubble observatory.

'Light buckets'

For now, astronomers are stuck with a mystery. But the next generation of telescopes will help them clear up the tantalising questions so far raised about the early Universe.

'Even the world's largest telescope, the Very Large Telescope in Chile, can't collect enough light from this object to really pin down its distance,' said Dr Norris.

'That will probably have to wait for optical telescopes now on the drawing board - ones with mirrors 30 metres across or even bigger.'

The first of these giant 'light buckets', the California Extremely Large Telescope, may be built in the next few years.

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