19 August 2006 Latest News
St Andrews-led team’s cosmic task

A NEW study led by St Andrews University scientists has found the universe has already “guzzled its way” through about 20% of its original fuel reserves, which have now turned into stars through matter produced by the “Big Bang.”

The statistics allied to the study are mind-numbing, and involve 10,000 giant galaxies, each comprising up to 10 billion stars, not to mention phenomena such as bulges, discs and super-massive black holes. The survey determined how much of the universe’s matter is locked in black holes, some a million billion times more massive than Earth.

Project leader Dr Simon Driver, of St Andrews, yesterday said the simplest prognosis is the universe will be able to form stars for a further 70 billion years, then will start to go dark.

“However, unlike our stewardship of the Earth, the universe is tightening its belt, with the rate new stars are forming steadily decreasing,” he said.

Tracking down what happened to normal matter dating back to the Big Bang 14 billion years ago has been a key goal for cosmologists for many years. The survey reveals about 20% is locked up in stars, 0.1% lies in dust expelled from the massive stars (and from which solid structures like the Earth and man are made), and about 0.01% is in the form of super-massive black holes.

“The remaining 80% is almost completely in gaseous form lying within and between galaxies and constitutes the reservoir from which future generations of stars may form.”

The survey involved scientists from Australia, Germany and the UK, and resulted in the Millennium Galaxy Catalogue (MGC), the first to catalogue reliable information on the bulge and disc components of so many galaxies. On average half the stars in the universe lie in the central bulges of galaxies, while the other half are found in discs surrounding the bulges.

“By measuring the stars in each galaxy’s bulge, we have also determined the super-massive black hole mass at the heart of each galaxy,” said Dr Alister Graham of the Australian National University. “It was then a simple matter of summing these up to determine how much of the universe’s matter is locked away in such huge black holes.”

The survey was presented at the general assembly of the International Astronomical Union in Prague.


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