Astronomers find stars 7 billion light years away

25 September 2007 | 06:14 Code : 15388 Geoscience events
A VICTORIAN astronomer is part of an international team that has discovered....

  A VICTORIAN astronomer is part of an international team that has discovered 14 galaxies, opening up a new era of galaxy hunting.The galaxies, which are about 7 billion light years from Earth, have until now been difficult to detect, because they lie in front of bright, distant objects known as quasars.The glare of the quasars drowns out the dim light from the galaxies, but a powerful infrared instrument in Chile helped the scientists uncover them."It effectively allows us to see through the glare of the quasar," said researcher Michael Murphy, of SwinburneUniversity."By chopping up the light into many finely dissected colours, we can essentially get rid of the quasar altogether, and see the galaxy coming through."The research team, headed by Germany's Max Planck Institute for Extraterrestrial Physics, began their search by using quasars as cosmic beacons to reveal the presence of a galaxy.Dr Murphy trawled through huge catalogues of quasars to find those with dips in their colour spectrum.This shows that a galaxy is in front of the quasar, absorbing some of its light before it reaches Earth.By studying the patches of sky around 20 of these quasars — using the European Southern Observatory's Very Large Telescope — the researchers detected the 14 new galaxies.There are estimated to be hundreds of billions of galaxies in the universe, but only about a dozen that sit in front of quasars have been detected at such a distance from Earth. The latest finds have doubled this tally.Light from the newly found galaxies comes from the time the universe was about 6 billion years old, less than half its current age. By studying the light, the researchers have determined they are starburst galaxies that form lots of new stars — the equivalent of 20 suns a year.Dr Murphy, who began working on the project while a research fellow at the University of Cambridge, described the results as a great leap forward. The findings have been accepted for publication in The Astrophysical Journal.

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