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New record for Universe's most distant object
« on: 2002-03-15 05:38:18 » |
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New record for Universe's most distant object , Hazel Muir, NewScientist.com news service, 17:19 14 March 02
 The arrow marks the position of the most distant galaxy in this red optical and infrared light image (Credit: Esther Hu)
The record for the most distant object in the Universe has been broken again. Astronomers have spied a galaxy burning an astonishing 13.6 billion light years away.
Because its light has taken billions of years to travel to Earth, astronomers are seeing the galaxy as it looked when the Universe was only about 900 million years old.
"This galaxy is forming stars at a time speculated to be in the 'Dark Ages' of the Universe when galaxies began to turn on," says Esther Hu at the University of Hawaii, who led the team.
Astronomers think the Universe formed in a giant explosion approximately 14.5 billion years ago. About half a million years later, the expanding fireball left a sea of neutral gas - mostly hydrogen and some helium.
The next period - the Dark Ages - is when the cold gas started to clump into galaxies. Then a cosmic dawn came as the stars lit up.
Early starter
Telescopes can spot quasars - superbright objects powered by black holes - around 13 billion light years away. But to see faint young galaxies so far away, they have to use the gravity of an intervening object as a "lens" to magnify the light.
This way, they have already seen telltale signs of star formation in galaxies about 13.4 billion light years away. Now Hu's team has found one 13.6 billion light years away, thanks to an intervening galaxy cluster called Abell 370, which magnified the light.
Team member Richard McMahon of Cambridge University says the galaxy is probably about half the size of our own Milky Way. "We've shown that the first galaxies formed earlier than some people thought," McMahon concludes.
He hopes new technology will soon allow astronomers to see even more distant galaxies that pioneered star formation 14 billion years ago.
Journal reference: Astrophysical Journal Letters (vol 568, p 75)
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