You are in: Sci/Tech | |||||||||||||||||||||||||||||||
|
Thursday, 14 March, 2002, 11:38 GMT
Far away stars light early cosmos
"This galaxy is forming stars at a time speculated to be in the so-called Dark Ages of the Universe, when galaxies began to turn on," said University of Hawaii Professor Esther Hu.
"Scaling the age of the Universe to a person's lifetime, we're showing you baby pictures. The last snapshot we obtained showed a toddler just past his fourth birthday. This new one is three and a half." The newly discovered galaxy has a redshift of 6.56, which means it is about 14 billion light-years distant and its light set off when the Universe was about 780 million years old. Zoom lens This is about 50 million years earlier than the view supplied by the most distant quasar found so far (redshift = 6.28). Until this discovery, the most distant objects and hence the earliest probes of the Universe had been quasars - extremely luminous galactic cores, believed to be powered by black holes. Ordinary galaxies are fainter and much harder to detect at such distances.
To reach faint and very distant galaxies they looked through a "gravitational lens" - a massive cluster of galaxies that bends and amplifies light from more distant objects behind. It is like a zoom lens that allows astronomers to peer even further into the depths of the Universe. In this case, the scientists used the galaxy cluster Abell 370, which is six billion light-years away and whose core contains a mass of several hundred galaxies. It magnified light from a galaxy behind it that is 15.5 billion light-years distant, almost at the edge of the observable Universe. Zoom lens The researchers then concentrated on a particular part of the light, where a bright hydrogen line called Lyman alpha could be seen. This line is usually prominent in galaxies that are undergoing large bursts of star formation.
Hawaii astronomer Len Cowie said: "The fact that this is a galaxy, and not a quasar, is important. When the first galaxies form, it's like turning on lights to clear out a fog bank. "Quasars are really bright though rare, so they can make large clear cavities around themselves, but the fact that light from the fainter but much more numerous galaxies is getting out means that a significant amount of early star formation has already taken place and much of the general fog has already dissipated."
|
See also:
Internet links:
The BBC is not responsible for the content of external internet sites Top Sci/Tech stories now:
Links to more Sci/Tech stories are at the foot of the page.
|
Links to more Sci/Tech stories
|
^^ Back to top News Front Page | World | UK | UK Politics | Business | Sci/Tech | Health | Education | Entertainment | Talking Point | In Depth | AudioVideo ---------------------------------------------------------------------------------- To BBC Sport>> | To BBC Weather>> ---------------------------------------------------------------------------------- © MMIII | News Sources | Privacy |