Oldest Stars in the Universe Observed |
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Written by spacetravel.org
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Wednesday, 27 July 2005 21:36 |
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Dr. Andrew Bunker and graduate student Laurence Eyles, both of the University of Exeter, have observed the oldest stars in the Universe, born shortly after the Big Bang. These stars are in galaxies about 13 billion light-years from Earth. This means that light left them less than a billion years after the beginning of the Universe, long before the Solar System was formed.
Bunker and Eyles first examined the Hubble Ultra Deep Field, the Hubble Space Telescopes longest exposure, to identify objects that are likely to be distant galaxies. They then used the ground-based Keck telescope to obtain their spectra. This allowed them to measure their redshifts and confirm their distances. Finally, they looked at infrared images of the galaxies taken with the Spitzer space telescope. They found that the stars in these galaxies were already hundreds of millions of years old. The light from these ancient stars may have ionized neutral hydrogen and helium, lighting up the Universe.
Professor Richard Ellis of Caltech says that the age of these stars challenges some theories of star formation. These galaxies were already quite old when the Universe was only 5 percent of its present age. This means that star formation must have started earlier in the Universes history than was previously believed.
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