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Old 09-05-2012, 08:24 PM
 
Location: Texas
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Windows to the past, stars can unveil the history of our universe, currently estimated to be 14 billion years old. The farther away the star, the older it is — and the oldest stars are the most difficult to detect. Current telescopes can only see galaxies about 700 million years old, and only when the galaxy is unusually large or as the result of a big event like a stellar explosion.

Now, an international team of scientists led by researchers at Tel Aviv University have developed a method for detecting galaxies of stars that formed when the universe was in its infancy, during the first 180 million years of its existence. The method is able to observe stars that were previously believed too old to find, says Prof. Rennan Barkana of TAU's School of Physics and Astronomy.
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Old 09-09-2012, 02:28 PM
 
Location: Wasilla, Alaska
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Currently the best estimate for the age of the universe is 13.75 ± 0.11 billion years. The oldest galaxy cluster that we have found is 13.1 billion light years away, or 650 million years after the Big Bang. The oldest single galaxy that we have found is 12.91 billion light years away, making it 840 million years after the Big Bang.

The James Webb space telescope, which is scheduled to be deployed in October 2018, should be able to see between 13.5 and 13.65 billion light years, between redshift 15 and 30, or between 100 and 250 million years after the Big Bang. Which puts it back to when they think star formation began, around 100 to 200 million years after Big Bang. These new Population III stars would have been entirely hydrogen and helium, with no metals, and super massive. Some may have been larger than 100 solar masses. These stars would have only lasted a few million years before going supernova creating new metals. However, the universe had not completed the Reionization by the time star formation began, which means that the universe was not as transparent as we see it today (~10% opacity). It took from around 340,000 years after the Big Bang to about 1 billion years after the Big Bang for the universe to become transparent. Which means at 150 million years after the Big Bang the universe was around 85% opaque. It is about as far as we will ever be able to see.

It is very possible that with the James Webb space telescope we should be able to see some of these Population III stars go supernova. At the very least we should be able to see the beginning of galaxy formation.

Sources:
Oldest galaxy discovered so far in the Universe is 12.91 billion years old
The James Webb Space Telescope
Judd D. Bowman: Reionization and the Dark Ages
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