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Older Than the Universe

2 Nov 2014, 19:40 UTC
Older Than the Universe
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The star HD 140283 is a subgiant star with an estimated age of 14.46 billion years. That might raise an eyebrow or two for those of you who remember that the age of the universe is estimated as 13.77 billion years. It would seem that this particular star, sometimes referred to as the Methuselah star is older than the universe. There are times when such an unusual finding forces us to rethink what we know about the universe, and generally leads to a revolution in our cosmological theories. This is not one of those times. To understand why, we need to look at just how we determine the age of such a star.The progression of most stars follows a particular pattern. A protostar gravitationally collapses, which causes hydrogen to start fusing in its core, making it a proper star. The star enters what is known as the main sequence, where it spends billions of years (depending on its size) as a stable star. As it exhausts its hydrogen it enters its final stage as red giant or similar before ending as a supernova/white dwarf/etc., again depending on its size.Determining the age of a main sequence star is difficult because they ...

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