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First stars now thought to be 400 MLY after BB?

  1. Mar 19, 2006 #1
    excellent websitehttp://www.solstation.com/x-objects/first.htm

    According to the site, WMAP's results show that the first stars (Population III) appeared about 400 million LightYears after the BB, instead of the 200 million LightYears previously thought.

    I have a question about this...

    Was the first star purely Hyrdrogen based? What is known about the composition of the first star(s)?
     
  2. jcsd
  3. Mar 19, 2006 #2

    SpaceTiger

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    The first stars were composed of the elements generated in primordial nucleosynthesis -- that is, almost entirely hydrogen and helium. There were tiny abundances of lithium and beryllium as well. By mass, the ratio of hydrogen to helium was about 3:1.
     
  4. Mar 19, 2006 #3
    Roger that ST, ty.

    Do cosmologists think the first stars were born 200-400 million LYs post BB? Is that the currently accepted view?
     
  5. Mar 20, 2006 #4

    SpaceTiger

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    That's right, somewhere in that ballpark. Current estimates favor the high end of that range, ~400 million years. Note that light years is a measure of distance, not time.
     
  6. Mar 21, 2006 #5

    Can't LY be a measurement of both, or does this lose meaning during Inflation when space (may?) have expanded superluminally?
     
  7. Mar 21, 2006 #6

    Chronos

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    Correct. The universe was much larger [think VERY much larger] than 380,000 light years when it was 380,000 years old due to inflation and expansion. But the redshift does not lie. It still reflects the relative age of the universe at the time the photons we now observe were liberated.
     
  8. Mar 21, 2006 #7

    SpaceTiger

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    A light year is the distance that light travels in a year. The analogous unit of time is just a "year".
     
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