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Possibly of interest: Very old star discovered

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  • Mark Andrew Holmes
    Saw this on BBC News. Mark A. Holmes http://news.bbc.co.uk/1/hi/sci/tech/4442503.stm Article begins.-- Relic star poses cosmic puzzles Astronomers have
    Message 1 of 1 , Apr 14, 2005
      Saw this on BBC News.

      Mark A. Holmes


      Article begins.--

      Relic star poses cosmic puzzles

      Astronomers have identified what could be one of the
      earliest stars formed in the Universe, Nature magazine

      Scientists think the cosmic relic may consist largely
      of elements created in the hot gas that existed just
      15 minutes after the Big Bang.

      The star has a very low iron content - an elemental
      signature that suggests it is made of fresh material
      that was never processed by an earlier star.

      But other such signatures are unusual for a very
      primitive stellar object.

      The new star HE0107-5240 and another star called
      HE1327-2326 have the lowest abundances of heavy
      elements known.

      About 13.7 billion years ago, the Universe consisted
      of a hot gas with a temperature high enough to produce
      the lightest chemical elements.

      The rapid expansion after the first 15 minutes of the
      Universe put an end to the synthesis of new elements
      by the process of nucleosynthesis.

      However, after about 200 million years, the Universe
      grew large enough for haloes of dark matter to form
      and this triggered the formation of the first stars.

      Unexpected elements

      These first stars synthesised all the heavier
      elements, from carbon to uranium, that form the basis
      of solid planets and organic life.

      Over the past 25 years, astronomers have been scouring
      the skies for stars with a composition that reflects
      these first stellar objects.

      The new star HE1327-2326 has an unexpectedly low
      abundance of the metal lithium and an unexpectedly
      high amount of the metal strontium for such a
      primitive star.

      "The lithium problem is immediately more troublesome.
      Many of the primitive stars studied in the past have
      lithium abundances that are very similar to one
      another," said co-author Timothy Beers, of Michigan
      State University in East Lansing, US.

      "It's remarkable but apparently what we see in these
      stars is the tiny amount of lithium produced in the
      Big Bang."

      "Yet in this star, it's not at that perfect value, so
      we're a bit confused as to why that might be."

      Further research on this star and others like it may
      help shed light on where the lithium in primitive
      stars came from.

      "When we get such extreme objects as this it really
      forces the people who model how these elemental
      abundances come about to take a close look at what
      they might be missing," Professor Beers told BBC News.

      One possibility is HE1327-2326 is a binary system. If
      the primitive star's binary companion had the
      opportunity to evolve, it might start to synthesise
      heavier metals including strontium.

      The evolving binary might then cast off its outer
      envelope, allowing some of the material to be accepted
      by its primitive companion, explaining the high
      strontium content.

      The research was an international collaboration
      involving researchers from Australia, Japan, Germany,
      Sweden and the US.

      --Article ends.

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