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Fine Tuning Problem

  1. Sep 12, 2014 #1
    Hi Guys,

    I have just started Modern Cosmology and please don't mind if the question is too naive.

    I wanted to know why does the amount of dust in the Inter-Stellar Medium scale roughly nearly with its metallicity? Please advise.

    Sorry about the incorrect heading. I cant seem to find where to edit that.

    Last edited: Sep 12, 2014
  2. jcsd
  3. Sep 14, 2014 #2
    Larger stars create more interstellar dust and are required to fuse the heavier elements.
  4. Sep 15, 2014 #3
    Wait i am confused. I am talking about ISM dust-metallicity relation. Kindly explain the given answer.
  5. Sep 15, 2014 #4


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    Most of that dust probably came from primordial supernova in the very early universe. Ginormous, short lived stars are believed to have been common back in the low metallicity days of the universe, and are blamed for polluting the infant cosmos.
  6. Sep 15, 2014 #5
    So let me see if i understand this correctly. Sorry if you find this a bit naive.
    The early ISM dust was with low metallicity but then the early stars burst rapidly into supernovas and filled the dust with metals which scales nearly similar to the current ISM metallicity.
    But here's my question - Is this a general phenomenon? I mean if you have Primordial Dust with lesser metals, do they result in more Massive stars and Further supernova, but if the metal content is less, the Stars are created normally hence the balance is maintained anyhow.
    Let me know if i am right? And if yes, what is the underlying principle dealing with the metallicity of dust and eventual star formation?
    Once again sorry for the trouble. :)
  7. Sep 15, 2014 #6


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    Supernova, in general, disperse large quantities of metals into the ISM. There are scattered knots of low metallicity gas clouds throughout the universe, but, most are heavily polluted. Low metallicity gas clouds disperse heat more efficiently than 'polluted' gas clouds when they collapse. This permits more massive stars to form before the gas cloud fragments. Once the temperature reaches the critical fusion ignition temperature, a newly formed star blows off much of the remaining mass of its 'mother' gas cloud. Low metallicity allows the protostar to gravitationally bind more of the gas cloud before reaching ignition temperature. The primordial ISM was comprised of virgin hydrogen and helium. The dust you are speaking of is principally the ashes of ancient pop III stars. See http://arxiv.org/abs/1404.5391, Dust Production Factories in the Early Universe: Formation of Carbon Grains in Red-supergiant Winds of Very Massive Population III Stars, for further discussion.
  8. Sep 15, 2014 #7


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    There is no hydrogen/helium dust, they just do not form solid clumps. Dust needs metals to form. I guess we can neglect primordial lithium, so all dust needs metals from stars.
  9. Sep 15, 2014 #8
    That solves my query. Thanks to all the experts and sincere apologies for asking such a naive question.
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