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Emergence of much smaller stars in early Universe?

  1. May 31, 2015 #1
    Anyone have any insight concerning the latest research underway at Heidelberg University... concerning the "smaller than once thought" earliest stars? Any thoughts on why these 'smaller than once thought stars' also contain carbon, when at this early stage of star formation in a very young Universe, they shouldn't yet?

    http://www.uni-heidelberg.de/presse...g-message-about-the-end-of-the-dark-ages.html

    Dr. Paolo Molaro from the Trieste observatory suspects that they belong to a special – completely new – class of original stars. Any thoughts?
     
  2. jcsd
  3. May 31, 2015 #2
    The most likely explanation I can think of is that the carbon must have originated from previous much more massive stars that were short lived
     
  4. May 31, 2015 #3

    Chronos

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    High redshift quasar spectra suggest they produce surprisingly high amounts of carbon.
     
  5. May 31, 2015 #4
    Since quasars are probably the most energetic things in the universe other than the initial 'big bang', it does seem plausible that they could produce lighter elements such as carbon through fusion processes that are at present beyond our understanding.
    Well, we do understand in the case of regular stars how that happens, and it doesn't seem unreasonable to suggest that conditions similar to a star core might occur within a quasar, or nearby.
     
  6. May 31, 2015 #5

    marcus

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    That Uni Heidelberg press release is based on this article:
    http://arxiv.org/abs/1504.05963

    This article proposes a reasonable explanation for the earlier puzzle. The class of low-mass carbon rich stars were in a binary pair with a larger star which became what is called "AGB" (asymptotic giant branch).
    AGB stars are not so massive that they explode as supernovae. But they are massive enough to develop helium-burning and make carbon. They also expel large quantities of their fusion products including carbon.

    The Uni publicity department made the existence of these stars seem more mysterious than the actual professional journal article did. The journal article suggests an explanation and ties up the loose ends.
     
  7. May 31, 2015 #6

    marcus

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    Here is a google search for "AGB stars"
    https://www.google.com/?gws_rd=ssl#q=agb+star

    Here are some lecture notes, an example of what the google search turns up:
    http://www2.astro.psu.edu/users/rbc/a534/lec24.pdf

    It describes the mechanism by which AGB stars expel fusion products. The AGB companion could be dumping carbon on its dwarf companion. At least the authors of the paper referred to in the press release think that is likely the way this class of stars got their extra carbon.

    They were not formed with it, and they did not make it themselves. They got it during their life as member of a binary system.
     
  8. Jun 1, 2015 #7
    Concerning your third question, you might be interested in Rovelli's "Planck stars" paper (arXiv.org > gr-qc > arXiv:1401.6562), just in case you haven't seen it yet. (This forum has two long intertwined threads about it.) He hypothesizes stars that had collapsed into black holes re-emerging into view upon the evaporation of their event horizon, after an interval very long to those outside it but short to whatever observer could survive the collapse: In one of two black hole scenarios he describes, the collapsed stars would have sizes smaller than the atomic scale but much larger than Planck's, so they would qualify as very small (in volume, not in mass), but I can offer no idea of either the relation of their remaining material to carbon or the relation of their age to the age of whatever universe would surround them. (Rovelli mentions, in passing, a bouncing universe scenario that, like the black hole ones, would rely on quantum pressure.)
     
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