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Change in Triple-Alpha Process?

  1. Jan 15, 2005 #1

    Labguy

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    Just came across this, didn't see it posted elsewhere. Could be significant in our stellar evolution models. (?)

    http://physicsweb.org/articles/news/9/1/8
     
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  3. Jan 21, 2005 #2

    Nereid

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    AFAIK, the great sensitivity of this process to temperature has been known for a long time. I would guess (and it is just a guess) that solar (and stellar) models are built with the reaction cross-sections as inputs, and that the models are run with at least the full range of values as determined experimentally.

    Many PRs and popular press articles, IMHO, contain 'marketing fluff' (shall we say) - not enough to trigger a law suit under any 'truth in advertising' rule maybe, but ...
     
  4. Jan 21, 2005 #3

    Labguy

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    The sensitivity, yes. But, a change in reaction rate as described would and/or could still have a significant affect on supernova models / rates. It doesn't affect main sequence stars anyway, just cores over 100 million K; ie, red giants.
     
  5. Feb 18, 2005 #4

    In all the papers i've read on solar models (one of which i've worked with directly) I've never seen this to be the case.
     
  6. Feb 20, 2005 #5

    Nereid

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    Which?
    a) reaction cross-sections built in?
    b) run with at least the full range of values as determined experimentally?
    c) both the above?
    d) something else?

    IIRC, one strand of the work done during the decades' long investigation of the solar neutrino problem was to see how much variation in neutrino output (of the solar models) was possible, within the (extended) range of experimental cross sections.

    From another perspective, without tests using different inputs, how can the robustness (among other things) of stellar models be (confidently) determined?
     
  7. Feb 20, 2005 #6

    Labguy

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    I would say "b" above is used often except that the values are determined mathematically rather than experimentally. But, the original post (link) seems to indicate that the "full range" has to be re-defined, so models would change also.

    A change in the Triple-Alpha process would have nothing at all to do with the so-called solar neutrino problem. That "problem" (since solved) arose from calculations on the output of the Proton-Proton Chain process by which most H in our sun is converted into He. Triple-Alpha is not going on at all until He can fuse into C and O (mostly) above at least 100 million K and several billion years from now.
     
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