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Only a short answer please

  1. Oct 28, 2005 #1
    Can somebody answer my question in a unique word? Are stars considered black bodies?
  2. jcsd
  3. Oct 28, 2005 #2
    the spectrum of a star is approximately black body.
  4. Oct 28, 2005 #3
    What does 'aproximately' mean? does any 'competely' black body exist somewhere or all black bodies are aproximately black bodies?
  5. Oct 28, 2005 #4
    approximately means not exactly. the cosmic microwave background is better approximated by a black body than a star. Hawking radiation, although not yet observed, is also black body.

    I don't think there exists any "perfect" black body.
  6. Oct 28, 2005 #5


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    Staff Emeritus
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    Blackbodies are a limiting case of thermodynamics. In that equilibrium calculations only truly apply in the limit of an infinite number of particles settling for an infinite amount of time, no blackbody will be perfect. However, the primary "imperfections" in most blackbody spectra are of a larger magnitude than this. In the case of stars, the imperfections are mostly absorption lines from the gas sitting above the photosphere.
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