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Surface brightness to luminosity

  1. Dec 8, 2012 #1
    Can anyone offer insight into the derivation of the surface brightness to solar luminosity conversion

    S(mag/arcsec^2) = Mabs + 21.572 - 2.5log S (Solar luminosities/pc^2)

    More or less my concern is the constant term, is it empirically observed value or is there a derivation for it?

    thanks
     
  2. jcsd
  3. Dec 9, 2012 #2

    mfb

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    2015 Award

    Staff: Mentor

    The definition of magnitude and parsec are arbitrary, and if you take the log of those (multiplicative) constants and add everything you should get 21.572 in some way.
     
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