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Luminosity of M type/Otpe

  1. Jul 17, 2006 #1
    Hello. what equation do i use to figure out how many .75*Msolar main sequence stars would it take to equal the luminosity of one 3*Msolar O tpe star?
    I know O type are much brighter but how many times brighter?

    thank you
  2. jcsd
  3. Jul 17, 2006 #2


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    You ought to be able to get most of this info from links starting on http://www.astronomynotes.com/starprop/chindex.htm" [Broken].

    or http://www.astro.caltech.edu/~kbundy/ay1page/lectures/class7.pdf".
    Last edited by a moderator: May 2, 2017
  4. Jul 17, 2006 #3


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    I would use a table, but if you can't find one, the mass-luminosity relation should be fine:

    [tex]\frac{L}{L_{sun}} \propto (\frac{M}{M_{sun}})^{3.5}[/tex]
  5. Jul 17, 2006 #4

    As a side note this requires that composition (hydrogen, helium, metal mass fractions) be the same. Higher helium content will mean higher luminosity as will lower metal content.
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