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Homework Help: Star time on main sequence

  1. Feb 4, 2007 #1
    1. The problem statement, all variables and given/known data

    A B0 star has a luminosity of ~ 16000 L(solar) and a mass of ~ 16 M(solar). Can you estimate the time on the main sequence for this star simply from considering the rest mass energy of the core of the star (~10% of the total, and fusion burns with an efficiency of about 0.7%) and its luminosity?

    2. Relevant equations

    I know that for main sequence stars, L is proportional to M^3

    3. The attempt at a solution

    I have no idea where to go with this question, i've trawled through so many webpages and textbooks without success. Any ideas?
  2. jcsd
  3. Feb 4, 2007 #2


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    Science Advisor
    Homework Helper

    You will need to figure out what fraction of the available fuel the star would need to burn every year to maintain its luminosity. This will let you project when it will run out. You shouldn't need to know much more than E=m*c^2 and the luminosity of the sun.
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