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Homework Help: Stellar lifetime methods

  1. May 24, 2012 #1
    1. The problem statement, all variables and given/known data

    I have to calculate the lifetime of a star that is 300,000 times as luminous as the sun and 24 solar masses.

    2. Relevant equations

    lifetime = k * m/l

    3. The attempt at a solution

    lifetime = 10^10 * (24/300000)
    lifetime = 800000 years

    I feel as if this is almost too easy and am wondering if I have made an error along the way. In addition, I found this equation on the internet and don't really understand how it works despite knowing (or thinking I know) how to use it. I was hoping someone could explain it to me and if I am wrong, someone could point me in the right direction.

    Many Thanks

  2. jcsd
  3. May 24, 2012 #2


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    Science Advisor

    1)The lifetime of the sun is about 10 billion years - this is the 10^10 in your equation.
    2) A star with 24 solar masses has 24 times as much fuel as the sun.
    3) A star 300,000 times as luminous as the sun is burning its fuel 300,000 times faster than the sun.

    This gives the equation in your post. Does this answer it?
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