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Finding the magnitude difference between two star

  1. Oct 7, 2007 #1
    1. The problem statement, all variables and given/known data

    Determine the apparent magnitude difference between sirius and the sun,as seen from the Earth. How much more luminosity is sirius than the Sun ?

    2. Relevant equations

    f=sigma*T^4(eff)
    m-n=2.5*log(f(m)/f(n))
    3. The attempt at a solution

    the apparent magnitude difference is m-n, m and n being the apparent magnitudes being the sun and sirius. I probably need the find the flux of each star. the flux=5.67e-8 W/(m^2*K^4)*T^4(eff). 30000 K is the effective temperature of Sirius and T(eff)=5780 K for the sun. f(sirius)/f(sun)=(30000 K)^4/(5780)^4=726 . Therefore, m(sirius)-n(sun)=2.5*log(726)=7.152
     
  2. jcsd
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