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    • Thread Starter

    Galaxy NGC2300 has an flat disk dominating the visible light image. Surface brightness is given by
    the exponential law
    I(R) = I0 exp(−R/Rd)
    where I0 is the central surface brightness, R distance from the center, and Rd = 4 kpc the exponential
    radial scale of the disk (e-folding distance). The total luminosity of the galaxy equals L = (2.5·10^10)L(sun).
    Considering that the total luminosity is surface brightness I(R) integrated over the area of the
    whole disk from R = 0 to R = ∞ (not over the radial distance, a mistake some people make!), compute
    I0 (in units of L(sun)/pc^2
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