1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Luminosity integral help

  1. Feb 8, 2007 #1
    If the total luminosity is given by

    [tex]L_T = \int_0^{\infty} e^{-(r/a)^{1/4}} r^2 dr[/tex]

    estimate the radius [tex]r(a)[/itex] corresponding to half of the total luminosity.

    This would be to integrate from zero to r and get a function [itex]r(a,L)[/itex] but this is impossible so anyone got an idea on how to estimate this?
     
  2. jcsd
  3. Feb 8, 2007 #2

    quasar987

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Well the primitive of the integrand exists, you knew that right?

    The difficult part is solving for [itex]r_{1/2}[/itex] in [tex]\int_0^{r_{1/2}} e^{-(r/a)^{1/4}} r^2 dr=L_T/2[/tex]. But computers are good with this.
     
    Last edited: Feb 8, 2007
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Luminosity integral help
  1. Integration help (Replies: 10)

  2. Help with integral (Replies: 26)

  3. Luminosity distance (Replies: 1)

  4. Collider luminosity (Replies: 9)

Loading...