Astronomy, Luminosity of 100 solar mass stars

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This is just a small part of one of my problems. I need to find the luminosity of a stellar population containing 100 solar mass stars and one 20 solar mass star.

I think that the 20 solar mass star will dominate, but I am not sure. Here is the formula to use:

L/Lsun = (M/Msun)^3.5

I am going to have to find the luminosity of the 100 stars, and the 20 solar mass star seperately, and then add the luminosities together. But I am not sure if I can do this...

L/Lsun = (100 Msun/1Msun)^3.5

Or would it simply be 100 Lsun is the total luminosity?

Also, I was not really sure whether to put this question here, or in the other sciences section. I figured this was more related to physics than other sciences.
 

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cepheid
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I am going to have to find the luminosity of the 100 stars, and the 20 solar mass star seperately, and then add the luminosities together. But I am not sure if I can do this...

L/Lsun = (100 Msun/1Msun)^3.5

No. This would be the luminosity of a single 100 M[itex]_\odot[/itex] star.

Or would it simply be 100 Lsun is the total luminosity?

Yes. One hundred separate 1 M[itex]_\odot[/itex] stars would have a combined luminosity of 100 L[itex]_\odot[/itex]. That is because each of them would have an individual luminosity of 1 L[itex]_\odot[/itex]. Just plug 1 M[itex]_\odot[/itex] into your mass-luminosity relation in order to see that the sentence before this one is true.
 
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cepheid
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Also just a note on your terminology. Most astronomers would parse your phrase "100 solar mass stars" as being equivalent to the phrase, "stars having a mass of 100 M[itex]_\odot[/itex]." In order to say what you actually meant, you'd have to say:

One hundred 1 solar-mass stars

or something like that.
 
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Thank you!
 

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