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First, since I'm just a physics teacher, and not an astrophysicist, my questions may sound "obscure" or badly formulated. Especially since I'm not an English native speaker. Sorry about that :shy:

I need a mathematical relation which could give the mass of a "theoretical" star as a function of its Luminosity, surface Temparature and possibly its Radius. I already know the standard Main Sequence Luminosity-Mass relation :

[tex]\frac{L}{L_{Sol}} = (\frac{M}{M_{Sol}})^a[/tex]

where typically [tex]3 < a < 4[/tex], and [tex]a \simeq 3.4[/tex]. This could be inverted to give the Mass as a function of the Luminosity. However, I would like something "stronger", if such a relation exists. So suppose I have access to the star's Luminosity, surface Temperature and Radius, what would be its theoretical Mass ?

M(L, T, R) = ???

I'm not taking any metallicity into account here.

Also, I would like to know a precise formulation of "Main Sequence stars" on a Hertzsprung-Russell diagram : what is the mathematical curve which could define the Main Sequence part of the H-R diagram ? In this case, I would like to know the Luminosity-Temperature function L(T) which could draw the "S" shaped curve on the H-R diagram :

L(T) = ???

and not just the Stefan-Boltzman law given by [tex]L(T) = 4 \pi \sigma R^2 T^4[/tex], since I don't know R as a function of T.

Any suggestion ?

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# Mass of star as function of Luminosity, Temperature and size

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