[nbos] Mass Luminosity Relationship
"Justin Akkerman"
Thu Feb 21st, 2008
G'Day, I go this from a text called "Introductory to Astronomy and
Astrophysics" 2nd Ed by Zelik and Smith. Page 216 has the following
Luminosity/Luminosity(sol)=(Mass/Mass(sol)) raised to Alpha.
Alpha is not a universal constant. It is about 2 for dim red stars of low
mass. It is about 3 for high mass luminous stars. It is equal to about 4 for
solar type stars.
Assuming you know the Luminosity, the star type and want to know the the
mass you would write the equation in excel as follows:
MassStar=MassSun(LuminosityStar/LuminositySun)^(1/Alpha)

The M-L Law does not apply to Red Giants - they have large extended
atmosphere which add considerably to their radius nor does it apply to White
Dwarfs - they contain degenerate matter rather than normal plasmas.

There is a relationship called the Russel-Vogt Theorem which has only one
solution for the parameters Mass, Radius and Luminosity is one of them and
the chemical compositions of the star are known. This was only described in
words, not spelled out in equations. Maybe this theorem is beyond and
introductory text.

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