mass-luminosity relation

The simple relation between the mass (M) and luminosity (L) of a star on the main sequence that takes the form L ~ Mn where the index n has the value 3.5 for stars of 7 solar masses or less. For stars with masses in the range 7 to 25 solar masses, n falls to 3.0 and is nearer 2.7 for masses in excess of 25 times the Sun's.