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Name: Matt L Rasmussen
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Question:
What is the formula for mass-luminosity relation?



Replies:
The various sources I have looked at do not give an equation as such; they merely state that if you graph Log(L) versus Log(M) for a number of stars on the main sequence, they tend to lie in a fairly thin band. But as the Encyclopedia of Physical Science and Technology points out, during the course of a star's lifetime its luminosity varies considerably, whereas its mass remains nearly constant; so it is clear that no single equation will work for all stars at all stages of stellar evolution. The above-mentioned source says that L increases approximately as M^3 for stars on the order of 10 solar masses, as M^4.5 for stars of around 1 solar mass, and as M^2 for low-mass stars. Further, this is only good for stars that have "just" entered the main sequence.

RC Winther


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