|
|
Detailed observations, particularly in binary star systems where masses can be determined with some reliability, indicate that there is a correlation between the mass of a star and its luminosity. The adjacent image illustrates for main sequence stars by plotting the logarithm of the luminosity (in units of solar luminosity) against the logarithm of mass (in units of solar mass).
We see that on this plot most stars fall very near a straight line. This is called the mass-luminosity relation for main-sequence stars. This particular relation between mass and luminosity holds only for stars on the main sequence. It does not hold, for example, for white dwarfs or for giant stars. The observation of a correlation between mass and luminosity for particular classes of stars suggests important systematics relating the light output of stars to their intrinsic structure that will later be exploited in the Hertzsprung-Russell Diagram.