mass-luminosity relation

mass-luminosity relation in astronomy, law stating that the luminosity of a star is proportional to some power of the mass of the star. More massive stars are in general more luminous. For stars on the main sequence of the Hertzsprung-Russell diagram , it is found empirically that the luminosity varies as the 3.5 power of the mass. This means that if the mass is doubled, the luminosity increases more than tenfold. The law can be derived theoretically and was confirmed by independently measuring the masses of many visual binary stars, all at approximately the same distance. A more exact formulation of the law takes into account the chemical composition of the star. One important use of the mass-luminosity relation is in estimating the mass of a star of known luminosity that is not in a binary system.

mass–luminosity relation The relationship between the luminosity of a star on the main sequence and its mass. Factors involved include whether radiation or convection is the dominant energy transport process, and, if the former, the type of opacity involved. For stars of less than 0.4 solar masses, which are fully convective, the luminosity varies as the square of the mass. For stars of mass similar to or slightly less than the Sun, the luminosity is approximately proportional to the mass to the fifth power (e.g. a star with twice the mass will have 32 times the luminosity). For more massive stars, the luminosity varies approximately as the mass cubed (e.g. a star with twice the mass will have about 8 times the luminosity).