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The mass/luminosity relationship can also be used to determine the lifetime of stars by noting that lifetime is approximately proportional to M/L although one finds that more massive stars have shorter lifetimes than that which the M/L relationship predicts. A more sophisticated calculation factors in a star's loss of mass over time.
The luminosity thus obtained is known as the bolometric luminosity. Masses are often calculated from the dynamics of the virialized system or from gravitational lensing . Typical mass-to-light ratios for galaxies range from 2 to 10 ϒ ☉ while on the largest scales, the mass to light ratio of the observable universe is approximately 100 ϒ ...
The mass, radius, and luminosity of a star are closely interlinked, and their respective values can be approximated by three relations. First is the Stefan–Boltzmann law, which relates the luminosity L, the radius R and the surface temperature T eff. Second is the mass–luminosity relation, which relates the luminosity L and the mass M.
Asymptotic giant branch – Stars powered by fusion of hydrogen and helium in shell with an inactive core of carbon and oxygen; Galaxy color–magnitude diagram – Chart depicting the relationship between brightness and mass of large star systems; Hayashi track – Luminosity–temperature relationship in stars
A mock-up of the galaxy color–magnitude diagram with three populations: the red sequence, the blue cloud, and the green valley. The galaxy color–magnitude diagram shows the relationship between absolute magnitude (a measure of luminosity) and mass of galaxies.
L ★ is the star's luminosity (bolometric luminosity) in watts L 0 is the zero point luminosity 3.0128 × 10 28 W M bol is the bolometric magnitude of the star
Since the magnitude of a star varies with its age, the determination of mass-luminosity relation should also take into account its age. For stars with masses above 0.7 M ☉, it takes more than 10 billion years for their magnitude to increase substantially. For low-mass stars with below 0.13 M ☉, it takes 5 × 10 8 years to reach main ...
If the luminosity exceeds the Eddington limit, then the radiation pressure drives an outflow. The mass of the proton appears because, in the typical environment for the outer layers of a star, the radiation pressure acts on electrons, which are driven away from the center.