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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 ...
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.
The properties and evolution of a star are closely related to its mass, so the IMF is an important diagnostic tool for astronomers studying large quantities of stars. For example, the initial mass of a star is the primary factor of determining its colour, luminosity, radius, radiation spectrum, and quantity of materials and energy it emitted ...
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.
Given the mass of the star, one can use this rate of increase in luminosity in order to determine the age of the star. This method only works for calculating stellar age on the main sequence , because in advanced evolutionary stages of the star, such as the red giant stage, the standard relationship for the determination of age no longer holds.
In astronomy, a period-luminosity relation is a relationship linking the luminosity of pulsating variable stars with their pulsation period. The best-known relation is the direct proportionality law holding for Classical Cepheid variables , sometimes called the Leavitt Law .
The apparent magnitude of stars in the same cluster is equivalent to their absolute magnitude and so this early diagram was effectively a plot of luminosity against temperature. The same type of diagram is still used today as a means of showing the stars in clusters without having to initially know their distance and luminosity. [4]