An Etymological Dictionary of Astronomy and Astrophysics

The ratio of the mass of a system, expressed in solar masses, to its visual luminosity, expressed in solar luminosities.

The Milky Way Galaxy has a mass-luminosity ratio in its inner regions of about 10, whereas a rich cluster of galaxies such as the Coma Cluster has a mass-luminosity ratio of about 200, indicating the presence of a considerable amount of dark matter.

See also: → mass; → luminosity; → ratio.