Luminosity of a Star

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Luminosity of a Star

 

the intensity of light from a star, that is, the magnitude of the luminous flux radiated by a star in a unit solid angle. The expression “luminosity of a star” does not correspond to the term “luminosity” in general photometry. The luminosity of a star may be referred to some region of the stellar spectrum, such as the visual or photographic stellar luminosity, or to the total radiation from the star—the bolometric luminosity of the star. The stellar luminosity is usually expressed in units equal to the luminosity of the sun, or 3 × 1027 international candles (3.8 × 1033 ergs/sec). The luminosities of individual stars differ greatly. Some stars—supergiants of spectral class O—have bolometric luminosities up to one-half million times greater than the sun luminosity. Others have a bolometric luminosity smaller than that of the sun by a factor of hundreds of thousands. It is believed there are stars with still lower luminosity. Along with the mass, radius, and surface temperature of a star, luminosity is an important stellar characteristic. The relations between these stellar characteristics are studied in theoretical astrophysics. The luminosity L of a star is related to the absolute stellar magnitude M by the equation M = – 2.5 log L + 4.77.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
and hence, because the luminosity of a star is [bar.L] = [??][[bar.R].sup.2], we obtain the mass-luminosity relation [bar.L] = [[bar.M].sup.3].
Thus, knowing that the luminosity of a star declines in proportion to the square of its distance from Earth, astronomers can use type 1A supernovas as yardsticks to measure several key parameters of the age and expansion of the universe.
Because [gamma.sub.c] determines the mass of a star (2.34) and ac determines the luminosity of a star, the "mass-luminosity" correlation should be contained in formula (2.36).