The luminosity indicates the characteristic of what emits or reflects the Lumière.

In Astronomy, it represents the total quantity of energy radiated per unit of time by a Astre; it thus has dimensions of a power.

In the field S radio and X-ray, the luminosity is sometimes given in Watt but it is more generally given in terms of Magnitude connect and absolute Magnitude.

The stellar luminosities are generally given in solar Luminosité L_O which are the report/ratio of the luminosity of the object and that of the Sun. To a absolute bolometric Magnitude M_bol = 0 corresponds a luminosity of 3×10²⁸ Watt. the stars having an absolute bolometric magnitude M_bol of -10 have a luminosity of 10⁶L (very luminous) and those having an absolute bolometric magnitude of +17 have a luminosity of 10^-5L (far from luminous).

The Diagramme of Hertzsprung-Russell connects the luminosity, the spectral Type and the temperature of surface of stars but also the nature of its composition (Gaz, Roche…).

Calculation

$\backslash \; frac\; \{L\}\; \{L\_\; \{sun\}\}\; =\; \backslash \; left\; (\backslash \; frac\; \{R\}\; \{R\_\; \{sun\}\}\; \backslash \; right)\; ^2\; \backslash \; left\; (\backslash \; frac\; \{T\_\; \{EFF\}\}\; \{T\_\; \{sun\}\}\; \backslash \; right)\; ^4$

Anecdote

The quantitative measurement of the luminosities brought to this against-intuitive observation that a piece of black velvet lit by the sun with the zenith emits more reflected light than a sheet of paper white lit by a moonlight . The adaptation of our pupil to the conditions of ambient luminosity prevents us in the everyday life from perceiving this fact.

See too

• Albedo

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