radiative transfer equation
hamugeš-e tarâvaž-e tâbeš
Fr.: équation de transfer radiatif, ~ ~ de rayonnement
The equation that describes the → radiative transfer. It states that the → specific intensity of radiation Iσ during its propagation in a medium is subject to losses due to → extinction and to → gains due to → emission: dIσ/dx = - μσ . Iσ + ρ . jσ, where x is the coordinate along the → optical path, μσ is the → extinction coefficient, ρ is the mass → density, and jσ is the → emission coefficient per unit mass.
Fr.: transition radiative
A transition between two states of an atomic or molecular entity, the energy difference being emitted or absorbed as photons.
Fr.: zone radiative
The region of a star in which the energy generated by → nuclear fusion in the core is transferred outward by → electromagnetic radiation and not by → convection. Such zones occur in the interior of low-mass stars, like the Sun, and the envelopes of → massive star. The radiative zone of the Sun starts at the edge of the core of the Sun, about 0.2 solar radii, and extends up to about 0.7 radii, just below the → convective zone.
radiatively driven wind
Fr.: vent radiatif
Same as → radiation-driven wind