Fr.: processus non radiatif
An process in which an excited state returns to the ground state without emitting radiation. → radiative process.
Of or pertaining to radiation.
Adjective of → radiation.
Fr.: accélération radiative
The acceleration imparted to matter by → radiation pressure.
Fr.: freinage radiatif
The slowing down of a star's rotation due to radiative momentum transfer caused by emission of electromagnetic radiation.
gir-oft-e tâbeši, gir-andâzi-ye ~
Fr.: capture radiative
Capture of a free electron by an ion with the subsequent emission of photons; also called → radiative recombination.
Fr.: collision radiative
A collision between charged particles in which part of the kinetic energy is converted into electromagnetic radiation.
Fr.: refroidissement radiatif
The process by which temperature decreases due to an excess of emitted radiation over absorbed radiation.
Fr.: diffusion radiative
A process of → radiative transfer in which photons are repeatedly absorbed and re-emitted by matter particles.
Fr.: envelope radiative
A → radiative zone occupying the outer parts of a star.
Fr.: équilibre radiatif
The balance between radiative emission and radiative absorption in a specified system.
Fr.: rétroaction radiative
The radiative energy put back to the environment through an astrophysical process. For example, in the process of → star formation → accretion disks form around → protostars. The material in the disk spirals inward and on to the protostar, provided that there is an efficient mechanism to redistribute → angular momentum outward in the disk. During this process → gravitational energy is transformed into radiation due to → viscous dissipation in the disk and at the → accretion shock around the protostar. This radiation heats the region around the protostar and may → suppress subsequent → fragmentation and further star formation. Thus, radiative feedback plays a critical role in regulating the stellar → initial mass function.
Fr.: flux radiatif
The radiative energy per unit time and unit area.
Fr.: chauffage radiatif
The process by which temperature increases due to an excess of absorbed radiation over emitted radiation.
Fr.: lévitation radiative
A physical process occurring in → stellar atmospheres whereby → radiation pressure selectively pushes certain → chemical elements outward, leading to an atmospheric overabundance of such elements. See also → gravitational settling.
Fr.: phase radiative
Fr.: processus radiatif
An process in which an excited state loses its absorbed energy by emission of radiation. → non-radiative process.
Fr.: recombinaison radiative
The process by which an ionized atom binds a free electron in a → plasma to produce a new atomic state with the subsequent radiation of photons.
toš-e tâbeši, šok-e ~
Fr.: choc radiatif
A → shock wave in which the → time-scale for → cooling is much shorter than the appropriate → dynamical or → evolutionary time-scale of the system that drives the shock. Radiative shock waves are believed to play a key role in a variety of different astrophysical environments, including → magnetic cataclysmic variables, → jets from → young stellar objects, → accretion in → T Tauri stars, → colliding stellar winds, and → supernova remnants.
tarâvâž-e tâbeš, ~ tâbeši
Fr.: transfer radiatif, ~ de rayonnement
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.