Fr.: flot d'accrétion
1) Flow of matter during an accretion process.
1) A broad glowing arc of radiance, sometimes seen high in the
western sky at → twilight,
caused by the → scattering effect of
→ fine dust particles
suspended in the → upper atmosphere.
Fr.: luminescence nocturne
The faint ever-present glow in the → night time → sky caused by the → collision of → atoms and → molecules in Earth's → upper atmosphere with high energy → particles and → radiation, mainly from the → Sun. The airglow, also called nightglow, varies with time of night, → latitude, and → season.
Fr.: bande permise
In solid-state physics, the range of energies which electrons can attain in a material.
P.p. of v. allow, from O.Fr. alouer "approve," from L. allaudare , compound of → ad- "to" + laudare "to praise."
Bând, → band; parzâmidé, p.p. of parzâmidan "to send through, permit, allow," from parzâm "permission," from par- "through" + zâm stem of zâmidan, Mid.Pers. zâmenidan "to send, lead;" → permit
adasi-ye Barlow (#)
Fr.: lentille de Barlow
A → negative lens placed in a telescope between the → objective and the → ocular. Its diverging action reduces the convergence of the light cone, forming a larger image at a slightly greater distance.
Peter Barlow (1776-1862), English physicist; → lens.
Fr.: flot bipolaire
Same as → bipolar outflow.
Fr.: flot bipolaire
A flow of gaseous material in two opposite directions emanating from protostellar regions or from → evolved stars during the early post-→ AGB evolution. In protostellar regions → molecular outflows are pushed by → bipolar jets.
1) To move along, carried by or as by the wind.
M.E., from O.E. blawan "blow, breathe, make an air current; kindle; inflate; sound a wind instrument;" cf. O.H.G. blaen, Ger. blähen; from PIE *bhle- "to swell, blow up."
Damidan, from Mid.Pers. damidan "to blow, breathe;" dam "breath, breath of an owen; bellows; smoke; air," also "moment, time;" Av. dāδmainya- "blowing up;" cf. Skt. dahm- "to blow," dhámati "blows;" Gk. themeros "austere, dark-looking;" Lith. dumti "to blow;" PIE dhem-/dhemə- "to smoke, to blow."
Fr.: flot champagne
The flow of → ionized gas escaping from a → molecular cloud due to the → champagne effect.
Fr.: flot circumstellaire
A stream of matter into the interstellar medium from a central star.
→ circumstellar; → outflow.
cold accretion flow
tacân-e farbâl-e sard
Fr.: écoulement d'accrétion froid
1) A type of → accretion flow by a
→ compact object
such as a → black hole
that consists of cool → optically thick
gas and has a relatively high mass → accretion rate,
in contrast to → hot accretion flows.
tacân-e tanjidani, ~ tanješpazir
Fr.: flot compressible
A flow in which changes of the density, induced by velocities and their fluctuations, are not negligible.
→ compressible; → flow.
Fr.: flot de refroidissement
A phenomenon observed in a → cluster of galaxies, whereby the cluster core loses energy via X-ray radiation because of the collisions between the gas particles. The radiation rate is proportional to the square of the density, and the → cooling time, which remains in the outer parts too large, becomes smaller than the → Hubble time in the core. As a result, the central regions of clusters of galaxies cool down; and since in the center of a cluster gas pressure and gravitational attraction are in equilibrium, the gas density has to rise to maintain the pressure necessary for supporting the outer layers of gas. To cause its density to rise, the cooled gas has to flow inward. As the densest gas, which cools quickest, is already concentrated in the center of the cluster, the inward flow will start at the center, soon followed by the outer layers. This flow of gas is called the cooling flow. Cooling flows are moderated through feedback due to the → supermassive black hole in the nucleus of the central galaxy. The gas inflow to the center fuels the → active galactic nucleus (AGN). The latter then heats again the gas through its → radio jets.
Fr.: écoulement de Couette
In fluid dynamics, the motion of an → incompressible → laminar flow passing between two parallel plates, when the upper plate is moving with some velocity while the lower one is stationary. The flow is driven owing to the fluid → viscosity and the applied pressure gradient parallel to the plates. See also → Taylor-Couette flow.
Named after Maurice Marie Alfred Couette (1858-1943), a French physicist who dealt mainly with fluid mechanics; → flow
Fr.: écoulement de Couette-Taylor
In fluid mechanics, the motion of a fluid between two concentric cylinders when one or both of the cylinders rotate.
→ Couette flow; Geoffrey Ingram Taylor (1886-1975), British physicist; → flow.
The movement of a fluid in the opposite direction to a fluid flowing in the same cross section of a turbulent medium.
Same as → gegenschein.
1) tacân; 2) tacidan
Fr.: 1) flot, écoulement; 2) couler, s'écouler
1a) Moving along in a → stream;
going as in a stream.
O.E. flowan, from P.Gmc. *flo- (cf. Du. vloeien "to flow," O.H.G. flouwen "to rinse, wash"), probably from PIE *pleu- "to flow, float" (cf. Skt. plavate "navigates, swims," plavayati "overflows;" Gk. plyno "I wash," pleo "swim, go by sea;" L. pluere "to rain;" Arm. helum "I pour;" Lith. pilu "to pour out").
1) Tacân, from tac- variant tâz- present stem of
tacidan, tâxtan, tâzidan "to run; to hasten; to assault,"
+ noun and adj. suffix -ân. Related to the first component are
Mod.Pers. tajan name of a river (initially "flowing, streaming, stream"),
tâzi "swift (greyhound)," tak "running, rush," from
Mid.Pers. tâz-, tâxtan "to flow, to cause to walk," tc- "to flow, to walk,"
tag "running, attack," tâzig "swift, fast;"
Khotanese ttajs- "to flow, to walk;" Av. tac- "to run, to flow,"
taciāp- "flowing water," tacinti (3pl.pers.act.) "to flow,"
tacar- "course," tacan "current, streaming;" cf.
Skt. tak- "to rush, to hurry," takti "runs;"
O.Ir. tech- "to flow;" Lith. teketi
"to walk, to flow;" O.C.S. tešti "to walk, to hurry;" Tokharian B cake
"river;" PIE base *tekw- "to run; to flow."
Fr.: ligne d'écoulement
Same as → streamline.
The amount of a substance, specifically a → fluid, moving across a specified unit → area in a given amount of → time.