Eddington-Sweet time scale
marpel-e zamâni-ye Eddington-Sweet
Fr.: échelle de temps d'Eddington-Sweet
The time required for the redistribution of → angular momentum due to → meridional circulation. The Eddington-Sweet time for a uniformly → rotating star is expressed as: τES = τKH . GM / (Ω2 R3), where τKH is the → Kelvin-Helmholtz time scale, R, M, and L designate the radius, mass, and luminosity respectively, Ω the → angular velocity, and G the → gravitational constant. The Eddington-Sweet time scale can be approximated by τES≅ τKH / χ, where χ is the ratio of the → centrifugal force to → gravity. For the Sun, χ ≅ 10-5 resulting in an Eddington-Sweet time scale which is too long (1012 years), i.e. unimportant. In contrast, for a rotating → massive star χ is not so much less than 1. Hence the Eddington-Sweet circulation is very important in massive stars.
Named after the prominent British astrophysicist Arthur S. Eddington (1882-1944), who was the first to suggest these currents (in The Internal Constitution of the Stars, Dover Pub. Inc., New York, 1926) and P. A. Sweet who later quantified them (1950, MNRAS 110, 548); → time scale.
A deviation in the steady flow of a fluid causing a vortex-like motion running
contrary to the general flow.
Late M.E., from O.E. ed- "turning" + ea "water;" akin to O.N. itha.
Gižâv, from dialectical Kurd. "whirlpool," from giž "turning," Pers. gij "giddy-headed, vertigio;" Laki géž "whirlpool," vagéža "whirlwind" + âv, variant âb "water" (Mid.Pers. âb "water;" O.Pers. ap- "water;" Av. ap- "water;" cf. Skt. áp- "water;" Hitt. happa- "water;" PIE āp-, ab- "water, river;" cf. Gk. Apidanos, proper noun, a river in Thessalia; L. amnis "stream, river" (from *abnis); O.Ir. ab "river," O.Prus. ape "stream," Lith. upé "stream;" Latv. upe "brook").
jarayân-e Foucault (#)
Fr.: courant de Foucault
An induced current circulating in masses of metal moving in a magnetic field or located in a changing magnetic field. Also known as → Foucault current.
1) labé (#); 2) tiqé (#)
Fr.: 1) bord; 2) tranchant, fil
1) A line or border at which a surface terminates.
M.E. egge; O.E. ecg "corner, edge;" cf. Ger. Eck "corner;" PIE base *ak- "sharp, pointed" (cf. L. acies; Gk. akis "point").
1) Labé "limb, edge," from lab "lip;" Mid.Pers. lap;
cognate with L. labium; E. lip; Ger. Lefze.
Fr.: galaxie vue par la tranche
Fr.: mettre au point, préparer, éditer
To modify or prepare for publication or public presentation by checking, improving, cutting, rearranging, etc.
Virâstan, from Mid.Pers. virâstan "to arrange, prepare, restore," from prefix vi- "apart, away from, out" (Av. vi-; O.Pers. viy- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + râstan "to arrange, to set in order," → coordinate.
1) virâyeš (#); 2) virâst (#)
1) The act or process of editing.
Verbal noun of → edit.
Fr.: rédacteur, éditeur
1) A person who edits material for publication or public presentation.
Agent noun of → edit.
Fr.: rédaction, éditorial
1) An article in a newspaper or other periodical or on a website presenting the opinion
of the publisher, writer, or editor.
To give knowledge or develop the faculties and powers of somebody by teaching. instruction.
From L. educatus, p.p. of educare "bring up, rear, educate," from → ex- "out" + ducere "to lead."
The act or process of educating.
Verbal noun of → educate.
1) Something brought about by a → cause or agent; a result.
From O.Fr. effect, from L. effectus "accomplishment, performance," from stem of efficere "to work out, accomplish," from → ex- "out" + facere "to do, to make," from PIE base *dhe- "to put, to do;" cf. Mod.Pers. dâdan "to give," Mid.Pers. dâdan "to give," O.Pers./Av. dā- "to give, grant, yield," dadāiti "he gives;" Skt. dadáti "he gives," Gk. didomi "I give," tithenai "to put, set, place;" L. dare "to give, offer;" Rus. delat "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do."
Oskar, from os-, → ex-, + kar-, kardan "to do, make;" Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build," Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base kwer- "to do, to make."
Actually in operation or in force; concrete; real.
M.E., from L. effectivus "practical," from effect(us), p.p. of efficere, → effect + -ivus "-ive."
Oskarmand, from oskar, → effect + -mand possession suffix.
Fr.: ouverture effective
Of an antenna, the ratio of the extracted power by the antenna to the power per unit area (power density) in the incident wave.
effective Eddington parameter
pârâmun-e Eddington-e oskarmand
Fr.: paramètre d'Eddington effectif
The effective value of the → Eddington parameter in a non-homogeneous system (porous opacity).
effective focal length
derâzâ-ye kânuni-ye oskarmand
Fr.: longueur focale effective
The focal length of an imaging system, which consists of several lenses or mirrors.
Fr.: gravité effective
In a → rotating star, the sum of the → gravity and the → centrifugal acceleration. The effective gravity is a function of the rotation velocity (Ω) and the → colatitude (θ). At the pole (θ = 0°) and the equator (θ = 90°) the effective gravity is radial. See also → total gravity.
Fr.: rayon effectif
Of a galaxy, the distance from its center within which half of the total luminosity is included.
Fr.: température effective
A measure of the surface temperature of a star derived from the total emitted energy, assuming that the star is a → blackbody emitter (→ Stefan-Boltzmann law, → Planck's radiation law). See also → brightness temperature; → color temperature.
The degree to which goals are achieved and the extent to which posed problems are solved. Compare → efficiency.