An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1251
Curie temperature
  دمای ِ کوری   
damâ-ye Curie (#)

Fr.: température de Curie   

The highest temperature for a given → ferromagnetic substance above which the → magnetization is lost and the substance becomes merely → paramagnetic. The Curie temperature of iron is about 1043 K and that of nickel 631 K.

Named after the French physicist Pierre Curie (1859-1906), a pioneer in magnetism, crystallography, and radioactivity. In 1903 he received the Nobel Prize in Physics with his wife Marie Curie (1867-1934, née Maria Skłodowska), and Henri Becquerel (1852-1908); → temperature.

curium
  کوریوم   
kuriom (#)

Fr.: curium   

A → radioactive element not found in nature but discovered in 1944 among the products of → plutonium-239 after bombardment by high-energy → alpha particles in a cyclotron at the University of California at Berkeley; symbol Cm. Atomic number 96; mass number of most stable isotope 247; melting point about 1,340°C; boiling point 3,110°C.

Named after French physicists Pierre Curie (1859-1906) and his wife Marie Curie (1867-1934, née Maria Skłodowska).

curl
  تاو   
tâv (#)

Fr.: rotationnel   

A vector → operator which is the vector product of the → del operator with a vector function. For a three-dimensional function, it is equal to the sum of the vector products of the unit vectors and → partial derivatives in each of the component directions: ∇ x F(x,y,z) = (∂Fz/∂y - ∂Fy/∂z)i + (∂Fx/∂z - ∂Fz/∂x)j + (∂Fy/∂x - ∂Fx/∂y)k. The curl of a vector field is a vector field. ∇ x F is sometimes called the rotation of F and written rot F.

Metathesis of crulle "curly," probably from an unrecorded O.E. word or from M.Du. krul "curly."

Tâv, variants tow, tâb "twist, swing," from tâbidan "to spin, to twist."

current
  جریان   
jarayân (#)

Fr.: courant   

Any steady movement of material in space. In particular, any movement of electric charge. → stream; → flow; → flux.

From O.Fr. corant "running," pr.p. of courre "to run," from L. currere "to run," from PIE *kers- "to run" (cf. Gk. -khouros "running," Lith. karsiu "go quickly," O.N. horskr "swift," Welsh carrog "torrent").

Jarayân from Ar.

current cosmological epoch
  زیمه‌ی ِ کیهانشناختی ِ کنونی   
zime-ye keyhânšenâxti-ye konuni

Fr.: époque cosmologique actuelle   

The Universe at the → redshift z = 0.

current; → present; → cosmological; → epoch.

current density
  چگالی ِ جریان   
cagâli-ye jarayân

Fr.: densité de courant   

The electric current per unit of cross-sectional area perpendicular to the direction of current flow. It is a vector quantity and represented by symbol J. Electric current density is usually expressed in amperes per square meter.

current; → density

cursor
  جابان   
jâbân

Fr.: curseur   

A movable, sometime blinking, indicator on a computer screen identifying the point that will be affected by input from the user (OxfordDictionaries.com).

From L. cursor "runner," also "errand-boy," from curs-, p.p. stem of currere "to run," → current.

Jâbân, literally "position/place keeper," or "position/place maker," from , → place, + -bân a suffix denoting "keeper, guard," sometimes forming agent nouns or indicating relation, → host.

curvaton
  کورواتون   
kurvaton

Fr.: curvaton   

A hypothetical → scalar field that is used to explain the → primordial curvature perturbation in the Universe. It is generally supposed that the primordial perturbation originates during → inflation, from the → quantum fluctuation of the inflation field. The curvaton model is an attempt to account for the primordial perturbation by a completely different origin, namely the quantum fluctuation during inflation of a light scalar field which is not the assumed slowly-rolling inflation. In this model, the curvaton field is an energetically sub-dominant component during inflation. As the energy density of the Universe drops after inflation, the fraction of this component becomes significant. At this time the curvaton perturbation is converted into an adiabatic curvature perturbation of the Universe. The amplitude of the final perturbation, which should match observations, depends on both how long the curvaton oscillates before it decays, and on the shape of the potential. The first curvaton model was proposed by D. H. Lyth & D.Wands and in 2002 (Physics Letters B524).

From curvat-, from → curvature, + → -on. Although not related, the term curvaton exists in Fr. meaning "small curve" with variants curvatone, courbaton, and corbatone (A. Jal, 1848, Glossaire nautique).

curvature
  خمیدگی   
xamidegi (#)

Fr.: courbure   

A measure of the amount by which a curve, a surface, or any other manifold deviates from a straight line, a plane, or a hyperplane. In particular, The reciprocal of the radius of the circle which most nearly approximates a curve at a given point.
See also:
curvature constant, → curvature of space-time, → field curvature, → primordial curvature perturbation.

From L. curvatura, from curvatus, p.p. of curvare "to bend," from curvus "curved," → curve.

Xamidegi, from xamidé "curved," from xamidag "curved" + noun suffix -i.

curvature constant
  پارامون ِ خمیدگی   
pârâmun-e xamidegi

Fr.: paramètre de courbure   

A parameter occurring in the → Friedmann equations of → general relativity describing the geometry of → space-time. A spatially → open Universe is defined by k = -1, a → closed Universe by k = + 1 and a → flat Universe by k = 0. See also the → Robertson-Walker metric. See also → curvature of space-time.

curvature; → parameter.

curvature of space-time
  خمیدگی ِ فضا-زمان   
xamidegi-ye fazâ-zamân (#)

Fr.: courbure de l'espace-temps   

According to → general relativity, → space-time is curved by the presence of → matter. The curvature is described in terms of → Riemann's geometry. In → cosmological models three types of curvature are considered: positive (spherical, → closed Universe), zero (Euclidean, → flat Universe), and negative (hyperbolic, → open Universe). See also → curvature constant.

curvature; → space-time.

curve
  خم   
xam (#)

Fr.: courbe   

A line that deviates from straightness in a smooth, continuous fashion. A line representing a variable on a graph.

From L. curvus "crooked, curved, bent;" cf. Av. skarəna- "round," Gk. kirkos, krikos "a ring;" PIE base *sker- "to turn, bend."

Xam, variant kamân "arc," Mid.Pers. kamân, probably from PIE *kamb- "to bend, crook," cf. Breton kamm "curved, bent."

curve fitting
  سز ِ خم، سزکرد ِ ~   
saz-e xam, sazkard-e ~

Fr.: ajustement de courbe   

Construction of mathematical functions whose graphs are curves that "best" approximate a given collection of data points.

curve; → fitting.

curve of growth
  خم ِ رویش   
xam-e ruyeš

Fr.: courbe de croissance   

A plot showing how the → equivalent width of an → absorption line, or the radiance of an → emission line, increases as a → function of the → number of → atoms that produce the line.

curve; → growth.

curved
  خمیده   
xamidé (#)

Fr.: courbé   

Not straight.

Adj. from → curve.

curvilinear
  خم‌خط   
xam-xatt

Fr.: curviligne   

Consisting of, represented by, or bound by curved lines. → rectilinear.

From → curve + → linear.

cusp
  تیزه   
tizé (#)

Fr.: cuspide   

1) General: Pointed end. A point of transition. → polar cusp.
2) Either point of a → crescent moon.
3) A steep power-law representing the number density of stars in the central region of a galaxy. Cusps are characteristic of low-mass ellipticals. They are thought to result from the gravitational attraction of a central → supermassive black hole.
4) A peaked concentration of dark matter in the center of galaxies, as predicted by the → cold dark matter (CDM) model of galaxy formation. See also → cusp problem.
5) Math: A tooth-like meeting of two branches of a curve, with sudden change of direction.

L. cuspis "point, spear, pointed end."

Tizé, noun from tiz "sharp, pointed," from Mid.Pers. tēz, tēž, tigr "sharp," O.Pers. tigra- "pointed," Av. taēža-, tighra- "pointed," Skt. taējas- "the sharp edge (of a knife), piercing (flame)", from tij- "to be sharp, to pierce," Gk. stizein "to prick, puncture," stigma "mark made by a pointed instrument," L. instigare "to goad," P.Gmc. *stik- "to pierce, prick, be sharp," O.H.G. stehhan, Ger. stechen "to prick," O.E. stician "to pierce, stab," E. stick "to pierce;" PIE *st(e)ig- "to stick; pointed".

cusp problem
  پراسه‌ی ِ تیزه   
parâse-ye tizé

Fr.: problème des cuspides   

A problem encountered by the → cold dark matter (CDM) model of galaxy formation. The numerical simulations with CDM predict a large concentration of dark matter in the center of galaxies, with a peaked density distribution, in contrast to the real, observed galaxies. See also: → angular momentum catastrophe; → missing dwarfs.

cusp; → problem.

cut
  بریدن   
boridan (#)

Fr.: couper   

To penetrate or divide something, as with a sharp-edged instrument.

M.E. cutten, kytten, kitten; O.E. *cyttan, cognate with O.Swed. kotta "to cut;" O.N. kuti "little knife," or from O.Fr. couteau "knife."

Boridan "to cut off;" Mid.Pers. brin-, britan, brinitan "to cut off," brin "cut, delimitation, determined;" Av. (pairi-) brī- "to shave, shear;" cf. Skt. bhrī- "to hurt, injure," bhrinanti "they hurt."

cutoff
  بره   
boré

Fr.: coupure   

1) A designated limit beyond which the passage of something must be stopped.
2) A device that cuts off a transmission of photons.

cut; → off.

Boré, from bor- present stem of boridan "to → cut" + noun suffix .

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