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: 285 Search : if
bifurcation
  دوگلش   
dogaleš

Fr.: bifurcation   

1) A branching or division into two parts; a splitting apart.
2) A sudden qualitative change in the behavior of a → dynamical system. The equation describing the evolution of the system finds several solutions for certain values of a parameter. Systems undergoing a bifurcation do not necessarily return to their original state, even if the parameter returns to its nominal value. See also → chaos.

Verbal noun of → bifurcate.

bifurcation point
  نقطه‌ی ِ دوگلش   
noqte-ye dogaleš

Fr.: point de bifurcation   

The point or moment in the evolution of a → dynamical system that occurs if a parameter passes through a critical point. At this point the system branches into any number of qualitatively new types of behavior.

bifurcation; → point.

bifurcation theory
  نگره‌ی ِ دوگلش   
negare-ye dogaleš

Fr.: théorie de bifurcation   

1) A theory which studies how, in certain nonlinear systems, there may be paths and shifts in behavior dependent on small changes in circumstances or the current position of the system.
2) Math.: The study of the behavior of a solution of a nonlinear problem in the neighborhood of a known solution, particularly as a parameter varies.

bifurcation; → theory.

binomial differential
  دگرسانه‌ی ِ دونامین   
degarsâne-ye donâmin

Fr.: binôme différentiel   

An expression of the form xm(a + bxn)pdx, where m, n, p, a, and b are constants.

binomial; → differential.

blueshift
  آبی-کیب   
âbikib

Fr.: décalage vers le bleu   

The apparent shift of the wavelength towards the shorter wavelength region of the radiation spectrum of an approaching object due to the Doppler effect.

blue; → shift.

blueshifted component
  همنه‌ی ِ آبی-کیب   
hamneye âbikib

Fr.: composante décalée vers le bleu   

A constituent of a composite astronomical object which has a motion directed towards the observer, as revealed by its spectrum.

blueshift; → component.

Boeshaar-Keenan classification
  رده‌بندی ِ بوسهار-کینان   
radebandi-ye Boeshaar-Keenan

Fr.: classification de Boeshaar-Keenan   

A system for the classification of → S-type stars. The system involves the designations of a C/O index and a temperature type. Moreover, when possible, it uses intensity estimates for → ZrO bands, the → TiO bands, the → Na I D-lines, the YO bands, and the Li I 6708 line.

Philip C. Keenan & Patricia C. Boeshaar, 1980, ApJS, 43, 379; → classification.

calculus of finite differences
  افماریک ِ دگرسانی‌ها‌ی ِ کرانمند   
afmârik-e degarsânihâ-ye karânmand

Fr.: calcul des différences finies   

A → claculus based on the properties of the successive values of → variable quantities and their → differences or → increments.

calculus, → finite, → difference.

Afmârik, → calculus, degarsânihâ, plural of degarsân, → difference, karânmand, → finite.

central uplift
  بالامد ِ مرکزی   
bâlâmad-e markazi

Fr.: pic central   

Same as → central peak.

central; → up; → lift.

central; → uplift.

centrifugal
  مرکزگریز   
markaz-goriz (#)

Fr.: centrifuge   

Acting or moving in a direction away from the axis of rotation or the center of a circle along which a body is moving.

From Mod.L., coined 1687 by Sir Isaac Newton from L. centri-, combining form of centrum, → center, + fugere "to run away, flee."

Markaz-goriz, from markaz, → center, + goriz "running away," from gorixtan, gorizidan "to run away," Mid.Pers. virextan, proto-Iranian *vi-raik, from vi- "apart, asunder" + *raik, Av. raek- "to leave, set free, let off," Mid./Mod.Pers. reg/rig (in mordé-rig "inheritance," Skt. ric- "to leave," rinakti "gives up, evacuates," Gk. leipein "to leave," L. linquere "to leave," from PIE *linkw-, from *leikw- "to leave behind" (cf. Goth. leihvan, O.E. lænan "to lend;" O.H.G. lihan "to borrow;" O.N. lan "loan").

centrifugal acceleration
  شتاب ِ مرکزگریز   
šetâb-e markaz-goriz (#)

Fr.: accélération centrifuge   

Of a point rotating in a circle round a central point, the outward acceleration away from the rotation axis. It corresponds to → centrifugal force. The centrifugal acceleration is given by ω x ω x r, or v2/r, where ω is → angular velocity, r the distance to the rotating axis, and v the → tangential velocity. The centrifugal and → centripetal accelerations are equal and opposite.

centrifugal; → acceleration.

centrifugal force
  نیروی ِ مرکزگریز   
niru-ye markaz-goriz (#)

Fr.: force centrifuge   

A force in a rotating reference frame directed outward from the axis of rotation.

centrifugal; → force.

clarification
  آرونش، رونه‌کرد   
âruneš, runekard

Fr.: clarification   

The action of making a statement or situation less confused and more comprehensible.

Verbal noun of → clarify.

clarify
  آرونیدن، رونه کردن   
ârunidan, runé kardan

Fr.: clarifier   

1) To make (an idea, statement, etc.) clear or intelligible; to free from ambiguity.
2) To remove solid matter from (a liquid); to make into a clear or pellucid liquid (Dictionary.com).

clear; → -fy.

classification
  رده بندی   
radebandi (#)

Fr.: classification   

The systematic grouping of astronomical objects into categories on the basis of physical, morphological, or evolutionary characteristics.

Classification, from O.Fr., from classifier, from → class + -fier, from L. -ficare, root of facere "to make, do;" PIE base *dhe- "to put, to do" (cf. Skt. dadhati "puts, places;" Av. dadaiti "he puts," O.Pers. ada "he made," Gk. tithenai "to put, set, place."

Radebandi, from radé, → class, + bandi, verbal noun of bastan "to bind, shut; to get, acquire, incur," from Mid.Pers. bastan/vastan "to bind, shut;" Av./O.Pers. band- "to bind, fetter," banda- "band, tie;" cf. Skt. bandh- "to bind, tie, fasten;" Ger. binden, E. bind, → band; PIE base *bhendh- "to bind."

cliff
  تندان   
tondân (#)

Fr.: falaise   

A very high steep rock or ice face, especially one that runs along a coastline. → scarp.

M.E., O.E. clif (cf. O.S. clif, O.N. klif, O.H.G. klep, M.Du. klippe, Ger. Klippe "cliff, steep rock").

Tondân, from tond "swift, rapid, brisk," → scarp + -ân a suffix of nuance/relation.

compactification
  همپکانش   
hampakâneš

Fr.: compactification   

1) Math.: A process applied to topological spaces having many dimensions to make them compact spaces.
2) Physics: In string theory, the process of "curling up" the extra dimensions (six in the superstring theory). According to these theories, the Universe actually has 10 spatial dimensions but that 7 of them have become "compactified" down to subatomic size and thus are unobservable.

Compactification, n. from → compactify.

compactify
  همپکانیدن   
hampakânidan

Fr.: compactifier   

Verbal form of → compactification.

Compactify, from → compact + -ify "cause to become," M.E. -fien, from O.Fr. -fier, from L. -ficare, root of facere "to make, do;" PIE base *dhe- "to put, to do" (cf. Skt. dadhati "puts, places;" Av. dadaiti "he puts," O.Pers. ada "he made," Gk. tithenai "to put, set, place."

Compton shift
  کیبِ کامپتون   
kib-e Compton

Fr.: décalage de Compton   

Of the → Compton effect, the amount of increase in the wavelength of an energetic photon upon its collision with an electron.

Compton; → shift.

conformal compactification
  همپکانش ِ همدیس   
hampakâneš-e hamdi

Fr.: compactification conforme   

A mapping of an infinite → space-time onto a finite one that may make the far away parts of the former accessible to study. The technique invented by Penrose defines an equivalence class of → metrics, gab being equivalent to ĝab = Ω2gab, where Ω is a positive scalar function of the space-time that modifies the distance scale making the asymptotics of the physical metric accessible to study.

conformal; → compactification.

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