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: 1965 Search : ion
Rayleigh's criterion
  سنجیدار ِ ریلی   
sanjidâr-e Rayleigh

Fr.: critère de Rayleigh   

A criterion for the instability of a basic swirling flow with an arbitrary dependence of angular velocity Ω(r) on the distance r from the axis of rotation. This states that in → inviscid fluids: Ω(r) < 0 for instability, where Ω = (1/r3) (d/dr)(r4Ω4).

Rayleigh; → criterion.

reaction
  واژیرش، واکنش   
vâžireš, vâkoneš

Fr.: réaction   

1) General: Action in response to some influence, event, stimulus.
2) An equal and opposite force exerted by a body against a force acting upon it. → principle of action and reaction.
3) A → nuclear reaction; → chain reaction.
4) → chemical reaction.

Verbal noun of → react.

reaction rate
  نرخ ِ واژیرش   
nerx-e vâžireš

Fr.: taux de réaction   

The speed with which a → chemical reaction takes place. In other words, the change in → concentration of a → substance divided by the → time interval during which the change is observed.

reaction; → rate.

real-time operation
  آپارش در زمان ِ هسیا   
âpâreš dar zamân-e hasyâ

Fr.: opération en temps réel   

The operation of a computer during the actual time that the related physical processes take place so that the results can be used to guide the physical processes.

real; → time; → operation.

recession
  دورشد، واروش   
duršod, vâraveš

Fr.: éloignement, récession   

1) The act of receding, going back, or withdrawing.
2) Economics: A period of an economic contraction, sometimes limited in scope or duration (Dictionary.com).

From Fr. récession "a going backward, a withdrawing," from L. recessionem "a going back," noun of action from p.p. stem of recedere "to go back, fall back; withdraw, retire," from → re- "back" + cedere "to go," → process.

Duršod, from dur, → remote, + šod "going," past stem of šodan "to go, to become," → change. Vâraveš, from vâ-, → re-, + raveš verbal noun of raftan "to go," → method.

recession velocity
  تندای ِ دورشدن   
tondâ-ye dur šodan

Fr.: vitesse d'éloignement   

The velocity with which an object moves away from another object or a reference point.

recession; → velocity.

recognition
  بازشناخت   
bâzšenâxt (#)

Fr.: rconnaissance   

An act of recognizing or the state of being recognized.

Verbal noun of → recognize.

recombination
  بازمیازش   
bâzmiyâzeš

Fr.: recombinaison   

1) The process or result of combining again.
2) The capture of an electron by a positive ion. It is the inverse process to → ionization.

Verbal noun of → recombine.

recombination coefficient
  همگر ِ بازمیازش   
hamgar-e bâzmiyâzeš

Fr.: coefficient de recombinaison   

A measure of the specific rate at which oppositely charged ions join to form neutral particles. It is given by the rate at which those ions recombine, divided by the product of the densities of the two species involved.

recombination; → coefficient.

recombination continuum
  پیوستار ِ بازمیازش   
peyvastâr-e bâzmiyâzeš

Fr.: continuum de recombinaison   

A recombination radiation that is continuous over a range of frequencies. Same as → continuum emission.

recombination; → continuum.

recombination epoch
  زیمه‌ی ِ بازمیازش   
zime-ye bâzmiyâzeš

Fr.: époque de recombinaison   

Same as → recombination era.

recombination; → epoch.

recombination era
  دوران ِ بازمیازش   
dowrân-e bâzmiyâzeš

Fr.: ère de recombinaison   

The era some 380,000 years after the → Big Bang (at a → redshift of about 1,100), when the Universe had cooled sufficiently so that protons and electrons combined to form → neutral hydrogen in a process called → recombination. The temperature was about 3,000 K and the ionization fraction low enough for Universe to become transparent to light. Consequently matter and radiation decouple from one another because no further → scattering of the radiation occurs. The observation of the → cosmic microwave background radiation provides a means of studying the Universe at the recombination era. Also called recombination epoch and → decoupling era.

recombination; → era.

recombination line
  خط ِ بازمیازش   
xatt-e bâzmiyâzeš

Fr.: raie de recombinaison   

An → emission line in a spectrum produced in an → H II region when a free electron combines with an ionized atom to form a neutral atom or an ion of lower → ionization stage. Same as → free-bound emission.

recombination; → line.

recombination radiation
  تابش ِ بازمیازش   
tâbeš-e bâzmiyâzeš

Fr.: rayonnement de recombinaison   

Radiation produced when a free electron in a plasma is captured by an ionized atom.

recombination; → radiation.

recombination rate
  نرخ ِ بازمیازش   
nerx-e bâzmiyâzeš

Fr.: taux de recombinaison   

In → H II regions the rate at which free electrons recombine with → ionized hydrogen atoms (protons).

recombination; → rate.

recombination time
  زمان ِ بازمیازش   
zamân-e bâzmiyâzeš

Fr.: temps de recombinaison   

The time period necessary for a cloud of atomic hydrogen to be → ionized by the ultraviolet photons of a central → massive stars.

recombination; → time.

reconciliation
  آشتی   
âšti (#)

Fr.: réconciliation   

1) An act of reconciling, as when former enemies agree to an amicable truce.
2) The state of being reconciled, as when someone becomes resigned to something not desired.
3) The process of making consistent or compatible (Dictionary.com).

From O.Fr. reconciliacion and directly from L. reconciliationem noun of action from p.p. stem of reconciliare. "to bring together again; regain," from → re- "again" + concilare "make friendly"

šti, from Mid.Pers. âštêh "peace;" Av. āšti- "peace, treaty of peace; agreement," āxšta-- "pacified, appeased."

rectification
  راستش   
râsteš

Fr.: rectification   

1) Math.: The process of determining the length of a curve.
2) Physics: Conversion of an alternating into a direct current.
3) Astro.: The process of rectifying a spectrum.

Verbal noun of → rectify.

rectilinear propagation of light
  توچش ِ راست‌خط ِ نور   
tuceš-e râst-xatt-e nur

Fr.: propagation rectiligne de la lumière   

The motion of light in the first approximation, as evidenced from the formation of shadows and other every day experience. However, → diffraction

rectilinear; → propagation; → light.

recurrence relation
  باز‌آنش ِ باز‌آمد   
bâzâneš-e bâzâmad

Fr.: relation de recurrence   

A → sequence based on a → rule that gives the next → term as a → function of the previous term(s). For example, the sequence 3, 9, 21, 45,... can be represented by the recurrence relation un+1 = 2un + 3, where u1 = 3 and n ≥ 1.

recurrence; → relation.

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