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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

<< < abs act att clu com dif ext Fre gal Ima int nul pro rea sol ult > >>

Number of Results: 309 Search : act
proton-proton reaction
  واژیرش ِ پروتون-پروتون   
vâžireš-e-e proton-proton

Fr.: réaction proton-proton   

A → thermonuclear reaction in which two protons collide at very high velocities and combine to form a → deuterium. See also → proton-proton chain.

proton; → reaction.

pycnonuclear reaction
  واژیرش ِ چگال‌هسته‌ای   
vâžireš-e cagâl-hasteyi

Fr.: réaction pycnonucléaire   

A nuclear reaction that takes place at high densities and relatively low temperatures. Pycnonuclear reactions are almost temperature independent and occur even at zero temperature. These reactions are extremely slow at densities typical for normal stars but intensify with increasing density. For example, carbon burns into heavier elements at densities over 1010 g cm-3.

Pycnonuclear, from pycno- a combining form meaning "dense, thick," from Gk. pyknos "dense, solid" + → nuclear; → reaction.

Vâžireš, → reaction; cagâl-hasteyi, from cagâl, → dense, + hasteyi, → nuclear.

quantum of action
  کو‌آنتوم ِ ژیرش   
kuântom-e žireš

Fr.: quantum d'action   

Since → Planck's constant has the dimension of → energy × → time, its sometimes called the quantum of → action.

quantum; → action.

radioactive
  پرتو-ژیرا   
partow-žirâ

Fr.: radioactive   

Possessing, or pertaining to, → radioactivity.

radio + → active.

radioactive dating
  سن‌یابی ِ پرتو-ژیرا   
sen yâbi-ye partow-žirâ

Fr.: datation radioactive   

Determining the age of an object from the → radioactive decay of its constituting material. The technique consists of comparing the → abundance ratio of a → radioactive isotope to its → decay product. This will yield the number of half-lives that have occurred since the sample was formed. More specifically, if an object is made up of 50 % decay product then it has gone through 1 → half-life. 75% decay product equals 2 half-lives, 87.5% decay product equals 3 half-lives, 93.76% decay product equals 4 half-lives, and so on. For example, the decay product of → uranium-238 (238U) is → lead-206 (206Pb). The half-life of 238U is 4.5 billion years. Hence, if the sample has gone through two half-lives, it is 9 billion years old. See also: → radiocarbon dating.

radioactive; → dating.

radioactive decay
  تباهی ِ پرتو-ژیرا   
tabâhi-ye partow-žirâ

Fr.: désintégration radioactive   

Spontaneous emission by a nucleus of photons or particles.

radioactive; → decay.

radioactive isotope
  ایزوتوپ ِ پرتو-ژیرا   
izotop-e partow-žirâ

Fr.: isotope radioactif   

A → nuclide that is radioactive.

radioactive; → isotope.

radioactive nuclide
  هسته‌وار ِ پرتو-ژیرا   
hastevâr-e partowžirâ

Fr.: nucléide radioactif   

A → nuclide that disintegrates by emitting radiation and transforms into another nuclide. Same as → radionuclide.

radioactive; → nuclide.

radioactive waste
  آخال ِ پرتو-ژیرا   
âxâl-e partow-žirâ

Fr.: déchets radioactifs   

The radioactive by-products from the operation of a nuclear reactor or from the reprocessing of depleted nuclear fuel. Also known as nuclear waste.

radioactive; → waste.

radioactivity
  پرتو-ژیرایی، پرتو-ژیرندگی   
partow-žirâyi, partow-žirandegi

Fr.: radioactivité   

The spontaneous disintegration of certain atomic nuclei, which is accompanied by the emission of either α- or β- particles and/or a γ rays.

radio; → activity.

rarefaction
  آلرش   
âlareš

Fr.: raréfaction   

The state of being rarefied, less dense.
An instantaneous reduction in density of a gas resulting from passage a sound wave; opposite of → compression.

M.E. rarefien, from M.Fr. rarefier, from L. rarefacere "make rare," from rarus "loose, wide apart, thin, infrequent."

Verbal noun from âlar present stem of âlaridanrarefy + , a suffix.

rarefaction wave
  موج ِ آلرش   
mowj-e âlareš

Fr.: onde de raréfaction   

A pressure wave in a fluid generated by rarefaction. It travels in the opposite direction to that of a shock wave in the medium.

rarefaction; → wave.

react
  واژیریدن   
vâžiridan

Fr.: réagir   

1) To act in response to an agent, influence, or stimulus.
2) To act in a reverse direction or manner; to act in opposition, as against some force.
3) Chem.: To undergo a → chemical reaction.

re-; → act.

reactance
  واژیرایی   
vâžirâyi

Fr.: réactance   

The opposition to the flow of alternating current caused by the inductance and capacitance in a circuit rather than by resistance.

From → react + -ance a suffix of nouns.

Vâžirâyi state noun of vâžirâ agent noun of vâžiridanreact.

reactant
  واژیرا   
vâžirâ

Fr.:   

1) General: A person or thing that reacts.
2) A substance on the left side of a → chemical equation.

From → react + -ant.

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.

reactive
  واژیرنده؛ واژیرشی   
vâžirandé; vâžireši

Fr.: réactif   

Tending to react. Pertaining to or characterized by reaction.

From → react + -ive a suffix of adjectives expressing tendency, disposition, function, connection, etc.

Vâžirandé verbal adj. of vâžiridanreact; vâžireši, adj. of vâžirešreaction.

reactivity
  واژیرندگی   
vâžirandegi

Fr.: réactivité   

1) General: The quality or condition of being reactive.
2) Physics: A measure of the deviation from the condition at which a → nuclear reactor is critical.
3) Chem.: The relative → capacity of an → atom, → molecule, or → redical to undergo a → chemical reaction with another atom, molecule, or → compound.

From → reactive + → -ity.

reactor
  واژیرگر   
vâžirgar

Fr.: réacteur   

1) A device for introducing reactance into an electrical circuit (e.g. a capacitor).
2) Same as → nuclear reactor.

From → react + → -or.

<< < abs act att clu com dif ext Fre gal Ima int nul pro rea sol ult > >>