An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 658
exchange particle
  ذره‌ی ِ گهولی   
zarre-ye gahuli

Fr.: particule d'échange   

In quantum field theory, a particle that transfers momentum and energy between interacting objects, and is said to mediate the interaction. All four of the fundamental forces involve the exchange of one or more particles. For example, photon is the exchange particle of the electromagnetic force.

exchange, → particle.


Fr.: excimère   

Chemistry: A complex formed from combination of a molecule with another molecule of the same type but in an → excited state. In other words, a → dimer in an electronically excited state. See also → exciplex.

From exci-, from → excited, + -mer, from → dimer.


Fr.: exciplexe   

Chemistry: A complex formed by association of a molecule in an → excited state and another molecule of a different type. See also → excimer.

From exci-, from → excited, + -plex, from → complex.


Fr.: excercle   

For a → triangle with two sides extended in the direction opposite their common → vertex, a circle that lies outside the triangle and is tangent to the three sides (two of them extended). The center of the excircle, called the → excenter, is the point of intersection of the bisector of the interior angle and the bisector of the exterior angles at the other two vertices.

ex-; → circle.


Fr.: exciser   

To cut out or off; to remove

M.E., from M.Fr. exciser, from L. excisus, p.p. of excidere "cut out, cut down, cut off," from → ex- + caedere "to cut," → precise.

Osunidan, from os-, → ex- + sun "cut," → precise.


Fr.: excision   

The act of removal; an excising. The surgical removal of a foreign body or of tissue.

Verbal noun of → excise.

  بر انگیزش   
barangizeš (#)

Fr.: excitation   

1) The addition of → energy to an → atomic or → molecular system, → transferring it from its → ground state to an → excited state.
2) A property of an → emission nebula usually expressed by the ratio [O III] 5007Å/Hβ.

Verbal noun of → excite; → -tion.

excitation energy
  کاروژ ِ بر انگیزش   
kâruž-e barangizeš

Fr.: énergie d'excitation   

Amount of energy (usually measured in → electron-volts) required to bring an electron from its → ground state to a given → excited state.

excitation; → energy.

excitation potential
  توند ِ بر‌انگیزش   
tavand-e barangizeš

Fr.: potentiel d'excitation   

In quantum mechanics, the energy that is necessary to change a system from a → ground state to a given → excited state; also called excitation energy.

excitation; → potential.

excitation temperature
  دمای ِ بر‌‌انگیزش   
damâ-ye barangizeš

Fr.: température d'excitation   

Of a gas or plasma, the temperature deduced from the → populations of atomic → excited states, as expressed by the Boltzmann formula: Nu/Nl = (gu/gl) exp (-ΔE/kTex), where Nu and Nl are the upper level and lower level populations respectively, gu and gl the statistical weights, ΔE = hν the energy difference between the states, k is → Boltzmann's constant, and hPlanck's constant. The higher the energy of the occupied states, the higher the excitation temperature.

excitation; → temperature.

barangixtan (#)

Fr.: exciter   

Verb of → excitation.

From L. excitare "to rouse, produce," freq. of exciere "to call forth, instigate," from → ex- "out" + ciere "to move, set in motion;" PIE base *kei- "to move to and fro" (cf. Av. šiyav-, š(ii)auu- "to move, go," šiyavati "goes," šyaoθna- "activity; action; doing, working;" O.Pers. šiyav- "to go forth, set," ašiyavam "I set forth;" Mod.Pers. šodan, šow- "to go; to become;" cf. Skt. cyu- "to move to and fro, shake about; to stir," cyávate "stirs himself, goes;" Gk. seuo "I start quickly after," kinein "to move;" Goth. haitan "call, be called;" O.E. hatan "command, call").

Barangixtan, from intensive prefix bar- "on, upon, up," → on-, + angixtan, angizidan "to excite, stimulate," from Mid.Pers. hangêxtan, hangêz- "to arouse, stimulate, stir up," from Proto-Iranian *hamgaiz-, from ham-, → com-, + *gaiz- "to disturb, stir, excite." The Mod.Pers. gij, giž "confused, astonished, dizzy" is from this stem (Cheung 2007).

excited atom
  اتم ِ بر‌انگیخته   
atom-e barangixté (#)

Fr.: atome excité   

An atom in which one or more of its bound electrons are at → energy levels higher than their normal level.

Excited p.p. of → excite; → atom.

excited state
  حالت ِ بر‌انگیخته   
hâlat-e barangixté (#)

Fr.: état excité   

The condition of a particle or system of particles (especially an atom, nucleus, molecule) after absorbing energy from outside and transiting to a higher → energy level than that of its → ground state. Excited states are transitory as they lose energy through emissions or collisions and return to ground state.

Excited, p.p. of → excite; → state.

exciting star
  ستاره‌ی ِ بر انگیزنده   
setâre-ye barangizandé

Fr.: étoile excitatrice   

A star associated with an interstellar ionized nebula (→ H II region or → planetary nebula) whose energetic → ultraviolet, → photons → ionize the nebula.

Exciting, verbal adj. of → excite; → star.


Fr.: exclure   

To shut or keep out; to hinder from being included, considered, or accepted. → exclusion.

From L. excludere "to keep out, shut out, hinder," from → ex- "out" + claudere "to close, shut," → include.

Sokolândan, from so-, variant os-, → ex-, + kolândan "to shut," → include.


Fr.: exclusion   

An act or instance of excluding; the state of being excluded.

Verbal noun of → exclude.

exclusion principle
  پروز ِ سکلان   
parvaz-e sokolân

Fr.: principe d'exclusion   

In → quantum mechanics, the principle according to which no → two → fermions of the same kind may simultaneously → occupy the same → quantum state. Also known as → Pauli exclusion principle.

exclusion; → principle.

  سکلاننده، سکلان‌مند   
sokolânandé, sokolânmand

Fr.: exclusif   

Excluding or having power to exclude; excluding all else; rejecting other considerations, possibilities, etc.

Adj. from → exclude.


Fr.: excrétion   

A process in which an astronomical body loses mass mainly in the direction of its → equatorial regions, as opposed to → accretion.

From L. → ex- + crescere "to grow," → accretion.

excretion disk
  گرده‌ی ِ اُسبال   
gerde-ye osbâl

Fr.: disque d'excrétion   

An expanding → equatorial → disk or → torus of material ejected by a star. The phenomenon may result from a stellar → merger or an increase in its rate of → rotation or → stellar winds. Contrasted with → accretion disk.

excretion; → disk.

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