An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 11 Search : excitation
collisional excitation
  بر‌انگیزش ِ همکوبشی   
barangizeš-e hamkubeši

Fr.: excitation collisionnelle   

A physical process which is caused by the free electrons that are energized either by → photoionization or → collisional ionization. Collisional excitation puts ions, atoms, and molecules into excited states from which they may decay radiatively. Collisional excitation is important in the → interstellar medium.

collisional; → excitation.

Coulomb excitation
  بر‌انگیزش ِ کولن   
barangizeš-e Coulomb

Fr.: excitation coulombienne   

The transition to a higher → energy level than → ground state undergone by an atomic nucleus when a → charged particle of appropriate energy moves past it.

coulomb; → excitation.

de-excitation
  فرو انگیزش   
foru-angizeš

Fr.: désexcitation   

Transition from an excited energy state to a lower energy level, as in spectral line formation or particle emission from an atomic nucleus.

From → de- + → excitation.

excitation
  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.

high-excitation blob (HEB)
  ژیگ ِ پر-بر‌انگیزش   
žig-e por-barangizeš

Fr.:   

A rare class of → H II regions in the → Magellanic Clouds. In contrast to the typical H II regions of the Magellanic Clouds, which are extended structures (sizes of several arc minutes corresponding to more than 50 pc, powered by a large number of exciting stars), HEBs are very dense and small regions (~ 4" to 10" in diameter corresponding to ~ 1-3 pc). They have a higher degree of → excitation ([O III] 5007Å /Hβ) with respect to the typical H II regions, and are, in general, heavily affected by local → dust. They are powered by a relatively smaller number of → massive stars.

high; → excitation; → blob.

photoexcitation
  شید-بر‌انگیزش   
šid-barangizeš

Fr.: photoexcitation   

The mechanism of raising an electron to higher energies by photon absorption, when the energy of the photon is too low to cause photoionization.

photo- + → excitation.

stochastic excitation
  بر‌انگیزش ِ کاتورگین   
barangizeš-e kâturgin

Fr.: excitation stochastique   

The mechanism arising from turbulent convection in the → convective zone of stars, which is responsible for the driving of stellar → pulsation modes. In stars cooler than typically ~ 7 500 K (→ F-type stars and cooler), the stochastic excitation occurs in the convection envelope. In massive stars, it may develop either in the → convective core or in the convective layer beneath the → photosphere. Recent studies suggest that in → Be stars stochastic excitation takes place in the convective core. The stochastic waves can transport → angular momentum from the core to the surface. Fast rotation, as in Be stars, amplifies the stochastic excitation.

stochastic; → mode.

thermal excitation
  بر‌انگیزش ِ گرمایی   
barangizeš-e garmâyi

Fr.: excitation thermique   

A process in which collisions that occur between particles cause atoms or molecules to obtain additional kinetic energy.

thermal; → excitation.