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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<< < alp mas > >>

Number of Results: 33 Search : emission
maser emission
  گسیل ِ میزری   
gosil-e meyzeri (#)

Fr.: émission maser   

An emission arising from the → maser process.

maser; → emission.

molecular emission
  گسیل ِ مولکولی   
gosil-e molekuli

Fr.: émission moléculaire   

An → electromagnetic radiation emitted by → interstellar molecules through → transitions between → energy states of → molecules.

molecular; → emission.

neutron emission
  گسیل ِ نوترون   
gosil-e notron (#)

Fr.: émission de neutrons   

A type of radioactive decay of atoms containing excess neutrons, in which a neutron is ejected from the nucleus.

neutron; → emission.

non-thermal emission
  گسیل ِ ناگرمایی   
gosil- nâgarmâyi (#)

Fr.: émission non thermique   

non-thermal radiation.

non-thermal; → emission.

radio continuum emission
  گسیل ِ پیوستار ِ رادیویی   
gosil-e peyvastâr-e râdio-yi

Fr.: émission de continuum radio   

A → continuum emission with frequencies in the radio range of the electromagnetic spectrum.

radio; → continuum; → emission.

radio emission
  گسیل ِ رادیویی   
gosil-e râdio-yi

Fr.: émission radio   

Electromagnetic radiation carried by → radio waves.

radio; → emission.

secondary emission
  گسیل ِ دومان   
gosil-e dovomân

Fr.: émission secondaire   

The emission of → secondary electrons from the surface of a material when an incident particle (often, charged particle such as electron or ion) impacts the material with sufficient energy.

secondary; → emission.

spontaneous emission
  گسیل ِ سرخود   
gosil-e sarxod

Fr.: émission spontanée   

The emission of electromagnetic radiation from an atom or molecule that does not depend on the presence of external fields.

spontaneous; → emission.

stimulated emission
  گسیل ِ گوازیده   
gosil-e gavâzidé

Fr.: émission stimulée   

The process by which an electron, which is already in an excited state (an upper energy level, in contrast to its lowest possible level or "ground state"), can "stimulate" a transition to a lower level, producing a second photon of the same energy. The quantum energy of the incoming photon should be equal to the energy difference between its present level and the lower level. This process forms the basis of both the → laser and → maser. Same as → induced emission.

Stimulated, p.p. of → stimulate; → emission.

thermal emission
  گسیل ِ گرمایی   
gosil-e garmâyi (#)

Fr.: émission thermique   

thermal radiation.

thermal; → emission.

thermionic emission
  گسیل ِ گرمایونی   
gosil-e garmâyoni

Fr.: émission thermionique   

Electrons gaining enough thermal energy to escape spontaneously from the cathode or dynodes and mimic photoelectrons.

thermion; → emission.

two-photon emission
  گسیل ِ دو-فوتونی   
gosil-e do-fotoni

Fr.: émission à deux photons   

The simultaneous emission of two photons whose sum of energies is equal to that of a single electron transition. The energy of each individual photon of the pair is not fixed, so that the spectrum of two-photon emission is continuous from the wavelength of that transition to infinity. In practice, there is a peak in wavelength distribution of the emitted photons. Two-photon emission is studied atomic physics with application in astrophysics, as it contributes to the continuum radiation from → planetary nebulae. It was recently observed in condensed matter and specifically in → semiconductors.

two; → photon; → emission.

weak emission-line central star (wel)
  ستاره‌ی ِ مرکزی با خط ِ گسیلی ِ نزار   
setâre-ye markazi bâ xatt-e gosili-ye nezâr

Fr.: étoile centrale à faibles raies d'émission   

A member of a class of cntral stars of planetary nebula, → CSPN, which have weaker and narrower emission lines than → Wolf-Rayet-like CSPNe (Tylenda et al. 1993, A&AS 102, 595).

weak; → emission; → line.

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