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: 18 Search : absorption
absorption
  درشم   
daršam

Fr.: absorption   

1) General: The process or fact of absorbing.
2) Physics: The action of energy or matter penetrating or being assimilated into a body of matter with no reflection or emission. → adsorption, → desorption, → sorption.
See also: → absorption band, → absorption coefficient, → absorption curve, → absorption feature, → absorption line, → absorption nebula, → absorption spectrum, → atmospheric absorption, → discrete absorption component, → foreground absorption, → intergalactic absorption, → internal absorption, → interstellar absorption, → mass absorption coefficient, → photoabsorption, → selective absorption, → self-absorption.

Verbal noun of → absorb; → -tion, from L. absorptionem.

absorption band
  باند ِ درشمی   
bând-e daršami

Fr.: bande d'absorption   

1) A series of very closely spaced absorption lines in stellar spectra resulting from the absorption of light by molecules. Bands caused by titanium oxide (→ TiO bands) and carbon compounds occur in the spectra of low temperature M and C stars.
2) A range of wavelengths, usually in electromagnetic radiation, that are absorbed by a given substance. Absorption bands are characteristic of molecules and correspond to changes of electron orbits in the molecules. See also → anomalous dispersion.

absorption; → band.

absorption coefficient
  همگر ِ درشم   
hamgar-e daršam

Fr.: coefficient d'absorption   

The fraction of normally incident light that is absorbed per unit path length or by a unit mass of absorbing medium.

absorption; → coefficient.

absorption curve
  خم ِ درشم   
xam-e daršam

Fr.: courbe d'absorption   

A graphic representation of the amount of radiant energy absorbed by a material as a function of the wavelength.

absorption; → curve.

absorption feature
  آرنگ ِ درشم   
ârang-e daršam

Fr.: motif d'absorption   

A dip in a spectrum indicating that light has been absorbed on the path from the emitting source to the observer. It may be a line, corresponding to a well-defined atomic or molecular transition, or a more complex feature whose physical origin is not necessarily understood.

absorption; → feature.

absorption line
  خط ِ درشمی   
xatt-e daršami

Fr.: raie d'absorption   

A dark line in the spectrum of a source produced by a lower temperature gas cloud lying between the source and the observer.

absorption; → line.

absorption nebula
  میغ ِ درشمی   
miq-e daršami

Fr.: nébuleuse par absorption, nébuleuse obscure   

A dark cloud of dust and gas that absorbs light from and impedes the view of background stars; dark nebula.

absorption; → nebula.

absorption spectrum
  بیناب ِ درشمی   
binâb-e daršami

Fr.: spectre d'absorption   

A spectrum of absorption lines or bands, produced when light from a hot source, itself producing a continuous spectrum, passes through a cooler gas.

absorption; → spectrum.

atmospheric absorption
  درشم ِ جوی   
daršam-e javvi

Fr.: absorption atmosphérique   

The absorption of → electromagnetic radiation in the → atmosphere mainly by → water vapor, → carbon dioxide, and oxygen. The atmosphere introduces two more limiting factors in → remote sensing: → atmospheric scattering and → atmospheric turbulence.

atmospheric; → absorption.

discrete absorption component (DAC)
  همنه‌ی ِ درشمی ِ گسسته   
hamne-ye daršami-ye gosasté

Fr.: composante d'absorption discrète   

The rapid, systematic changes in the absorption parts of the → P Cygni profiles of the ultraviolet → resonance lines (Si IV, C IV, and N V) observed in a majority of massive → hot stars. DACs are typically seen to accelerate to the → blue wing of the profile over a few days, becoming narrower as they approach the → terminal velocity.

discrete; → absorption; → component.

foreground absorption
  درشم ِ پیش-زمینه   
daršam-e pišzaminé

Fr.: absorption d'avant-plan   

Loss of radiant energy received from an astronomical object due to the presence of absorbing matter situated between the object and observer.

foreground; → absorption.

intergalactic absorption
  درشم ِ اندرکهکشانی   
daršam-e andarkahkešâni

Fr.: absorption intergalactique   

Absorption features in the spectra of bright sources like → quasars attributed to a tenuous matter filling the medium between galaxies.

intergalactic; → absorption.

internal absorption
  درشم ِ درونی   
daršam-e daruni

Fr.: absorption interne   

Of an → H II region, the absorption of photons by the dust which is mixed with ionized gas, in contrast to the absorption by the → interstellar dust on the line of sight.

internal; → absorption.

interstellar absorption
  درشم ِ اندر-اختری   
daršam-e andaraxtari

Fr.: absorption interstellaire   

The absorption of light from stars and other objects by intervening gas and dust in interstellar space.

interstellar; → absorption.

mass absorption coefficient
  همگر ِ درشم ِ جرمی   
hamgar-e daršm-e jermi

Fr.: coefficient d'absorption de masse   

A measure of the rate of absorption of radiation, expressed as the linear absorption coefficient divided by the density of the medium through which radiation is passing.

mass; → absorption; → coefficient.

photoabsorption
  شید-درشم   
šid-daršam

Fr.: photoabsorption   

A situation in which all of the energy of a photon is transferred to an atom, molecule, or nucleus.

photo- + → absorption.

selective absorption
  درشم ِ گزینشی   
daršam-e gozineši

Fr.: absorption sélective   

Absorption which varies with the wavelength of radiation incident upon an absorbing substance.

Selective, verbal noun of → select; → absorption.

self-absorption
  خود-درشم   
xod-daršam

Fr.: auto-absorption   

The decrease in the radiation from a material caused by the absorption of a part of the radiation by the material itself.

self-; → absorption.