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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 3106 Search : on
forbidden emission line
  خط ِ گسیلی ِ بژکم   
xat-e gosili-ye bažkam

Fr.: raie d'émission interdite   

A → forbidden line in → emission.

forbidden; → emission; → line.

forbidden transition
  گذرش ِ بژکم   
gozareš-e bažkam

Fr.: transition interdite   

A transition between two quantum mechanical → states that → violates the quantum mechanical → selection rules.

forbidden; → transition.

forced oscillation
  نوش ِ زوری   
naveš-e zuri

Fr.: oscillation forcée   

The oscillation of a system or object induced by an external periodic force. See also → free oscillation.

forced; → oscillation.

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.

formalization
  دیسه‌ورش   
disevareš

Fr.: formalisation   

1) The act of giving something a form or structure by introducing rules and procedures.
2) The act of formalizing.

formalize; → -tion.

formation
  دیسش   
diseš

Fr.: formation   

1) The act or process of forming or the state of being formed, such as → star formation.
2) Geology: A laterally continuous rock unit with a distinctive set of characteristics that make it possible to recognize and map from one → outcrop or well to another. The basic rock unit of stratigraphy.

Verbal noun of → form, + -ate + -ion.

Diseš, verbal noun of disidan, → from dis-, → form, + -eš.

formulation
  دیسولش   
disuleš

Fr.: formulation   

1) The act or process of formulating.
2) A particular expression of an idea, thought, or theory.
3) Something prepared according to a → formula.

formulate; → -tion.

four-dimensional operator
  آپارگر ِ چهار-وامونی   
âpârgar-e cahâr-vâmuni

Fr.: opérateur à quatre dimensions   

An operator defined as: ▫ = (∂/∂x, ∂/∂y, ∂/∂z, 1/(jc∂/∂t).

four; → dimensional; → operator.

fourth contact
  پرماس ِ چهارم   
parmâs-e cahârom

Fr.: quatrième contact   

The end of a solar eclipse marked by the disk of the Moon completely passing away from the disk of the Sun.

From M.E. fourthe, O.E. féowertha, from four, from O.E. feower, from P.Gmc. *petwor- (cf. Du. and Ger. vier, O.N. fjorir, Dan. fire, Sw. fyra), from PIE *qwetwor (cf. Mod.Pers. cahâr, Av. caθwar-, catur-, Skt. catvarah, Gk. tessares, L. quattuor) + -th a suffix used in the formation of ordinal numbers, from M.E. -the, -te, O.E. -tha, -the; cf. O.N. -thi, -di; L. -tus; Gk -tos; → contact.

Parmâs, → contact; cahârom cardinal form from cahâr "four," cognate with E. four, as above.

fraction
  برخه   
barxé (#)

Fr.: fraction   

A rational number of the form a/b where a is called the numerator and b is called the denominator.

From L.L. fractionem (nom. fractio) "a breaking in pieces," from frangere "to break," from PIE base *bhreg- "to break" (cf. Goth. brikan, O.E. brecan "to break;" Lith. brasketi "crash, crack").

Barxé, from barx "lot, portion," variant bahr, from Mid.Pers. bahr "lot, share, portion," Av. baxəδra- "portion."

fractional
  برخه‌ای   
barxe-yi

Fr.: fractionnaire, fractionné, partiel   

1) Math.: Pertaining to fractions; constituting a fraction.
2) Chemistry: Of or relating to any process by which parts of a mixture are separated by exploiting differences in their physical properties, such as their boiling points, solubility, or other characteristics.

fraction; → -al.

fractional sky coverage
  پوشش ِ برخه‌ای ِ آسمان   
pušeš-e barxe-yi-ye âsmân

Fr.: couverture partielle du ciel   

The portion of the 4π → steradians of the sky that a radiotelescope can observe from a given location on Earth over a 24-hour time interval.

fractional; → sky; → coverage.

fractionate
  برخاندن   
barxândan

Fr.: fractionner   

1) To break something up into smaller parts.
2) To separate a mixture into ingredients or portions having different properties, as by distillation or otherwise.

From → fraction + -ate a suffix forming verbs or nouns, from L. -atus, -ata, -atum.

Barxândan, from barx, barxé, → fraction, + -ândan suffix of transitive verbs.

fractionation
  برخانش   
barxâneš

Fr.: fractionnement   

1) Any of various methods of separating the components of a mixture into fractions of different properties.
2) → isotope fractionation

Verbal noun from → fractionate.

fragmentation
  لتپارش   
latpâreš

Fr.: fragmentation   

Generally, the process of breaking up into smaller parts. In particular, the splitting of a large molecular cloud into smaller, denser clumps. → cloud fragmentation.

From → fragmenta + -ation, a combination of -ate and -ion, used to form nouns from stems in -ate.

Latpâreš, verbal noun from latpâridan, → fragment.

fragmentation process
  فراروند ِ لتپارش   
farâravand-e latpâreš

Fr.: processus de fragmentation   

The succession of physical events that results in the breaking of a → molecular cloud into several → fragments.

fragmentation; → process.

free electron
  الکترون ِ آزاد   
elektron-e âzâd (#)

Fr.: électron libre   

An electron that is not attached to an → atom, → molecule, or → ion and is free to move under the influence of a present electric or magnetic field.

free; → electron.

free expansion phase
  فاز ِ سپانش ِ آزاد   
fâz-e sopâneš-e âzâd

Fr.: phase d'expansion libre   

The first phase of → supernova remnant (SNR) evolution in which the surrounding → interstellar medium (ISM) has no influence on the expansion of the → shock wave, and the pressure of the interstellar gas is negligible. The shock wave created by the → supernova explosion moves outward into the interstellar gas at highly → supersonic speed. Assuming that most of the → supernova energy  ESN is transformed into → kinetic energy of the ejected gas, the ejection velocity ve can be estimated from ESN by using ESN = (1/2) Meve2, which leads to ve = (2ESN / Me)(1/2), where Me is the ejected mass. The schematic structure of the SNR at this phase can be described as follows: behind the strong → shock front which moves outward into the ISM, compressed interstellar gas accumulates forming a → shell of interstellar gas. This shell of swept-up material in front of shock does not represent a significant increase in the mass of the system. After some time the accumulated mass equals the ejected mass of stellar material, and it will start to affect the expansion of the SNR. By definition, this is the end of the free expansion phase, and the corresponding radius of the SNR, called → sweep-up radius, RSW, is defined by Me = (4π/3) RSW3ρ0, that is RSW = (3Me / 4πρ0)(1/3), where ρ0 is the initial density of the ISM. This radius is reached at the sweep-up time tSW = RSW/ve. The free expansion phase lasts some 100-200 years until the mass of the material swept up by the shock wave exceeds the mass of the ejected material. Then the following → snowplow phase starts.

free; → expansion; → phase.

free oscillation
  نَوِش ِ آزاد   
naveš-e âzâd

Fr.: oscillation libre   

Oscillation of any system in stable equilibrium under the influence of internal forces only, or of a constant force originating outside the system, or of both.

free; → oscillation.

free-bound emission
  گسیل ِ آزاد-بندیده   
gosil-e âzâd-bandidé

Fr.: émission libre-liée   

The radiation emitted when a → free electron is captured by an → ion. See also: → free-free emission; → bound-free transition.

free; → bound; → emission.

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