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: 888
angular frequency
  بسامد ِ زاویه‌ای   
basâmad-e zaviye-yi (#)

Fr.: fréquence angulaire   

The number of complete rotations per unit time, expressed in radian per second: ω = 2πν, where ν is the frequency (cycles per second).

angular; → frequency.

angular kinetic energy
  کاروژ ِ جنبشی ِ زاویه‌ای   
kâruž-e jonbeši-ye zâviye-yi

Fr.: énergie cinétique angulaier   

Same as → rotational energy.

angular; → kinetic; → energy.

angular momentum
  جنباک ِ زاویه‌ای   
jonbâk-e zâviye-yi

Fr.: moment angulaire, moment cinétique   

The product of → moment of inertia and → angular velocity; synonymous with moment of momentum about an axis. Angular momentum is a vector quantity; it is conserved in an isolated system.

angular; → momentum.

angular momentum catastrophe
  نگونزار ِ جنباک ِ زاویه‌ای   
negunzâr-e jonbâk-e zâviye-yi

Fr.: catastrophe du moment angulaire   

A problem encountered by the → cold dark matter model of galaxy formation. The model predicts too small systems lacking → angular momentum, in contrast to real, observed galaxies. → cusp problem; → missing dwarfs.

angular; → momentum; → catastrophe

angular momentum parameter
  پارامون ِ جنباک ِ زاویه‌ای   
pârâmun-e jonbâk-e zâviye-yi

Fr.: paramètre de moment angulaire   

The ratio J/M, where J is the → angular momentum of a → rotating black hole and M the mass of the black hole.

angular; → momentum; → parameter.

angular momentum problem
  پراسه‌ی ِ جنباک ِ زاویه‌ای   
parâse-ye jonbâk-e zâviye-yi

Fr.: problème de moment angulaire   

1) The fact that the Sun, which contains 99.9% of the mass of the → solar system, accounts for about 2% of the total → angular momentum of the solar system. The problem of outward → angular momentum transfer has been a main topic of interest for models attempting to explain the origin of the solar system.
2) More generally, in star formation studies, the question of the origin of the angular momentum of a star and the evolution of its distribution during the early history of a star. Consider a filamentary molecular cloud with a length of 10 pc and a radius of 0.2 pc, rotating about its long axis with a typical → angular velocity of Ω = 10-15 s-1. At a matter density of 20 cm-3, the cloud is about 1 → solar mass. The cloud collapses to form a star with radius of 6 x 1010 cm. The conservation of angular momentum (∝ ΩR2) requires that as the radius decreases from 0.2 pc to the stellar value, a factor of 107, the value of Ω must increase by 14 orders of magnitude to 10-1 s-1. The star's rotational velocity will be 20% the speed of light and the ratio of → centrifugal force to gravity at the equator will be about 104. Observational data, however, indicate that the youngest stars are in fact rotating quite slowly, with rotational velocities of 10% of the → break-up velocity. The angular momentum problem was first studied in the context of single stars forming in isolation (L. Mestel, 1965, Quart. J. R. Astron. Soc. 6, 161). For more information see, e.g., P. Bodenheimer, 1995, ARAA 33, 199; H. Zinnecker, 2004, RevMexAA 22, 77; R. B. Larson, 2010, Rep. Prog. Phys. 73, 014901, and references therein.

angular; → momentum; → problem.

angular momentum transfer
  تراوژ ِ جنباک ِ زاویه‌ای   
tarâvaž-e jonbâk-e zâviye-yi

Fr.: transfert de moment angulaire   

A process whereby in a rotating, non-solid system matter is displaced toward (→ accretion) or away from (→ mass loss) the rotation center. See also → magnetorotational instability.

angular; → momentum; → transfer.

angular momentum transport
  ترابرد ِ جنباک ِ زاویه‌ای   
tarâbord-e jonbâk-e zâviye-yi

Fr.: transfert de moment angulaire   

Same as → angular momentum transfer.

angular; → momentum; → transport.

angular power spectrum
  بیناب ِ توانی ِ زاویه‌ای   
binâb-e tavâni-ye zâviye-yi

Fr.: spectre de puissance angulaire   

Of the → cosmic microwave background radiation, a plot of how much the temperature varies from point to point on the sky versus the angular frequency. This spectrum answers fundamental questions about the nature of the Universe. → cosmic microwave background anisotropy; → dipole anisotropy.

angular; → power; → spectrum.

angular resolution
  واگشود ِ زاویه‌ای   
vâgošud-e zâviye-yi

Fr.: résolution angulaire   

Of a telescope, the smallest angle betwwen two → point sources that produces distinct images. It depends on both the wavelength at which observations are made and on the diameter of the telescope. Same as → spatial resolution.

angular; → resolution.

angular size distance
  اپست ِ زاویه‌ای   
apest-e zâviye-yi

Fr.: distance angulaire   

Same as → angular diameter distance.

angular; → size; → distance.

angular velocity
  تندا‌ی ِ زاویه‌ای   
tondâ-ye zâviye-yi

Fr.: vitesse angulaire   

A measure of the angular displacement per unit time. Of a particle traveling on a circular path or a rotating body, the ratio of the angle traversed to the amount of time it takes to traverse that angle: ω = dθ/dt. For a rigid body, all lines in it rotate through the same angle in the same time, and the angular velocity is the characteristic of the body as a whole. The angular velocity is related to the linear velocity by the equation v = rω, where r is the distance of the point from the rotation axis. → vector angular velocity.

angular; → velocity.

animal
  جانور   
jânevar (#)

Fr.: animal   

Any living creature that is distinguished from plants by independent movement and responsive sense organs.

From L. animale "living being, being which breathes," neuter of animalis "animate, living; of the air," from anima "breath; soul; breeze," cognate with Pers. jân, as below.

Jânevar, jânvar, Mid.Pers. gyânwar "animal; animate," literally "living, alive; quick," from jân, Mid.Pers. (+ prefix *ui-) gyân "(breathing) soul," gyânig "spiritual, vital;" Av. viiānayā "spirit(ness)"; Proto-Iranian *HanH- "to breathe" cf. Skt. ani- "to breathe," aniti "breathes;" Gk. anemos "wind;" L. animus "soul, spirit," anima "breeze, breath, soul;" Goth. uz-anan "to exhale" (Cheung 2007) + -e epenthesis + -var possession suffix; also hen o hen "to pant;" dialects, e.g. Lori, Kurd., henâs, henâsa "breath," henowša "panting."

animate
  فرهنیدن   
farhanidan

Fr.: animer   

1) To give life to; make alive; make lively or vigorous; give motion to.
2) To give an image or cartoon character the appearance of movement using animation techniques.

From L. animatus p.p. of animare "give breath to," also "to endow with a particular spirit, to give courage to," from anima "life, breath"  L. animus "soul, spirit," anima "breeze, breath, soul;" Goth. uz-anan "to exhale;" Gk. anemos "wind;" PIE root *ane- "to blow, to breathe;" cognate with Pers. jân "vital spirit, soul, mind," as below.

Farhanidan, from far- perfection prefix + han variant of jân "vital spirit, soul;" hen o hen "to pant;" Lori, Kurd., henâs, henâsa "breath," henowša "panting;" Mid.Pers. (+ prefix *ui-) gyân "(breathing) soul," gyânig "spiritual, vital;" Av. viiānayā "spirit(ness);" Proto-Iranian *HanH- "to breathe" cf. Skt. ani- "to breathe," aniti "breathes;" Gk. and L., as above, + -idan infinitive suffix.

animation
  فرهنش   
farhaneš

Fr.: animation   

1) An act or instance of animating or enlivening; the state or condition of being animated.
2) The technique of imaging successive drawings or positions of cartoons to create an illusion of movement when the film is shown as a sequence.

animate; → -tion.

anion
  آنیون   
ânion (#)

Fr.: anion   

A → negatively charged → ion or → radical. Anions in a liquid subjected to electric potential are attracted toward the → anode. See also → cation.

From Gk. anienai "to go up," from an-, from → ana- "up," + -i-, from ire, eo "to go, walk," cf. Pers. ây-, → assembly, + -on, as in → ion.

anisoplanatism
  انیزوبیراهی، انیزوبیراهمندی   
anizobirâhi, anizobirâhmandi

Fr.: anisoplanatisme   

In an imaging system, the dependence of its performance on field angle. In other words, the spatial variability of the → point spread function for off-axis sources.

an- + → isoplanatism.

anisoplanicity
  انیزوبیراهیگی   
anizobirâhigi

Fr.: anisoplanicité   

The departure from → isoplanicity.

an-; → isoplanicity.

anisotropic
  نا-ایزوگرد   
nâ-izogard

Fr.: anisotrope   

Describing a medium in which certain physical properties are different in different directions.

anisotropy; → -ic.

anisotropic homogeneous cosmological model
  مدل ِ کیهانشناختی ِ همگن و نا-ایزوگرد   
model-e keyhânšenâxti-ye hamgen o nâ-izogard

Fr.: modèle cosmiologique homogène mais anisotrope   

A solution to Einstein's theory of → general relativity that is spatially homogeneous but allows for rotation and/or shear. See also → Bianchi cosmological model.

anisotropic; → homogeneous; → cosmological; → model.

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