An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 155 Search : ratio
elliptic aberration
  بیراهش ِ بیضی‌گون   
birâheš-e biyzigun

Fr.: aberration elliptique   

That part of → annual aberration proportional to the → eccentricity of the Earth's orbit.

elliptic; → aberration.


Fr.: émigration   

An act or instance of emigrating; a body of emigrants; emigrants collectively.

Verbal noun of → emigrate.

energy generation equation
  هموگش ِ آزانش ِ کاروژ   
hamugeš-e âzâneš-e kâruž

Fr.: équation de génération d'énergie   

Of a stellar → nuclear fusion, the equation describing the → energy generation rate as a function of → density and → temperature.

energy; → generation; → equation.

energy generation rate
  نرخ ِ آزانش ِ کاروژ   
nerx-e âzâneš-e kâruž

Fr.: taux de génération d'énergie   

Of a stellar → nuclear fusion, the energy produced per unit mass per unit time, usually denoted ε (erg g-1s-1). The general form of the energy generation equation is: ε = ε0ρλTν, where ε0, ρ, and λ are constants over some efficiently restricted range of → temperature T, → density ρ, and → chemical composition. The temperature exponent ν is about 4, 15, and 40 for → proton-proton chain, → CNO cycle, and → triple alpha process, respectively.

energy; → generation; → rate.


Fr.: évaporation   

The physical process by which a liquid is transformed to the gaseous state, usually by means of heat; the opposite of → condensation. Also called vaporization.

From L. evaporationem (nom. evaporatio), from evaporare "to disperse in vapor," from → ex- "out" + → vapor "steam."

Boxârš, verbal noun of boxâridan "to evaporate," from boxâr, → vapor.

puyeš (#)

Fr.: exploration   

1) An act or instance of exploring or investigating; examination.
2. The investigation of unknown regions.
3) The process of searching for minerals by means of geological studies.
4) Medicine: An examination or investigation for diagnostic purposes, usually involving endoscopy or a surgical procedure.

Verbal noun of → explore.

extreme mass ratio inspiral (EMRI)
  فروپیچه با وابر ِ استوم ِ جرم   
forupicé bâ vâbar-e ostom-e jerm

Fr.: orbite plongeante d'un trou noir binaire, au rapport de masse extrême   

A compact stellar remnant (e.g., a → white dwarf, → neutron star, or → black hole) that undergoes → inspiral into a much more massive object (→ supermassive black hole found → galactic centers). EMRIs are potential sources of low-frequency → gravitational waves. Predictions of the EMRI event rates span a wide range, from ~ 10-9 to 10-6 yr-1 per galaxy (Merritt et al. 2011, Physical Review D 84, 044024). See also → resonant relaxation.

extreme; → mass; → ratio; → inspiral.


Fr.: fédération   

1) The act of federating or uniting in a league.
2) A political unit formed from smaller units on a → federal basis.

Verbal noun of → federate.

flux calibration
  کبیزش ِ شار   
kabizeš-e šârr

Fr.: calibration de flux   

The → calibration of the flux received by a detector in terms of absolute units.

flux; → calibration.

focal ratio
  وابر ِ کانونی   
vâbar-e kânuni

Fr.: rapport focal   

The ratio of the → focal length of a reflecting surface or lens to its effective diameter, i.e. to its → aperture. The smaller the focal ratio, the smaller the image scale and the more luminous the image for a given aperture.

focal; → ratio.

gas-to-dust ratio
  وابر ِ گاز به غبار   
vâbar-e gâz bé qobâr

Fr.: rapport gaz/poussière   

The mass ratio of gas to dust. It amounts to approximately 100 in the → interstellar medium, but may vary in → molecular clouds and → circumstellar disks due to dust → grain evaporation, → dust settling, → condensation of gas, etc. The gas-to-dust ratio depends on the → metallicity. It is larger in galaxies with lower metallicity.

gas; → dust; → ratio.


Fr.: génération   

1) A coming into being.
2) The → production of → energy (→ heat or → electricity).

Verbal noun of → generate.

geometrical libration
  رخگرد ِ هندسی   
roxgard-e hendesi (#)

Fr.: libration géométrique   

Libration resulting from changes in the location of the observer with respect to body. More specifically, a lunar libration motion that results from the Earth based observer seeing the Moon from different directions at different times. There are three types of geometrical libration: → libration in longitude, → libration in latitude, and → diurnal libration. See also → physical libration.

geometric; → libration.

golden ratio
  وابر ِ زرین   
vâbar-e zarrin

Fr.: nombre d'or   

If a line segment is divided into a larger subsegment (a) and a smaller subsegment (b), when the larger subsegment is related to the smaller exactly as the whole segment is related to the larger segment, i.e. a/b = (a + b)/a. The golden ratio, a/b is usually represented by the Greek letter φ. It is also known as the divine ratio, the golden mean, the → golden number, and the golden section. It was believed by Greek mathematicians that a rectangle whose sides were in this proportion was the most pleasing to the eye. Similarly, the ratio of the radius to the side of a regular → decagon has this proportion. The numerical value of the golden ratio, given by the positive solution of the equation φ2 - φ - 1 = 0, is φ = (1/2)(1 + √5), approximately 1.618033989. The golden ratio is an → irrational number. It is closely related to the → Fibonacci sequence.

golden; → ratio.

grain evaporation
  بخارش ِ دانه   
boxâreš-e dâné

Fr.: évaporation des grains   

Conversion of dust grains into smaller grains due to high environmental temperatures.

grain; → evaporation.

gravitational acceleration
  شتاب ِ گرانشی   
šetâb-e gerâneši (#)

Fr.: accélération gravitationnelle   

The acceleration caused by the force of gravity. At the Earth's surface it is determined by the distance of the object form the center of the Earth: g = GM/R2, where G is the → gravitational constant, and M and R are the Earth's mass and radius respectively. It is approximately equal to 9.8 m s-2. The value varies slightly with latitude and elevation. Also known as the → acceleration of gravity.

gravitational; → acceleration.

helium-argon calibration
  کبیزش ِ هلیوم-آرگون   
kabizeš-e heliyom-ârgon

Fr.: calibration hélium-argon   

A wavelength calibration of astronomical spectra using a helium-argon light source.

helium; → argon; → calibration.

HESS collaboration
  همکاری ِ HESS   
hamkâri-ye HESS

Fr.: collaboration HESS   

High Energy Stereoscopic System (H.E.S.S.).

H.E.S.S.; → collaboration.

  هیدرش، آبش   
hidreš, âbeš (#)

Fr.: hydratation   

The process of combining with → water.

Verbal noun of → hydrate.

image restoration
  بازسازی ِ وینه، ~ تصویر   
bâzsâzi-ye vine, ~ tasvir (#)

Fr.: restauration d'image   

The process by virtue of which the original image can be created by removing the blurring and the noise that occur during image formation.

image; → restoration.

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