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: 3079 Search : on
edition
  ۱) ویرایش؛ ۲) ویراست   
1) virâyeš (#); 2) virâst (#)

Fr.: édition   

1) The act or process of editing.
2) A version of anything, printed or not, presented to the public.

Verbal noun of → edit.

education
  فرهیزش   
farhizeš (#)

Fr.: éducation   

The act or process of educating.
The knowledge or abilities gained through being educated.

Verbal noun of → educate.

effective Eddington parameter
  پارامون ِ ادینگتون ِ اسکرمند   
pârâmun-e Eddington-e oskarmand

Fr.: paramètre d'Eddington effectif   

The effective value of the → Eddington parameter in a non-homogeneous system (porous opacity).

effective; → Eddington limit; → parameter.

eigenfunction
  ویژکریا   
viž-karyâ

Fr.: fonction propre   

1) Math.: An → eigenvector for a linear → operator on a → vector space whose vectors are → functions. Also known as proper function.
2) Quantum mechanics: A → wave function corresponding to an → eigenvalue. Eigenfunctions represent the stationary → quantum states of a system.

From Ger. Eigenfunktion, from eigen- "characteristic, particular, own" (from P.Gmc. *aigana- "possessed, owned," Du. eigen, O.E. agen "one's own") + → function.

Viž-karyâ, from viž, contraction of vižé "particular, charcteristic" + karyâ, → function. Vižé, from Mid.Pers. apēcak "pure, sacred," from *apa-vēcak "set apart," from prefix apa- + vēcak, from vēxtan (Mod.Pers. bixtan) "to detach, separate, sift, remove," Av. vaēk- "to select, sort out, sift," pr. vaēca-, Skt. vic-, vinakti "to sift, winnow, separate; to inquire."

Einstein notation
  نمادگان ِ اینشتین   
namâdgân-e Einstein

Fr.: convention Einstein   

A notation convention in → tensor analysis whereby whenever there is an expression with a repeated → index, the summation is done over that index from 1 to 3 (or from 1 to n, where n is the space dimension). For example, the dot product of vectors a and b is usually written as: a.b = Σ (i = 1 to 3) ai.bi. In the Einstein notation this is simply written as a.b = ai.bi. This notation makes operations much easier. Same as Einstein summation convention.

Einstein; → notation.

Einstein's field equations
  هموگش‌های ِ میدان ِ اینشتین   
hamugešhâ-ye meydân-e Einstein

Fr.: équations de champ d'Einstein   

A system of ten non-linear → partial differential equations in the theory of → general relativity which relate the curvature of → space-time with the distribution of matter-energy. They have the form: Gμν = -κ Tμν, where Gμν is the → Einstein tensor (a function of the → metric tensor), κ is a coupling constant called the → Einstein gravitational constant, and Tμν is the → energy-momentum tensor. The field equations mean that the curvature of space-time is due to the distribution of mass-energy in space. A more general form of the field equations proposed by Einstein is: Gμν + Λgμν = - κTμν, where Λ is the → cosmological constant.

Named after Albert Einstein (1879-1955); → field; → equation.

Einstein's gravitational constant
  پایای ِ گرانشی ِ اینشتین   
pâyâ-ye gerâneši-ye Einstein (#)

Fr.: constante gravitationnelle d'Einstein   

The coupling constant appearing in → Einstein's field equations, expressed by: κ = 8πG/c4, where G is the Newtonian → gravitational constant and c the → speed of light.

einstein; → gravitational; → constant.

Einstein-Hilbert action
  ژیرش ِ اینشتین-هیلبرت   
žireš-e Einstein-Hilbert

Fr.: action de Einstein-Hilbert   

In → general relativity, the → action that yields → Einstein's field equations. It is expressed by:
SEH = (1/2κ)∫d4x (-g)1/2R + Sm,
where κ ≡ 8πG and Sm is the matter part of the action.

Einstein; → Hilbert space; → action.

ejection
  اشانش   
ešâneš

Fr.: éjection   

Act or instance of ejecting; the state of being ejected.

Verbal noun of → eject.

elastic collision
  همکوبش ِ کشایند   
hamkubš-e kešâyand

Fr.: collision élastique   

A collision between two particles which conserves the total kinetic energy and momentum of the system.

elastic; → collision.

elastic deformation
  وادیسش ِ کشایند   
vâdiseš-e kešâyand

Fr.: déformation élastique   

A deformation of a → solid body in which the change (→ strain) in the relative position of points in the body disappears when the deforming stress is removed. See also → elastic limit.

elastic; → deformation.

electrical conductivity
  هازندگی ِ برقی   
hâznadegi-e barqi

Fr.: conductivité électrique   

A measure of a material's ability to conduct an electrical current. It is the reciprocal of the → resistivity. Conductivity is expressed by σ = ne2l/(2mv), where n is the number of electrons per cm3 volume of the → conductor, e is the → electron charge, l is the → mean free path, m is the → electron mass, and v is the arithmetic mean velocity of thermal motion of electrons at a given temperature.

electrical; → conductivity.

electromagnetic induction
  درهازش ِ برقامغناتی   
darhâzeš-e barqâmeqnâti

Fr.: induction électromagnétique   

The production of an → electromotive force in a circuit caused by a variation in the magnetic flux through the circuit. If this variation is produced by a change in the current flowing in the circuit itself, it is called → self-induction. If due to the variation in a current in some other circuit, it is called mutual induction. See also → Faraday's law of induction.

electromagnetic; → induction.

electromagnetic radiation
  تابش ِ برقامغناتی   
tâbeš-e barqâmeqnâti

Fr.: rayonnement électromagnétique   

Radiation propagating in the form of an advancing wave in electric and magnetic fields. It includes radio waves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

electromagnetic; → radiation.

electron
  الکترون   
elektron (#)

Fr.: électron   

The → elementary particle that possesses the smallest possible negative → electric charge. This structureless particle has an intrinsic → spin (1/2), a mass of 9.109 382 91 (40) x 10-31 kg, and an electric charge of 1.602 176 565(35) × 10-19 → coulombs, or 4.803 204 51(10) × 10-10 → esu.

Term first suggested in 1891 by Irish physicist G. J. Stoney (1826-1911); from electr-, from → electric + -on, a suffix used in the names of subatomic particles, probably extracted from → ion.

electron affinity
  کرونی ِ الکترونی   
karvani-ye elektroni

Fr.: affinité électronique   

The amount of energy released or absorbed in the process in which an electron is added to a neutral atom or molecule in gaseous state to form a negative ion.

electron; → affinity.

electron capture
  گیر‌افت ِ الکترون   
giroft-e elektron

Fr.: capture d'électron   

A process whereby an → unstable atom becomes stable. In this process, an → electron in an atom's inner shell is drawn into the → nucleus where it combines with a → proton, forming a → neutron and a → neutrino. The neutrino escapes from the atom's nucleus. The result is an element change, because the atom loses a proton. For example, an atom of → carbon (with 6 protons) becomes an atom of → boron (with 5 protons). Electron capture is also called K-capture since the captured electron usually comes from the atom's K-shell. See also → neutronization.

electron; → capture.

electron charge
  بار ِ الکترون   
bâr-e elektron (#)

Fr.: charge de l'électron   

The charge of one electron, e = -1.602 176 × 10-19coulombs or -4.803 204 51 × 10-10statcoulombs.

electron; → charge.

electron configuration
  همپیکرش ِ الکترونی   
hampeykareš-e elektroni

Fr.: configuration électronique   

Of an atom, a form of notation which shows how the electrons are distributed among the various atomic orbital and energy levels. The format consists of a series of numbers, letters and superscripts. For example, 1s2 2s2 2p3 means: 2 electrons in the 1s subshell, 2 electrons in the 2s subshell, and 3 electrons in the 2p subshell.

electron; → configuration.

electron degeneracy
  واگنی ِ الکترون   
vâgeni-ye elektron (#)

Fr.: dégénérescence des électrons   

A → degenerate matter in which electrons are very tightly packed together, as in a white dwarf, but cannot get closer than a certain limit to each other, because according to quantum mechanics laws (→ Pauli exclusion principle) the lowest energy levels can be occupied by only one electron. Therefore, electrons are forced into high energy states. And the significant pressure created by these high energy electrons supports white dwarf stars against their own gravity.

electron; → degeneracy.

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