An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 438
gas-rich galaxy
  کهکشان ِ پرگاز   
kahkešân-e porgâz

Fr.: galaxie riche en gaz   

A galaxy, usually young, which has a relatively important gas content.

gas; → rich; → galaxy.

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.

gâzi (#)

Fr.: gazeux   

1) Existing in the → state of a gas.
2) Pertaining to or having the characteristics of gas.

gas; → -eous.

gaseous diffusion
  پخش ِ گازی   
paxš-e gâzi

Fr.: diffusion gazeuse   

An → isotope separation process using the different diffusion speeds of → atoms or → molecules for separation. This process is used to divide → uranium hexafluoride (UF6) into two separate streams of U-235 and U-238. Before processing by gaseous diffusion, uranium is first converted from → uranium oxide (U3O8) to UF6. The UF6 is heated and converted from a solid to a gas. The gas is then forced through a series of compressors and converters that contain porous barriers. Because uranium-235 has a slightly lighter isotopic mass than uranium-238, UF6 molecules made with uranium-235 diffuse through the barriers at a slightly higher rate than the molecules containing uranium-238. At the end of the process, there are two UF6 streams, with one stream having a higher concentration of uranium-235 than the other (EVS, a Division of Argonne National Laboratory).

gaseous; → diffusion.

gaseous nebula
  میغ ِ گازی   
miq-e gâzi

Fr.: nébuleuse gazeuse   

An → H II region, a → planetary nebula, or a → supernova remnant.

gaseous; → nebula.

  گز؛ گز کردن   
(n.) gaz; (v.) gaz kardan

Fr.: jauge   

1) (n.) A standard of measure or measurement, size, or quantity.
2) Any of a wide variety of devices or instruments used for measuring a parameter or characteristic of an object, such as its dimension, quantity, or mechanical accuracy.
3) Physics: One of the family of choices for a constant in the expression of → potential energy in a central force field. Force is connected with potential energy by the relation F = - ∂U/∂r, U = ∫F.dr. The upper limit in the integral can be chosen arbitrarily. The potential energy is usually considered zero at infinity.
4) (v.) To determine the exact dimensions, capacity, quantity, or force of; measure.

From Fr. jauge "gauging rod," perhaps from Frankish galga "rod, pole for measuring;" cf. O.N. gelgja "pole, perch;" O.H.G. galgo; Lith. zalga "pole, perch;" Arm. dzalk "pole;" E. gallows; see below.

Gaz "a yard for measuring cloth; a length of 24 finger-breadths, or six hands; the tamarisk-tree," from Mid.Pers. gaz "tamarisk," may be of the same origin as gauge. In verbal form with kardan "to do, to make" (Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build;" Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base kwer- "to do, to make").

gauge boson
  بوزون ِ گز   
bozon-e gaz

Fr.: boson de jauge   

A class of elementary particles that includes the gluon, photon, W+, W-, and Z0 particles, each having an integral spin.

gauge; → boson.

gauge group
  گروه ِ گز   
goruh-e gaz (#)

Fr.: groupe de jauge   

The mathematical group associated with a particular set of gauge transformations.

gauge; → group.

gauge invariance
  ناورتایی ِ گز   
nâvartâyi-ye gaz

Fr.: invariance de jauge   

The invariance of any field theory under gauge transformation.

gauge; → invariance.

gauge symmetry
  همامونی ِ گز   
hamâmuni-ye gaz

Fr.: symétrie de jauge   

A principle underlying the quantum-mechanical description of the three non-gravitational forces. It allows a system to behave in the same way even though it has undergone various transformations. The earliest physical theory which had a gauge symmetry was Maxwell's electrodynamics.

gauge; → symmetry.

gauge theory
  نگره‌ی ِ گز   
negare-ye gaz (#)

Fr.: théorie de jauge   

A field theory in which it is possible to perform a transformation without altering any measurable physical quantity.

gauge; → theory.

gauge transformation
  ترادیس ِ گز   
tarâdis-e gaz (#)

Fr.: transformation de jauge   

A change of the fields of a gauge theory that does not change the value of any measurable quantity.

gauge; → transformation.



A technique in which the thickness, density, or quantity of a material is determined by the amount of radiation it absorbs.

Gauging, from → gauge + → -ing, suffix of nouns formed from verbs, expressing the action of the verb or its result.

Gazkard, from gaz, → gauge, + kard past stem of kardan "to do, make," → gauge.

Gaunt factor
  کروند ِ گاؤنت   
karvand-e Gaunt

Fr.: facteur de Gaunt   

In the atomic theory of spectral line formation, a quantum mechanical correction factor applied to the absorption coefficient in the transition of an electron from a bound or free state to a free state.

Gaunt, after John Arthur Gaunt (1904-1944), English physicist born in China, who significantly contributed to the calculation of continuous absorption using quantum mechanics; → factor

gauss (#)

Fr.: gauss   

The c.s.g. unit of magnetic flux density (or magnetic induction), equal to 1 maxwell per square centimeter, or 10-4 tesla.

Named after the German mathematician and physicist Carl Friedrich Gauss (1777-1855).

Gauss's law for electricity
  قانون ِ گاؤس در برق   
qânun-e Gauss dar barq

Fr.: loi de Gauss en électricité   

The total electric flux ψ out of an arbitrary closed surface in free space is equal to the net charge within the surface divided by the → permittivity. In differential form: ∇ . E = ρ/ε0, where ρ is the → charge density and ε0 the permittivity. The integral form of the law: ∫E . dS = Q0 (closed surface integral). This is one of the four → Maxwell's equations.

gauss; → law; → electricity.

Gauss's law for magnetism
  قانون ِ گاؤس در مغنات‌مندی   
qânun-e Gauss dar meqnâtmandi

Fr.: loi de Gauss en magnétisme   

The → magnetic flux through an arbitrary closed surface equals zero. Mathematically, in differential form: ∇ . B = 0 and in integral form: ΦB = ∫B.dS = 0 (closed surface integral). This is one of the four → Maxwell's equations. This law expresses the fact that there are no free magnetic poles (→ monopoles) in nature and that all the lines of force of a magnetic field are closed curves.

gauss; → law; → magnetism.

Gauss's lemma
  نهک ِ گاؤس   
nehak-e Gauss

Fr.: lemme de Gauss   

If a → polynomial with → integer coefficients can be → factorized into polynomials with → rational number coefficients, it can be factorized using only integers.

Gaussian; → lemma.

Gauss's theorem
  فربین ِ گاؤس   
farbin-e Gauss

Fr.: théorème de Gauss   

The total normal induction over any closed surface drawn in an electric field is equal to 4π times the total charge of electricity inside the closed surface. Gauss's theorem applies also to other vector fields such as magnetic, gravitational, and fluid velocity fields. The theorem can more generally be stated as: the total flux of a vector field through a closed surface is equal to the volume → integral of the vector taken over the enclosed volume. Also known as → divergence theorem, Ostrogradsky's theorem, and Gauss-Ostrogradsky theorem.

gauss; → theorem.

Gaussi (#)

Fr.: gaussien   

Of or relating to Carl Friedrich Gauss or his mathematical theories of magnetism, electricity, astronomy, or probability. → Gaussian distribution; → Gaussian profile.


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