An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1965 Search : ion
synchrotron radiation
  تابش ِ سنکروترون   
tâbeš-e sankrotron

Fr.: rayonnement synchrotron   

The electromagnetic radiation emitted by high-energy particles that are moving in magnetic fields, as in a synchrotron particle accelerator. The acceleration of the moving charges causes the particles to emit radiation. Radio galaxies and supernova remnants are intense sources of synchrotron radiation. Characteristics of synchrotron radiation are its high degree of polarization and nonthermal spectrum.

synchrotron; → radiation.

synthetic division
  بخش ِ هندایشی   
baxš-e handâyeši

Fr.: division synthétique   

A method of dividing a polynomial in the special case of dividing by a linear factor. Synthetic division allows one to do long division problems much quicker. It is related to the → Ruffini-Horner method.

synthetic; → division.

T association
  آهزش ِ T   
âhazeš-e T

Fr.: association T   

A → stellar association containing many → T Tauri stars. Examples include the Taurus-Auriga T association, the nearby → TW Hydrae association, and Vela T1 and T2.

T, letter of alphabet; → association.

tangential motion
  جنبش ِ سایانی   
jonbeš-e sâyâni

Fr.: mouvement tangentiel   

That component of a an object's motion which is perpendicular to the observer's → line of sight.

tangential; → motion.

Taylor-Goldstein equation
  هموگش ِ تیلر-گلدشتاین   
hamugeš-e Taylor-Goldstein

Fr.: équation de Taylor-Goldstein   

Fluid mechanics: A second order differential equation that governs the vertical structure of a perturbation in a stratified parallel flow.

Named after G. I. Taylor (Effect of variation in density on the stability of superposed streams of fluid, 1931, Proc. R. Soc. Lond. A, 132, 499), → Taylor number, and S. Goldstein (On the stability of superposed streams of fluids of different densities, 1931, Proc. R. Soc. Lond. A, 132, 524); → equation.

temperature inversion
  واگردانی ِ دما   
vâgardâni-ye damâ

Fr.: inversion de température   

Meteo.: A reversal in the normal temperature decrease, the temperature rising with increased elevation in the atmosphere instead of falling. A layer in which temperature increases with altitude.

temperature; → inversion.

temporal resolution
  واگشود ِ زمانی   
vâgošud-e zamâni

Fr.: résolution temporelle   

The measure of the ability of an observing system to clearly separate events in time. In other words, the shortest time interval that can be determined between two different events.

temporal hour; → resolution.

taneš (#)

Fr.: tension   

General: The act of stretching or straining; the state of being stretched or strained.
Mechanics: The longitudinal deformation of an elastic body that results in its elongation.
Electricity: Voltage or potential; electromotive force.

M.E., from M.Fr. tension, from L. tensionem (nominative tensio) "a stretching," from tensus, p.p. of tendere "to stretch," cognate with Pers. taneš, as below.

Taneš, verbal noun from tanidan "to spin, twist, weave;" Mid.Pers. tanitan; Av. tan- to stretch, extend;" cf. Skt. tan- to spin, stretch;" tanoti "stretches," tantram "loom;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" PIE base *ten- "to stretch"), Pers. târ "string," tân "thread," tur "fishing net, net, snare," and tâl "thread" (Borujerdi dialect) belong to this family; variants tanta "cobweb," tanadu, tafen, kartané, kârtané, kâtené, Pashtu tanistah "cobweb;" cf. Skt. tantu- "cobweb, thread, string."

tensor contraction
  ترنگش ِ تانسور   
terengeš-e tânsor

Fr.: contraction de tenseur   

An operation of tensor algebra that is obtained by setting unlike indices equal and summing according to a summation convention.

contraction; → tensor.

tensor perturbation
  پرتورش ِ تانسوری   
partureš-e tânsori

Fr.: perturbation tensorielle   

The perturbation in the → primordial Universe plasma caused by → gravitational waves. These waves stretch and squeeze space in orthogonal directions and bring about → quadrupole anisotropy in incoming radiation temperature.

tensor; → perturbation.

termination shock
  تش ِ پایانی، شوک ِ ~   
toš-e pâyâni, šok-e ~

Fr.: choc terminal   

A → shock wave inside the → heliopause where the → supersonic → solar wind abruptly slows from an average speed of 500 km s-1 to → subsonic and becomes denser and hotter.

Termination, verbal noun from terminate, from → term; → shock.

Toš, šok, → shock; pâyâni, → terminal.

terrestrial gravitational constant
  پایای ِ گرانشی زمینی   
pâyâ-ye gerâneši-ye zamini

Fr.: constante gravitationnelle terrestre   

A parameter representing the product of the → gravitational constant by the Earth's mass. It is 3.987 x 1014 m3s-2 or 3.987 x 105 km3s-2.

terrestrial; → gravitational; → constant.


Fr.: thématisation   

The act or process of thematizing.

thematize; → -tion.

thermal agitation
  ژیلش ِ گرمایی   
ſileš-e garmâyi

Fr.: agitation thermique   

1) The random movement of the molecules of a substance, the energy of which is, by kinetic theory, synonymous with the heat content of the substance.
2) Solid state physics: The random motion of free electrons in a conductor due to heat energy.

thermal; → agitation.

thermal conduction
  هازش ِ گرمایی   
hâzeš-s garmâyi

Fr.: conduction thermale   

A process that occurs in a medium where a → temperature gradient exists: dQ = -κ(dT/dx)dA.dt, where dQ is the amount of heat passing through the time dt across an area dA in the direction of the normal x to this area and toward the reduction in temperature, κ is the → thermal conductivity, and (dT/dx) the temperature gradient.

thermal; → conduction.

thermal diffusion
  پخش ِ گرمایی   
paxš-e garmâyi

Fr.: diffusion thermique   

A physical process resulting from → temperature gradients in stellar interiors, whereby more highly charged and more massive chemical species are concentrated toward the hottest region of the star, its center. Therefore, thermal diffusion and → gravitational settling tend to make heavier species sink relative to the light ones.

thermal; → diffusion.

thermal emission
  گسیل ِ گرمایی   
gosil-e garmâyi (#)

Fr.: émission thermique   

thermal radiation.

thermal; → emission.

thermal excitation
  بر‌انگیزش ِ گرمایی   
barangizeš-e garmâyi

Fr.: excitation thermique   

A process in which collisions that occur between particles cause atoms or molecules to obtain additional kinetic energy.

thermal; → excitation.

thermal expansion
  سپانش ِ گرمایی   
sopâneš-e garmâyi

Fr.: expansion thermique   

The change in dimensions of a material resulting from a change in temperature.

thermal; → expansion.

thermal motion
  جنبش ِ گرمایی   
jonbeš-e garmâyi

Fr.: mouvement thermique   

The random motions and collisions of molecules, atoms, electrons, or other subatomic particles constituting an object at all temperatures above → absolute zero. The thermal motion of particles rises with the temperature of those particles and is governed by the laws of → thermodynamics. The most convincing experimental proof of thermal motion → Brownian motion.

thermal; → motion.

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