An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 86 Search : action
fundamental interaction
  اندرژیرش ِ بنیادین   
andaržireš-e bonyâdin

Fr.: interaction fondamentale   

Any of the four interactions in nature between bodies of matter and that are mediated by one or more particles. Also called the → fundamental force. In order of decreasing strength, the four fundamental interactions are the → strong interaction, the → electromagnetic interaction, the → weak interaction, and the → gravitational interaction.

fundamental; → interaction.

geodetic refraction
  شکست ِ زمین‌سنجیک   
šekast-e zamin-sanjik

Fr.: réfraction géodésique   

The limiting case of → astronomical refraction when the light path is entirely within the Earth's atmosphere.

geodetic; → refraction.

gravitational attraction
  درکشش ِ گرانشی   
darkešeš-e gerâneši

Fr.: attraction gravitationnelle   

The force that pulls material bodies toward one another because of → gravitation.

gravitational; → attraction.

gravitational contraction
  ترنگش ِ گرانشی   
terengeš-e gerâneši

Fr.: contraction gravitationnelle   

Decrease in the volume of an astronomical object under the action of a dominant, central gravitational force.

gravitational; → contraction.

gravitational interaction
  اندرژیرش ِ گرانشی   
andaržireš-e gerâneši

Fr.: interaction gravitationnelle   

Mutual attraction between any two bodies that have mass.

gravitational; → interaction.

horizontal refraction
  شکست ِ افقی   
šekast-e ofoqi (#)

Fr.: réfraction horizontale   

The angular distance of an object below the horizon when it appears to lie on the horizon.

horizontal; → refraction.

index of refraction
  دیشن ِ شکست   
disšan-e šekast

Fr.: indice de réfraction   

Same as → refractive index.

index; → refraction.

interaction
  اندرژیرش   
andaržireš

Fr.: interaction   

General: Mutual or reciprocal action or influence.
Physics: 1) What happens between a system and its surroundings when an observable change in one corresponds to or correlates with an observable change in the other.
2) The natural phenomenon of the transfer of energy between two particles. The four known kinds of interactions, in the order of increasing strength, are: → gravitational, → weak, → electromagnetic, and → strong.

Interaction, from → inter-; + → action.

interactional
  اندرژیرشی   
andaržireši

Fr.:   

Capable of acting on or influencing each other

From → interaction; + → -al.

isotope fractionation
  برخانش ِ ایزوتوپی   
barxâneš-e izotopi

Fr.: fractionnement isotopique   

A slight difference between the → abundances of → isotopes of the same → chemical element owing to → physical or → chemical  → processes. It results in the → enrichment or → depletion of an isotope. Same as → isotopic fractionation.

isotope; → fractionation

isotopic fractionation
  برخانش ِ ایزوتوپی   
barxâneš-e izotopi

Fr.: fractionnement isotopique   

Same as → isotope fractionation.

isotopic; → fractionation

Kelvin-Helmholtz contraction
  ترنگش ِ کلوین-هلمهولتس   
terengeš-e Kelvin-Helmholtz

Fr.: contraction de Kelvin-Helmholtz   

The contraction of a volume of gas under its → gravity, accompanied by the → radiation of the lost → potential energy as → heat.

After the Scottish physicist William Thomson, also known as Lord Kelvin (1824-1907) and the German physicist and physician Hermann Ludwig Ferdinand von Helmholtz (1821-1894), who made important contributions to the thermodynamics of gaseous systems; → contraction.

law of refraction
  قانون ِ شکست   
qânun-e šekast (#)

Fr.: loi de réfraction   

One of the two laws governing → refraction of light when it enters another transparent medium: a) The → incident ray, normal to the surface, and refracted ray, all lie in the same plane. b) → Snell's law is satisfied.

law; → refraction.

length contraction
  ترنگش ِ درازا   
terengeš-e derâzâ

Fr.: contraction de longueur   

Same as → Lorentz contraction.

length; → contraction.

line of action
  خط ِ ژیرش، ~ کنش   
xatt-e žireš, ~ koneš

Fr.: ligne d'action   

Of a force, the straight line along which the force → vector is directed. The action of a force on a → rigid body does not change when its point of application is displaced along the line of action. Hence, forces applied to a rigid body can be regarded as non-localized, or sliding, vectors.

line; → action.

liquefaction
  آوش   
âveš

Fr.: liquéfaction   

1) The act or process of liquefying or making liquid.
2) The state of being liquefied.

liquefy; → -tion.

Lorentz contraction
  ترنگش ِ لورنتز   
terengeš-e Lorentz

Fr.: contraction de Lorentz   

The decrease in the length of a body moving in the direction of its length as measured by an observer situated in that direction. The shortening factor is [1 - (v/c)2]1/2, where v is the relative velocity and c light speed.

Lorentz; → contraction.

mass fraction
  برخه‌ی ِ جرم   
barxe-ye jerm

Fr.: fraction de masse   

The fractional amount (by mass) of a given element or nuclide in a given composition.

mass; → fraction.

nuclear reaction
  واژیرش ِ هسته‌ای   
vâžireš-e haste-yi

Fr.: réaction nucléaire   

A process in which the energy, composition, or structure of an atomic nucleus changes.

nuclear; → reaction.

nulling fraction (NF)
  برخه‌ی ِ نولش   
barxe-ye nuleš

Fr.: fraction de phase d'arrêt   

The fraction of time that a → pulsar undergoes → pulse nulling. For most → nulling pulsars this fraction can range from zero (for the → Vela pulsar) to more than 50%.

null; → -ing; → fraction.

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