An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 450

Fr.: hydrodynamique   

Of or pertaining to → hydrodynamics.

hydro- + → dynamic.

hydrodynamic equation
  هموگش ِ هیدروتوانیک   
hamugeš-e hirdrotavânik

Fr.: équation hydrodynamique   

Fluid mechanics: A → partial differential equation which describes the motion of an element of fluid subjected to different forces such as pressure, gravity, and frictions.

hydrodynamic; → equation.

hydrodynamic equilibrium
  ترازمندی ِ هیدروتوانیک   
tarâzmandi-ye hirdrotavânik

Fr.: équilibre hydrodynamique   

The state of a star when all its internal forces are in equilibrium. The main forces are gas pressure, radiation pressure due to thermonuclear fusion that tends to disrupt the star, and the opposing gravity. → hydrostatic equilibrium.

hydrodynamic; → equilibrium.


Fr.: hydrodynamique   

The branch of physics dealing with the motion, energy, and pressure of neutral → fluids.

hydro- + → dynamics.

hydrogen (H)
hidrožen (#)

Fr.: hydrogène   

The most abundant → chemical element in the Universe. Symbol H; → atomic number 1; → atomic weight 1.00794; → melting point -259.14°C; → boiling point -252.87°C. It was discovered by the English physicist Henry Cavendish in 1766, who called it the "inflammable air."
See also:
antihydrogen, → atomic hydrogen, → heavy hydrogen, → hydrogen bond, → hydrogen burning, → hydrogen coma, → hydrogen cyanide, → hydrogen fusion, → hydrogen ion, → hydrogen line, → hydrogen shell burning, → hydrogenate, → hydrogenation, → hydrogenize, → ionized hydrogen region, → metallic hydrogen, → molecular hydrogen, → neutral hydrogen, → orthohydrogen, → parahydrogen, → triatomic hydrogen molecular ion.

Hydrogen, from Fr. hydrogène, from Gk. hydro-, combining form of hydor "water" → hydro- + Fr. -gène "producing," → -gen; coined in 1787 by the French chemist Guyton de Morveau (1737-1816) because it forms water when exposed to oxygen.

hydrogen bond
  بند ِ هیدروژنی   
band-e hidroženi

Fr.: liaison hydrogène   

The attractive force between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule. Usually the electronegative atom is oxygen, nitrogen, or fluorine, which has a partial negative charge. The hydrogen then has the partial positive charge.

hydrogen; → bond.

hydrogen burning
  سوزش ِ هیدروژن   
suzeš-e hidrožen

Fr.: combustion de l'hydrogène   

proton-proton chain.

hydrogen; → burning.

hydrogen coma
  گیس ِ هیدروژنی   
gis-e hidroženi

Fr.: chevelure d'hydrogène   

The cometary cloud of hydrogen, detectable in ultraviolet light, that is immensely bigger than even the huge visible coma it surrounds. It is produced by the dissociation of water into hydrogen and oxygen and by other processes set into motion by solar radiation and and the solar wind.

hydrogen, → coma.

hydrogen cyanide (HCN)
  سیانور ِ هیدروژن   
siyânur-e hidrožen (#)

Fr.: cyanure d'hydrogène   

A colorless or light blue liquid or gas, a triatomic cyanide, which is extremely flammable. HCN is an important industrial chemical and over a million tonnes are produced yearly in the world. It is produced industrially by reacting methane and ammonia in air at high temperature. A wide range of combustion processes produce HCN gas in the smoke or fumes. HCN is found naturally throughout the environment at low levels as it is released from volcanoes and certain plants and bacteria. Hydrogen cyanide is abundant in all kinds of astronomical environments, from dark clouds to star-forming regions and circumstellar envelopes. The first detection of interstellar HCN (at 88.6 GHz) and H13N (at 86.3 GHz) was reported by Buhl & Snyder (1971, ApJ 163, L47). Also called → hydrocyanic acid and → prussic acid.

hydrogen; → cyanide.

hydrogen fusion
  ایوش ِ هیدروژن   
iveš-e hidrožen

Fr.: fusion de l'hydrogène   

A → nuclear reaction where hydrogen (H) nuclei combine to form helium (4He) nuclei. Same as the → proton-proton chain.

hydrogen; → fusion.

hydrogen ion
  هیدرون، یون ِ هیدروژن   
hidron, yon-e hidrož

Fr.: hydron, ion hydrogène   

Chemistry: The → positively charged hydrogen atom, H+, formed by removal of the orbital electron. Same as → proton.

hydrogen; → ion.

hydrogen line
  خط ِ هیدروژن   
xatt-e hidrožen (#)

Fr.: raie de l'hydrogène   

An → emission or → absorption line in the spectra of various astronomical objects produced by the presence of hydrogen atoms in particular physical conditions.

hydrogen, → line.

hydrogen shell burning
  سوزش ِ پوسته‌ی ِ هیدروژن   
suzeš-e puste-ye hidrožen

Fr.: combustion de la coquille d'hydrogène   

A phase in the life of a star that has left the → main sequence. When no more hydrogen is available in the core, the core will start to contract as it is no longer releasing the necessary energy whose pressure supports the surrounding layers. As a result of this contraction, gravitational energy is converted into thermal energy and the temperature will rise. Therefore a shell of unprocessed material surrounding the original core will be heated sufficiently for hydrogen burning to start. During the evolution of → asymptotic giant branch stars hydrogen shell burning occurs alternatively with helium shell burning. → double shell burning.

hydrogen; → shell; → burning.


Fr.: hydrogéner   

To undergo or cause to undergo a reaction with hydrogen. Same as → hydrogenize.

hydrogen; → -ate.


Fr.: hydrogénisation   

The process of combining or exposing to → hydrogen.


Fr.: hydrogéner   


hydrogen; → -ize.

âbnegâri (#)

Fr.: hydrographie   

The study, measurement, and description of depths and currents in open seas, lakes, estuaries, and rivers.

hydro- + → -graphy.

hydrologic cycle
  چرخه‌ی ِ آب‌شناسیک، ~ آب‌شناختی   
carxe-ye âbšenâsik (#), ~ âbšenâxti (#)

Fr.: cycle hydrologique   

The vertical and horizontal transport of water in all its states between the earth, the atmosphere, and the seas; often called the water cycle.

Hydrologic, pertaining to → hydrology; → cycle.

âbšenâsi (#)

Fr.: hydrologie   

The study of the waters of the earth, especially with relation to the effects of precipitation and evaporation upon the occurrence and character of water in streams, lakes, and on or below the land surface.

Hydrology, from → hydro-; + → -logy.


Fr.: hydromagnétisme   

Same as → magnetohydrodynamics.

hydro-; → magnetics.

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