An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 417

Fr.: graphique   

(Adj.) Pertaining to the use of diagrams, graphs, mathematical curves, or the like.
Math.: Pertaining to the determination of values, solution of problems, etc., by direct measurement on diagrams instead of by ordinary calculations.
(n.) A product of the graphic arts, as a drawing or print. A computer-generated image.

graph + → -ic.

gerâfit (#)

Fr.: graphite   

A particular crystalline form of → carbon occurring as a soft, black, lustrous mineral. The carbon atoms in graphite are strongly bonded together in sheets. Because the bonds between the sheets are weak, other atoms can easily fit between them, causing graphite to be soft and slippery to the touch. Graphite conducts electricity and is used in lead pencils and electrolytic anodes, as a lubricant, and as a moderator in nuclear reactors. If graphite is subjected to high pressure, it will be transformed into → diamond.
Graphite is present in the → interstellar medium; it forms in circumstellar shells and supernova ejecta. In particular, the 2175 Å interstellar extinction feature is accounted for by small graphite grains.

From Ger. Graphit, from Gk. graph(ein) "to write, draw," so called because it was used for pencils, → graph + -it a suffix of chemical compounds, equivalent to E. -ite.

  توری، ~ ِ پراش   
turi, ~ -e parâš (#)

Fr.: réseau   

Same as → diffraction grating.

M.E. grating, M.L. grata "a grating," variant of crata, from crat-, stem of cratis "wickerwork."

Turi, from tur "fishing net, net, snare," variants târ "thread, warp, string," tâl "thread" (Borujerdi dialect), cognate with tanidan, tan- "to spin, twist, weave" (Mid.Pers. tanitan; Av. tan- to stretch, extend;" Skt. tan- to stretch, extend;" tanoti "stretches," tantram "loom;" tántra- "warp; essence, main point;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" Lith. tiñklas "net, fishing net, snare," Latv. tikls "net;" PIE base *ten- "to stretch").

grating angle
  زاویه‌ی ِ توری   
zâviye-ye turi (#)

Fr.: angle de réseau   

The angle between the incident optical beam and the normal to the grating. It is the angle to which the grating must be set to place the desired wavelength at the center of the detector.

grating; → angle.

grating efficiency
  کار‌آیی ِ توری   
kârâyi-ye turi (#)

Fr.: efficacité de réseau   

The measure of the light intensity diffracted from a grating.

grating; → efficiency.

grating groove
  شیار ِ توری   
šiyâr-e turi (#)

Fr.: trait du réseau, sillon ~ ~   

One of thousands of long, narrow indentations in the surface of a → diffraction grating.

grating; → groove.

gerânidan (#)

Fr.: graviter   

To move or tend to move under the influence of gravitational force.

From L. gravitatus, p.p. of gravitâre, from gravis "heavy," → gravity.

Gerânidan, infinitive of gerân, → gravity.

gerâneš (#)

Fr.: gravitation   

1) The universal phenomenon of attraction between material bodies. → Newton's law of gravitation.
2) The act or process of moving under the influence of this attraction.

Verbal noun of → gravitate.

gerâneši (#)

Fr.: gravitationnel   

Of or relating to or caused by → gravitation.

Adj. of → gravitation.

gravitational acceleration
  شتاب ِ گرانشی   
šetâb-e gerâneši (#)

Fr.: accélération gravitationnelle   

The acceleration caused by the force of gravity. At the Earth's surface it is determined by the distance of the object form the center of the Earth: g = GM/R2, where G is the → gravitational constant, and M and R are the Earth's mass and radius respectively. It is approximately equal to 9.8 m s-2. The value varies slightly with latitude and elevation. Also known as the → acceleration of gravity.

gravitational; → acceleration.

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 collapse
  رمبش ِ گرانشی   
rombeš-e gerâneši (#)

Fr.: effondrement gravitationnel   

Collapse of a mass of material as a result of the mutual → gravitational attraction of all its constituents.

gravitational; → collapse.

gravitational constant
  پایای ِ گرانشی   
pâyâ-ye gerâneši (#)

Fr.: constante gravitationnelle   

A fundamental constant that appears in → Newton's law of gravitation. It is the force of attraction between two bodies of unit mass separated by unit distance: G = 6.673 x 10-8 dyn cm2 g-2 or 6.673 x 10-8 cm3s-2g-1, or 6.673 x 10-11 N m2 kg-2 or 6.673 x 10-11 m3s-2kg-1. It was first measured in 1798 by Henry Cavendish (1731-1810), 71 years after Newton's death. Same as the → Newtonian constant of gravitation.

gravitational; → constant.

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 encounter
  رویارویی ِ گرانشی   
ruyâruyi-ye gerâneši

Fr.: rencontre gravitationnelle   

An encounter in which two moving bodies alter each other's direction and velocity by mutual → gravitational attraction.

gravitational; → encounter.

gravitational energy
  کاروژ ِ گرانشی   
kâruž-e gerâneši

Fr.: énergie gravitationnelle   

Same as → gravitational potential energy.

gravitational; → energy.

gravitational equilibrium
  ترازمندی ِ گرانشی   
tarâzmandi-ye gerâneši (#)

Fr.: équilibre gravitationnel   

The condition in a celestial body when gravitational forces acting on each point are balanced by some outward pressure, such as radiation pressure or electron degeneracy pressure, so that no vertical motion results.

gravitational; → equilibrium.

gravitational field
  میدان ِ گرانشی   
meydân-e gerâneši (#)

Fr.: champ gravitationnel   

The region of space in which → gravitational attraction exists.

gravitational; → field.

gravitational force
  نیروی ِ گرانشی   
niru-ye gerâneši (#)

Fr.: force gravitationnelle   

The weakest of the four fundamental forces of nature. Described by → Newton's law of gravitation and subsequently by Einstein's → general relativity.

gravitational; → force.

gravitational instability
  ناپایداری ِ گرانشی   
nâpâydâri-ye gerâneši (#)

Fr.: instabilité gravitationnelle   

The process by which fluctuations in an infinite medium of size greater than a certain length scale (the Jeans length) grow by self-gravitation.

gravitational; → instability.

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