An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 998
plasma beta
  پارامون ِ بتا   
pârâmun-e betâ

Fr.: paramètre bêta   

In plasma physics, a dimensionless quantity which is the ratio of the plasma thermal pressure to the magnetic pressure: β = nkT/(B2/2μ0). When β is much smaller than 1, like in the → solar corona, the magnetic forces dominate over the plasma forces.

plasma; β, Gk. letter of alphabet.

plasma cosmology
  کیهان‌شناسی ِ پلاسمایی   
keyhânšenâsi-ye plâsmâyi

Fr.: cosmologie plasma   

An alternative cosmology, initially conceived by Hannes Alfvén in the 1960s, that attempts to explain the development of the visible Universe through the interaction of electromagnetic forces on astrophysical plasma. Like the steady state model, plasma cosmology hypothesizes an evolving Universe without beginning or end.

plasma; → cosmology.

plasma frequency
  بسامد ِ پلاسما   
basâmad-e plâsmâ

Fr.: fréquence de plasma   

The natural frequency at which internal oscillations of a plasma occur. The plasma frequency is proportional to the square root of the electron density. → plasma oscillation.

plasma; → frequency.

plasma mantle
  روپوش ِ پلاسما   
rupuš-e plâsmâ (#)

Fr.: manteau de plasma   

(Geophysics): A layer of plasma located on the night-side of Earth, inside the magnetosphere and along its boundary. Under the action of electromagnetic forces, plasma contained in the mantle drifts equator-ward, along the tail axis.

plasma; → mantle.

plasma oscillation
  نوِش ِ پلاسما   
naveš-e plâsmâ

Fr.: oscillation de plasma   

The oscillatory motion of electrons in a neutral plasma around their equilibrium position while the ions remain at rest. When electrons are displaced by any kind of perturbation with respect to ions, a pair of positive and negative charged regions is formed. The Coulomb force accelerates back the displaced electrons, which get kinetic energy. The electrons overshoot their original positions by the same amount as their first displacement.

plasma; → oscillation.

plasma physics
  فیزیک ِ پلاسما، پلاسمافیزیک   
fizik-e plâsmâ (#), plâsmâ fizik (#)

Fr.: physique des plasmas   

The study of the physical properties of the various forms of plasmas and their processing.

plasma; → physics.

plasma tail
  دنباله‌ی ِ پلاسمایی   
donbale-ye plâsmâyi

Fr.: queue de plasma   

The ionized component of a comet's tail, driven nearly straight away from the Sun by the solar wind. Also called ion tail and gas tail.

plasma; → tail.

plasmapause
  پلاسمامرز   
plâsmâmarz

Fr.: plasmapause   

The sharp outer boundary of the plasmasphere, at which the plasma density decreases by a factor of 100 or more.

plasma + pause "break, cessation, stop," from M.Fr. pause, from L. pausa "a halt, stop, cessation," from Gk. pausis "stopping, ceasing," from pauein "to stop, to cause to cease."

plasma + marz "frontier, border, boundary," from Mid.Pers. marz "boundary;" Av. marəza- "border, district," marəz- "to rub, wipe;" Mod.Pers. parmâs "contact, touching" (→ contact), mâl-, mâlidan "to rub;" PIE base *merg- "boundary, border;" cf. L. margo "edge" (Fr. marge "margin"); P.Gmc. *marko; Ger. Mark; E. mark, margin.

plasmasphere
  پلاسماسپهر   
pelâsmâsepehr

Fr.: plasmasphère   

In the magnetosphere, a region of relatively cool (low energy) and dense plasma that may be considered an outer extension of the ionosphere with which it is coupled. Like the ionosphere, the plasmasphere tends to co-rotate with the Earth.

plasma + → sphere.

plasmon
  پلاسمون   
plâsmon

Fr.: plasmon   

Physics: The quasiparticle resulting from the → quantization of → plasma oscillations. Plasmons are collective oscillations of free electrons inside or on surfaces of materials.

From plasm-, from → plasma + → -on.

plasmonics
  پلاسمونیک   
plâsmonik

Fr.: plasmonique   

The research area dealing with the interaction of → plasmons and → photons and the technology of its practical use. Plasmonics represents one of the most active research fields at the interface of → nanotechnology and → optics.

plasmon; → -ics.

plastic
  شوکایند   
šukâyand

Fr.: plastique   

1a) Capable of being → deformed continuously and permanently without → rupture.
1b) Capable of being molded.
1c) Made or consisting of a plastic.
2) → plastic substance.

From L. plasticus, from Gk. plastikos "that may be molded, pertaining to molding," from plassein "to mold."

Šukâyand, literally "moldable," from šuk, contraction of šuka (Dehxodâ) "a mold in which ingots are cast" + âyand agent noun form of âmadan "to come; to become," → elastic.

plastic deformation
  وادیسش ِ شوکایند   
vâdiseš-e šukâyand

Fr.: déformation plastique   

Permanent → deformation of a → solid subjected to a → stress.

plastic; → deformation.

plastic substance
  زیریست ِ شوکایند   
zirist-e šukâyand

Fr.: substance plastique   

A substance which remains → deformed after an applied → force ceases to act.

plastic; → substance.

plasticity
  شوکایندی   
šukâyandi

Fr.: plasticité   

The property which enables a material to be → deformed permanently without → rupture during the application of a → force. An → elastic material becomes plastic above its → yield point. See also → elasticity, → ductility.

plastic; → -ity.

plate
  ۱) تیغه؛ ۲)؛ ۳) پلاک   
1) tiqé (#); 2); 3) pelâk (#)

Fr.: 1) lame; 2); 3) plaque   

1) Optics: Any crystalline material whose length is much less than its measured diameter. → half-wave plate.
2) A flat piece of material on which a picture or text has been produced.
3) Any of the large movable segments into which the Earth's lithosphere is divided. → plate tectonics.

M.E., from O.Fr. plate "thin piece of metal," from M.L. plata "plate, piece of metal," perhaps via V.L. *plattus, from Gk. platys " flat, broad."

1) Tiqé, from tiq "blade," related to tiz "sharp," variants tig, tež, tej, tij; Mid.Pers. tigr, têz, têž "sharp," O.Pers. tigra- "pointed," tigra.xauda- "pointed helmet (epithet of Scythians)," Av. tiγra- "pointed," tiγray- "arrow," tiži.arštay- "with the pointed spear," cf. Skt. tikta- "sharp, pungent, bitter," tejas- "sharpness, edge, point or top of a flame;" PIE base *st(e)ig- "to stick; pointed." Cognates in other IE languages: Gk. stizein "to prick, puncture," stigma "mark made by a pointed instrument," L. in-stigare "to goad," O.H.G. stehhan, Ger. stechen "to stab, prick," Du. stecken, O.E. sticca "rod, twig, spoon," E. stick.
2); 3) loanword from Fr., as above.

plate center
  مرکز ِ پلاک   
markaz-e pelâk

Fr.: centre de plaque   

The celestial coordinates of the center of the field of an astronomical photographic plate.

plate; → center.

plate scale
  مرپل ِ پلاک   
marpel-e pelâk

Fr.: échelle de plaque   

The scale factor for converting linear measure on a photographic plate to angular measurement on the sky.

plate; → scale.

plate tectonics
  سازانیک ِ پلاک   
sâzânik-e pelâk

Fr.: tectonique des plaques   

The theory supported by a wide range of evidence in which the Earth's crust is composed of several large, thin, relatively rigid plates that move relative to one another. The interaction of the plates at their boundaries causes seismic and tectonic activity along these boundaries. See also → continental drift.

plate; → tectonics.

plateau
  تختال   
taxtâl

Fr.: plateau   

1) An extensive area with a fairly level surface raised sharply above adjacent land.
2) A period, phase, or state of little or no growth or decline in something. → Spite plateau.

From Fr. plateau, from O.Fr. platel "flat piece of metal, wood, etc.," diminutive of plat "flat surface or thing," → plate.

Taxtâl, from taxt "flat;" Mid.Pers. taxtag "tablet, plank, (chess)board" + -âl, → -al.

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