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: 39 Search : rain
axiom of constraints
  بنداشت ِ پاوندها   
bondâšt-e pâvandhâ

Fr.: axiome des contraintes   

An axiom in → statics, stating that any → constrained body can be treated as a → free body detached from its → constraints, provided the latter are represented by their → reactions.

axiom; → constraint.

big grain
  دانه‌ی ِ بزرگ   
dâne-ye bozorg

Fr.: gros grain   

A type of → interstellar dust grains with a size ranging from 150 to 1000 Å. Big grains consist of graphite and silicates. They are in → thermal equilibrium with the radiation field and their emission can be described by a modified → blackbody radiation following from → Kirchhoff's law.

big; → grain.

Cassegrain focus
  کانون ِ کسگرن   
kânun-e Cassegrain (#)

Fr.: foyer Cassegrain   

The main focus in → Cassegrain telescope.

Cassegrain telescope; → focus.

Cassegrain telescope
  دوربین ِ کسگرن، تلسکوپ ~   
durbin Cassegrain, teleskop-e ~ (#)

Fr.: Télecope Cassegrain   

A reflecting telescope whose primary mirror has a hole bored through the center to allow the reflected light from the convex secondary mirror be focused beyond the back end of the tube.

Cassegrain, named after the French priest and school teacher Laurent Cassegrain (1629-1693), who invented this system in 1672; → telescope.

constrain
  پاوندیدن، پاوند کردن   
pâvandidan, pâvand kardan

Fr.: contraindre   

To confine forcibly, as by bonds; to force, compel, or oblige; to repress or restrain. → constrained body, → constrained system.

constraint.

constrained body
  جسم ِ پاوندیده   
jesm-e pâvandidé

Fr.: corps lié   

A → rigid body whose displacement is prevented because it is under → constraint or a body that can move only in certain directions. Contrasted with → free body.

Constrained, p.p. of → constrain; → body.

constrained system
  راژمان ِ پاوندیده   
râžmân-e pâvandidé

Fr.: système contraint   

Opposite of a → free system. See also → constraint.

Constrained, p.p. of → constrain; → system.

constraint
  پاوند   
pâvand (#)

Fr.: contrainte   

1) General: Limitation or restriction.
2) Mechanics: Any restriction imposed on the position or motion of a material system. Constraints are said to be internal if they do not impede free displacement of the system. All other kinds of constraints are called external. Systems subject only to internal constraints are free material systems.
3) Physics: A fact or condition, usually observational, that allows to reduce the number of free parameters in a theoretical model.

M.E. constreinte, from M.F., from constreindre, from L. constringere "to bind together, tie tightly," from → com- "together" + stringere "to bind, draw tight."

Pâvand "fetter, shackle," from "foot" (Mid.Pers. pâd, pây; Khotanese fad; Av. pad-; cf. Skt. pat-, Gk. pos, genitive podos; L. pes, genitive pedis; P.Gmc. *fot, E. foot, Ger. Fuss, Fr. pied; PIE *pod-/*ped-) + vand, variant band "tie, band," (Mod.-Mid./Pers. bastan/vastan "to bind, shut," Av./O.Pers. band- "to bind, fetter," banda- "band, tie," Skt. bandh- "to bind, tie, fasten," PIE *bhendh- "to bind," cf. Ger. binden, E. bind).

coronal rain
  باران ِ هورتاجی   
bârân-e hurtâji

Fr.: pluie coronale   

Material that condenses in the Sun's corona and appears to rain down into the chromosphere, as observed at the solar limb above strong sunspots.

coronal; → rain.

Draine field
  میدان ِ درین   
meydân-e Draine

Fr.: champ de Draine   

A unit used to express the strength of → far ultraviolet (FUV) average → interstellar radiation field. It is equal to ~ 1.7 → Habing field.

Named after B. T. Draine, 1978, ApJS 36, 595.

dust grain
  دانه‌ی ِ غبار   
dâne-ye qobâr (#)

Fr.: grains de poussière   

A small, solid flake of → graphite and/or → silicates coated with water ice, found in the → interstellar medium or the → interplanetary medium. Dust grains are irregularly shaped with sizes from microns to Angstroms (→ very small grain; → big grain; → PAH). It is believed that the dust is mainly formed in the cool outer layers of → red giants and dispersed in the interstellar medium. In dense environments, such as → molecular clouds and around → protostars, dust grains grow due to collisions (→ grain growth). Therefore, dust grains in → protostellar disks should be larger than interstellar grains. Dust grains absorb and scatter optical and ultraviolet light and re-radiate in infrared (→ dust emission). Dust acts as a catalyst in the interstellar medium, because molecules form via reactions on the surface of dust grains.

dust; → grain.

fluffy dust grain
  دانه‌ی ِ غبار ِ کرکوار   
dâne-ye qobâr-e korkvâr

Fr.: grain de poussière duveteux   

An aggregate of small particles loosely stuck together. Same as → porous dust grain.

fluffy; → dust; → grain.

grain
  دانه   
dâné (#)

Fr.: grain   

1) A small, hard seed of plants, especially the seed of cereals.
2) A tiny portion or particle of something such as sand or salt; → dust grain.

M.E. grain, grein, from O.Fr. grein, from L. granum "seed;" akin to corn.

Dâné "grain, seed;" Mid.Pers. dân, dânag "seed, corn;" Av. dānô- in dānô.karš- "carrying grains; an ant;" cf. Skt. dhânâ- "corn, grain;" Tokharian B tāno "grain;" Lith. duona "corn, bread."

grain coagulation
  ماسش ِ دانه   
mâseš-e dâné

Fr.: coagulation des grains   

Sticking together of micron- to centimetre-sized grains occurring in the interstellar and protoplanetary environments to form larger grain agglomerates.

grain; → coagulation.

grain evaporation
  بخارش ِ دانه   
boxâreš-e dâné

Fr.: évaporation des grains   

Conversion of dust grains into smaller grains due to high environmental temperatures.

grain; → evaporation.

grain formation
  دیسش ِ دانه   
diseš-e dâné

Fr.: formation des grains   

The process by which dust grains are assembled or produced.

grain; → formation.

grain growth
  رویش ِ دانه   
ruyeš-e dâné (#)

Fr.: croissance des grains   

The increase of dust grains to micron sizes in the interstellar environments due to various physical processes, for example mutual collisions and accumulation of ice mantles.

grain; → growth.

grain mantle
  روپوش ِ دانه   
rupuš-e dâné (#)

Fr.: manteau de grain   

A layer of icy molecules covering interstellar dust grains.

grain; mantle, from O.E. mentel "loose, sleeveless cloak," from L. mantellum "cloak," perhaps from a Celtic source.

Rupuš "overgarment, cloak," from ru "surface, face; aspect; appearance" (Mid.Pers. rôy, rôdh "face;" Av. raoδa- "growth," in plural form "appearance," from raod- "to grow, sprout, shoot;" cf. Skt. róha- "rising, height") + puš "covering, mantle," from pušidan "to cover; to put on" (Mid.Pers. pôšidan, pôš- "to cover; to wear;" cf. Mid.Pers. pôst; Mod.Pers. pust "skin, hide;" O.Pers. pavastā- "thin clay envelope used to protect unbaked clay tablets;" Skt. pavásta- "cover," Proto-Indo-Iranian *pauastā- "cloth").

grain sputtering
  ا ُسپرانی ِ دانه   
osparâni-ye dâné

Fr.: érosion des grains par pulvérisation   

The ejection of atoms from interstellar dust grains due to impact by gas ions, which leads to grain destruction.

grain; sputtering, from sputter "to spit with explosive sounds," cognate with Du. sputteren.

Osparâni, verbal noun of osparândan, from os- "out of, outside," → ex- + parândan "to eject," transitive of paridan "to fly" (from Mid./Mod.Pers. par(r) "feather, wing," Av. parəna- "feather, wing;" cp. Skt. parna "feather," E. fern; PIE *porno- "feather").

interstellar dust grain
  دانه‌ی ِ غبار ِ اندر‌اختری   
dâne-ye qobâr-e andaraxtari

Fr.: grain de poussière interstellaire   

dust grain.

interstellar; → dust; → grain.

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