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: 224
vegetate
  گیاهیدن   
giyâhidan

Fr.: végéter   

1) To grow or sprout as a plant by nutriment imbibed through roots and leaves.
2) To lead a passive life without much physical, mental, or social activity.

Ultimately from L. vegetatus, p.p. of vegetare "to enliven, to animate," from vegetus "vigorous, enlivened, active," from vegere "to be alive, active;" akin to Skt. vaja- "force, strength;" PIE root *weg- "to be strong, be lively."

Giyâhidan, infinitive forum giyâh, → plant.

vegetation
  گیاهش   
giyâheš

Fr.: végétation   

1) All the plants or plant life of a place.
2) (Botany) Plant life as a whole, especially the plant life of a particular region.
3) The act or process of vegetating.

Verbal noun from → vegetate.

vegetative
  گیاهوار   
giyâhvâr

Fr.: végétatif   

1) Of, relating to, or characteristic of plants or their growth.
2) Noting the parts of a plant not specialized for reproduction (TheFreeDictionary.com).

vegetate; → -ive.

Giyâhvâr, from giyâh, → plant, + -vâr suffix denoting "resembling, like," → -oid.

veil
  واشامه   
vâšâmé (#)

Fr.: voile   

1) A piece of opaque or transparent cloth worn by women as a covering for the head and shoulders.
2) Something that covers, screens, or conceals.

M.E. veile; O.Fr. voile "a head-covering" (also "sail"), from L. vela, plural of velum "curtain, covering; sail."

Vâšâmé "veil," variants vâšâm, bâšâmé, bâšâm, from Mid.Pers. *varšâmak (loaned in Arm. varšamak "veil, scarf"); cf. Sogd. wâršâmé "veil;" from Proto-Ir. *varšāmaka-, from *varšām-, from *varš-, from var- "to cover;" cf. Av. var- "to cover, conceal;" Skt. var- "to cover;" Mid.Pers. warr "garment," prefixed uzvâr-, uzvârdan "to uncover, show, apprehend, interprete;" Mod.Pers. šalvâr "trousers" (literally "thigh cover;" the first component šal "thigh," šelang "thigh; step, distance between feet when walking," cognate with Gk. skelos "leg"); Kurd. (Soriani) barg "cover; clothes," da barg girtin "to wrap in a cover."

Veil Nebula
  میغ ِ واشامه   
miq-e vâšâmé

Fr.: Nébuleuse du Voile   

A part of the → Cygnus loop, an old → supernova remnant.

veil; → nebula.

veiling
  واشامش   
vâšâmeš

Fr.: voilage   

1) General: An act of covering with or as if with a veil.
2) A weakening of the → spectral lines of a star that occurs when the spectral lines are filled in by → continuum emission or light from a → companion star.

Verbal noun from veil (v.).

vein
  سیاهرگ   
siyâhrag (#)

Fr.: veine   

Any of the tubes forming part of the blood circulation system of the body, carrying mainly oxygen-depleted blood towards the heart (OxfordDictionaries.com).

M.E. veine, from O.Fr. veine "vein, artery, pulse," from L. vena "a blood vessel," also "a water course, a vein of metal," of unknown origin.

Siyâhrag, literally "black vessel," from siyâh, → black, + rag, → vessel.

Vela
  بادبان   
Bâdbân (#)

Fr.: Voile   

The Sail. A part of the constellation Argo in the Southern hemisphere, which was later divided into three parts, the others being Carina and Puppis. Vela is situated at about 10h right ascension, -50° declination. Abbreviation: Vel; Genitive: Velorum.

From L. vela, plural of velum "sail, curtain, covering," velare "to cover, veil."

Bâdbân "sail," literally "wind keeper," from bâdwind + -bân a suffix denoting "keeper, guard," sometimes forming agent nouns or indicating relation, → host.

Vela pulsar
  پولسار ِ بادبان، تپار ِ ~   
pulsâr-e Bâdbân, tapâr-e ~

Fr.: pulsar du Voile   

A pulsar with a short period (89 milliseconds) associated with the → Vela supernova remnant. It is approximately 1500 light-years distant. The Vela pulsar is one of the few pulsars detectable optically. Its optical flashes, of visual magnitude 26, were detected in 1977. Also named PSR 0833-45.

Vela; → pulsar.

Vela supernova remnant
  بازمانده‌ی ِ اَبَر-نو‌اَختر ِ بادبان   
bâzmânde-ye abar-now-axtar-e Bâdbân

Fr.: reste de supernova du Voile   

A → supernova remnant located in the southern Milky Way in the constellation → Vela. It has a large angular diameter of about 8° and lies 250 ± 30 pc away (Cha et al. 1999, ApJ 515, L25). Its overall emission is dominated by the interaction of the → supernova blast wave with the → interstellar medium. This SNR is also notable for a number of protrusions extending well beyond its rim, which were suggested to be fragments of ejecta from the supernova explosion. X-ray spectroscopy has since confirmed several of these protrusions to indeed be strongly enriched with ejecta. The age of the SNR is estimated to be ~11,000 years, based on the spin-down rate of the associated → Vela pulsar, but ages as large as 20,000-30,000 years have also been argued.

Vela; → supernova remnant.

Vela X
  بادبان X   
Bâdbân X

Fr.: Vela X   

A compact radio source about 1500 light-years distant associated with the Vela supernova remnant. It has a nonthermal radio spectrum and is about 20 percent polarized. It is associated with the Gum Nebula, the Vela pulsar, and the X-ray source 2U 0832-45.

Vela; X for → X ray.

velocity
  تندا   
tondâ

Fr.: vitesse   

The time rate of change of position in a given direction, measured as length per unit time. → speed.

L. velocitatem (nominative velocitas) "swiftness, speed," from velox (genitive velocis) "swift."

Tondâ, from tond "swift, rapid, brisk; fierce, severe" (Mid.Pers. tund "sharp, violent;" Sogdian tund "violent;" cf. Skt. tod- "to thrust, give a push," tudáti "he thrusts;" L. tundere "to thrust, to hit" (Fr. percer, E. pierce, ultimately from L. pertusus, from p.p. of pertundere "to thrust or bore through;" PIE base *(s)teud- "to thrust, to beat") + noun suffix .

velocity curve
  خم ِ تندا   
xam-e tondâ

Fr.: courbe de vitesse   

A plot of the radial velocity of an object against time, derived from the Doppler shift of spectral lines.

velocity; → curve.

velocity dispersion
  پاشش ِ تندا   
pâšeš-e tondâ

Fr.: dispersion de vitesses   

The → standard deviation of a velocity → distribution. It indicates how objects of the sample move relative to one another. Objects with similar velocities have a small velocity dispersion, whereas objects with very different velocities have a large velocity dispersion.

velocity; → dispersion.

velocity gradient
  زینه‌ی ِ تندا   
zine-ye tondâ

Fr.: gradient de vitesse   

Fluid Mechanics: The rate at which the velocity changes with the distance across the flow. When a fluid flows past a stationary wall, the fluid right close to the wall does not move. However, away from the wall the flow speed is not zero. Therefore a velocity gradient exists, which is due to adhesive, cohesive, and frictional forces. The amount of the velocity gradient is characteristic of the fluid.

velocity; → gradient.

velocity law
  قانون ِ تندا   
qânun-e tondâ

Fr.: loi de vitesse   

In the theory of → radiation-driven winds, an equation that describes the behavior of the → wind velocity of → hot stars as a function of distance from the star. This velocity β-law is given by the expression: v(r) = v(1 - R*/r)β, where v is the → terminal velocity, R* is the stellar radius, and r the distance from the center. For → O-type stars, the exponent is estimated to be β = 0.8.

velocity; → law.

velocity of light
  تندی ِ نور، تندای ِ ~   
tondi-ye nur, tondâ-ye ~

Fr.: vitesse de la lumière   

A → physical constant which represents the ultimate speed limit for anything moving through space, according to the theory of → special relativity. It is the speed of propagation of → electromagnetic waves in a vacuum, equal to 299,792.458 km/s (nearly 3 x 108 m/s). The velocity of light appears as the connecting link between mass and energy in the → mass-energy relation. Usually denoted by c, from L. celeritas "swiftness," from celer "swift," → acceleration.

velocity; → speed; → light.

velocity pressure
  فشار ِ توانیک   
fešâr-e tavânik

Fr.: pression dynamique   

dynamic pressure.

velocity; → pressure.

velocity profile
  فراپال ِ تندا   
farâpâl-e tondâ

Fr.: profil de vitesse   

A plot of the fluid velocity as a function of position.

velocity; → profile.

velocity space
  فضای ِ تندا، ~ تنداها   
fazâ-ye tondâyi, ~ tondâhâ

Fr.: espace de vitesses   

Of a dynamical system, a three-dimensional space which consists of the set of values that the velocity can take (vx, vy, vz). → phase space.

velocity; → space.

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