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vary vartidan Fr.: changer, varier 1) To undergo change in form, substance, appearance, etc. M.E. varien, from O.Fr. varier, from L. variare "change, alter, make different," from varius "variegated, different, spotted." Vartidan "to change," from Mid.Pers. vartitan "to change, turn" (Mod.Pers. gardidan "to turn, to change"); Av. varət- "to turn, revolve;" cf. Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend." |
vector bordâr (#) Fr.: vecteur Any physical quantity which requires a direction to be stated in order to define it completely, for example velocity. Compare with → scalar. From L. vector "one who carries or conveys, carrier," from p.p. stem of vehere "carry, convey;" cognate with Pers. vâz (in parvâz "flight"); Av. vaz- "to draw, guide; bring; possess; fly; float," vazaiti "guides, leads" (cf. Skt. vah- "to carry, drive, convey," vahati "carries," pravaha- "bearing along, carrying," pravāha- "running water, stream, river;" O.E. wegan "to carry;" O.N. vegr; O.H.G. weg "way," wegan "to move," wagan "cart;" M.Du. wagen "wagon;" PIE base *wegh- "to drive"). Bordâr "carrier," agent noun from bordan "to carry, transport" (Mid.Pers. burdan; O.Pers./Av. bar- "to bear, carry," barəθre "to bear (infinitive);" Skt. bharati "he carries;" Gk. pherein "to carry;" L. ferre "to carry;" PIE base *bher- "to carry"). |
vector analysis ânâlas-e bordâri Fr.: analyse vectorielle The study of → vectors and → vector spaces. |
vector angular velocity bordâr-e tondâ-ye zâviye-yi Fr.: vecteur de vitesse angulaire Of a rotating body, a vector of magnitude ω (→ angular velocity) pointing in the direction of advance of a right-hand screw which is turned in the direction of rotation. |
vector boson boson-e bordâri Fr.: boson vectoriel In nuclear physics, a → boson with the spin quantum number equal to 1. |
vector calculus afmârik-e bordâri Fr.: calcul vectoriel The study of vector functions between vector spaces by means of → differential and integral calculus. |
vector density cagâli-ye bordâr Fr.: densité de vecteur A → tensor density of → order 1. |
vector field meydân-e bordâri (#) Fr.: champ vectoriel A vector each of whose → components is a → scalar field. For example, the → gradient of the scalar field F, expressed by: ∇F = (∂F/∂x)i + (∂F/∂y)j + (∂F/∂z)k. |
vector function karyâ-ye bordâri Fr.: fonction vectorielle A function whose value at each point is n-dimensional, as compared to a scalar function, whose value is one-dimensional. |
vector meson mesoon-e bordâri Fr.: meson vectoriel Any particle of unit spin, such as the W boson, the photon, or the rho meson. |
vector perturbation partureš-e bordâri Fr.: perturbation vectorielle The perturbation in the → primordial Universe plasma caused by → vorticity. These perturbations cause → Doppler shifts that result in → quadrupole anisotropy. → vector; → perturbation. |
vector product farâvard-e bordâri Fr.: produit vectoriel Of two vectors, a vector whose direction is perpendicular to the plane containing the two initial vectors and whose magnitude is the product of the magnitudes of these vectors and the sine of the angle between them: A x B = C, C = |AB sin α|. The direction of C is given by the → right-hand screw rule. Same as → cross product. See also → scalar product. |
vector space fazâ-ye bordâri (#) Fr.: espace vectoriel A system of mathematical objects consisting of a set of (muultidimensional) vectors associated with a set of (one-dimensional) scalars, such that vectors can be added together and vectors can be multiplied by scalars while preserving the ordinary arithmetic properties (associativity, commutativity, distributivity, and so forth). |
Vega (α Lyr) Vâqe', Nasr-e Vaqe' (#) Fr.: Véga The brightest star in the constellation → Lyra and the 5th brightest star in the sky. It is an A type → main sequence star of visual magnitude 0.03. Vega is also one of the closer stars to the Earth, lying just 25.0 light-years away. Vega's axis of rotation is nearly pointing at the Earth, therefore it is viewed pole-on. Fast rotation has flattened Vega at its poles, turning it from a sphere into an oblate spheroid. The polar diameter of Vega is 2.26 times that of the Sun, and its equatorial diameter 2.75 solar. The poles are therefore hotter (10,150 K) than the equator (7,950 K). Vega, from Ar. al-Waqi' contraction of
an-Nasr al-Waqi' ( |
veil vâšâmé (#) Fr.: voile 1) A piece of opaque or transparent cloth worn by women as a covering for the
head and shoulders. 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 miq-e vâšâmé Fr.: Nébuleuse du Voile A part of the → Cygnus loop, an old → supernova remnant. |
veiling vâšâmeš Fr.: voilage 1) General: An act of covering with or as if with a veil. Verbal noun from veil (v.). |
Vela 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 bâd→ wind + -bân a suffix denoting "keeper, guard," sometimes forming agent nouns or indicating relation, → host. |
Vela pulsar 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 supernova remnant 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. |
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