An Etymological Dictionary of Astronomy and Astrophysics
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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; → field.

A function whose value at each point is n-dimensional, as compared to a scalar function, whose value is one-dimensional.

→ vector; → function.

Any particle of unit spin, such as the W boson, the photon, or the rho meson.

→ vector; → meson.

The perturbation in the → primordial Universe plasma caused by → vorticity. These perturbations cause → Doppler shifts that result in → quadrupole anisotropy.

→ vector; → perturbation.

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; → product.

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).

→ vector; → space.

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' (النسر‌الواقع) "swooping eagle," from an-Nasr "eagle, vulture" + al-Waqi' "falling, swooping."

1) Any of various herbaceous plants having parts that are used as food, such as peas, beans, cabbage, potatoes, cauliflower, and onions.
2) Botany: Of, relating to, characteristic of, derived from, or consisting of plants or plant material (e.g. vegetable oils) (TheFreeDictionary.com).

→ vegetate; → -able.

1) Sabzijât "class or category of greens," from sabzi, → green, + -jât a suffix denoting class, group, or division of things.
2) Giyâhi, related to giyâh, → plant.

Of, relating to, or characteristic of plants.

→ vegetate; → -al.

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.

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.

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.

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."

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

→ veil; → nebula.

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.).

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.

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.

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.

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.

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.