Fr.: Wolf-Rayet WNE
In theoretical models, a → Wolf-Rayet star without hydrogen at its surface (< 10-5 in number) and with surface carbon abundance smaller than nitrogen abundance.
Fr.: étoile de type WNh
A → WN Wolf-Rayet star which is hydrogen rich. WNh stars are initially more massive and have lost relatively little mass compared to other WR stars. It is suggested that these types are core hydrogen burning → main sequence objects. The most massive stars currently known are all WNh stars rather than O-type main sequence stars.
Fr.: Wolf-Rayet WNL
In theoretical models, a → Wolf-Rayet star with hydrogen at its surface (> 10-5 in number). A star enters the Wolf-Rayet phase as a WNL, then may evolve through the sequence WNL → WNE, → WC, → WO. It can end its evolution at any of these stages.
Fr.: Wolf-Rayet WO
A → Wolf-Rayet star whose spectrum shows emission lines of carbon and strong emission lines of oxygen O VI 3811-34 Å. In theoretical models, a W-R star whose carbon abundance at surface is larger than nitrogen abundance and has the abundance ratio (C + O) / He > 1 (in number).
Fr.: étoile WO1
An oxygen-rich → Wolf-Rayet star whose spectrum shows the following emission line characteristics: No O IV 3400 Å, strong O VI 3811-34 Å, O V 5572-98 Å about or stronger than C IV 5801-12 Å, no C III 5696 Å.
Fr.: étoile WO2
An oxygen-rich → Wolf-Rayet star whose spectrum shows the following emission line characteristics: No O IV 3400 Å, strong O VI 3811-34 Å, O V 5572-98 Å weaker than C IV 5801-12 Å, no C III 5696 Å.
1) palâpelidan; 2) palâpel
Fr.: chanceler, osciller, vaciller; chancellement, vacillement
1a) To incline to one side and to the other alternately, as a wheel, top, or
other rotating body when not properly balanced.
Probably from Low Ger. wabbeln "to wobble;" cognate with O.N. vafla "hover about, totter," related to vafra "move unsteadily."
Palâpel "wobbling, unsteady motion" in Âštiyâni dialect, variant in colloquial Persian pilipili, pelpel (pilipili raftan, pilipili xordan).
Fr.: minimum de Wolf
Fr.: nombre de Wolf
Named after Johann Rudolf Wolf of Zurich who introduced the number in 1852; → number.
A → dwarf irregular galaxy that is a remote and rather isolated member of the → Local Group. Also known as DDO 221 and LEDA 143. It is a dim galaxy located in the constellation → Cetus, about three million → light-years from the → Milky Way. Its nearest neighbor, the → dwarf galaxy IC 1613, is one million light-years away. Quite elongated, with a largest extension of more than 8,000 light-years, WLM is about 12 times smaller than the Milky Way, a measurement that includes a → halo of extremely → old stars. WLM has a → metallicity only about one-tenth that of the Milky Way.
Named after astronomer Max Wolf (1863-1932), who discovered the galaxy in 1909, and astronomers Knut Lundmark (1889-1958) and Philibert Jacques Melotte (1880-1961), who identified it as a galaxy some fifteen years later.
Fr.: galaxie Wolf-Rayet
A subset of → starburst galaxies whose integrated spectra show broad emission features attributed to the presence of hundreds to thousands → Wolf-Rayet stars. The most massive stars formed in the burst evolve rapidly into a substantial population of Wolf-Rayet stars in aggregations of ionized gas.
Fr.: étoile Wolf-Rayet
A type of very luminous, very hot (as high as 50,000 K) stars whose spectrum is characterized by broad emission lines (mainly He I and He II), which are presumed to originate from material ejected from the star at very high (~ 2000 km s-1) velocities. The most massive → O stars (M > 25 → solar masses for → solar metallicity) become W-R stars around 2 and 3 million years after their birth, spending only some few hundreds of thousands of years (≤ 106 years) in this phase until they explode as → type Ib and → type Ic supernovae. The minimum stellar mass that an O star needs to reach the W-R phase and its duration is dependent on → metallicity. → WC Wolf-Rayet; → WNE Wolf-Rayet; → WNL Wolf-Rayet; → WO Wolf-Rayet. For a review see: P. A. Crowther, 2007, Annu. Rev. of Astron. Astrophys. 45, 177.
Named after the French astronomers Charles Wolf (1827-1918) and Georges Rayet (1839-1906), of the Paris Observatory. In 1867 they discovered three stars in the constellation Cygnus (now designated HD191765, HD192103, and HD192641), that displayed broad emission bands in their spectra; → star.
manšur-e Wollaston (#)
Fr.: prisme de Wollaston
An optical device for producing and analyzing polarized light. It divides incoming unpolarized light into two orthogonal, linearly polarized beams. It consists of two prisms of either quartz or calcite cemented together.
After the English scientist William Hyde Wollaston (1766-1828); → prism.
Fr.: théorème de Woltjer
In magnetohydrodynamics, in the limit of zero resistivity, the magnetic field B satisfies the induction equation ∂B/∂t = ∇ x (v x B), then for a plasma confined by a perfectly conducting boundary, the → magnetic helicity is conserved. If the normal field is fixed on the boundary, the minimum-energy state is the linear → force-free magnetic field that conserves the total → magnetic helicity.
The female human being.
M.E. womman, wimman, O.E. wifman, from wif "female" + man "human being."
Zan "woman, wife;" Mid.Pers. zan "woman, wife;" kaniz "maid, virgin, girl;" Av. jəni- "woman, wife;" cf. Skt. jáni- "woman, wife;" Gk. gyne "woman, wife;" O.E. cwen "queen, woman, wife" (E. queen; Arm. kin "woman;" PIE base *gwenh- "woman, wife."
A unit of language, consisting of one or more sounds or their written representation, that communicates a meaning. → stopword
M.E., from O.E. word; cf. Du. woord, O.H.G., Ger. wort, Goth. waurd; related to verb, from L. verbum "verb;" from PIE *wer- "to speak, say."
Vâžé "word;" Mid.Pers. vâc, vâcak "word, speech;" related to âva "voice, sound," âvâz "voice, sound, song," bâng "voice, sound, clamour" (Mid.Pers. vâng); Av. vacah- "word," vaocanghê "to decalre" (by means of speech), from vac- "to speak, say;" cf. Skt. vakti "speaks, says," vacas- "word;" Gk. epos "word;" L. vox "voice;" PIE base *wek- "to speak."
If a force F acting on a body moves its point of application through a distance r, the work is defined by the product F.r.cosθ, where θ is the angle between the line of action of the force and the displacement. Work can be positive, negative, or zero.
M.E.; O.E. weorc, worc "something done, action, military fortification," from P.Gmc. *werkan (cf. O.S., O.Fris., Du. werk, O.N. verk, O.H.G. werah, Ger. Werk), from PIE base *werg- "to work;" cognate with Pers. varz-, varzidan "to labor, practise," → erg.
Kâr "work," Mid.Pers kâr; Mod./Mid.Pers. kardan "to do, to work," Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build," Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base kwer- "to do, to make."
Fr.: travail d'extraction
The least amount of energy required to remove an electron from the surface of a solid, to a point just outside the solid where the electron has zero kinetic energy. See also → photoelectric effect.
Fr.: principe travail-énergie
The → work of the resultant force exerted on a particle equals the change in kinetic energy of the particle.
Fr.: groupe de travail
A group of people working together to achieve a stated goal.