An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 221
Wolf-Rayet galaxy
  کهکشان ِ وُلف-رایه   
kahkešân-e Wolf-Rayet

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.

Wolf-Rayet star; → galaxy.

Wolf-Rayet star
  ستاره‌ی ِ وُلف-رایه   
setâre-ye Wolf-Rayet

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.

Wollaston prism
  منشور ِ وُلاستون   
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.

Wolter telescope
  تلسکوپ ِ ولتر   
teleskop-e Wolter

Fr.: télescope Wolter   

A → grazing incidence telescope designed to observe → X-ray emission from astronomical objects. Wolter telescopes use a combination of two elements, a parabolic mirror followed by a hyperbolic mirror and come in three different optical configurations. The design most commonly used by X-ray astronomers is the Type I since it has the simplest mechanical configuration. In addition, the Type I design offers the possibility of nesting several telescopes inside one another, thereby increasing the useful reflecting area. This is an extremely important attribute, since virtually all X-ray sources are weak, and maximizing the light-gathering power of a mirror system is critical. The → Chandra X-Ray Observatory is a Wolter Type I telescope that has four thick nested mirrors coated in iridium. The Japanese X-ray observatory Suzuki uses a conical approximation of the Wolter Type I design. Its mirrors are coated in gold, and they are far thinner than the ones used in Chandra. This allows for denser nesting, so there are 700 mirrors instead of four. The result is a much higher collecting efficiency at a reduced weight. For comparable apertures and grazing angles, the primary advantage of Type II over Type I is that higher magnifications are attainable. This is because the second reflection is off the outside of a surface, which allows longer focal lengths. However, since off-axis images suffer much more severely from blurring in Type II configurations, the Wolter Type II is useful only as a narrow-field imager or as the optic for a dispersive spectrometer. The Wolter Type III has never been employed for X-ray astronomy (NASA Imagine the Universe!).

Named after Hans Wolter (1911-1978), a German physicist who designed the optical configuration.

Woltjer's theorem
  فربین ِ وُلتشر   
farbin-e Woltjer

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.

Named after the Dutch astrophysicist Lodewijk Woltjer, who discovered the phenomenon in 1958 while studying the → Crab Nebula; → theorem.

zan (#)

Fr.: femme   

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."

vâžé (#)

Fr.: mot   

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."

kâr (#)

Fr.: travail   

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."

work function
  کریای ِ کار   
karyâ-ye kâr

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.

work; → function.

work-energy principle
  پروَز ِ کار-کاروژ   
parvaz-e kâr-kâruž

Fr.: principe travail-énergie   

The → work of the resultant force exerted on a particle equals the change in kinetic energy of the particle.

work; → energy; → principle.

working group
kâr-goruh (#)

Fr.: groupe de travail   

A group of people working together to achieve a stated goal.

work; → -ing; → group.

working surface
  زنار ِ اندر-آژیرش   
zonâr-e andar-âžireš

Fr.: zone d'interaction   

The double shock structure formed in any two fluids that collide supersonically. A working surface consists of two → shocks, a → bow shock where the ambient material is shocked and accelerated, and a jet shock or → Mach disk, where the → jet material is decelerated. It is common to find multiple working surfaces along the axis of an → Herbig-Haro jet, testifying to recurrent eruptions of the underlying source.

work; → -ing; → surface.

kârgâh (#)

Fr.: atelier   

1) A place where manual work is done, especially manufacturing or repairing.
2) A group of people working on a creative project, discussing a topic, or studying a subject.

work + shop M.E. shoppe, O.E. sceoppa; cf. O.H.G. scopf "porch," Ger. Schuppen "a shed").

Kârgâh "workshop," from kâr, → work, + gâh "place; time" (Mid.Pers. gâh, gâs "time;" O.Pers. gāθu-; Av. gātav-, gātu- "place, throne, spot;" cf. Skt. gâtu- "going, motion; free space for moving; place of abode;" PIE *gwem- "to go, come").

jahân (#)

Fr.: monde   

1) The Earth with its inhabitants. Compare → cosmos and → Universe.
2) Other planets, particularly → exoplanets.
3) Any realm, or domain, with all pertaining to it.
4) Physics: The → space-time in four dimensions, as distinguished from three-dimensional space. → world line.

M.E.; O.E. woruld, weorold; cf. O.S. werold, O.Fris. warld, Du. wereld, O.N. verold, O.H.G. weralt, Ger. Welt.

Jahân, variants keyhân, geyhân "world," giti "world, material world, time;" Mid.Pers. gêhân "world," gêtig "the material world; wordly," Manichean Mid.Pers. gyh "world," gyh'n "worlds;" Av. gaēθā- "being, world, matter, mankind" (O.Pers. gaiθā- "livestock"), gaya- "life, manner of living," root gay- "to live" (present tense jiva-), cognate with Skt. jīv- "to live," jīva- "alive, living;" Gk. bios "life," L. vivus "living, alive," vita "life;" PIE base *gwei- "to live" (cf. O.E. cwic "alive;" O.C.S. zivo "to live;" Lith. gyvas "living, alive;" O.Ir. bethu "life," bith "age, life, world;" Welsh byd "world"). The Pers. words zistan "to live," zendé "alive," zendegi "life," and jân "vital spirit, soul; mind" belong to this family.

world line
  خط ِ جهان، جهان-خط   
xatt-e jahân, jahân-xatt (#)

Fr.: ligne d'univers   

In relativity, the path traced out in four-dimensional → space-time that represents a continuous sequence of events relating to a given particle. A point on a world line is called an → event. Any straight world line corresponds to an → inertial motion. Curved world lines represent → accelerated motion. A world line that curves corresponds to an accelerated observer. World lines are shown on space-time diagrams.

world; → line.

  کرم-سوراخ، سوراخ ِ کرم   
kerm-surâx, surâx-e kerm

Fr.: trou de ver   

A hypothetical topological feature, based on → general relativity, that connects two different points like a "tunnel" in → space-time. The most common concept of a wormhole is an → Einstein-Rosen bridge. A trip through the wormhole could take much less time than a journey between the same starting and ending points in normal space. Wormholes have various types, intra-universe wormholes (connecting two distant regions of our Universe with each other) and inter-universe wormholes (that connect our Universe with another universe).

The term was coined by the Princeton physicist John Wheeler (1911-2008), from worm, M.E., O.E. wurm "serpent, dragon;" cf. O.S., O.H.G., Ger. wurm, O.Fris., Du. worm, Goth. waurms "serpent, worm;" akin to Pers. kerm "worm," as below; → hole.

Kerm "worm;" Mid.Pers. kirm "worm, snake, dragon;" cf. Skt. krmi- "worm, maggot;" O.Ir. cruim "worm;" Lith. kirmis "worm;" L. vermis "worm;" E. worm, as above; surâx, → hole.

wrinkle ridge
  روک ِ چروکدار   
ruk-e corukdâr


A low, sinuous tectonic ridge on a planetary surface that resembles a wrinkle in skin or cloth. These features were first detected on the Moon, but they have also been identified on other planetary bodies such as Mars, Mercury, and Venus.

M.E., back formation from wrinkled, from O.E. gewrinclod "wrinkled, crooked," p.p. of gewrinclian "to wind, crease," from perfective prefix ge- + -wrinclian "to wind;" → ridge

Ruk, → ridge; corukdâr, from coruk "wrinkle" + dâr "having, possessor" (from dâštan "to have, to possess," Mid.Pers. dâštan, O.Pers./Av. root dar- "to hold, keep back, maitain, keep in mind;" cf. Skt. dhr-, dharma- "law;" Gk. thronos "elevated seat, throne;" L. firmus "firm, stable;" Lith. daryti "to make;" PIE *dher- "to hold, support").

neveštan (#)

Fr.: écrire   

To trace or form (letters, words, or other symbols) on a surface, typically paper, with a pen, pencil, or other similar instrument.

M.E. writen, O.E. writan "to score, outline, draw," later "to set down in writing;" cf. O.Frisian writa "to write," O.Saxon writan "to tear, scratch, write," O.Norse rita "write, scratch," O.H.G. rizan "to write, scratch, tear," Ger. reissen "to tear, pull, sketch, draw."

Neveštan, nevis- "to write," variants Kurd. (Sor.) nus, nusen, Lori nisane "to write," Kurd. (Kurm.) âvîtin, âvêntin, (Sor.) havîštin, hâvîtin "to compose (a song), to change (color);" Mid.Pers. (+ → ni-) nibištan, nebês- "to write," pēsīdan "to adorn;" O.Pers. pais- "to cut, adorn, engrave;" Av. paēs- "to paint, adorn," paēsa- "adornment;" cf. Skt. piśáti "adorns; cuts;" Gk. poikilos "multicolored;" L. pingit "embroiders, paints;" O.C.S. pisati "to write;" O.H.G. fēh "multicolored;" Lith. piēšti "to draw, adorn;" PIE base *peik- "colored, speckled."

nâdorost (#)

Fr.: faux   

1) Not in accordance with what is morally right or good: a wrong deed.
2) Deviating from truth or fact; erroneous: a wrong answer.
3) Not correct in action, judgment, opinion, method, etc., as a person; in error (
See also: → false, → invalid.

M.E. wrong, wrang, O.E. wrang "twisted, crooked," from O.N. rangr "crooked, wry, wrong;" cf. Dan. vrang "crooked, wrong," Du. wrang "sour, bitter."

Nâdorost, from nâ- "not," → a-, + dorost, → right.


Fr.: Wronskien   

The → determinant of order n associated with a set of n functions, in which the first row consists of the functions, the second row consists of the first → derivatives of the functions, the third row consists of their second derivatives, and so on. For example, If y1 and y2 are functions of x, the determinant W(y1,y2) = y1 . y2' - y1' . y2 is called the Wronskian of the given function.

Named after the Polish mathematician Józef Hoene-Wroński (1776-1853).

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