An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc coh col col col Com com com com com com com com Com con con con con con con con con con con con con coo Cor Cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg ura uti val var vec Vel ver Ver vie Vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>

Number of Results: 13116 Search : far
voltage
  ولتاژ   
voltâž (#)

Fr.: voltage, tension   

The electric potential difference expressed in volts.

From → volt.

voltaic
  ولتایی   
voltâyi (#)

Fr.: voltaïque   

Of, relating to electricity or electric currents, especially when produced by chemical action, as in a cell. → photovoltaic detector.

Alessandro Volta (1745-1827), Italian physicist, known for his pioneering work in electricity.

volume
  گنج   
gonj (#)

Fr.: volume   

The amount of space occupied by a three-dimensional object or region of space, expressed in cubic units.

M.E. volum(e), from O.Fr. volume, from L. volumen (genitive voluminis) "roll (as of a manuscript), coil, wreath," from volvere "to turn around, roll."

Gonj "volume," gonjidan "to be contained or held; to hold;" gonjâyeš "capacity, holding, containing;" Mid.Pers. winj- "to be contained;" Proto-Iranian *uiac-/*uic-; cf. Skt. vyac- "to contain, encompass," vyás- "extent, content, extension;" L. uincire "to bind."

volume-limited survey
  بردید با گنج ِ حدمند   
bardid bâ gonj-e hyaddmand

Fr.: relevé limité en volume   

A survey in which the observed objects are contained in a given volume of space.

volume; → limited; → survey.

von Zeipel paradox
  پارادخش ِ فون زایپل   
pârâdxš-e von Zeipel

Fr.: paradoxe de von Zeipel   

A → rotating star cannot simultaneously achieve → hydrostatic equilibrium and → rigid body rotation. The paradox can be solved if → baroclinic flows (essentially a → differential rotation and a → meridional circulation) are included. For a broader view of the subject see: M. Rieutord, 2006, in Stellar Fluid Dynamics and Numerical Simulations: From the Sun to Neutron Stars, ed. M. Rieutord & B. Dubrulle, EAS Publ., 21, 275, arXiv:astro-ph/0608431.

von Zeipel theorem; → paradox.

von Zeipel theorem
  فربین ِ فون زایپل   
farbin-e von Zeipel

Fr.: théorème de von Zeipel   

A theorem that establishes a relation between the → radiative flux at some → colatitude on the surface of a → rotating star and the local → effective gravity (which is a function of the → angular velocity and colatitude). For a rotating star in which → centrifugal forces are not negligible, the → equipotentials where gravity, centrifugal force, and pressure are balanced will no longer be spheres. The theorem states that the radiative flux is proportional to the local effective gravity at the considered colatitude, F(θ) ∝ geff (θ)α, where α is the → gravity darkening coefficient. As a consequence, the stellar surface will not be uniformly bright, because there is a much larger flux and a higher → effective temperature at the pole than at the equator (Teff (θ) ∝ geff (θ)β, where β is the → gravity darkening exponent. In → massive stars this latitudinal dependence of the temperature leads to asymmetric → mass loss and also to enhanced average → mass loss rates. Also called → gravity darkening. See also → von Zeipel paradox; → meridional circulation; → baroclinic instability; → Eddington-Sweet time scale.

Named for Edvard Hugo von Zeipel, Swedish astronomer (1873-1959), who published his work in 1924 (MNRAS 84, 665); → theorem.

von Zeipel's law
  قانون ِ فون زایپل   
qanun-e von Zeipel

Fr.: loi de von Zeipel   

Same as the → von Zeipel theorem.

von Zeipel theorem; → law.

vortex
  گردشار   
gerdšâr (#)

Fr.: vortex   

Meteo.: A whirling mass of water or air.
A pattern of rotation in which the rotation direction rotates by 360° along any path which surrounds the centre of the vortex.

From L. vortex, variant of vertex "whirlpool; whirlwind, an eddy of water, wind, or flame;" from stem of vertere "to turn," cognate with Pers. gardidan, as below.

Gerdšâr (on the model of gerdâb "whirlpool" and gerdbâd "whirlwind"), from gard present stem of gardidan "to turn, to change" (Mid.Pers. vartitan "to change, to turn;" 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") + šâr, from šâré, → fluid.

vortical
  گردشاری   
gerdšâri (#)

Fr.: vorticiel   

Of or pertaining to a → vortex.

Adj. from → vortex.

vorticity
  گردشاریگی   
gerdšârigi

Fr.: vorticité   

In fluid mechanics, a measure of the rate of rotational spin in a fluid. Mathematically, vorticity is a vector field defined as the curl of the velocity field: ω = ∇ x v.
Meteo.: The rotation of air around a vertical axis.

From L. vortic-, from → vortex + → -ity.

Gerdšârigi, from gerdšârvortex + -igi, → -ity.

vowel
  خود‌آوا   
xodâvâ (#)

Fr.: voyelle   

A speech sound that is produced as a stream of air that is not obstructed or blocked in any way by the vocal organs, but only modulated by the position of the tongue, lips, etc.

M.E., from O.Fr. vouel, from L. vocalis shortening of littera vocalis, literally "vocal letter," from  → vox "voice," cognate with Pers. âvâ, → phone, vâžé, → word.

Xodâvâ, literally "self-voice," as Ger. Selbstlaut, from xod-, → self-, + âvâ, → phone.

Vulcan
  وولکان   
Vulkân (#)

Fr.: Vulcain   

A hypothetical small planet proposed in the 19-th century to exist in an orbit between Mercury and the Sun. In order to explain some characteristics of Mercury's orbit, the French astronomer Urbain Jean Joseph Le Verrier (1811-1877) hypothesized the presence of another planet, which he named Vulcan. Those particularities of Mercury's orbit were later explained by Albert Einstein's theory of general relativity.

L. Vulcanus in Roman mythology the blacksmith god of fire and volcanoes, a word of Etruscan origin

vulgar
  جرگوار   
jargvâr

Fr.: vulgaire   

1) Characterized by ignorance of or lack of good breeding or taste.
2) Spoken by, or being in the language spoken by, the people generally; vernacular (Dictionary.com).

From L. vulgaris, volgaris "of or pertaining to the common people, common, vulgar, low, mean," from vulgus "the common people, multitude, crowd, throng" (cognates: Skt. varga- "a company, group, section," Pers. jarga, as below, Gk. eilein "to press, throng," Welsh gwala "sufficiency, enough").

Jargvâr, from jarg, jarga, jargé "a group of people, a ring of men or beasts;" cf. Lori, Laki jarga "group, throng," jarra "bundle;" Kurd. jerge, cerge "assembly, club;" + -vâr a suffix denoting "suiting, befitting, resembling, in the manner of, possession."

vulgar fraction
  برخه‌ی ِ همدار   
barxe-ye hamdâr

Fr.: fraction d'entiers   

Same as → common fraction.

M.E., from L. vulgaris, from vulgus "the common people," + -aris, → -ar.

common; → fraction.

Vulpecula
  روباهک   
Rubâhak (#)

Fr.: Petit Renard   

The Little Fox. A faint constellation in the northern hemisphere, at 20h right ascension, +25° declination, between Cygnus and Aquila. Abbreviation: Vul; Genitive: Vulpeculae.

L. Vulpecua, from vulpes "fox," cognate with Pers. rubâh, as below, + diminutive suffix -cula, variant of → -ule.

Rubâhak "little fox," from rubâh

VY Canis Majoris (VY CMa)
   VY سگ ِ بزرگ   
VY Sag-e Bozorg

Fr.: VY Grand Chien   

A → red supergiant star which is one of the largest and most intrinsically luminous stars in the sky. It has a radius of about 1,420 solar radii (→ solar radius) and a luminosity of 3 × 105 Lsun (→ solar luminosity). It is about 3,900 → light-years from the Earth. Excluding solar system bodies, VY CMa is the third brightest object in the sky at 10 µm. It has a large optical → reflection nebula, visible through even small telescopes, created by its prodigious mass loss (> 10-4 Msun per year). Its initial mass is estimated to be about 25 Msun and its current mass 17 Msun. Recent observations have shown the presence of submicron → dust grains, with an average radius of ~ 0.5 μm, in the ejecta. These grains are 50 times larger than those found in the diffuse → interstellar medium (P. Scicluna et al., 2015, A&A, 584L, 10S).

V and Y, following the → variable star designation scheme; → Canis Major.

Vz star
  ستاره‌ی ِ Vz   
setâre-ye Vz

Fr.: étoile de type Vz   

A class of → O-type stars whose spectra show He II 4686 absorption line much stronger than any other He line especially He II 4541 or He I 4471. Vz stars are thought to be young stars lying close to the → ZAMS (Walborn & Parker 1992, ApJ 399, L87). Alternatively, the Vz characteristics may be related to the wind properties rather than to the youth of the star (Martins et al., 2005, A&A 441, 735).

V indicating → main sequence, z for "zero age;" → star.

W 43
     
W 43

Fr.: W 43   

One of the most massive → star formation regions in the → Galaxy, situated in the constellation → Aquila at the junction point of the → Galactic bar and the → spiral arms. It lies at a distance of about 6 kpc from the Sun and covers a vast area of the → Galactic plane with l = (29° to 32°) and b = (-1° to + 1°). W 43 is a complex of more than 20 → molecular clouds in 13CO emission with systemic velocities ranging from 12 km s-1 to 110 km s-1. The total → virial mass is estimated to be several 106Msun. Close to its center, W 43-Main is undergoing a remarkably efficient episode of → star formation and qualifies as a mini-starburst Among the 15 dense cores of W 43-Main (0.2 pc FWHM size and 5 × 105 cm-3 density), three extremely massive, → dense cores are potentially forming → massive stars: W 43-MM1 (M = 3600 Msun), W 43-MM2 (M = 1600 Msun), and W 43-MM3 (M = 1000 Msun). Adjacent to W 43-Main is a → giant H II region, illuminated by a cluster of → Wolf-Rayet and → OB stars, emitting ~ 1051 → Lyman continuum photons per second and a → far-infrared  → continuum luminosity of ~ 3.5 × 106  Lsun. It is not yet clear what the impact is of this → starburst cluster on the W 43-Main cloud located 2-10 pc away. With its special characteristics, W 43 represents a type of molecular cloud complex which hosts high luminosity embedded clusters. Other well-known examples are W 49 and W 51 (e.g., Nguyen Luong et., 2013, arXiv:1306.0547).

Number 43 in the following catalog: Gart Westerhout, 1958, Bull. Astron. Inst. Netherlands, 14, 215, A survey of the continuous radiation from the galactic system at a frequency of 1390 Mc/s.

W boson
  بوسون ِ W   
boson-e W

Fr.: boson W   

A → boson particle that, along with → Z boson, mediates the → weak force in particle interactions. Two kinds of W bosons exist, the W+ and its antiparticle W-. With a mass of 80.4 GeV/c2, the W boson is almost 100 times as massive as the → proton.

W for → weak; → boson.

W Virginis star
  ستاره‌ی ِ W-دوشیزه   
setâre-ye W dušizé

Fr.: étoile de type W Virginis   

A member of a class of → pulsating stars with a period of 1 to 35 days located in the → instability strip of the → H-R diagram. Also known as type II Cepheid variables, W Virginis stars are typically 1.5 mag fainter than classical Type I Cepheids and have a mass less than that of the Sun. They also exhibit a period-luminosity relation which is distinct, but works in a similar way to the relation for Type I Cepheids. Hence W Virginis stars can also be used to measure Galactic and extragalactic distances.

W, alphabetical letter; → variable star designation; → Virgo; → star.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc coh col col col Com com com com com com com com Com con con con con con con con con con con con con coo Cor Cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg ura uti val var vec Vel ver Ver vie Vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>