An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13116 Search : far
weak emission-line central star (wel)
  ستاره‌ی ِ مرکزی با خط ِ گسیلی ِ نزار   
setâre-ye markazi bâ xatt-e gosili-ye nezâr

Fr.: étoile centrale à faibles raies d'émission   

A member of a class of cntral stars of planetary nebula, → CSPN, which have weaker and narrower emission lines than → Wolf-Rayet-like CSPNe (Tylenda et al. 1993, A&AS 102, 595).

weak; → emission; → line.

weak encounter
  رویارویی ِ نزار   
ruyâruyi-ye nezâr

Fr.: rencontre faible   

In a → star cluster, an → encounter that occurs at a distance and produces only very small changes in a star's velocity.

weak; → encounter.

weak equivalence principle
  پروز ِ هموگ‌ارزی ِ نزار   
parvaz-e hamug-arzi-ye nezâr

Fr.: principe d'équivalance faible   

All structureless bodies fall along the same → path in a → gravitational field, independent of their composition. Also known as → universality of free fall. See also: → equivalence principle, → Einstein equivalence principle.

weak; → equivalence; → principle.

weak force
  نیروی ِ نزار، ~ کمزور   
niru-ye nezâr, ~ kamzur

Fr.: force faible   

Same as → weak interaction.

weak; → force.

weak gravitational lensing
  لنزش ِ گرانشی ِ نزار   
lenzeš-e gerâneši-ye nezâr

Fr.: effet de lentille gravitationnelle faible   

A gravitational bending of light by structures in the Universe that distorts the images of distant galaxies. The distortion allows the distribution of → dark matter and its evolution with time to be measured, thereby probing the influence of → dark energy on the growth of structures. Weak gravitational lensing is generally difficult to identify in individual images, in contrast to → strong gravitational lensing (see, e.g., Bartelmann & Peter Schneider, 2001, Phys. Rept. 340, 291).

weak; → gravitational; → lensing.

weak interaction
  اندرژیرش ِ نزار، ~ کمزور   
andaržireš-e nezâr, ~ kamzvr

Fr.: interaction faible   

One of the fundamental forces of nature that accounts for some particle interaction, such as → beta decay (→ radioactivity), the decay of free → neutrons, → neutrino interactions, and so forth. It is short-ranged, dominating at distances of 10-16 cm and occurs at a rate slower than that of the → strong interaction by a factor of about 10-13, hence its name. Although the weak interaction also includes interactions in which no neutrinos are emitted, neutrino emission accompanies all weak interactions of interest to astrophysics. Weak interaction plays an important role in the evolution of the stars from birth to death. For example, the → proton-proton reaction is a weak interaction. Also called → weak force or → weak nuclear force.

weak; → interaction.

weak lensing
  لنزش ِ نزار   
lenzeš-e nezâr

Fr.: effet de lentille faible   

The → gravitational lensing in which the images are only weakly distorted, and do not form wide arcs or multiple image systems. This happens if the → gravitational lens mass in front of a source is not concentrated enough to form multiple images. The resulting small distortions cannot be seen on individual sources, as we do not know their unlensed, "intrinsic" shape. However, if an entire population of background sources is available, the distortions can be revealed, either statistically or by local averaging. See also → strong lensing.

weak; → lensing.

weak nuclear force
  نیروی ِ هسته‌ای ِ نزار، ~ ~ کمزور   
niru-ye hasteyi-ye nezâr, ~ ~ kamzur

Fr.: force nucléaire faible   

Same as → weak interaction.

weak; → nuclear; → force.

weak wind problem
  پراسه‌ی ِ باد ِ نزار، ~ ~ کمزور   
parâse-ye bâd-e nezâr, ~ ~ kamzur

Fr.: problème de faible vent   

The discrepancy between the observed → mass loss rates and the predicted values for → weak-wind O-type stars.

weak; → wind; → problem.

weak-line T Tauri star
  ستاره‌ی ِ T-گاو با خط‌های ِ نزار   
setâre-ye T-Gâv bâ xatthâ-ye nezâr

Fr.: étoile T Tauri à raies faibles   

A T Tauri star that lacks strong emission lines in its optical spectrum, and lacks both strong → stellar wind and → infrared excess. These objects are believed to be → pre-main sequence stars without obvious signs for disk → accretion. Weak-line T Tauri stars result from the evolution of → classical T Tauri stars.

weak; → line; → T Tauri star.

weak-wind O-type star
  ستاره‌ی ِ O با باد ِ نزار، ~ ~ ~ ~ کمزور   
setâre-ye O bâ bâd-e nezâr, ~ ~ ~ ~ kamzur

Fr.: étoile O de faible vent   

A → main sequence → O star with low luminosity and surprisingly weak → stellar wind compared to "classical" dwarfs. The → mass loss rates are lower than 10-8 solar masses per year and the → modified wind momenta nearly 2 orders of magnitude smaller than that expected from wind models for typical O stars. Weak-wind O-type stars occur in both → metal-rich and → metal-poor environments. Their nature is not yet fully understood. same as → weak wind problem.

weak; → wind; → O-type star.

weather
  هواب، هوا   
havâb, havâ (#)

Fr.: temps   

The state of the → atmosphere, mainly with regard to its effects of temperature, cloudiness, rainfall, wind, etc. upon life and human activities. As distinguished from → climate, weather consists of the short-term variations in the atmosphere.

M.E., from O.E. weder; cf. M.Du., Du. weder, O.H.G. wetar, Ger. Wetter "storm, wind, weather."

Havâb, short for havâ "weather; air" (see below) + âbwater, from âb o havâ "weather; climate."
Havâ, from Ar., probably itself a loanword from Mid.Pers. vây "weather, air," Av. vayah-, vaya- "weather," from va- "to blow;" cf. Skt. va-, Gk. aemi- "to blow;" Av. vâta- "wind," Skt. vata-, L. ventus, Mod. Pers. bâd "wind." PIE *we- "to blow;" havâb contraction of havâ + âb "→ water," from âb o havâ "weather," literally "water and air."

weathering
  سایند   
sâyand (#)

Fr.: altération atmosphérique   

Geology: The various processes, such as the actions of wind, rain, temperature changes and so forth, which mechanically and chemically cause exposed rocks to decompose.

From → weather + → -ing.

Sâyand, from sâyidan "to touch, to rub," variants sâbidan, pasâvidan; Khotanese sauy- "to rub;" Sogdian ps'w- "to touch;" ultimately Proto-Iranian *sau- "to rub."

web
  وپ، کرو؛ کاتنه   
vap, karu kâtené

Fr.: toile   

1) A network of fine threads constructed by a spider from fluid secreted by its spinnerets, used to catch its prey.
2) A complex system of interconnected elements (OxfordDictionaries.com)

M.E., from O.E. webb "woven fabric, woven work, tapestry," from (cf. O.Sax. webbi, O.Norse vefr, Du. webbe, O.H.G. weppi, Ger. Gewebe "web"); Skt. ubhnati "he laces together," Per. baftan "to weave," as below; Gk. hyphe, hyphos "web;" PIE *webh- "to weave."

Vap, variant of Mid.Pers. waf-, wap- "to weave;" Baluchi gwapit, gwapt/gwap-, Yazdi vôpt/vôp- "to weave;" Mod.Pers. bâf-/bâftan; Av. ubdaēna- "made from woven material;" Proto-Ir. *uab/f "to weave;" cognate with web, as above.

weber (Wb)
  وبر   
weber (#)

Fr.: weber   

The → SI unit of → magnetic flux. It is equal to 108 → maxwells.

Named after German physicist Wilhelm Eduard Weber (1804-1891).

Weber-Fechner law
  قانون ِ وبر-فشنر   
qânun-e Weber-Fechner (#)

Fr.: loi de Weber-Fechner   

A physiological relationship stating that to make a sensation increase in arithmetical proportion, the stimulus must increase in geometrical progression. In acoustics, the → bel (B) unit is used to relate the intensity of sound to an intensity level corresponding to the human hearing sensation. Similarly, the division of stars into a scale of → magnitudes is based upon the Weber-Fechner law. Same as Fechner's law.

After Ernst Heinrich Weber (1795-1878), a German physician, was one of the first people to approach the study of the human response to a physical stimulus in a quantitative fashion, and Gustav Theodor Fechner (1801-1887), a German physicist who founded psycho-physics and proposed the mathematical formulation in 1860; → law.

wedge
  گو ِه   
gové (#)

Fr.: coin   

A glass prism of very small angle used as an optical element to divert the path of a beam of light for a particular purpose. → absorbing wedge.

M.E. wegge; O.E. wecg "a wedge," cf. M.Du. wegge, Du. wig, O.H.G. weggi "wedge," Ger. Weck "wedge-shaped bread roll."

Gové "wedge;" Av. vada- "wedge," xvaδa- "deadly weapon;" cf. Skt. vadhá- "killer, deadly weapon," vadh- "to slay, kill;" Gk. othein "to push" (root of → osmosis).

wedge photometer
  نورسنج ِ گُوه‌ای   
nursanj-e gove-yi

Fr.: photomètre à coin   

A photometer in which an → absorbing wedge is inserted in the brighter of two beams until the flux densities of the two light sources are equal.

wedge; → photometer.

week
  هفته   
hafté (#)

Fr.: semaine   

A division of time containing 7 successive days, which is completely independent of the month or the year. Unlike the month and the year, the week is an artificial unit of time, lacking an equivalent astronomical period.

M.E. weke; O.E. wice, cf. O.N. vika, M.Du. weke, O.H.G. wecha, Ger. Woche, akin to L. vicis "turn, change."

Hafté "week, hebdomad," from haft "seven" → hepta-.

Weierstrass approximation theorem
  فربین ِ نزدینش ِ وایرشتراس   
farbin-e nazdineš-e Weierstrass

Fr.: théorème d'approximation de Weierstrass   

If a function φ(x) is continuous on a closed interval [a,b], then for every ε > 0 there exists a polynomial P(x) such that |f(x) - P(x)| <ε, for every x in the interval.

After German mathematician Karl Wilhelm Theodor Weierstrass (1815-1897); → approximation; → theorem.

<< < -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 > >>