An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -fy fac fal fas fee Fer Fib fil fin fir fix flo flu foc for for fou fra fre Fre FU fuz > >>

Number of Results: 431
fluorescent lamp
  لامپ ِ فلوءورست   
lâmp-e fluorest

Fr.: ampoule fluorescente   

A tubular → electric discharge lamp in which light is produced by the → fluorescence → phosphors coating the inside of the tube.

fluorescent; → lamp.


Fr.: fluorure   

A compound (salt of hydrofluoric acid) containing → fluorine.

fluorine; → -id.

fluor (#)

Fr.: fluor   

Gaseous chemical element; symbol F. It is the most reactive of all chemical elements. It is a yellowish, corrosive gas, which reacts with most organic and inorganic substances. → Atomic number 9; → atomic weight 18.9984; → melting point -219.62 °C; → boiling point -188.14 °C; → density 1.696 grams per liter at STP; → valence -1. Fluorine and its compounds are used in producing uranium (from the → hexafluoride) and more than 100 commercial fluorochemicals, including many high-temperature plastics.

From L. fluere "flow, → flux," since fluorspar (CaF2) was used as a flux in metallurgy because of its low melting point. It was discovered in hydrofluoric acid by the Swedish pharmacist and chemist Carl-Wilhelm Scheele in 1771 but it was not isolated until 1886 by the French pharmacist and chemist Ferdinand Moisson.


Fr.: fluorite, fluorine   

A → mineral composed of calcium fluoride, CaF2, also called → fluorspar, that is often → fluorescent under → ultraviolet light.

From fluor-, → fluorine, + → -ite.


Fr.: fluorine   

Same as → fluorite.

From fluor-, → fluorine, + spar "a crystalline mineral."

šâr (#)

Fr.: flux   

The amount of energy, fluid, or particles passing in a given direction in a unit of time.

O.Fr. flux, from L. fluxus, p.p. of fluere "to flow," PIE base *bhleug- (cf. L. flumen "river;" Gk. phluein "to boil over, bubble up," phlein "to abound").

Šâr "outpouring of water, wine, etc.," šâridan "to flow (as rivers), with a great noise; to pour," âbšâr "waterfall;" saršâr "overflowing; brim-full;" Ossetic ægzælyn "to pour down;" Pashto zγâstəl/zγâl- "to swim;" Av. γžār- "to flow;" cf. Skt. ksar- "to flow;" Gk. phtheirein "to destroy, perish."

flux calibration
  کبیزش ِ شار   
kabizeš-e šârr

Fr.: calibration de flux   

The → calibration of the flux received by a detector in terms of absolute units.

flux; → calibration.

flux density
  چگالی ِ شار   
cagâli-ye šârr

Fr.: densité de flux   

Flux of radiation that falls on a detector per unit surface area of the detector per unit bandwidth of the radiation per unit time.

flux; → density.

flux unit
  یکای ِ شار   
yekâ-ye šârr

Fr.: unité de flux   

In radio astronomy, same as → jansky (symbol Jy), a unit of electromagnetic flux equivalent to 10-26 watts per square meter per Hertz.

flux; → density.

  پرواز کردن، پروازیدن   
parvâz kardan (#), parvâzidan (#)

Fr.: voler   

To move through the air using wings. Travel through the air or outer space.

M.E. flien, O.E. fleogan; cognate with O.H.G. fliogan, Ger. fliegen, O.Norse fljuga.

Infinitive from parvâz, → flight.


Fr.: survol   

A trajectory that takes a → space probe close to a Solar System body (planet, satellite, asteroid, comet) but does not permit it to enter an orbit about the body.

fly + by, from M.E., from O.E. be or bi, from P.Gmc. *bi "around, about" (cf. Du. bij, Ger. bei "by, at, near"), from *umbi, (cf. L. ambi "around, about," Gk. amphi "around, about," Skt. abhi "on both sides," Av. aibi, aiwi, O.Pers. aiby "to, against, in addition to," Mid.Pers. aw-, ab-, Mod.Pers. af- (as in afzudan "to increase, add," afruxtan "to inflame, kindle, blaze," afqân "lamentation, groaning, cires for help").

Barvâz, from bar- "on, up; upon, over," → on-, + vâz, as in parvâz, → flight.

kânuni (#)

Fr.: focal   

Of or relating to a focus; placed at or measured from a focus.

focus + → -al.

focal distance
  دورای ِ کانونی   
durâ-ye kânuni

Fr.: distance focale   

same as → focal length.

focal; → distance.

focal length
  درازای ِ کانونی   
derâzâ-ye kânuni

Fr.: longueur focale   

The distance between the optical center of a lens, or the surface of a mirror, and its focus.

focal; → distance.

focal plane
  هامن ِ کانونی   
hâmon-e kânuni

Fr.: plan focal   

A plane at right angles to the principal axis of a lens or mirror on which the best image is formed.

focal; → plane.

focal point
  نقطه‌ی ِ کانونی   
noqte-ye kânuni

Fr.: point focal   

Same as → focus.

focal; → point.

focal ratio
  وابر ِ کانونی   
vâbar-e kânuni

Fr.: rapport focal   

The ratio of the → focal length of a reflecting surface or lens to its effective diameter, i.e. to its → aperture. The smaller the focal ratio, the smaller the image scale and the more luminous the image for a given aperture.

focal; → ratio.

focal reducer
  کاهنده‌ی ِ کانونی، باز‌هازنده‌ی ِ ~   
kâhande-ye kânuni, bâzhâzande-ye ~

Fr.: réducteur focal   

An optical component or system for changing the image scale of a telescope to achieve a better match between the → seeing disk and the → pixel size.

focal; → reducer.

  ۱) کانون؛ ۲) کانونیدن   
1) kânun; 2) kânunidan

Fr.: 1) foyer; 2) focaliser   

1) (n.) A point where parallel light rays from an object are gathered together by a lens or a concave mirror. It is the place where the clearest image of a distant object forms. Also called focal point. See also → focal distance.
2) (v.) To adjust the eyepiece or objective of a telescope so that the image is clearly seen by the observer.

From L. focus "hearth, fireplace," of unknown origin,

Kânun "hearth, fireplace."


Fr.: focalisé   

Of an optical system, being in focus or brought into focus; adjusted to produce a clear image.

Past participle of → focus.

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