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: 431
fixed star
  ستاره‌ی ِ برجا، ~ ایستاده، ~ بیابانی   
setâre-ye barjâ, ~ istâdé, ~ biyâbâni (#)

Fr.: étoile fixe   

A → heavenly body that, in → contrast to the → planets, does not appear to change its relative → position on the → celestial sphere.

Fixed, p.p. of → fix; → star.

Setâré, → star; barjâ, → fixed.
Istâdé (Biruni in at-Tafhim) "standing," from istâdan "to stand;" O.Pers./Av. sta- "to stand, stand still; set" (cf. Skt. sthâ- "to stand;" Gk. histemi "put, place, weigh;" stasis "a standing still;" Lith. statau "place;" Goth. standan; L. stare "to stand;" PIE base *sta- "to stand");
Biyâbâni (Biruni in at-Tafhim), from Mid.Pers. awiyâbânig "fixed," from negation prefix → a- + wiyâbânig "wandering," from wiyâbân "deluded, seduced," wiyâbânênidan "to lead astray, deceive," from Av. vi- "apart, away from, out" (O.Pers. viy- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + dab- "to deceive;" cf. Skt. vimugdha- "confused, bewildered," vimohita- "confused, infatuated." Note that biyâbân "desert" is from an other origin.

Fizeau test
  آزمون ِ فیزو   
âzmun-e Fizeau

Fr.: test de Fizeau   

The determination of the shape of an optical surface by means of → interferometry using a → fringe pattern formed with respect to a reference surface.

Named after the French physicist Armand Hippolyte Louis Fizeau (1819-1896), see also → toothed-wheel experiment; → test.

flame
  آیژ   
âyež (#)

Fr.: flamme   

1) Burning gas or vapor, as from wood or coal, that is undergoing combustion; a portion of ignited gas or vapor.
2) Any flame-like condition; glow; inflamed condition (Dictionary.com).

M.E. flaume, variant of flaumbe from Anglo-French flaume, flaumbe "a flame;" O.Fr. flambe, from L. flammula "small flame," diminutive of flamma "flame, blazing fire," from PIE *bhleg- "to shine, flash," from root *bhel- (1) "to shine, flash, burn."

Âyež, from (Dehxodâ) âyež "flame," variants âyiž, âyežé, ižak, of unknown origin.

Flamsteed designation
  نامگزینی ِ فلمستید   
nâmgozini-ye Flamsteed

Fr.: designation de Flamsteed   

A stellar designation system in which each star is assigned a number followed by the Latin genitive of its corresponding → constellation, such as → 61 Cygni and 82 Eridani. Compare with the → Bayer designation.

Named after John Flamsteed (1646-1719), founder of the Greenwich Observatory, and the first astronomer royal of England, who introduced this system in his catalog Historia Coelestis Britannica (1725); → designation.

flare
  آلاو   
âlâv (#)

Fr.: éruption, sursaut   

1) A sudden blaze or burst of fire or light.
2) → solar flare.

From v. flare "to spread out," said of hair, a ship's sides, etc., of unknown origin.

Âlâv, "blaze, fire," variants alow, Borujerdi elew "fire," Garkuyeyi alôv "flame," Hamadâni elow "flame," Lori alô "flame," Tabari aluk "flame, spark," Torbat-Heydariyeyi alow "flame;" cf. Gk. aithos "fire," aitho "to kindle;" Skt. edh- "to set alight, kindle," édha-, édhas- "firewood;" Av. aēsma- "firewood;" Mod.Pers. hizom, himé "firewood;" PIE base *aidh- "to burn," *aidhos- "fire."

flare star
  ستاره‌ی ِ آلاوی، آلاو-ستاره   
setâre-ye âlâvi, âlâv-setâré

Fr.: étoile à éruption   

A member of a class of dwarf stars that undergoes sudden, intense outbursts of light (mean amplitude about 0.5-0.6 mag).

flare; → star.

flared disk
  گرده‌ی ِ برون‌گشا، دیسک ِ ~   
gerde-ye borun-gošâ, disk-e ~

Fr.: disque évasé   

A model of → accretion disk around a → pre-main sequence star or a → protostar in which the ratio of the disk thickness to the distance from the star increases outward. Current models of the irradiation of flared disks by stellar radiation predict that a central hole is created around the young star due to the evaporation of dust by the stellar radiation. The inner rim of the disk, at 0.5 to 1 AU from the star, is irradiated by the star "frontally" (at 90° angle). The heat produced by the irradiation causes the inner rim to puff up. A part of the disk, from about 1 to 6 AU, lies in the shadow of the puffed-up inner rim. The surface layers in this region do not receive stellar photons directly. Therefore, there is no significant heating of the disk midplane by reprocessed stellar flux from the disk surface. The midplane temperatures in the shadowed part of the disk are governed by the → near infrared emission of the inner rim, scattering of stellar light by dust particles outside the disk plane, and radial diffusion which exchanges energy between adjacent slabs. As for the outer parts of the disk, the surface is irradiated by the central star thanks to the outward widening of the disk. These parts remain flared, because the absorbed stellar flux is partially emitted toward the midplane, keeping the internal temperatures high enough to push the surface layers up. The flattened-disk model explains the observed → spectral energy distribution of some objects such as HD 179218. It also accounts for the observed strong → far-infrared, → excess, strong → PAH emission, and strong [O I] emission. Compare with → self-shadowed disk. See also → protoplanetary disk.

Flared, from flare "to spread gradually outward, as the end of a trumpet, having a gradual increase in width," of unknown origin; → disk.

Gerdé, → disk; borun-gošâ "opening outward," from borun "out, the outside" (Mid.Pers. bêron, from "outside, out, away" + rôn "side, direction;" Av. ravan- "(course of a) river") + gošâ stem of gošâdan, gošudan "to open;" Mid.Pers. wišâdan "to open, let free;" Khotanese hiyā "bound;" O.Pers. višta "untied, loosend;" vištāspa- (personal name) "with loosened horses;" Av. višta "untied," hita- "fastened, tied on;" cf. Skt. sā- "to bind, fasten," syáti "binds."

flash
  درخش   
deraxš (#)

Fr.: flash, éclair   

A Sudden, brief burst of light. In particular, → green flash.

From M.E. flasshen "to sprinkle, splash," from flasken, probably imitative.

Deraxš, present stem of deraxšidan "to shine, radiate," from raxš "lightening, reflection of light," raxšidan "to shine, flash," O.Pers. raucah-, Av. raocah- "light" (cf. Skt. roka- "brightness, light," Gk. leukos "white, clear," L. lux "light" (also lumen, luna), E. light, Ger. Licht, Fr. lumière; PIE base *leuk- "light, brightness"); cognate with Mod.Pers. words ruz "day," rowšan "bright, clear," foruq "light," and afruxtan "to light, kindle."

flash spectrum
  بیناب ِ درخشی   
binâb-e deraxši

Fr.: spectre-éclair   

The spectrum of the solar → chromosphere obtained during a → solar eclipse in the instant before or after → totality. In the flash spectrum the usual solar → absorption lines are replaced with bright → emission lines. This is because in that very short interval only the → photosphere is eclipsed by the Moon, and not the chromosphere. The American astronomer Charles A. Young was the first to observe it during the the solar eclipse of 1870 (December 22) in Spain.

The flash designation comes from the fact that the change from dark-line to bright-line spectrum is very rapid; → flash; → spectrum.

flat
  تخت   
taxt (#)

Fr.: plat   

Level and horizontal, without any slope; even and smooth, without any bumps or hollows.
See also:
flat manifold, → flat Universe, → flat-field, → flatness problem.

Flat, from O.N. flatr, from P.Gmc. *flataz (cf. O.H.G. flaz "flat, level," O.E. flet, O.H.G. flezzi "floor"), perhaps from PIE *pla- (cf. Gk. platys "broad, flat;" Av. pərətu- "broad, wide;" Skt. prthu- "broad, wide, large").

Taxt "flat;" Mid.Pers. taxtag "tablet, plank, (chess)board."

flat manifold
  بسلای ِ تخت   
baslâ-ye taxt

Fr.: variété plate   

A manifold with a → Riemannian metric that has → zero → curvature.

flat; → manifold.

flat rotation curve
  خم ِ چرخش ِ تخت   
xam-e carxeš-e taxt

Fr.: courbe de rotation plate   

A galactic → rotation curve in which the → rotation velocity is constant in the outer parts. The flat component is preceded by a rising curve that shows solid body rotation in the very center of the → galaxy. A flat rotation curve implies that the mass is still increasing linearly with radius. See also → dark matter.

flat; → rotation; → curve.

flat Universe
  گیتی ِ تخت   
giti-ye taxt

Fr.: univers plat   

A Universe where the → geometry is → Euclidean, i.e. parallel lines remain parallel when extended into the distance and the sum of the interior angles of a triangle is 180°. The → space-time in a flat Universe has a null → curvature constant, k = 0. See also → closed Universe, → open Universe.

flat; → universe.

flat-field
  میدان ِ تخت   

Fr.: champ plat   

Exposure of a diffuse and uniform source in order to calibrate the non-uniformity of an imaging detector such as a CCD.

flat; → field.

Meydân, → field; taxt, → flat.

flatness problem
  پراسه‌ی ِ تختی   
parâse-ye yaxti

Fr.: problème de la platitude   

The observed fact that the → geometry of the → Universe is very nearly flat, in other words its density is very close to the → critical density. This would be an extreme coincidence because a → flat Universe is a special case. Many attempts have been made to explain the flatness problem, and modern theories now include the idea of → inflation.

flat; → problem.

flavor
  چاشنی   
câšni (#)

Fr.: saveur   

11 Taste, especially the distinctive taste of something as it is experienced in the mouth. A particular quality noticeable in a thing (Dictionary.com).
2) Any of the six labels given to the distinct kinds of → quark: up, down, strange, charm, bottom, and top.
3) → neutrino flavor.

M.E., from O.Fr. flaor "smell, odor; action of smelling, sense of smell," probably from V.L. flator "odor," literally "that which blows," in L. "blower," from flareQ "to blow, puff," which is cognate with O.E. blawan, → blow.

Câšni "taste; taste by way of a sample; quality," related to cašidan, caš- "to taste," câšt "breakfast," cašté "bait;" Mid.Pers. câšt "meal," câšnig "taste;" cf. Skt. cas- "to eat;" Proto-Ir. caš- "to eat, to drink; to drip."

Fleming's rules
  رزن‌های ِ فلمینگ   
razanhâ-ye Fleming

Fr.: règles de Fleming   

Two rules used to assist in remembering the relative directions of the magnetic field, current, and motion in electrical machines, using one's fingers. The right hand refers to generators, the left hand to motors. The three directions are represented by the thumb (for force or motion), forefinger (for field), and second finger (for current), all held at right angles to each other.

Devised by the British physicist and electrical engineer John Ambrose Fleming (1849-1945).

flight
  پرواز   
parvâz (#)

Fr.: vol   

The act, manner, or power of flying.

O.E. flyht "a flying, flight," from P.Gmc. *flukhtiz (cf. Ger. Flucht).

Parvâz, from Mid.Pers. parwâz; Av. pāirivāza- "overrunning," from pāiri- "over (of space), from" + vāza- from vaz- "to fly, float; to drive;" cf. Skt. vah-, vahati. Also Mid.Pers. vâz "jump, flight," Mod.Pers. Lori, Gilaki, Tabari vâz "jump, leap."

flint glass
  فلینت، شیشه‌ی ِ ~   
flint, šiše-ye ~ (#)

Fr.: flint, flint-glass   

A basic type of optical glass containing lead oxide and a smaller amount of potassium, characterized by its brilliance, clarity, and durability. It has a high → dispersion relative to its → refractive index, as compared to, e.g. → crown glass. Flint glass is sometimes used as the diverging lens component of an → achromatic lens. It is also used in the manufacture of table glassware.

Flint, because it was originally made of calcined flints, from M.E., O.E.; cf. M.Du. vlint, O.H.G. flins, Dan. flint; Gk. plinthos "brick, tile."

flocculent spiral galaxy
  کهکشان ِ مارپیچ ِ پشمین   
kahkešân-e mârpic-e pašmin

Fr.: galaxie spirale floculente   

A galaxy that has short segments of patchy spiral structure so that the disk appears like the fleece of a sheep. Examples: NGC 2841 and NGC 5055.

From L. floccus "flock of wool" + -ulent; → spiral galaxy.

Kahkešân, → galaxy; mârpic, → spiral; pašmin "woolly, woollen," from pašm "wool" (Mid.Pers. pašm "wool;" Av. pašna- "eyelash, eyelid;" cp. Skt. páksman- "eyelashes;" Gk. pekos "wool, fleece," pek(t)ein "to comb, pluck;" Lith. pešti "to pluck;" O.N. fax "mane").

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