setâre-ye barjâ, ~ istâdé, ~ biyâbâni (#)
Fr.: étoile fixe
Setâré, → star; barjâ,
Fr.: test de Fizeau
1) Burning gas or vapor, as from wood or coal, that is undergoing combustion;
a portion of ignited gas or vapor.
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.
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.
Fr.: éruption, sursaut
1) A sudden blaze or burst of fire or light.
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."
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).
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 bê "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."
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."
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.
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."
Fr.: variété plate
flat rotation curve
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.
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.
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.
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.
11 Taste, especially the distinctive taste of something as it is experienced in the mouth.
A particular quality noticeable in a thing (Dictionary.com).
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."
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).
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, 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
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").