An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 452
fertile isotope
  ایزوتوپ ِ بارور   
izotop-e bârvar

Fr.: isotope fertile   

An → isotope not itself → fissile but that is converted into a fissile isotope, either directly or after a short → decay process following absorption of a → neutron. Example: U-238 can capture a neutron to give U-239. U-239 then decays to Np-239 which in turn decays to fissile Pu-239. The most important fertile isotope is U-238. This is by far the most abundant isotope of natural uranium, making up 99.28%. The important transformation chain is: 92U238 + 0n193Np239 + β- (23.5 minutes) → 94Pu239 + β- (2.36 days).

fertile; → isotope .

Feynman diagram
  نمودار ِ فاینمن   
nemudâr-e Feynman

Fr.: diagramme de Feynman   

A schematic representation, in quantum electrodynamics and quantum chromodynamics, of the way elementary particles like electrons and protons interact with each other by exchanging photons. Use of Feynman diagrams can greatly reduce the amount of computation involved in calculating a rate or cross section of a physical process.

After the American physicist Richard P. Feynman (1918-1988), Nobel prize 1965; → diagram.

FHB star
  ستاره‌ی ِ FHB   
setâre-ye FHB

Fr.: étoile FHB   

Same as → field horizontal branch star.

field; → horizontal; → branch; → star.

fibr (#)

Fr.: fibre   

optical fiber.

From Fr. fibre, from O.Fr. fibre, from L. fibra "a fiber, filament," of uncertain origin, perhaps related to L. filum "thread."

Fibr, loan from Fr., as above.

Fibonacci number
  عدد ِ فیبوناچی   
'adad-e Fibonacci

Fr.: nombre de Fobonacci   

One of the numbers in the → Fibonacci sequence.

Fibonacci sequence; → number.

Fibonacci sequence
  پی‌آیه‌ی ِ فیبوناچی   
peyâye-ye Fibonacci

Fr.: suite de Fibonacci   

An infinite sequence of integers, starting with 0 and 1, where each element is the sum of the two previous numbers. For example: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ... As the sequence develops, the ratio of the consecutive terms converges to the → golden ratio, about 1.618.

Leonardo Pisano Fibonacci (1170-1250), medieval Italian mathematician who wrote Liber abaci (1202; Book of the Abacus), the first European work on Indian and Arabian mathematics, which introduced "Arabic" numerals in Europe; → sequence.

târcé (#)

Fr.: fibrille   

A linear pattern in the → chromosphere of the → Sun, as seen through an → H-alpha filter, occurring near strong → sunspots and → plages or in → filament channels. They are magnetically confined tubes of hot → plasma. Individually, they are about 10,000 km long and last for 10 to 20 minutes.

From Mod.L. fibrilla, from fibr(a) "fiber" + -illa diminutive suffix.

Târcé, from târ "thread, warp, → string" + diminutive suffix -cé, from Mid.Pers. -cak, variants -êžak (as in kanicak "little girl," sangcak "small stone," xôkcak "small pig"), also Mod.Pers. -ak.


Fr.: péroné   

Anatomy: The outer and thinner of the two bones of the human leg, extending from the knee to the ankle.

Fom L. fibula "clasp, brooch; bolt, peg, pin," related to figere "to drive in, insert, fasten," → fix.

Nâzok-ney, literally "fine reed," from nâzok "→ fine" + ney "reed, pipe, flute."


Fr.: fiction   

1) Literary works invented by the imagination, such as novels or short stories.
2) An invented story or explanation; lie.
3) The act of inventing a story or explanation.
4) Law: Something assumed to be true for the sake of convenience, though probably false (

M.E., from O.Fr. ficcion "dissimulation, ruse; invention, fabrication" and directly from L. fictionem "a fashioning or feigning," noun of action from p.p. stem of fingere "to shape, form, devise, feign," originally "to knead, form out of clay," from PIE *dheigh- "to build, form, knead;" akin to Skt. dehah "body," literally "that which is formed," dih- "to besmear;" Gk. teikhos "wall;" L. fingere "to form, fashion," Gothic deigan "to smear;" O.Irish digen "firm, solid."

Formed on the model of fiction, as above, from diz- "to build, to form;" (related to Pers. dež, dez "fortress"); cf. Mid.Pers. dys-/dēs- "to build;" Sogd. dys "to build;" Av. (+ *pari-) daēz- "to build (around);" Proto-Ir. *daiz- "to build, form;" from PIE *dheigh- "to build, form," as above, + suffix -an.

meydân (#)

Fr.: champ   

1) General: An expanse of anything.
2) Physics: A region or space defined by the presence of a physical force, such as electric, magnetic, or gravitational.
3) Math.: A mathematical entity for which addition, subtraction, multiplication, and division are well-defined.

M.E., from O.E. feld "plain, open land," probably related to O.E. folde "earth, land," from P.Gmc. *felthuz "flat land" (cf. Ger. Feld), from PIE *pel(e)-tu-,from base *pele- "flat, to sprea;" cf. L. planus "flat, level," → plane.

Meydân "field, arena, extensive plain; town square; gathering place" from Mid.Pers. mêdân "arena, field." Meydân has been borrowed into various languages: Ar. maydân, Turkish meydan, Crimean Tatar, Ukrainian maidan, Polish maidan, also in Pakistan, India, Indonesia, Nepal.

field curvature
  خمیدگی ِ میدان   
xamidegi-ye meydân (#)

Fr.: courbure de champ   

An aberration in an optical instrument, common in Schmidt telescopes, in which the focus changes from the center to the edge of the field of view. Owing to this aberration, a straight object looks curved in the image.

field; → curvature.

field equation
  هموگش ِ میدان   
hamugeš-e meydân

Fr.: équation de champ   

In a physical theory, an equation that describe how a fundamental force interacts with matter. Einstein's equations of → general relativity are called field equations since they describe the → gravitational field. Similarly, → Maxwell's equations describe the electromagnetic field.

field; → equation.

field galaxy
  کهکشان ِ میدان   
kahkešân-e meydân

Fr.: galaxie de champ   

A galaxy that lies in the direction of a → cluster of galaxies, but is not a member of the cluster. Field galaxies are rare, less than about 5% of all galaxies.

field; → galaxy.

field horizontal branch star
  ستاره‌ی ِ شاخه‌ی ِ افقی ِ میدانی   
setâre-ye šâxe-ye ofoqi-ye meydâni

Fr.: étoile de la branche horizontal du champ   

A → horizontal branch star with high velocity.

field; → horizontal; → branch; → star.

field lens
  عدسی ِ میدان   
adasi-ye meydân

Fr.: lentille de champ   

A lens placed at or near the focal plane of a telescope to create an image of the primary mirror inside the instrument.

field; → lens.

field O star
  ستاره‌ی ِ Oی ِ میدان   
setâre-ye O-ye meydân

Fr.: étoile O de champ   

An → O-type star which is apparently not associated with a → star cluster. A significant fraction of → massive stars in the → Milky Way and other galaxies are located far from star clusters and → star-forming regions. It is known that some of these stars are → runaways, i.e. possess high → space velocities (determined through the → proper motion and/or → radial velocity measurements), and therefore most likely were formed in embedded clusters and then ejected into the field because of dynamical interactions or → binary-→ supernova explosions. However, there exists a group of field O stars whose runaway status is difficult to prove via direct proper motion measurements or whose low space velocities and/or young ages appear to be incompatible with their large separation from known star clusters. The existence of this group led some authors to believe that these stars can form → in situ. The question of whether or not O stars can form in isolation (→ isolated massive star formation) is of crucial importance for → star formation models (Gvaramadze et al., 2012, MNRAS, 424, 3037).

field; → O star.

field object
  بر‌آخت ِ میدان   
barâxt-e meydân

Fr.: objet de champ   

An astronomical object that is seen in the direction of a group but not physically belonging to the group. → field galaxy.

field; → object.

field of force
  میدان ِ نیرو   
meydân-e niru (#)

Fr.: champ de force   

The region of → space surrounding a body, such as a mass of → matter, a → charged particle, or a → magnet, within which it can exert a → force on another similar body not in contact with it.

field; → force.

field of view
  میدان ِ دید   
meydân-e did (#)

Fr.: champ de vue   

The entire angular expanse of the sky viewed by an optical instrument.

field; → view.

field rotation
  چرخش ِ میدان   
carxeš-e meydân

Fr.: rotation de champ   

The effect of the Earth's rotation on the position of the image formed on the → focal plane of a telescope during long exposures. In the case of → equatorial mounting, the image remains fixed, whereas it turns continuously with an → altazimuth mounting. In the latter case the image motion must be compensated by an appropriate mechanism, → field rotator.

field; → rotation.

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