An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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 fermion   فرمیون   fermion (#)Fr.: fermion   An elementary particle, such as → electron, → proton, or → neutron, having a half integral value of → spin. Fermions obey the → Pauli exclusion principle.From Fermi → fermi + → -on. ferric iron   آهن ِ فریک   âhan-e ferrikFr.: fer ferrique, fer trivalent   Iron in a plus-3 → oxidation state. Ferric iron needs to share three electrons with an oxygen molecule to make the ion neutral.→ ferric; → iron. ferrous iron   آهن ِ فرور   âhan-e fervarFr.: fer ferreux, fer bivalent   Iron in a plus-2 → oxidation state.→ ferrous; → iron. Fibonacci number   عدد ِ فیبوناچی   'adad-e FibonacciFr.: nombre de Fobonacci   One of the numbers in the → Fibonacci sequence. Fibonacci sequence   پی‌آیه‌ی ِ فیبوناچی   peyâye-ye FibonacciFr.: 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. fiction   دیزن   dizanFr.: 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 (Dictionary.com).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. field equation   هموگش ِ میدان   hamugeš-e meydânFr.: 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 horizontal branch star   ستاره‌ی ِ شاخه‌ی ِ افقی ِ میدانی   setâre-ye šâxe-ye ofoqi-ye meydâniFr.: étoile de la branche horizontal du champ   A → horizontal branch star with high velocity.→ field; → horizontal; → branch; → star. field rotation   چرخش ِ میدان   carxeš-e meydânFr.: 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. fine-structure constant   پایای ِ ساختار ِ نازک   pâyâ-ye sâxtâr-e nâzokFr.: constante de la structure fine   A measure of the strength of → interaction between a → charged particle and the → electromagnetic field. It is a → dimensionless number expressed (in → cgs units) by α = e2/ħc, where e is the → electron charge, ħ is the → reduced Planck's constant, and c is the → speed of light. It is approximately equal to 1/137 or 7.3 x 10-3. The smallness of this number is of great importance since it determines the size of → atoms and the → stability of → matter. fingering convection   همبز ِ انگشتوار   hambaz-e angoštvârFr.:   A weak yet important kind of mixing that results from → fingering instability in stars within → radiative zones that have an unstable mean → molecular weight  → gradient. Also called → thermohaline convection.→ finger; → -ing; → convection. finite population   پرینش ِ کرانمند   porineš-e karânmandFr.: population finie   A → statistical population consisting of individuals or items which are finite in number.→ finite; → population. first approximation   نزدین ِ نخست   nazdin-e naxostFr.: première approximation   1) Generally, an expression to indicate that a comment or result is only approximate. 2) Math.: In calculus, limiting a differential equation to its → first derivative, for example: ex≅ 1 + x. Also called → linear approximation.→ first; → approximation. first contact   پرماس ِ نخست   parmâs-e naxostFr.: premier contact   1) The beginning of a → solar eclipse when the eastern part of the lunar limb touches the western limb of the Sun, marking the beginning of an eclipse. 2) For a → lunar eclipse, the moment when the eastern limb of the Moon is the first to enter the Earth's shadow.→ first; → contact. first degree equation   هموگش ِ درجه‌ی ِ یکم   hamugeš-e daraje-ye yekomFr.: équiation du premier degré   A equation in which the highest → exponent of the → variable is 1. Same as → linear equation.→ first; → degree; → equation. first-order differential equation   هموگش ِ دگرسانه‌ای ِ رایه‌ی ِ نخست   hamugeš-e degarsâne-yi-ye râye-ye naxostFr.: équation différentielle du premier ordre   A → differential equation containing only the first → derivative. For example, dy/dx = 3x and 2y(dy/dx) + 3x = 5.→ first; → order; → differential; → equation. fission   شکافت   šekâft (#)Fr.: fission   1) The act or process of splitting or breaking into parts. 2) Splitting of the nucleus of an atom into two or more fragments of comparable size, usually as the result of the impact of a neutron on the nucleus. Same as → nuclear fission.Fission, from L. fissionem "a breaking up, cleaving," from root of findere "to split."Šekâft, stem of šekâftan "to split, break, tear," akin to kaftan, kâftan "to split; to dig," Parthian Mid.Pers. q'f- "to split;" Sogdian kβ "to split;" Chorasmian kf- "to split, be split;" Proto-Iranian *kap-, *kaf- "to split." fission products   فر‌آورده‌های ِ شکافت   farâvardehâ-ye šekâft (#)Fr.: produits de fission   Nuclides generated by the fission of higher mass elements or by subsequent radioactive decay of nuclides directly generated by fission.→ fission; → product. fissionable   شکافت‌پذیر   šekâftpazir (#)Fr.: fissile   The material that can be fissioned by fast neutrons, such as uranium-238. Commonly used as a synonym for → fissile material.From → fission + → -able. fixation   برجایش   barjâyešFr.: fixation   The act of fixing or the state of being fixed.Verbal noun of → fix; → -tion.