# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 732
 differential and integral calculus   افماریک ِ دگرسانه‌ای و درستالی   afmârik-e degarsâne-yi va dorostâliFr.: calcul différentiel et intégral   The two branches of mathematics that make up the → calculus. → differential calculus; → integral calculus.→ differential; → integral; → calculus. differential calculus   افماریک ِ دگرسانه‌ای، ~ دگرسانه‌ها   afmârik-e degarsâneyi, ~ degarsânehâFr.: calcul différentiel   A branch of calculus which is concerned with the instantaneous rate of change of quantities with respect to other quantities, or more precisely, the local behavior of functions. → integral calculus.→ differential; → calculus. differential equation   هموگش ِ دگرسانه‌ای   hamugeš-e degarsâneyiFr.: équation différentielle   An equation expressing a relationship between an → independent variable, x, an unknown → function, y = f(x), and its → derivatives. The general form of a differential equation is: F(x, y, y', y'', ..., y(n)) = 0, or F(x,y, dy/dx, d2y/dx2, ..., dny/dxn) = 0. See also: → ordinary differential equation; → partial differential equation; → linear differential equation; → exact differential equation; → first-order differential equation; → homogeneous linear differential equation; → nonhomogeneous linear differential equation; → differential equation with separated variables; → differential equation with separable variables.→ differential; → equation. differential equation with separable variables   هموگش ِ دگرسانه‌ای با ورتنده‌های ِ جدایی-پذیر   hamugeš-e degarsâne-yi bâ vartandehhâ-ye jodâyi-pazirFr.: équation différentielle à variables séparables   A → differential equation of the form: M1(x) N1(y) dx + M2(x) N2(y) dy = 0, which can be reduced to a → differential equation with separated variables. → differential; → equation; → separate; → variable. differential equation with separated variables   هموگش ِ دگرسانه‌ای با ورتنده‌های ِ جدا   hamugeš-e degarsâne-yi bâ vartandehhâ-ye jodâFr.: équation différentielle à variables séparées   A → differentail equation that can be transformed into the form: M(x)dx + N(x)dy = 0. → differential; → equation; → separate; → variable. differential geometry   هندسه‌ی ِ دگرسانه‌ای   hendese-ye degarsâneyiFr.: géométrie différentielle   The study of curved spaces using differential calculus.→ differential; → geometry. differential image motion monitor (DIMM)   پهره‌گر ِ جنبش ِ دگرسانه‌ای ِ تصویر   pahregar-e jonbeš-e degarsâneyi-ye tasvirFr.: moniteur de mouvements d'images différentiels, moniteur seeing   A device that is commonly used to measure the → seeing at optical astronomical sites. The DIMM delivers an estimate of the → Fried parameter based on measuring the variance of the differential image motion in two small apertures, usually cut out in a single larger telescope pupil by a mask. The DIMM concept was introduced by Stock & Keller (1960, in Stars and Stellar Systems, Vol. 1, ed. G. P. Kuiper & B. M. Middlehurst, p. 138), whereas its modern implementation was first described by Sarazin & Roddier (1990, A&A 227, 294).→ differential; → image; → motion; → monitor. differential refraction   شکست ِ دگرسانه‌ای   šekast-e dagarsâneyiFr.: refraction différentielle   A problem encountered in astronomical spectroscopy, which consists of a loss of light from some wavelengths due to → atmospheric dispersion. In simple terms, differential refraction means that at nonzero → zenith distances an object cannot be simultaneously placed at the same position within a → slit at all wavelengths. This problem becomes more important for increasing → airmass, larger → spectral range, and smaller → slitwidths. To remedy this drawback, the slit should always be oriented along a direction perpendicular to the horizon, since differential refraction occurs in that direction. differential rotation   چرخش ِ دگرسانه‌ای   carxeš-e degarsâneyiFr.: rotation différentielle   1) Of a single body (such as a star or a gaseous planet), the axial rotation of equatorial latitudes faster than polar latitudes. 2) Of a galaxy, the orbiting of stars nearer the center faster than those at the edge.→ differential; → rotation. differentially rotating system   راژمان ِ دگرسانه چرخان   râžmân-e degarsâné carxânFr.: système en rotation différentielle   A system characterized by → differential rotation. In such a system the → angular velocity decreases as the distance from the rotation center increases.→ differential; → rotating; → system. differentiate   دگرسانیدن   degarsânidanFr.: différencier   General: To perceive or show the difference in or between. Math.: To obtain the differential or the derivative of.M.L. differentiatus "distinguished," p.p. of differentiare.Degarsânidan, verbal form of → difference. differentiated interior   درونه‌ی ِ دگرسانیده   darune-ye degarsânidéFr.: intérieur différencié   A description of a planet's interior which is composed of a rocky, dense inner core and a less dense outer crust.Differentiated, p.p. of → differentiate; → interior. differentiated meteorite   شخانه‌ی ِ دگرسانیده، شهاب‌سنگ ِ ~   šaxâne-ye degarsânidé, šahâbsang-e ~Fr.: météorite différenciée   A meteorite that has distinctly separated stone, metal, and glass. It is derived from a differentiated parent body and hence not primitive. The parent body accreted surrounding material until it was large enough to start melting in the middle. The denser metals sank to the center and the stones and glasses floated to the top. A differentiated meteorite made completely of metal comes from the center of a parent meteoroid which was broken apart. → undifferenciated meteorite.Differentiated, p.p. of → differentiate; → meteorite. differentiation   دگرسانش   degarsânešFr.: (Math.) dériver; (Astro.) différenciation   1) Math.: The operation of finding the → derivative of a function. 2) Astro.: Process by which an originally homogeneous planetary or asteroidal body is separated into regions of different composition, such as core, mantle, and crust.Verbal noun of → differentiate. diffract   پراشیدن   parâšidan (#)Fr.: diffracter   Verbal form of → diffraction. diffraction   پراش   parâš (#)Fr.: diffraction   A wave property of light which allows it to curl around obstacles whose size is about that of the wavelength of the light. As a → wavefront of light passes by an opaque edge or through an opening, secondary weaker wavefronts are generated, apparently originating at that edge. These secondary wavefronts will interfere with the primary wavefront as well as with each other to form a → diffraction pattern. Related terms: → diffusion; → dispersion; → distribution; → scatter; → scattering.From Fr. diffraction, from Mod.L. diffractionem, from L. diffrac-, stem of diffringere "break in pieces," from → dis- "apart" + frangere "to break."Parâš "dispersion, scattering," variant of pâš, pâšidan, → dispersion. diffraction grating   توری ِ پراش   turi-ye parâš (#)Fr.: réseau de diffraction   An optical device containing thousands of very fine parallel grooves which produce interference patterns in a way which separates out all the components of the light into a spectrum.→ diffraction; → grating. diffraction pattern   الگوی ِ پراش   olgu-ye parâš (#)Fr.: tache de diffraction   A series of concentric rings of dark and light color produced by interference.→ diffraction; → pattern.Olgu, loanword from Turkish; parâš→ diffraction. diffraction spike   سیخک ِ پراش   sixak-e parâšFr.: aigrette de diffraction   One of several light rays emanating from a bright light source in images taken with → reflecting telescopes. They are artifacts caused by light diffracting around the support or → spider vanes of the → secondary mirror.→ diffraction; → spike. diffraction-limited   کران‌مند به پراش   karânmand bé parâšFr.: limité par la diffraction   The quality of an → optical system that is capable of producing images with angular resolution as small as the theoretical limit of the → Airy disk.→ diffraction; limited, adj. of → limit.Karânmand "bounded, limited," from karân→ boundary + -mand possession suffix; parâš→ diffraction.