# 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: 22 Search : differential
 angular differential imaging (ADI)   تصویرگری ِ دگرسانه‌ای ِ زاویه‌ای   tasvigari-ye degarsâne-yi-ye zâviye-yiFr.: imagerie différentielle angulaire   A high-contrast imaging technique that reduces minute temporal and spatial → seeing fluctuations and facilitates the detection of faint point sources, in close separation from their stars. It consists of the acquisition of a sequence of images with an → altazimuth mounting telescope while the instrument field derotator is switched off. This keeps the instrument and telescope optics aligned and allows the field of view to rotate with respect to the instrument. For each image, a reference → point spread function (PSF) is constructed from other appropriately selected images of the same sequence and subtracted to remove quasistatic PSF structure (Marois et al. 2006, ApJ 641, 556).→ angular; → differential; → imaging. binomial differential   دگرسانه‌ی ِ دونامین   degarsâne-ye donâminFr.: binôme différentiel   An expression of the form xm(a + bxn)pdx, where m, n, p, a, and b are constants.→ binomial; → differential. differential   ۱) دگرسانه؛ ۲) دگرسانه‌ای   1) degarsâné; 2) degarsâneyiFr.: différentiel   1) Noun. 1a) General: A difference or the amount of difference, as in rate, cost, quantity, degree, or quality, between things that are comparable. 1b) Math.: An infinitesimally small change in a variable; a function of two variables that is obtained from a given function, y = f(x), and that expresses the increment in the given function as the derivative of the function, f'(x), times the increment in the independent variable, written as dy = f'(x) dx. 1c) Electronics: Referring to a circuit, device, or machine whose principle of operation depends on the difference between two opposing effects. 2) Adjective. 2a) General: Of, relating to, or constituting a difference. 2b) Physics: Pertaining to or involving the difference of two or more motions, forces, etc. 2c) Math.: Pertaining to or involving a → derivative or derivatives.From M.L. differentialis, from differenti(a), → difference, + → -al.Degarsâné, from degarsân, → different + noun suffix -é. 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 ِ وینه، ~ ~ ~ تصویر   pahregar-e jonbeš-e degarsâneyi-ye vine, ~ ~ ~ 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. exact differential   دگرسانه‌ی ِ رزین   degarsâne-ye razinFr.: différentielle exacte   If N(x,y) is a → function of two → independent variables, then dN = (∂N/∂x)dx + (∂N/∂y)dy is the exact differential.→ exact; → differential. exact differential equation   هموگش ِ دگرسانه‌ای ِ رزین   hamugeš-e degarsâneyi-ye razinFr.: équation différentielle exacte   A → differential equation composed of → continuous  → differentiable functions for which certain conditions are fulfilled. The equation M(x,y)dx + N(x,y)dy = 0 is called exact if M(x,y) and N(x,y) are continuous differentiable functions for which the following relationship is fulfilled: ∂M/∂y = ∂N/∂x, and ∂M/∂y and ∂N/∂x are continuous in some region.→ exact; → differential; → 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. homogeneous linear differential equation   هموگش ِ دگرسانه‌ای ِ خطی همگن   hamugeš-e degarsâne-yi-ye xatti hamgenFr.: équation différentielle linéaire homogène   A → linear differential equation if the right-hand member is zero, Q(x) = 0, on interval I.→ homogeneous; → linear; → differential; → equation. linear differential equation   هموگش ِ دگرسانه‌ای ِ خطی   hamugeš-e degarsâne-yi-ye xattiFr.: équation différentielle linéaire   An equation in which the → dependent variable y and all its differential coefficients occur only in the first degree. A linear differential equation of → order  order n has the form: fn(x)y(n) + fn-1(x)y(n-1) + ... + f1(x)y' + f0(x)y = Q(x), where f0(x), f1(x), ..., fn(x) and Q(x) are each continuous functions of x defined on a common interval I and fn(x)≠ 0 in I. A linear differential equation cannot have, for example, terms such as y2 or (y')1/2. See also: → homogeneous linear differential equation; → nonhomogeneous linear differential equation.→ linear; → differential; → equation. linearized differential equation   هموگش ِ دگرسانه‌ای ِ خطی   hamugeš-e degarsâneyi-ye xattiFr.: équation différentielle linéarisée   A differential equation that has been derived from an original nonlinear equation.Linearized, p.p. of → linearize; → differential; → equation. nonhomogeneous linear differential equation   هموگش ِ دگرسانه‌ای ِ خطی ناهمگن   hamugeš-e degarsâne-yi-ye xatti nâhamgenFr.: équation différentielle linéaire non homogène   A → linear differential equation if Q(x)≠ 0 on interval I.→ nonhomogeneous; → linear; → differential; → equation.

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