# 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: 128 Search : form
 affine transformation   ترادیس ِ کروَن   tarâdis-e karvanFr.: transformation affine   Any → transformation preserving → collinearity.→ affine; → transformation. Aristotelian form   دیسه‌ی ِ ارسطویی   dise-ye ArastuyiFr.: forme aristotelienne   Any of the four main → proposition forms treated in Aristotle's → syllogism: The A form (universal affirmative): All P's are Q's, The E form (universal negative): No P's are Q's, The I form (particular affirmative): Some P's are Q's, and The O form (particular negative) Some P's are not Q's.Greek philosopher Aristotle (384-322 BC); → form. Balmer formula   دیسول ِ بالمر   disul-e BâlmerFr.: formule de Balmer   A special solution of the mathematical formula which represents the wavelengths of the various spectral series of hydrogen in which the lower energy level is n = 2.→ Balmer; → formula. Bekenstein formula   دیسول ِ بکنشتاین   disul-e BekensteinFr.: formule de Bekenstein   The mathematical expression giving the → entropy, S, of a → black hole as a function of the area of its → event horizon, A: S = (kc3A)/(4Għ), where k is → Boltzmann's constant, ħ is the → reduced Planck's constant, and G the → gravitational constant. It can also be expressed by S = (kA)/(4lP2), where lP is the → Planck length. The existence of this entropy led to the prediction of the → Hawking radiation, because an entropy is associated with a temperature and a temperature to a → thermal radiation. The entropy of a black hole increases continuously because the fall of material into it increases its area.For Jacob D. Bekenstein (1947-), an Israeli theoretical physicist, who contributed to the foundation of black hole thermodynamics; → formula. biased galaxy formation   دیسش ِ ورکدار ِ کهکشانها   diseš-e varakdâr-e kahkašânhâFr.: formation biaisée de galaxies   The theory that bright galaxies form preferentially from anomalously overdense perturbations in the → early Universe.→ biased; → galaxy; → formation. bimodal star formation   دیسش ِ دومد ِ ستارگان   diseš-e domod-e setâregânFr.: formation bimodale d'étoile   A concept of → star formation in which → high-mass stars and → low-mass stars form in different physical conditions involving different → molecular clouds. Following the pioneering suggestion of Herbig (1962), successive investigations have generally supported the idea that star formation proceeds bimodally with respect to stellar mass. The star formation rate appears to differ both spatially and temporally for low mass and → massive stars. This is of considerable importance for galactic evolution, since the low-mass stars lock up mass and are long-lived, low luminosity survivors to the present epoch, whereas massive stars are short-lived, recycle and enrich interstellar gas, and leave dark remnants while producing a high luminosity per unit of mass (Silk, J., 1988, in Galactic and Extragalactic Star Formation, p. 503, eds. R. E. Pudritz and M. Fich).→ bimodal; → star; → formation. bioinformatics   زیست-ازداییک   zist-azdâyikFr.: bioinformatique   The retrieval and analysis of biochemical and biological data using mathematics and computer science, as in the study of genomes (Dictionary.com).→ bio-; → informatics. Boltzmann's entropy formula   دیسول ِ درگاشت ِ بولتسمن   disul-e dargâšt-e BoltzmannFr.: formule d'entropie de Boltzmann   In → statistical thermodynamics, a probability equation relating the → entropy S of an → ideal gas to the quantity Ω, which is the number of → microstates corresponding to a given → macrostate: S = k. ln Ω. Same as → Boltzmann's relation.→ Boltzmann's constant; → entropy; → formula. bottom-up structure formation   دیسش ِ ساختار از پایین به بالا   diseš-e sâxtâr az pâyin bé bâlâFr.: formation des structures du bas vers le haut   A → structure formation scenario in which small galaxies form first, and larger structures are then formed in due course. Contrary to → top-down structure formation.→ bottom; → up; → structure; → formation; → galaxy. burst of star formation      belk-e diseš-e setâregânFr.: flambée de formation d'étoiles   An intense → star formation activity in a region of → interstellar medium or, more globally, in a → galaxy. It is characterized by a → star formation rate which is much higher than the corresponding average. Same as → starburst.→ burst; → star; → formation. canonical form   دیسه‌یِ هنجاروار   dise-ye hanjârvârFr.: forme canonique   The simplest expression of an equation, statement, or rule. → canonical; → form. cluster formation efficiency (CFE)   کارایی ِ دیسش ِ خوشه   kârâyiè-ye diseš-e xušeFr.: efficacité de formation d'amas   The fraction of → star formation which happens in → bound clusters. It is defined as the ratio between the → cluster formation rate and → star formation rate (Bastian, 2008, MNRAS 390, 759, arxiv/0807.4687).→ cluster; → formation; → efficiency. cluster formation rate (CFR)   نرخ ِ دیسش ِ خوشه   nerx-e diseš-e xušeFr.: taux de formation d'amas   A parameter used in star formation models representing the ratio of the total mass in → star clusters to the corresponding age range (Bastian, 2008, MNRAS 390, 759, arxiv/0807.4687).→ cluster; → formation; → rate. CO formation   دیسش ِ CO   diseš-e COFr.: formation de CO   The chemical reaction that gives rise to → carbon monoxide in the → interstellar medium. According to models, several processes may lead to CO formation. For example, HCO+ + e → CO + H. The molecule HCO+ is itself produced through several paths, for example: H3+ + C → CH2+ + H, CH2+ + H2 → CH3+ + H, CH3+ + O → HCO+ + H. Alternatively: C+ + H2O → HCO+ + H. Another possibility: C+ + OH → CO+ + H, CO+ + H2→ HCO+ + H. collective star formation   دیسش ِ گرد‌آمدی ِ ستارگان   diseš-e gerdâmdi-ye setâregânFr.: formation collective d'étolies   Formation of stars, especially → massive stars, in group as opposed to individual formation.→ collective; → star; → formation. color transformation   ترادیس ِ رنگ   tarâdis-e rangFr.: transformation de couleur   Empirical mathematical transformation applied to the observed magnitudes in order to convert them into a standard system, or into a different system.→ color; → transformation. compound angle formula   دیسول ِ زاویه‌ی ِ همنات   disul-e zaviye-ye hamnâtFr.: formule d'angle composé   One of eight equations that give the → trigonometric functions of → compound angles. sin(A± B) = sinA.cosnd angleB± cosA.sinB cos(A + B) = cosA.cosB - sinA.sinB cos(A - B) = cosA.cosB + sinA.sinB tan(A + B) = (tanA + tanB)/(1 - tanA.tanB) tan(A - B) = (tanA - tanB)/(1 + tanA.tanB).→ compound; → angle; → formula. conformal   همدیس   hamdisFr.: conforme   Math.: Of, pertaining to, or specifying a mapping of a surface upon another surface so that all angles between intersecting curves remain unchanged.→ con- + → form + → -al. conformal compactification   همپکانش ِ همدیس   hampakâneš-e hamdiFr.: compactification conforme   A mapping of an infinite → space-time onto a finite one that may make the far away parts of the former accessible to study. The technique invented by Penrose defines an equivalence class of → metrics, gab being equivalent to ĝab = Ω2gab, where Ω is a positive scalar function of the space-time that modifies the distance scale making the asymptotics of the physical metric accessible to study. conformal mapping   همتایش ِ همدیس   hamtâyeš-e hamdisFr.: application conforme   A continuous mapping u = f(x) of a domain D in an n-dimensional Euclidean space (n≥ 2) into the n-dimensional Euclidean space is called conformal at a point x0∈ D if it has the properties of constancy of dilation and preservation of angles at this point.→ conformal; → mapping.

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