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statistics âmâr (#) Fr.: statistique A branch of applied mathematics that deals with the collection and interpretation of quantitative data and the use of probability theory to estimate population parameters. From Ger. Statistik "political science," from Mod.L. statisticus (collegium) "state affairs," from It. statista "person skilled in statecraft," from stato "state," ultimately from L. status "position, form of government;" cognate with Pers. ist-, istâdan "to stand" (Mid.Pers. êstâtan; O.Pers./Av. sta- "to stand, stand still; set;" Av. hištaiti; cf. Skt. sthâ- "to stand;" Gk. histemi "put, place, weigh," stasis "a standing still;" L. stare "to stand;" Lith. statau "place;" Goth. standan; PIE base *sta- "to stand"). Âmâr "computation, arithmetic; statistics," from âmârdan "to reckon, to calculate," related to ošmârdan, šomârdan, šomordan "to count, to calculate," mar, mâr- "count, reckon, measure," bimar "countless," nahmâr "great, large, big;" Mid.Pers. âmâr "calculating, reckoning;" Av. base mar- "to have in mind, remember, recall," hišmar-; cf. Skt. smr-, smarati "to remember, he remembers," L. memor, memoria, Gk. mermera "care," martyr "witness." |
status estâté Fr.: status 1) The position of an individual in relation to another or others, especially in regard
to social or professional standing. From L. status "condition, position, state, attitude" from p.p. stem of stare "to stand," from PIE *ste-tu-, from root *sta- "to stand," → state., + -tus suffix of action. Estâté, from estat, → state, + nuance suffix -é. |
steady flow tacân-e pâyâ Fr.: écoulement constant, ~ stationnaire A flow in which the characterizing conditions, such as → streamlines or velocity at any given point, do not change with time. Tacân, → flow; pâyâ "steady, constant," from pâyidan "to stand firm, to be constant, steady," from Mid.Pers. pattây-, pattutan "to last, endure, stay." |
steady state theory negare-ye hâlat-e pâyâ Fr.: théorie de l'état stationnaire A → cosmological model according to which the → Universe has no beginning and no end and maintains the same mean density, in spite of its observed expansion, by the continual creation of matter throughout all space. The theory was first put forward by Sir James Jeans in about 1920 and again in revised form in 1948 by Hermann Bondi and Thomas Gold. It was further developed by Sir Fred Hoyle to deal with problems that had arisen in connection with the alternative → Big Bang model. Observations since the 1950s have produced much evidence contradictory to the steady state theory and supportive of the Big Bang model. More specifically, the steady state theory attributed the → cosmic microwave background to → thermal radiation from → dust clouds, but this cannot account for a single → blackbody spectrum. Moreover, the steady state theory lacked a plausible mechanism for the creation of matter in space. See also → perfect cosmological principle. |
steam boxâr (#) Fr.: vapeur The vapor into which water is changed when boiled. From M.E. steme, O.E. steam; cognate with Du. stoom, of unknown origin. Boxâr, → vapor. |
steam engine mâšin-e boxâr (#) Fr.: machine à vapeur An engine in which the energy of hot → steam is converted into → mechanical power, especially an engine in which the force of expanding steam is used to drive one or more → pistons. The source of the steam is typically external to the part of the machine that converts the steam energy into → mechanical energy (Dictionary.com). |
steel pulâd (#) Fr.: acier A strong → alloy of → iron containing up to 1.5 percent → carbon along with small amounts of other → chemical elements such as → manganese, → chromium, → nickel, and so forth. O.E. style; cf. O.S. stehli, O.N., M.L.G. stal, Dan. staal, Swed. stål, M.Du. stael, Du. staal, O.H.G. stahal, Ger. Stahl. Pulâd, variant fulâd, from Mid.Pers. pôlâwad, pôlâvat, loaned in Arm. polopat, polovat, maybe related to Skt. pavīra- "a weapon with metallic point, a spear, a lance." |
steelyard qapân (#) Fr.: balance romaine A balance used for weighing loads that has a two beams of different lengths. The shorter beam has a hook or the like for holding the object to be weighed and the longer one supports a movable counterpoise that slides to attain a balance. → steel; yard, from M.E. yard(e), O.E. gerd "straight twig;" cognate with Du. gard, Ger. Gerte "rod." Qapân, from kapân "a large balance with one scale, being kept in equilibrium by a weight on the other end of the beam, a lever balance" (Steingass). |
Stefan-Boltzmann constant pâyâ-ye Stefan-Boltzmann Fr.: constante de Stefan-Boltzmann The constant of proportionality present in the → Stefan-Boltzmann law. It is equal to σ = 5.670 × 10^{-8} W m^{-2} K^{-4} or 5.670 × 10^{-5} erg cm^{-2} s^{-1} K^{-4}. → Stefan-Boltzmann law; → constant. |
Stefan-Boltzmann law qânun-e Stefan-Boltzmann Fr.: loi de Stefan-Boltzmann The flux of radiation from a blackbody is proportional to the fourth power of its absolute temperature: L = 4πR^{2}σT^{4}. Also known as Stefan's law. Ludwig Eduard Boltzmann (1844-1906), an Austrian physicist, who made important contributions in the fields of statistical mechanics and statistical thermodynamics and Josef Stefan (1835-1893), an Austrian physicist; → law. |
Steiner's theorem farbin-e Steiner Fr.: théorème de Steiner The → moment of inertia of a body about an arbitrary axis x' is equal to the sum of its moment of inertia about axis x, passing through the center of mass of the body and parallel to axis x', and the product of the mass M of the body by the square of the distance d between axes x and x': I_{x'} = I_{x} + Md^{2}. Same as → parallel axis theorem. Named after Jakop Steiner (1796-1863), a Swiss mathematician who derived this statement; → theorem. |
Steins 2867 Šteins Fr.: 2867 Šteins A small → main belt → asteroid of size 5.9 x 4 km, discovered in 1969 by N. S. Chernykh. It was visited by the → Rosetta space probe in 2008. Named after Karlis Šteins (1911-1983), a Latvian and Soviet astronomer. |
stellar aberration birâheš-e setâre-yi Fr.: aberration stellaire Same as → aberration of starlight . |
stellar association âhazeš-e setâre-yi Fr.: association stellaire 1) A large, loose grouping of 10 to 1000 stars that are of similar spectral type and
share a common origin. The members move together
through space, but have become gravitationally → unbound.
Stellar associations are primarily identified by their common
movement vectors and ages.
→ OB association;
→ T association;
→ R association. The concept of stellar association was first introduced by Viktor A. Ambartsumian (1908-1996), Armenian astrophysicist (1947, Stellar Evolution and Astrophysics, Armenian Acad. of Sci.; German translation, Abhandl. Sowjetischen Astron. Ser. 1. 33, 1951). → stellar; → association. |
stellar astronomy axtaršenâsi-ye setâreyi (#) Fr.: astronomie stellaire The branch of astronomy that deals with the study of stars, their physical properties, formation, and evolution. Same as → stellar astrophysics and → stellar physics. |
stellar astrophysics axtarfizik-e setâre-yi Fr.: astrophysique stellaire The field of → astrophysics concerned with the study of the physical characteristics of stars, more specifically their → internal structure, physical processes taking place in their interiors, atmospheres, → stellar winds, → mass loss, interaction with the → interstellar medium, as well as the physical laws governing → star formation. Same as → stellar physics and → stellar astronomy. → stellar; → astrophysics. |
stellar atmosphere javv-e setâre-yi, havâsephre ~ Fr.: atmosphère stellaire The outer envelope of gas and plasma that surrounds a star; characterized by pressure, temperature, density, chemical composition, and opacity at varying altitudes. → stellar; → atmosphere. |
stellar atmosphere model model-e javv-e setâré Fr.: modèle d'atmosphère stellaire A model that computes the radiation field crossing the boundary layers of a star at all frequencies. The parameters used for the characterization of a stellar atmosphere model are: → effective temperature, → surface gravity, and → metallicity. → stellar; → atmosphere; → model. |
stellar black hole siyah câl-e setâre-yi Fr.: trou noir stellaire A → black hole with a mass in the range 3-30 → solar masses representing the end-product of → massive star evolution. Since → neutron stars cannot have masses larger than 3 solar masses, compact objects more massive than this must be black holes. There is good observational evidence for the existence of stellar black holes, based in particular on dynamical measurements of the masses of compact objects in → transient X-ray sources. Same as → stellar-mass black hole. |
stellar creation function karyâ-ye âfarineš-e setâregân Fr.: fonction de création stellaire The number of stars born per unit area in the mass range log M to log M + d log M during the time interval t to t + dt. The integration of the creation function over time gives the → present-day mass function (Miller & Scalo, 1797, ApJSS 41, 513). |
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