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symbiotic B[e] star (symB[e]) setâre-ye B[e]-ye hamzi Fr.: étoile B[e] symbiotique A → B[e] star whose spectrum shows the presence of a cool component characterized mainly by → TiO bands. |
symbiotic star setâre-ye hamzi Fr.: étoile symbiotique A stellar object whose optical spectrum displays lines characteristic of gases of two very different temperatures, typically of an M star (3500 K) and a B star (20 000 K) superimposed. A symbiotic star is in fact a close binary system. |
symbol namâd (#) Fr.: symbole 1) Something that stands for or represents something else,
especially an object representing an abstraction. M.E., from L.L. symbolum "creed, token, mark," from Gk. symbolon "sign, mark," from → syn- "together" + stem of ballein "to throw." Namâd variant of namud, nemud past stem of nemudan "to show;" Mid.Pers. nimūdan, nimây- "to show," from O.Pers./Av. ni- "down; into," → ni- (PIE), + māy- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure." |
symbolic nemâdin (#) Fr.: symbolique Of or relating to a symbol or symbols; serving as a symbol. |
symbolic logic guyik-e nemâdin Fr.: logique symbolique A modern development of → formal logic based on a system of → symbols and → axiomatics in accordance with precise rules. It uses a formalized → artificial language to avoid the ambiguities and logical inadequacies of → natural languages. Symbolic logics are → polyvalent when they admit → truth values other than → true and → false. |
symmetric relation bâzâneš-e hamâmun Fr.: relation symétrique A relation between two quantities such that the first is to the second as the second is to the first. In symbols: a R b = b R a. For example, multiplication is an operation with a symmetric relation between the factors: 5 x 3 = 3 x 5. |
symmetric tensor tânsor-e hamâmun Fr.: tenseur symétrique A tensor that is → invariant under any → permutation of its indices (→ index). In other words, a tensor that equals its → transpose. For example, a second-order → covariant tensor A_{jk} if its components satisfy the equality: A_{jk} = A_{kj}. |
symmetric, symmetrical hamâmun Fr.: symétrique Characterized by or exhibiting → symmetry. Adj. of → symmetry. |
symmetry hamâmuni Fr.: symétrie 1) A quality of a geometric figure that has exactly similar parts with respect
to a point, a line, or a plane of its own. From L. symmetria, from Gk. symmetria "agreement in dimensions, due proportion, arrangement," from symmetros "having a common measure, even, proportionate," from → syn- "together" + metron "meter;" PIE base *me- "to measure;" cf. O.Pers., Av. mā- "to measure;" Skt. mati "measures;" L. metri "to measure." Hamâmun from ham-, → syn- "together," + -â- epenthetic vowel + mun, variant mân "measure," as in Pers. terms pirâmun "perimeter," âzmun "test, trial," peymân "measuring, agreement," peymâné "a measure; a cup, bowl," from O.Pers./Av. mā(y)- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure." |
symmetry group goruh-e hamâmuni Fr.: groupe de symétrie A group of symmetry-preserving operations composed of all rigid motions or similarity transformations of some geometric object onto itself. |
syn- ham-, han- Fr.: syn- A prefix occurring in loanwords from Gk., having the same function as → co-; used, with the meaning "with, together," in the formation of compound words. Variants sy-, syl-, sym-, sys-. From Gk. syn "with, together with," of unknown origin. Ham- "together, with; same, equally, even," Mid.Pers. ham-, like L. com- and Gk. syn- with neither of which it is cognate. O.Pers./Av. ham-, Skt. sam-; also O.Pers./Av. hama- "one and the same," Skt. sama-, Gk. homos-; originally identical with PIE numeral *sam- "one," from *som-. The Av. ham- appears in various forms: han- (before gutturals, palatals, dentals) and also hem-, hen-. |
synchrone hamgâm Fr.: synchrone A line connecting the dust grains in a comet tail that left the nucleus at the same time. → syndyne. From L. synchronus "simultaneous," from Gk. synchronos "happening at the same time," from → syn- "together" + khronos "time." |
synchronous hamgâm (#) Fr.: synchrone 1) Going on at the same rate and exactly together.
Compare → simultaneous. From L. synchronus "simultaneous," from Gk. synchronos "happening at the same time," from → syn- "together" + khronos "time." Hamgâm literally "at the same pace," from ham-, → syn-, + gâm "step, pace," Mid.Pers. gâm, O.Pers. gam- "to come; to go," Av. gam- "to come; to go," jamaiti "goes," Mod.Pers. âmadan "to come," Skt. gamati "goes," Gk. bainein "to go, walk, step," L. venire "to come," Tocharian A käm- "to come," O.H.G. queman "to come," E. come; PIE root *gwem- "to go, come." |
synchronous orbit madâr-e hamgâm Fr.: orbite synchrone → synchronous; → orbit. |
synchronous rotation carxeš-e hamgâm (#) Fr.: rotation synchrone Of a body orbiting another, where the orbiting body takes as long to rotate on its axis as it does to make one orbit. Therefore it always keeps the same hemisphere pointed at the body it is orbiting. Both bodies are tidally locked (→ tidal locking). This phenomenon is a natural consequence of → tidal braking. Synchronous rotation is common throughout the → solar system. It is found among the satellites of → Mars (→ Phobos and → Deimos), → Jupiter (most of Jupiter satellites, including the → Galilean Moons) and → Saturn (e.g. → Iapetus). Similarly, → Pluto and its moon → Charon are locked in mutual synchronous rotation, with both of them keeping the same faces towards each other. → synchronous; → rotation. |
synchrotron sankrotron Fr.: synchrotron A type of → accelerator that accelerates charged subatomic particles (generally protons) in a circular path. Unlike → cyclotrons, in which particles follow a spiral path, synchrotrons consist of a single ring-shaped tube through which the particles loop numerous times, guided by precisely synchronized magnetic fields and accelerated at various points in the loop by electric field bursts. See also → synchrotron frequency, → synchrotron radiation. From synchro- a combining form representing synchronized or synchronous in compound words, from L. synchronus "simultaneous," from Gk. synchronos "happening at the same time," from → syn- "together" + khronos "time" + → -tron. Sankrotron, from Fr., as above. |
synchrotron frequency basâmad-e sinkrvtrvn Fr.: fréquence synchrotron The revolution frequency of a → relativistic particle of charge q and mass m in the → uniform magnetic field B of a synchrotron. It is expressed by: f_{syn} = qB/2πγm, where γ is the → Lorentz factor. This frequency is lower than → cyclotron frequency for a → non-relativistic case. → synchrotron; → frequency. |
synchrotron radiation tâbeš-e sankrotron Fr.: rayonnement synchrotron The electromagnetic radiation emitted by high-energy particles that are moving in magnetic fields, as in a synchrotron particle accelerator. The acceleration of the moving charges causes the particles to emit radiation. Radio galaxies and supernova remnants are intense sources of synchrotron radiation. Characteristics of synchrotron radiation are its high degree of polarization and nonthermal spectrum. → synchrotron; → radiation. |
syndyne hamtavân Fr.: syndyne Of a comet, a curve of points calculated assuming dust grains are emitted continuously at successive instants with a constant value of the radiation pressure to gravitational attraction; also called syndyname. → synchrone. |
synergy hamkâruži Fr.: synergie The working together or simultaneous action of separate elements or agencies when the result is greater than the sum of the individual effects or capabilities. From Mod.L. synergia, from Gk. synergia "joint work, help," from synergos "working together," related to synergein "to work together, help another," from → syn- "together" + → ergon, → work, → erg. Hamkâruži, from ham- "together," → syn-, + kâruž, → energy, + -i noun suffix. |
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