An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1286

Fr.: symbiotique   

Of or pertaining yo symbiosis in biology, denoting a close, prolonged association between two or more different organisms of different species that may be, but does not necessarily, of mutual benefit. → symbiotic star.

From Mod.L., from Gk. symbiosis "a living together," from symbioun "live together," from symbios "(one) living together (with another), partner," from → syn- "together" + bios "life," → bio-.

Hamzi "living together," from ham- "together," → syn-, + zi- present stem of zistan "to live," → bio-.

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; → B[e] star.

symbiotic star
  ستاره‌ی ِ همزی   
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.

symbiotic; → star.

namâd (#)

Fr.: symbole   

1) Something that stands for or represents something else, especially an object representing an abstraction.
2) A conventional sign or character that represents something in a specific context, e.g. an operation or quantity in mathematics or music.

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."

nemâdin (#)

Fr.: symbolique   

Of or relating to a symbol or symbols; serving as a symbol.

symbol; → -ic.

symbolic logic
  گوییک ِ نمادین   
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.

symbolic; → logic.

symmetric relation
  بازانش ِ همامون   
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; → relation.

symmetric tensor
  تانسور ِ همامون   
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 Ajk if its components satisfy the equality: Ajk = Akj.

symmetric; → tensor.

symmetric, symmetrical

Fr.: symétrique   

Characterized by or exhibiting → symmetry.

Adj. of → symmetry.


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.
2) A geometric transformation that does not alter neither the shape nor the size of a figure.
3) A property of a mathematical function whose value does not change when its variables are interchanged.
4) Of physical phenomena, the property of remaining invariant under certain changes (as of rotation, reflection, inversion in space, the sign of the electric charge, parity, or the direction of time flow). See also → Noether's theorem.
See also:
asymmetry, → axial symmetry, → axisymmetry, → baryon asymmetry, → charge-parity symmetry, → dissymmetry, → gauge symmetry, → parity symmetry, → spherical symmetry, → spontaneous symmetry breaking, → supersymmetry, → symmetry group, → T-symmetry.

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
  گروه ِ همامونی   
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.

symmetry; → group.

  هم-، هن-   
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-.


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."

Hamzamân, from ham-, → syn- "together" + zamân, → time.

hamgâm (#)

Fr.: synchrone   

1) Going on at the same rate and exactly together. Compare → simultaneous.
2) Having the same period and phase of oscillation or cyclic movement.

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
  مدار ِ همگام   
madâr-e hamgâm

Fr.: orbite synchrone   

synchronous rotation.

synchronous; → orbit.

synchronous rotation
  چرخش ِ همگام   
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.


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
  بسامد ِ سینکروترون   
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: fsyn = qB/2πγm, where γ is the → Lorentz factor. This frequency is lower than → cyclotron frequency for a → non-relativistic case.

synchrotron; → frequency.

synchrotron radiation
  تابش ِ سنکروترون   
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.


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.

From → syn- + dyne, → dynamics.

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