An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

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.

The interval of 29.530 588 days (29d 12h 44m 2.80s), on average, between two successive → new Moons. Same as → lunation.

→ synodic; → month.

Grammar: A word having the same or nearly the same meaning as another in the language. Opposite of → antonym.

From L. synonymum, from Gk. synonymon "word having the same sense as another," from synonymos "having the same name as, synonymous," from → syn- "together, same" + onyma, → name.

Hamcem, from ham-, → syn-, + cem, → meaning.

A method of dividing a polynomial in the special case of dividing by a linear factor. Synthetic division allows one to do long division problems much quicker. It is related to the → Ruffini-Horner method.

→ synthetic; → division.

A → stellar association containing many → T Tauri stars. Examples include the Taurus-Auriga T association, the nearby → TW Hydrae association, and Vela T1 and T2.

T, letter of alphabet; → association.

A hypothetical subatomic particle that travels faster than the speed of light.

From tachy- a combining form meaning "swift," from Gk. tachys "swift" + → -on.

That component of a an object's motion which is perpendicular to the observer's → line of sight.

→ tangential; → motion.

Fluid mechanics: A second order differential equation that governs the vertical structure of a perturbation in a stratified parallel flow.

Named after G. I. Taylor (Effect of variation in density on the stability of superposed streams of fluid, 1931, Proc. R. Soc. Lond. A, 132, 499), → Taylor number, and S. Goldstein (On the stability of superposed streams of fluids of different densities, 1931, Proc. R. Soc. Lond. A, 132, 524); → equation.

The science or art of assembling, shaping, or ornamenting materials in construction; the constructive arts in general. → plate tectonics

L.L. tectonicus, from Gk. tektonikos "pertaining to building," from tekton (genitive tektonos) "builder, carpenter," → technique.

Sâzânik, from sâzân pr.p. of sâz-, sâxtan "to build, make, fashion; to adapt, adjust, be fit" (Mid.Pers. sâxtan, sâz-, Manichean Parthian s'c'dn "to prepare, to form;" Av. sak- "to understand, to mark," sâcaya- (causative) "to teach") + -ik, → -ics.

Meteo.: A reversal in the normal temperature decrease, the temperature rising with increased elevation in the atmosphere instead of falling. A layer in which temperature increases with altitude.

→ temperature; → inversion.

An elementary unit of time defined as the duration which is necessary for light to travel a distance equal to the classical radius of an electron. Thus, one tempon (τ) is equal to (e²/mc²)(1/c)≅ 10^-23 seconds.

From tamp, from L. tempus "time" + → -on.

The measure of the ability of an observing system to clearly separate events in time. In other words, the shortest time interval that can be determined between two different events.

→ temporal hour; → resolution.

General: The act of stretching or straining; the state of being stretched or strained.
Mechanics: The longitudinal deformation of an elastic body that results in its elongation.
Electricity: Voltage or potential; electromotive force.

M.E., from M.Fr. tension, from L. tensionem (nominative tensio) "a stretching," from tensus, p.p. of tendere "to stretch," cognate with Pers. taneš, as below.

Taneš, verbal noun from tanidan "to spin, twist, weave;" Mid.Pers. tanitan; Av. tan- to stretch, extend;" cf. Skt. tan- to spin, stretch;" tanoti "stretches," tantram "loom;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" PIE base *ten- "to stretch"), Pers. târ "string," tân "thread," tur "fishing net, net, snare," and tâl "thread" (Borujerdi dialect) belong to this family; variants tanta "cobweb," tanadu, tafen, kartané, kârtané, kâtené, Pashtu tanistah "cobweb;" cf. Skt. tantu- "cobweb, thread, string."

An operation of tensor algebra that is obtained by setting unlike indices equal and summing according to a summation convention.

→ contraction; → tensor.

The perturbation in the → primordial Universe plasma caused by → gravitational waves. These waves stretch and squeeze space in orthogonal directions and bring about → quadrupole anisotropy in incoming radiation temperature.

→ tensor; → perturbation.

A → shock wave inside the → heliopause where the → supersonic → solar wind abruptly slows from an average speed of 500 km s^-1 to → subsonic and becomes denser and hotter.

Termination, verbal noun from terminate, from → term; → shock.

Toš, šok, → shock; pâyâni, → terminal.

A parameter representing the product of the → gravitational constant by the Earth's mass. It is 3.987 x 10¹⁴ m³s^-2 or 3.987 x 10⁵ km³s^-2.

→ terrestrial; → gravitational; → constant.

Same as → quadrangle.

From Gk. tetragonon, from → tetra- + -gon "angled, angular," from gonia "angle," related to gony "knee;" L. genu "knee;" Mod.Pers. zânu "knee;" Av. žnav-, žnu- "knee;" Skt. janu-; PIE base *g(e)neu-.

Cahârguš "four-cornered," from cahâr, câr "four," cognate with L. quattuor, → four, + gušé, guš "corner, angle;" Mid.Pers. gôšak "corner."

A solid figure having four plane faces.

→ tetra-; → -hedron.

The act or process of thematizing.

→ thematize; → -tion.