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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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SIMBAD
     
SIMBAD

Fr.: SIMBAD   

A large on-line astronomical database, developed at the Centre de Données astronomiques de Strasbourg, → CDS in France. It provides a large collection of astronomical data, including cross-identifications, bibliography, and measurements for astronomical objects outside the solar system.

SIMBAD, short for Set of Identifications, Measurements, and Bibliography for Astronomical Data.

solar irradiance
  تابشداری ِ خورشیدی   
tâbešdâri-ye xoršidi

Fr.: irradiation solaire   

The radiative power per unit area in all wavelengths from the Sun received by the Earth at its average distance from the Sun. Its mean value is called the → solar constant. The solar irradiance changes over a year by about 6.6% due to the variation in the Earth/Sun distance. Moreover, solar activity variations cause irradiance changes of up to 1%.

solar; → irradiance.

solar radiation
  تابش ِ خورشیدی   
tâbeš-e xoršidi

Fr.: rayonnement solaire   

All the constituents making up the Sun's emission: photons, electrons, protons, neutrinos, and atomic nuclei.

solar; → radiation.

solar radiation pressure
  فشار ِ تابش ِ خورشید   
fešâr-e tâbeš xoršid (#)

Fr.: pression du rayonnement solaire   

The → radiation pressure of solar photons, which pushes a comet's dust outward to form a → dust tail.

solar; → radiation; → pressure.

solar radii
  شعاع(های) ِ خورشید   
šo'â'(hây)-e xoršid

Fr.: rayons solaires   

Plural form of → solar radius.

solar; → radii.

solar radius
  شعاع ِ خورشید   
šo'â'-e xoršid

Fr.: rayon solaire   

A unit of length, representing the radius of the → Sun, used to express the size of stars in astrophysics. It is equivalent to: 695,700 km, 0.00465047 → astronomical units, 7.35355 × 10-8 → light-years, and 2.32061 → light-seconds.

solar; → radius.

spade
  بیل   
bil (#)

Fr.: pelle   

A digging tool with a flat blade attached to a shaft so that it can be pushed into the ground with the foot.

M.E., from O.E. spadu; cognate with Gk. spathe "blade of a sword or oar."

Bil "spade," variants Kurd. bêr, Baluci bard, Gabri bard(a); Mid.Pers. bêl, bêr; Proto-Iranian *barda- metathesis of *badar-; cf. Av. vadar- "weapon" (Gershevitch 1962).

sporadic meteor
  شهاب ِ گهگاهی   
šahâb-e gahgâhi

Fr.: météore sporadique   

A meteor occurring occasionally, and not associated with any known meteor shower.

Sporadic, from M.L. sporadicus "scattered," from Gk. sporadikos "scattered," from sporas (genitive sporados) "scattered," from spora "seed, a sowing;" related to sporos "sowing," and speirein "to sow," from PIE *sper- "to strew;" → meteor.

Šahâb, → meteor; gahgâhi "from time to time," from gah, gâh "time; place" (Mid.Pers. gâh, gâs "time;" O.Pers. gāθu-; Av. gātav-, gātu- "place, throne, spot;" cf. Skt. gâtu- "going, motion; free space for moving; place of abode;" PIE *gwem- "to go, come").

spread
  ۱) گستردن؛ ۲) گسترش   
1) gostardan (#); 2) gostareš

Fr.: 1) déployer, répandre; 2) propagation, portée, envergure   

1a) To draw, stretch, or open out, especially over a flat surface, as something rolled or folded (often followed by out).
1b) To stretch out or unfurl in the air, as folded wings, a flag, etc.
2) An act or instance of spreading; expansion, extension, or diffusion (Dictionary.com).

M.E. spreden, from O.E. sprædan "to spread, extend," cf. Dan. sprede, O.Swed. spreda, M.Du. spreiden, O.H.G. and Ger. spreiten "to spread," from PIE root *sper- "to strew."

Gostardan "to spread; to diffuse, to expand," from Mid.Pers. wistardan "to extend; to spread;" Proto-Iranian *ui.star-; Av. vi- "apart, away from, out" (O.Pers. viy- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + Av. star- "to spread," starati "spreads" (cf. Skt. star- "to spread out, extend, strew," strnati "spreads;" Gk. stornumi "I spread out," strotos "spread, laid out;" L. sternere "to spread;" Ger. Strahlung "radiation," from strahlen "to radiate," from Strahl "ray;" from M.H.G. strāle; from O.H.G. strāla "arrow," stripe; PIE base *ster- "to spread").

steady flow
  تچان ِ پایا   
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.

steady; → flow.

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
  نگره‌ی ِ حالت ِ پایا   
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.

steady; → state; → theory.

steradian (sr)
  استرادیان   
esterâdiân (#)

Fr.: stéradian   

The solid angle subtended at the center of a sphere by an area on its surface numerically equal to the square of the radius. → square degree.

From ste(reo)-, → stereo- + → radian.

submillimeter radiation
  تابش ِ زیر-میلیمتری   
tâbeš-e zir-milimetri

Fr.: rayonnement sub-millimétrique   

That part of the → electromagnetic radiation with a → wavelength beyond 300 → microns.

submillimeter; → radiation.

superadiabatic temperature gradient
  زینه‌ی ِ دمای ِ اَبَر-بی‌دررو   
zine-ye damâ-ye abar-bidarrow

Fr.: gradient de température super-adiabatique   

A condition in which there is an excess of the actual temperature gradient over the → adiabatic temperature gradient corresponding to the same pressure gradient. A region with superadiabatic temperature gradient is convectively unstable. → Hayashi forbidden zone.

super-; → adiabatic; → temperature; → gradient.

sweep-up radius
  شعاع ِ روبش   
šo'â'-e rubeš

Fr.: rayon de balayage   

The → radius of a → supernova remnant (SNR) when, at the end of the → free expansion phase, the mass of the swept-up → shell equals that of the ejected gas from the → supernova explosion. It is given by RSW = (3Me / 4πρ0)(1/3), where Me is the ejected mass and ρ0 is the initial density of the → interstellar medium.

Sweep, from M.E. swepen, from O.E. swapan "to sweep;" cognate with Ger. schweifen; → up; → radius.

Šo'â', → radius; rubeš, noun from ruftan, rubidan "to sweep," → scan.

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.

tadpole
  وگیز   
vagiz

Fr.: têtard   

The aquatic larva of → frogs and → toads, having internal gills and a tail (TheFreeDictionary).

From M.E. taddepol, from tadde "toad" + polle "head," from M.L.G. or M.Du. pol "head, top."

Vagiz, from Tabari vag "→ frog" + -iz, -ize diminutive suffix (variants -ce, -že, -ak, Mid.Pers -cak).

tadpole orbit
  مدار ِ وگیزی   
madâr-e vagizi

Fr.: orbite en forme de têtard   

A shorter → horseshoe orbit confined to the → Lagrangian points L4 or L5.

tadpole; → orbit.

temperature gradient
  زینه‌ی ِ دما   
zine-ye damâ (#)

Fr.: gradient de température   

A physical quantity that describes the rate of change of temperature with displacement in a given direction from a given reference point. Same as → thermal gradient.

temperature; → gradient.

tetrad
  چهارگان   
cahârgân

Fr.: tétrade   

1) A group of four.
2) A sequence of four → total lunar eclipses occurring at approximately six month intervals. Tetrads are relatively rare events. The first → total eclipse of a tetrad occurred on 15 April 2014, the next eclipse of the series will happen on 8 October 2014 and the next two eclipses on 4 April and 28 September 2015, respectively. The previous tetrad happened in 2003-2004 and the next one will be in 2032-2033.

From Gk. tetrad-, stem of tetras "group of four."

Cahârgân, from cahâr, → four, + -gân suffix of plurality.


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