An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 737
âqareš (#)

Fr.: dopage   

The addition of minute quantities of impurities to a semiconductor to achieve a desired characteristic.

Verbal noun of → dope.

Doppler broadening
  پهنش ِ دوپلر   
pahneš -e Doppler

Fr.: élargissement Doppler   

In atomic physics, the broadening of an emission or absorption line due to the Doppler effect. Random motions of molecules or atoms of the gas that is emitting or absorbing the radiant energy shift the apparent wavelength of each emitter, and the cumulative effect of indivisual shifts is to broaden the line.

Doppler effect; → broadening.

Doppler effect
  اسکر ِ دوپلر   
oskar-e Doppler

Fr.: effet Doppler   

Change in frequency of a wave (light, sound) due to the relative motion of source and receiver. Approaching objects have their wavelengths shortened. Receding objects have emitted wavelengths lengthened.

Doppler, after Christian Andreas Doppler (1803-1853), Austrian physicist who first described how the observed frequency of sound and light waves is affected by the relative motion of the source and the detector; → effect.

Doppler profile
  فراپال ِ دوپلر   
farâpâl-e Doppler

Fr.: profil Doppler   

The shape of the spectral line resulting from the Doppler broadening.

Doppler effect; → profile.

Doppler shift
  کیب ِ دوپلر   
kib-e Doppler

Fr.: décalage Doppler   

Effect of the relative motion of a wave source (light, sound) and the observer. If the source is moving away, the wavelength is stretched (shifted toward lower frequencies). If the source is approaching, the wavelength is compressed (shifted toward higher frequencies). These effects, known as Doppler shifts, are in the case of light waves called redshift and blueshift, respectively.

Doppler effect; → shift.

Doppler tomography
  برش نگاری ِ دوپلر   
borešnegâri-ye Doppler

Fr.: tomographie Doppler   

A technique using a series of Doppler-shifted line profiles at different orbital phases in cataclysmic variable stars (CVs) to image the compact system in the light of a particular emission line. Although developed for CVs, the method has wider applications. An alternative method is → eclipse mapping.

Doppler effect; → tomography.

  ماهی ِ زرین، زرین ماهی   
Mâhi-ye zarrin, zarrin mâhi (#)

Fr.: Dorade   

The Swordfish. A constellation in the southern hemisphere near → Reticulum and → Pictor. It contains most of the → Large Magellanic Cloud which laps over to some extent into the neighboring constellation → Mensa. The south → ecliptic pole also lies within this constellation. Abbreviation: Dor, Genitive: Doradus.

Dorado, from Sp., from L.L. deaurutus, p.p. of deaurare "to gild," from → de- + aurium "gold." Dorado (Coryphaena hippurus) is a surface-dwelling fish found in off-shore tropical and subtropical waters worldwide. It is distinguished by dazzling golden colors on the sides.

Mâhi "fish," from Mid.Pers. mâhik, Av. masya-, cf. Skt. matsya-, Pali maccha-.
Zarrin "golden," from zarr "gold," Mid.Pers. zarr, Av. zaranya-, zarənu- "gold," O.Pers. daraniya- "gold," Skt. hiranya- "gold;" also Av. zaray-, zairi- "yellow, green," Mod.Pers. zard "yellow," Skt. hari- "yellow, green," Gk. Khloe lit. "young green shoot," L. helvus "yellowish, bay," Rus. zeltyj "yellow," P.Gmc. *gelwaz, Du. geel, Ger. gelb, E. yellow.

dot product
  فر‌آورد ِ مرپلی   
farâvard-e marpeli

Fr.: produit scalaire   

Same as → scalar product.

O.E. dott "speck, head of a boil," perhaps related to Norw. dot "lump, knot," Du. dot "knot, wisp;" cognate with O.H.G. tutta "nipple;" → product.

Bastâk, → product; marpeli, → scalar.

dotâyi (#)

Fr.: double   

1) Composed of two like parts or members.
2) Twice as large, heavy, strong, etc.
3) Anything that is twofold in size or amount or twice the usual size, quantity, strength, etc.

From O.Fr. duble, from L. duplus "twofold" (Gk. diplos "double"), from duo "two" + -plus "fold."

Dotâyi, from dotâ, from do "two," akin to L. duo, + "fold, plait, ply; piece, part," Mid.Pers. tâg "piece, part."

double integral
  درستال ِ دوتایی   
dorostâl-e dotâyi

Fr.: intégrale double   

The simplest case of a → multiple integral.

double; → integral.

double pulsar
  پولسار ِ دوتایی، تپار ِ ~   
pulsâr-e dotâyi, tapâr-e ~ (#)

Fr.: pulsar double   

A → binary pulsar consisting of two pulsars. The only known example is PSR J0737-3039 (A and B), discovered in 2003 (Burgay et al. Nature 426, 531). The rotation periods of the pulsars are 22.7 and 2.8 milliseconds respectively. Each of them has a mass about 1.3 times that of the Sun and revolves around their → center of gravity with a period of 2.4 hours. According to the theory of → general relativity, such a binary should lose energy through the emission of → gravitational waves. As deduced from the change in orbital period, the separation of the pulsars is reducing by about 7 mm per day, in exact agreement with theory. It is expected that the pulsars will eventually merge in about 85 million years.

double; → pulsar.

double refraction
  شکست ِ دوتایی   
šekast-e dotâyi

Fr.: double réfraction   

Formation of two refracted rays of light from a single incident ray; property of certain crystals, notably calcite.

double; → refraction.

double root
  ریشه‌ی ِ دوتایی   
riše-ye dotâyi

Fr.: racine double   

A → root x0 of function f(x), if f(x0) = 0, df/dx | x0 = 0, and d2f/dx2 | x0≠ 0. See also → simple root.

double; → root.

double shell burning
  سوزش ِ پوسته‌ی ِ دوتایی   
suzeš-e puste-ye dotâyi

Fr.: combustion double coquille   

A situation in the evolution of an → asymptotic giant branch star whereby both hydrogen and helium shells provide energy alternatively. As the burning → helium shell approaches the hydrogen-helium discontinuity, its luminosity decreases because it runs out of the fuel. As a consequence, the layers above contract in response, thus heating the extinguished → hydrogen shell until it is re-ignited. However, the shells do not burn at the same rate: the He burning shell becomes thermally unstable and undergoes periodic → thermal pulses.

double; → shell; → burning.

double slit
  شکاف ِ دوتایی   
šekâf-e dotâyi (#)

Fr.: fente double   

A pair of adjacent holes or slits made on a dark and plane surface, used in optical experiments, such as interference and diffraction.

double; → slit.

double star
  ستاره‌ی ِ دوتایی   
setâre-ye dotâyi (#)

Fr.: étoile double   

An apparently single star which better observational resolution shows it to be a pair of closely lying stars. They may or may not be physically related.

double; → star.

double vision
dobini (#)

Fr.: vision double   

Same as → diplopia.

double; → vision.

double white dwarf
  سفیدکوتوله‌ی ِ دوتایی   
sefid kutule-ye dotâyi

Fr.: naine blanche double   

A → double-lined binary with two → white dwarf components. Short-period double white dwarfs can lose → orbital angular momentum by emitting → gravitational radiation and if the total mass of the binary exceeds the → Chandrasekhar limit, their eventual → merger might produce a → Type Ia supernova.

double; → white; → dwarf.

double-degenerate binary system
  راژمان ِ درین ِ دوبار واگن   
râžmân-e dorin-e dobâr vâgen

Fr.: système binaire doublement dégénéré   

A system of evolved → binary stars in which both → components have ejected their envelopes and evolve toward → white dwarf stage. So far a half dozen double-degenerate → binary systems are known, for example Henize 2-248 (M. Santander-Garcia et al., 2015, 518, 5).

double; → degenerate; → binary; → system.

double-diffusive convection
  همبز ِ دوپخشی   
hambaz-e do paxši


An instability involving two layers of fluid with opposite gradients of properties. Same as → fingering instability. See also → salt finger. Double-diffusive instabilities commonly occur in any astrophysical fluid that is stable according to the → Ledoux criterion, as long as the entropy and chemical stratifications have opposing contributions to the dynamical stability of the system. They drive weak forms of convection, and can cause substantial heat and compositional → mixing. Two cases can be distinguished. In fingering convection, entropy is stably stratified (∇ - ∇ad < 0), but chemical composition is unstably stratified (∇μ < 0); it is often referred to as → thermohaline convection by analogy with the oceanographic context in which the instability was first discovered. In oscillatory double-diffusive convection, entropy is unstably stratified (∇ - ∇ad > 0), but chemical composition is stably stratified (∇μ > 0); it is related to semiconvection, but can occur even when the → opacity is independent of composition (P. Garaud, 2014, arXiv:1401.0928).

double;→ diffusive; → system.

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