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

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.

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.

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

→ Doppler effect; → profile.

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.

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.

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.

1) The giving of a dose.
2) Regulation or determination of doses.
3) The addition of an ingredient or the application of an agent in a measured dose (Merriam-Webster.com).

From Fr. dosage, → dose.

1a) A specified quantity of medicine taken at any one time.
1b) The amount of radiation administered as therapy to a given site.
2a) To give or prescribe something, such as medicine, in specified amounts.
2b) To give someone a dose of medicine to.

M.E., from M.Fr. dose, from L.L. dosis, from Gk. dosis "a portion prescribed," literally "a giving," used by Galen and other Gk. physicians to mean an amount of medicine, from stem of didonai "to give."

Doz, loan from Fr., as above. Dozidan infinitive from doz.

1) The administration of a dose.
2) → dosage.

→ dose; → -ing.

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.

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, + tâ "fold, plait, ply; piece, part," Mid.Pers. tâg "piece, part."

An electron-photon interaction that can be thought of as a → Compton scattering event associated with the production or destruction of an extra photon.

→ double; → Compton; → scattering.

The simplest case of a → multiple integral.

→ double; → integral.

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.

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

→ double; → refraction.

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.

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.

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.

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.

Same as → diplopia.

→ double; → vision.