double-degenerate binary system
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).
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).
Fr.: binaire à double raies
double-lined eclipsing binary
dorin-e gerefti-ye doxatté
Fr.: binaire à éclipse à double raies
double-lined spectroscopic binary
dorin-e doxatte-ye binâbnemâyik
Fr.: binaire spectroscopique à double raies
Same as → double-lined binary.
double-lobed radio source
xan-e râdioyi bâ lap-e dotâyi
Fr.: radio source à double lobe
A → galaxy that emits radio energy from two regions located on opposite sides of the galaxy.
âzmâyeš-e šekâf-e dotâyi (#)
Fr.: expérience de double fente
A pair of forbidden spectral lines of the same atom arising from
a common upper excitation level, for example [O III] λ 5007 and
[O III] λ 4959, [N II] λ 6584 and [N II] λ 6548, and [S II] λ 6717,
[S II] λ 6731.
From O.Fr. doublet, from → double + -et diminutive suffix.
Dotâyé, from dotâ→ double + -(y)é nuance suffix.
dobâr-, dv-, dotâyi
Fr.: double, à ~
dobâr yonidé (#)
Fr.: deux fois ionisé
An atom that has lost two of its external electrons, for example O++ ([O III]).
doubly refracting crystal
bolur-e šakst-e dotâyi
Fr.: cristal à double réfraction
A → transparent → crystalline substance (such as calcite, quartz, and tourmaline) that is → anisotropic relative to the → speed of light. A ray incident normally on such crystals is broken up into two rays in traversing the crystal, → ordinary ray and → extraordinary ray.
Fr.: en bas, vers le bas
M.E. doun, from O.E. dune "downward," short for adune, ofdune, from a-, of "off, from" + dune "hill."
Pâyin "bottom, below; at the foot of," from pâ(y) "foot; step;" Mid.Pers. pâd, pây; Av. pad- "foot;" cf. Skt. pat; Gk. pos, genitive podos; L. pes, genitive pedis; E. foot; Ger. Fuss; Fr. pied; PIE *pod-/*ped-.
Fr.: déclasser, dévaloriser
1) A downward slope, especially of a road.
1) bârgereftan; 2) bârgiri (#)
Fr.: 1) télécharger; 2) téléchargement
1) To transfer data from any other computer to one's computer.
A scenario of galaxy formation whereby massive galaxies formed earlier in the history of the → Universe (i.e. at high → redshifts) and completed their → star formation process more rapidly than low-mass galaxies. This scenario contrasts with what might be expected from simple → hierarchical structure formation scenarios, which predict that large galaxies formed in more recent times through the → merging of small galaxies.
Downsizing, first suggested by Cowie et al. (1996, AJ 112, 839), from downsize (v.), is a new sense for this term. Its current main meaning in non astrophysical contexts is "to make in a smaller size, or become smaller in size (in particular in economic vocabulary, by reductions in personnel)," from → down + → size.
Fr.: en aval
1) With or in the direction of the current of a stream. → upstream.
DQ white dwarf
sefid kutule-ye DQ
Fr.: naine blanche DQ
A → white dwarf whose spectrum shows carbon features of any kind.
The Dragon. A large constellation that winds around the north → celestial pole, appearing to encircle → Ursa Minor. The north → ecliptic pole also lies within Draco. Abbreviation: Dra, genitive form: Draconis.
O.Fr. dragon, from L. draco "serpent, dragon," from Gk. drakon "serpent, seafish," from drak-, strong aorist stem of derkesthai "to see clearly," perhaps literally "the one with the (deadly) glance," cf. Av. darəs- "to look," huuarə.darəsa- "having the appearance of the sun," Skt. darś- "to see, appear, look, show," dárśya- "worthy of being seen;" PIE base *derk- "to look."
Eždahâ, from Mid.Pers. aždahâg, ažidahâk, from Av. aži.dahāka- "the name of an evil king in the Iranian mythology," from aži- "serpent; dragon, monster" (Mid.Pers. až, âž, aži), cf. Skt. áhi- "snake, adder," Gk. ékhis, óphis "snake," L. anguis "snake," Arm. auj, Russ. už, Lith. angis; PIE base *angw(h)i- "snake, worm." The etymology of the second component, Av. dahāka-, is a matter of discussion. It is probably related to dahaka- "stinging, tormenting," from dah- "to sting, to do harm."
Fr.: Naine du Dragon
A dwarf elliptical galaxy that is a satellite of our Galaxy and lies at a distance of about 250,000 light-years from the Galactic center. Its diameter is only about 3,500 light-years, and its absolute magnitude -8.6, making it the least luminous galaxy known.