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Fr.: deuxième dragage
A → dredge-up process that occurs after core helium burning, in which the convective envelope penetrates much more deeply, pushing hydrogen burning shell into close proximity with the helium burning shell (→ first dredge-up). This arrangement is unstable and leads to burning pulses. The reason is that the hydrogen shell burns out until there is enough helium for the helium combustion to occur and all the helium is rapidly burnt. Afterward the hydrogen shell again burns outward and the process repeats.
second generation star
setâre-ye âzâneš-e dovom
Fr.: étoile de deuxième génération
second law of black-hole mechanics
qânun-e dovom-e mekânik-e siyah-câl
Fr.: deuxième loi de la mécanique des trous noirs
The surface area of a black hole's horizon can never decrease.
second law of thermodynamics
qânun-e dovom-e garmâtavânik
Fr.: deuxième loi de la thermodynamique
1) Heat cannot be transferred from a colder to a hotter body without some other effect, i.e.
without → work being done. Expressed in terms of
→ entropy: the entropy of an
→ isolated system tends toward a maximum and its
available energy tends toward a minimum.
Fr.: deuxième quantification
In quantum mechanics, the quantization of the field that replaces potential in Newtonian mechanics, whereby the field variables become operators from which the creation (of particle) operators and destruction operators can be constructed.
guyik-e râye-ye dovom
Fr.: logique du seconde ordre
1) Derived or derivative; not primary or original.
From → second + -ary a suffix occurring on adjectives (elementary; honorary; stationary) and nouns denoting objects, especially receptacles or places (library; rosary; glossary).
Dovomân, from dovom, → second.
javv-e dovomân, havâsepehr-e ~
Fr.: atmosphère secondaire
An atmosphere of a planet that forms after primordial gases had been lost or had failed to accumulate. A secondary atmosphere develops from internal volcanic outgassing, or by accumulation of material from comet impacts. It is characteristic of terrestrial planets, such as Earth, Mercury, Venus, and Mars. → primordial atmosphere.
Fr.: corps secondaire
Fr.: calibrateur secondaire
An indicator of extragalactic distances that relies on → primary calibrators in our Galaxy. Secondary calibrators of the distance scale depend on statistical measures of the properties of a class of objects, such as the brightness of H II regions, globular clusters, red and blue stars, or the neutral hydrogen 21-cm line width or velocity dispersion (of spiral galaxies), etc. Same as secondary distance indicator.
secondary cosmic rays
partowhâ-ye keyhâni-ye dovomân
Fr.: rayons cosmiques secondaires
A burst of secondary charged and neutral particles arising when → primary cosmic rays collide with the atmospheric oxygen or nitrogen nuclei in the upper atmosphere. The collision produces mostly → pions (π), along with some → kaons (K), → antiprotons, and → antineutrons. Neutral pions very quickly decay, usually into two → gamma rays. Charged pions also decay but after a longer time. Therefore, some of the pions may collide with yet another nucleus of the air before decaying, which would be into a → muon and a → neutrino. The fragments of the incoming nucleus also interact again, also producing new particles.
lâvak-e dovomân, kandâl-e ~
Fr.: cratère secondaire
A crater formed by the relatively low-velocity impact of fragments ejected from a large primary crater. Secondary craters tend to cluster in a ring around the primary crater.
Fr.: éclipse secondaire
Fr.: électrons secondaires
Electrons ejected from the atoms of a material when bombarded with high energy electrons. Secondary electrons are produced when an incident electron excites an electron in the material and loses some of its energy in the process. The excited electron moves toward the surface of the sample undergoing elastic and inelastic collisions until it reaches the surface, where it can escape if it still has sufficient energy. The secondary electron yield depends on many factors, and is generally higher for high atomic number targets, and at higher angles of incidence.
Fr.: émission secondaire
The emission of → secondary electrons from the surface of a material when an incident particle (often, charged particle such as electron or ion) impacts the material with sufficient energy.
Fr.: miroir secondaire
The second reflecting surface in a → reflecting telescope. It directs the light either out a side opening of the tube (→ Newtonian telescope) or back toward a → focal point behind and through the → primary mirror (→ Cassegrain telescope). The secondary is usually suspended in the beam and therefore obstructs part of the primary.
Fr.: arc-en-ciel secondaire
A fainter rainbow appearing about 10° above the → primary rainbow, as viewed by the observer. The secondary rainbow is about twice as wide, and has its colors reversed.
Fr.: étoile secondaire
1) Something that is or is kept secret, hidden, or concealed; a
From L. secretus "set apart, withdrawn; hidden, concealed," p.p. of secernere "to set apart, part, divide; exclude," from se- "without, apart," properly "on one's own" + cernere "to separate," → crisis.
Râz, from Mid.Pers. râz "secret, mystery;" cognate with Mod.Pers. rastan/rah- "to escape, be liberated;" O.Pers. (+*aua-) avarad- "to leave, abandon;" cf. Skt. rah- "to be lost, be lonely," rahas- "loneliness, privacy; a secret, mystery" (Cheung 2007).