An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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secondary
  دومان   
dovomân

Fr.: secondaire   

1) Derived or derivative; not primary or original.
2) Belonging or pertaining to a second order, division, stage, period, rank, grade, etc.
3) → secondary body.
See also:
secondary atmosphere, → secondary calibrator, → secondary cell, → secondary cosmic rays, → secondary crater, → secondary eclipse, → secondary electrons, → secondary emission, → secondary mirror, → secondary star.

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.

secondary atmosphere
  جوّ ِ دومان، هواسپهر ِ ~   
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.

secondary; → atmosphere.

secondary body
  جسم ِ دومان   
jesm-e dovomân

Fr.: corps secondaire   

A body that revolves around a more massive body under the → gravitational attraction of the latter is called the → primary body.
The less massive component in a → binary system.

secondary; → body.

secondary calibrator
  کبیزنده‌ی ِ دومان   
kabizande-ye dovomân

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; → calibrator.

secondary cell
  پیل ِ دومان   
pil-e dovomân

Fr.:   

An electric cell that can be charged by passing a current through it in reverse direction to its discharge. Same as → accumulator. See also → primary cell.

secondary; → cell.

secondary cosmic rays
  پرتوهای ِ کیهانی ِ دومان   
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.

secondary; → cosmic; → ray.

secondary crater
  لاوک ِ دومان، کندال ِ ~   
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.

secondary; → crater.

secondary eclipse
  گرفت ِ دومان   
gereft-e dovomân

Fr.: éclipse secondaire   

Of a transiting → exoplanet, the event and the interval of time during which the planet passes behind its host star. → primary eclipse.

secondary; → eclipse.

secondary electrons
  الکترون‌های ِ دومان   
elektronhâ-ye dovomân

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.

secondary; → electron.

secondary emission
  گسیل ِ دومان   
gosil-e dovomân

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.

secondary; → emission.

secondary mirror
  آینه‌ی ِ دومان   
âyene-ye dovomân

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.

secondary; → mirror.

secondary rainbow
  رنگین‌کمان ِ دومان   
rangin-kamân-e dovomân

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.

secondary; → rainbow.

secondary star
  ستاره‌ی ِ دومان   
setâre-ye dovomân

Fr.: étoile secondaire   

In a → binary system, the star that revolves around the more massive → primary component.

secondary; → star.

section
  سکنج   
sekanj (#)

Fr.: section   

A part that is cut off or separated.
A distinct part or subdivision of anything. → cross section; → intersection

From M.Fr. section, from L. sectionem "a cutting, division," from secare "to cut;" PIE base *sek- "cut" (cf. O.C.S. seko, sesti "to cut," Lith. isekti "to engrave, carve;" O.S. segasna, O.E. sigðe "scythe;" O.E. secg "sword," seax "knife, short sword").

Sekanj "a scraping, shaving, cutting," cognate with Pers. šekast-, šekastan "to break;" Av. skand- "to break," Skt. khand- "to break," khanda- "piece;" Pers. dialect Tabari šag "a special razor used to make incisions in the walls of unripe opium poppies in order to extract the milky sap," may be related to PIE *sek- "cut," as above.

secular aberration
  بیراهش ِ دیریاز   
birâheš-e diryâz

Fr.: aberration séculaire   

The smallest component of the aberration of starlight which is caused by the motion of the solar system through space. → annual aberration; → diurnal aberration.

secular; → aberration.

secular acceleration
  شتاب ِ دیریاز   
šetâb-e diryâz

Fr.: accélération séculaire   

The apparent gradual increase in the → Moon's motion in its orbit, as measured relative to → mean solar time. Secular acceleration corresponds to an extremely gradual reduction in the speed of the → Earth's rotation. The slow-down of the Earth's spin comes mainly from → tidal frictions from the Moon. Historically, Edmond Halley (1656-1742) was the first to suggest that the Moon's mean rate of motion relative to the stars was gradually increasing. In 1693, Halley compared eclipses of recent, medieval, and classical Babylonian time, and discovered that the Moon's mean motion had been gradually increasing. Using Lunar Laser Ranging measurement, based on laser reflectors left by the Apollo astronauts on the Moon's surface (1969 to 1972), the secular acceleration is derived to be -25".4 ± 0".1 century 2 (Xu Huaguan et al., 1996, in Earth, Moon and Planets 73, 101). This corresponds to a linear increase of about 3.5 cm yr-1 in the mean Earth-Moon distance.

secular; → acceleration.

secular perturbation
  پرتورش ِ دیریاز   
partureš-e diryâz

Fr.: perturbation séculaire   

A variation of planetary orbital elements which is always in the same direction as time increases.

secular; → perturbation.

secular variation
  ورتش ِ دیریاز   
varteš-e diryâz

Fr.: variation séculaire   

Same as → secular perturbation.

secular; → variation.

secularization
  گیانش   
giyâneš

Fr.: laïcisation   

The process of organizing society or aspects of social life around non-religious values or principles.

Verbal noun of secularize "giyânidan" (گیانیدن); → secular

seeing monitor
  پهره‌گر ِ شکان   
pahregar-e šekân

Fr.: moniteur de seeing   

An optical instrument that follows the variation of → atmospheric turbulence by continuously measuring the → seeing conditions.

seeing; → monitor.

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