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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1310
cutoff voltage
  ولتاژ ِ بره   
voltâž-e boré

Fr.: tension de coupure   

The electrode voltage which reduces the value of a dependent variable, e.g. anode current, to a specified low value.

cutoff; → voltage.

cutoff wavelength
  موج-طول ِ بره   
mowj-tul-e boré

Fr.: longueur d'onde de coupure   

Wavelength at which the transmittance of a filter, or the detectivity of a detector, has fallen to one-half its peak value.

cutoff; → wavelength.

cyanide
  سیانور   
siyânur (#)

Fr.: cyanure   

A chemical compound that contains the → cyano radical, -CN. Most cyanides are highly toxic.

cyano-; → -ide.

cyano radical
  رادیکال ِ سیانو   
râdikâl-e siyâno

Fr.: radical cyano   

A diatomic chemical radical composed of carbon and nitrogen atoms. The triple bonds of C to H leave one electron available, which makes the CN radical very reactive. Organic molecules with the -CN group are potential sources of → prebiotic amino acids. Same as the → CN molecule. The CN radical was first identified by Gay-Lussac, who in 1815 published an extensive study of the derivatives of prussic acid (→ hydrogen cyanide). He showed that the cyano radical remained intact throughout a series of chemical transformations. Also called cyanogen radical.

cyano-; → radical.

cyano-
  سیانو-   
siyâno- (#)

Fr.: cyano-   

1) A combining form meaning "blue, dark blue," used in the formation of compound words. Also cyan- before a vowel.
2) A combining form representing → cyanide in the formation of chemical compounds.

From Gk. kyanos "dark blue, lapis lazuli," because of its presence in the Prussian blue, Fe7(CN)18, a dye which was first accidentally made around 1706, by heating substances containing iron and carbon and nitrogen.

cyanogen
  سیانوژن   
siyânožen (#)

Fr.: cyanogène   

1) A colorless, very poisonous, flammable gas with a smell of bitter almonds. Chemical formula: C2N2. It was discovered by Louis Joseph Gay-Lussac (1778-1850) in 1848.
2) A univalent radical, CN, found in simple and complex cyanide compounds. CN exists in → interstellar medium and is one of the main molecules detected in → comets. It has energy levels at 113 and 227 GHz (2.6 and 1.3 mm wavelength) above the ground level.

cyano- + → -gen.

cyanogen band
  باند ِ سیانوژن   
bând-e siyânožen (#)

Fr.: bande de cyanogène   

An → absorption band of molecular origin characterizing the spectra of → late-type stars (G0 and later, e.g. → S star). → Cyanogen absorption is an important → luminosity criterion for → low-mass stars, and is more pronounced in → giant stars than in → dwarf stars of the same → spectral type.

cyanogen; → band.

cycle
  چرخ، چرخه   
carx (#), carxé (#)

Fr.: cycle   

1) A sequence of changes that are repeated regularly, such as revolution, rotation, vibration, oscillation, wave motion.
2) One complete set of changes in the value of a → periodic function during one period.
3) A period of time at the end of which an event or sequence of events are repeated.
carbon cycle, → Carnot cycle, → CNO cycle, → hydrologic cycle, → Metonic cycle, → Milankovich cycle, → solar activity cycle, → solar cycle, → solar magnetic cycle, → sunspot cycle, → epicycle, → recycle.
4) In → graph theory, a closed → path with at least one → edge.

From L.L. cyclus, from Gk. kyklos "circle, wheel," from PIE base *kw(e)-kwl-o- "wheel, circle," from *kwel- "to turn, move around, sojourn, dwell," (cf. Av. caxra- "wheel," caraiti "he moves, approaches;" Mod.Pers. carx "wheel;" Skt. cakra- "wheel, circle; cycle," carati "he moves, wanders;" Gk. polos "axis of a sphere," polein "move around;" L. colere "to dwell in, to cultivate, move around," colonus "farmer, settler;" O.E. hweol "wheel;" Rus. koleso "awheel").

Carx "every thing performing a circulatory motion; a wheel; a cart," Mid.Pers. chr "wheel," Parthian cxr "wheel," Ossetic, Khotanese calx "wheel," Av. caxra- "wheel," cognate with Gk. kyklos "circle, wheel," as above. Carxé from carx + nuance suffix .

cyclic
  چرخه‌ای   
carxe-yi (#)

Fr.: cyclique   

Of, pertaining to, or constituting a cycle or cycles.

cycle; → -ic.

cyclic coordinate
  همارای ِ نادیده‌انگاشته   
hamârâ-ye nâdidé engâshté

Fr.: coordonnée ignorée   

Same as → ignorable coordinate.

cyclic; → coordinate.

cyclic group
  گروه ِ چرخه‌ای   
goruh-e carxe-yi

Fr.: groupe cyclic   

A group in which each element can be expressed as a power of any other element.

cyclic; → group.

cyclic process
  فراروند ِ چرخه‌ای   
farâravand-e carxe-yi

Fr.: processus cyclique   

Any sequence of changes in a → thermodynamic system that returns the system into its → initial  → state.

cyclic; → process.

cyclic quadrilateral
  چهاربر ِ چرخه‌ای   
cahârbar-e carxe-yi

Fr.: quadrilatère cyclique   

A quadrilateral in which all four vertices lie on the circumference of a circle.

cyclic; → quadrilateral.

cycloid
  چرخزاد   
carxzâd (#)

Fr.: cycloïde   

The curve traced by a point on the circumference of a circle that rolls along a straight line. The cycloid has a → cusp at every point where it touches the straight line. The distance between cusps is 2πR, where R is the radius of the circle.

Cycloid, from Gk. kykloeides "circular," fr. kyklos "circle," → cycle + eides "form," → -oid.

Carxzâd, from carx "wheel, circle," → cycle + zâd "produced, created, born," from zâdan "give birth" (Av. zan- "to bear, give birth to a child, be born," infinitive zazâite, zâta- "born," cf. Skt. janati "begets, bears," Gk. gignesthai "to become, happen" L. gignere "to beget," gnasci "to be born," PIE base *gen- "to give birth, beget").

cyclone
  چرخند   
carxand (#)

Fr.: cyclone   

Any circulatory wind system in the atmosphere in which the motion is anticlockwise in the northern hemisphere (that is in the same sense as that of Earth) and clockwise in the southern hemisphere, around a center of low pressure.

From Gk. kyklon "moving in a circle, whirling around," pr.p. of kykloun "move in a circle, whirl," from kyklos "circle," cognate with Pers. carxcycle.

Carxand "moving in a circle," from carxidanrotate, from carx, → cycle.

cyclotron
  سیکلوترون   
siklotron (#)

Fr.: cyclotron   

An → accelerator in which charged subatomic particles generated at a central source are accelerated to acquire energies up to several tens of millions of → electron-volts. The cyclotron consists of two flat, semicircular metal boxes or electrodes, called dees or D's because of their shape. An alternating electric field between the dees continuously accelerates the particles from one dee to the other, while the magnetic field bends their direction guiding them in a circular path. As the speed of the particles increases, so does the radius of their path, and the particles spiral outward. See also → cyclotron frequency, → synchrotron.

From cyclo- a combining form meaning → cycle + → -tron.

cyclotron frequency
  بسامد ِ سیکلوترون   
basâmad-e siklotron

Fr.: fréquence cyclotron   

The frequency with which a → non-relativistic particle of charge q and mass m turns in a cyclotron with → uniform magnetic field B. The equality of the → centripetal force to the → Lorentz force leads to the expression: by: fcycl = qB/2πm. For → relativistic case, the frequency is smaller and is called → synchrotron frequency.

cyclotron; → frequency.

cyclotron radius
  شعاع ِ سیکلوترون   
šo'â'-e siklotron

Fr.: rayon de cyclotron   

Same as → Larmor radius.

cyclotron; → radius.

Cygnus
  ماکیان   
Mâkiyân (#)

Fr.: Cygne   

The Swan. A prominent northern → constellation that lies in the glowing band of the Milky way, east of Lyra and north of Vulpecula, and represents a swan. The brightest stars of Cygnus form a cross, so it is also known as the Northern Cross. Abbreviation: Cyg, genitive: Cygni.

From L. cygnus "swan," from Gk. kuknos.

Mâkiyân "a hen, fowl."

Cygnus A
  ماکیان A   
Mâkiyân A

Fr.: Cygnus A   

The strongest extragalactic radio source in the sky approximately 109 light-years away in the → constellation  → Cygnus. Also called 3C 405.

Cygnus.

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