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: 39 Search : arm
arm
  بازو   
bâzu (#)

Fr.: bras   

A slender part of a structure projecting from a main part, such as a → spiral arm. → Orion Arm; → Perseus Arm; → Scutum-Crux Arm.

From O.E. earm "arm," from P.Gmc. *armaz (cf. M.Du., Ger. Arm, O.N. armr, O.Fris. erm), from PIE base *ar- "to fit, join;" cf. Mod.Pers. arm "arm, from the elbow to the shoulder;" Av. arma-, arəmo- "arm;" Skt. irma- "arm;" Gk. arthron "a joint;" L. armus "shoulder."

Bâzu "arm," from Mid.Pers. bâzûk "arm;" Av. bāzu- "arm;" Mod.Pers. bâhu "stick, staff; arm;" cf. Skt. bāhu- "arm, forearm;" Gk. pechys "forearm, arm, ell;" O.H.G. buog "shoulder;" Ger. Bug "shoulder;" Du. boeg; O.E. bôg, bôh "shoulder, bough;" E. bough " a branch of a tree;" PIE *bhaghu- "arm").

armillary sphere
  ذات‌الحلق   
zâtolhelaq (#)

Fr.: sphère armillaire   

An ancient instrument, used since ancient times until the Middle ages and later, to determine positions of celestial bodies. It consisted of an assemblage of rings, all circles of the same sphere, designed to represent the positions of the important circles of the celestial sphere.

L. armillarius, from armilla "arm ring, bracelet," from armus "arm" + → sphere.

Zâtolhelaq from Ar. "multi-ringed," from zât "holder, keeper" + helaq "rings," from halqah "ring."

backwarming effect
  ا ُسکر ِ فروگرمی   
oskar-e forugarmi

Fr.: effet de rétro-réchauffement   

A sort of → greenhouse effect in → stellar atmospheres where the deeper layers heat up due to overlying → opacity. The presence of numerous → bound-bound opacities of → metals amplifies the → scattering of → photons, in particular their → backscattering, forcing the → temperature to increase in order to conserve the radiation flux and the transport of energy from the interior to the outer parts of the atmosphere.

back; → warming; → effect.

Carina arm
  بازوی ِ افزل   
bâzu-ye Afzal

Fr.: bras de Carène   

A → spiral arm in the Milky Way galaxy seen at its best in the → constellation → Carina, but also crossing the constellations → Vela, → Crux, and → Centaurus. It may be a continuation of the → Sagittarius arm; the combined feature is called Sagittarius-Carina arm.

Carina; → arm.

Carme (Jupiter XI)
  کارمه   
Kârme (#)

Fr.: Carmé   

The fourteenth of Jupiter's known satellites; 40 km in size; → retrograde orbit. It was discovered by Nicholson in 1938.

In Gk mythology, Carme was a wife of Zeus, and the mother of Britomartis, a Cretan goddess.

global warming
  گرمایش ِ جهانی   
garmâyeš-e jahâni

Fr.: réchauffement climatique   

An increase in the average → temperature of the Earth's → atmosphere that brings about climatic changes.

global; → warming.

harmonic
  هماهنگ   
hamâhang (#)

Fr.: harmonique   

(adj.) Of, pertaining to, or noting a series of oscillations in which each oscillation has a frequency that is an integral multiple of the same basic frequency.
(n.) A wave motion, superimposed on a fundamental wave, having a frequency which is an integral multiple of the fundamental frequency. → overtone.

From L. harmonicus, from Gk. harmonikos "harmonic, musical," from harmonia "agreement, concord of sounds," related to harmos "joint," arariskein "to join together;" PIE base *ar- "to fit together."

Hamâhang, "harmonious, concordant," from ham- "together, with; same, equally, even" (Mid.Pers. ham-, like L. com- and Gk. syn- with neither of which it is cognate. O.Pers./Av. ham-; Skt. sam-; also O.Pers./Av. hama- "one and the same," Skt. sama-; Gk. homos-; originally identical with PIE numeral *sam- "one," from *som-) + âhang "melody, pitch, tune; harmony, concord," from Proto-Iranian *āhang-, from prefix ā- + *hang-, from PIE base *sengwh- "to sing, make an incantation;" cf. O.H.G. singan; Ger. singen; Goth. siggwan; Swed. sjunga; O.E. singan "to chant, sing, tell in song;" maybe cognate with Gk. omphe "voice; oracle."

harmonic mean
  میانگین ِ هماهنگ   
miyângin-e hamâhang

Fr.: moyenne harmonique   

A number whose reciprocal is the → arithmetic mean of the reciprocals of a set of numbers. Denoted by H, it may be written in the discrete case for n quantities x1, ..., xn, as: 1/H = (1/n) Σ(1/xi), summing from i = 1 to n. For example, the harmonic mean between 3 and 4 is 24/7 (reciprocal of 3: 1/3, reciprocal of 4: 1/4, arithmetic mean between them 7/24). The harmonic mean applies more accurately to certain situations involving rates. For example, if a car travels a certain distance at a speed speed 60 km/h and then the same distance again at a speed 40 km/h, then its average speed is the harmonic mean of 48 km/h, and its total travel time is the same as if it had traveled the whole distance at that average speed. However, if the car travels for a certain amount of time at a speed v and then the same amount of time at a speed u, then its average speed is the arithmetic mean of v and u, which in the above example is 50 km/h.

harmonic; → mean.

harmonic motion
  جنبش ِ هماهنگ   
jonbeš-e hamâhang (#)

Fr.: mouvement harmonique   

A motion that repeats itself in equal intervals of time (also called periodic motion).

harmonic; → motion.

harmonic oscillator
  نَو ِشگر ِ هماهنگ   
navešgar-e hamâhang (#)

Fr.: oscillateur harmonique   

Any oscillating particle in harmonic motion.

harmonic; → oscillator.

harmonic progression
  فرایازی ِ هماهنگ   
farâyâzi-ye hamâhang

Fr.: progression harmonique   

Math.: Any ordered set of numbers, the reciprocals of which have a constant difference between them. For example 1, ½, 1/3, ¼, ..., 1/n. Also called → harmonic sequence.

harmonic; progression.

harmonic sequence
  پی‌آیه‌ی ِ هماهنگ   
peyâye-ye hamâhang

Fr.: suite harmonique   

harmonic progression.

harmonic; → sequence.

harmonic series
  سری ِ هماهنگ   
seri-ye hamâhang

Fr.: série harmonique   

Overtones whose frequencies are integral multiples of the → fundamental frequency. The fundamental frequency is the first harmonic.

harmonic; → series.

interarm region
  ناحیه‌ی ِ اندربازو، ~ ِ اندر-ا َرم   
nâhiye-ye andarbâzu, ~ andararm

Fr.: région interbras   

A low-density region separating the spiral arms of a galaxy.

Interarm, from → inter- + arm "body part," from O.E. earm "arm," from P.Gmc. *armaz (cf. M.Du., Ger. arm, O.N. armr, O.Fris. erm), from PIE base *ar- "to fit, join;" Mod.Pers. arm "arm, from the elbow to the shoulder;" Av. arma-, arəmo- "arm;" Skt. irma- "arm;" Gk. arthron "a joint," L. armus "shoulder;" → region.

Andarbâzu, from andar-, → inter-, + bâzu "arm," from Mid.Pers. bâzûk "arm;" Av. bāzu- "arm;" cf. Skt. bāhu- "arm, forearm;" Gk. pechys "forearm, arm, ell;" O.H.G. buog "shoulder;" Ger. Bug "shoulder;" Du. boeg; O.E. bôg, bôh "shoulder, bough;" E. bough " a branch of a tree;" PIE *bhaghu- "arm"); nahiyé, → region. Andararm, from andar-, → inter-, + arm, as above.

Larmor frequency
  بسامد ِ لارمور، فرگی ِ ~   
basâmad-e Larmor (#), feregi-ye ~ (#)

Fr.: fréquence de Larmor   

The frequency of precession of a charged particle describing a circular motion in a plane perpendicular to the magnetic induction in a uniform magnetic field.

Named after Joseph Larmor (1857-1942), an Irish physicist, the first to calculate the rate at which energy is radiated by an accelerated electron, and the first to explain the splitting of spectrum lines by a magnetic field; → frequency.

Larmor radius
  شعاع ِ لارمور   
šoâ'-e Larmor (#)

Fr.: rayon de Larmor   

The radius of the circular motion of a → charged particle moving in a → uniform magnetic field. Same as → gyroradius, → radius of gyration, → cyclotron radius. The Larmor radius (rL) is obtained by equating the → Lorentz force with the → centripetal force: qvB = mv2/rL, which leads to rL = p/(ZeB), where p is → momentum, Z is → atomic number, e is the → electron charge, and B is → magnetic induction. The frequency of this circular motion is known as the → gyrofrequency.

Larmor frequency; → radius.

Larmor's theorem
  فربین ِ لارمور   
farbin-e Larmor

Fr.: théorème de Larmor   

If a system of → charged particles, all having the same ratio of charge to mass (q/m), acted on by their mutual forces, and by a central force toward a common center, is subject in addition to a weak uniform magnetic field (B), its possible motions will be the same as the motions it could perform without the magnetic field, superposed upon a slow → precession of the entire system about the center of force with angular velocity ω = -(q/2mc)B.

Larmor frequency; → theorem.

lever arm
  بازوی ِ اهرم   
bâzu-ye ahrom (#)

Fr.: bras de levier   

The distance between the point of application of a → force and the → axis around which the object could → rotate.

lever; → arm.

Local Arm
  بازوی ِ محلی   
bâzu-ye mahali

Fr.: bras local   

One of the → spiral arms of the → Milky Way Galaxy which contains our → solar system. Same as → Orion Arm.

local; → arm.

lukewarm
  ولرم   
velarm (#)

Fr.: tiède   

Moderately warm; tepid.

M.E. lukewarme "tepid," from luke "tepid," of unknown origin, + → warm.

Velarm "lukewarm, tepid," of unknown origin.

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