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: 425
formulate
  دیسولیدن   
disulidan

Fr.: formuler   

To express in precise → form; state definitely or systematically. To reduce to or express in a → formula.

Verbal form of → form.

formulation
  دیسولش   
disuleš

Fr.: formulation   

1) The act or process of formulating.
2) A particular expression of an idea, thought, or theory.
3) Something prepared according to a → formula.

formulate; → -tion.

Fornax
  کوره   
Kuré (#)

Fr.: Fourneau   

The Chemical Furnace. A faint → constellation in the southern sky, representing a chemist's furnace. Its brightest star, Alpha Fornacis, is a double of magnitudes 4.0 and 6.5. Abbreviation: For; genitive: Fornacis.

L. fornax "oven, kiln," related to fornus, furnus "oven," and to formus "warm," from PIE base *ghworm-/*ghwerm- "warm" (cf. Mod./Mid.Pers. garm "warm;" O.Pers./Av. garəma- "hot, warm;" Skt. gharmah "heat;" Gk. thermos "warm;" cf. O.E. wearm; O.H.G., Ger. warm).
Fornax was created and named by Abbé Nicolas Louis de Lacaille (1713-1762) in honor of Antoine Lavoisier, the French chemist, who was guillotined in the French Revolution in 1794. He created it out of several faint stars in the constellation → Eridanus.

Kuré "furnace;" Tabari kalə "furnace," kəlen "ash;" Laki koira; Kurd. kulan, kulandan "to cook;" Laki koira; Kurd. kulan, kulandan "to cook;" related to garm "warm;" cf. Skt. ghar- "to burn;" E. kiln "furnace, oven," from L. culina "cooking stove, kitchen;" PIE root *gwher- "to warm, be warm," → warm.

Fornax cluster
  خوشه‌ی ِ کوره   
xuše-ye kuré

Fr.: amas de Fourneau   

The second richest → cluster of galaxies within 100 million light-years, although it is much smaller than the → Virgo cluster.

Fornax; → cluster.

forty
  چهل   
cehel (#)

Fr.: quarante   

A cardinal number, ten times four.

M.E. fourti, O.E. feowertig, from feower, → four, + tig "group of ten" (cf. O.S. fiwartig, Du. veertig, O.H.G. fiorzug, Ger. vierzig, Goth. fidwor tigjus.

Cehel (short form cel); Mid.Pers. cehel "forty;" Av. caθwarəsa(n)t- "forty," from caθwar-, → four, + sant-, sat "ten;" cf. Skt. catvārimśát- "forty."

forward
  پیش-سو؛ ۲) پیش-سو کردن   
1) piš-su; 2) piš-su kardan

Fr.: en avant, en avance   

1a) To or toward what is ahead or in front.
1b) Directed toward a point in advance.
2) To send forward; transmit, especially (a letter or email) to a different address.

From fore "before, in front of," cognate with Pers. farâ, → pro-,+ → -ward.

Piš-su, from piš "forward; in front of; before;" Mid.Pers. pêš, + su, → direction.

forward scattering
  پراکنش ِ پیش-سو   
parâkaneš-e piš-su

Fr.: diffusion en avant   

Scattering in which photons emerge from the → scattering medium travelling predominantly in the same direction as they entered. The → halos around the Sun and Moon in wet weather are caused by forward scattering by water droplets in the Earth's atmosphere. → backscattering.

forward; → scattering.

forward shock
  تش ِ پیش-سو   
toš-e piš-su

Fr.: choc en avant   

A highly → supersonic → shock wave created in a → supernova remnant as the expanding stellar ejecta runs into the → interstellar medium (ISM). This forward shock wave produces sudden, large changes in pressure and temperature behind the shock wave. The forward shock wave also accelerates electrons and other charged particles to extremely high energies. The forward shock front has a velocity of 104 km s-1 and can heat the shocked gas to temperatures ~ 109 K. While the forward shock continues to expand into the ISM, it creates a → reverse shock that travels back into the freely expanding → supernova ejecta.

forward; → shock.

fossil
  سنگواره   
sangvâré (#)

Fr.: fossile   

A relic, remnant, or representation of an organism that existed in a past geological age.

From Fr. fossile, from L. fossilis "dug up," from fossus, p.p. of fodere "to dig."

Sangâré literally "resembling stone," from sang, → stone, + -vâré, from -vâr, → -oid.

fossil magnetic field
  میدان ِ مغناتیسی ِ سنگواره، ~ ~ سنگواره‌ای   
meydân-e meqnâtisi-ye sangvâré, ~ ~ sangvâre-yi

Fr.: champ magnétique fossile   

In a physical system, the → magnetic field belonging to an earlier magnetic process or event. A fossil magnetic field may be a vanished one or exist in relic forms. As an example, the solar magnetic field, which was present during the formation of the Sun, has disappeared over the last 4.6 billions years.

fossil;→ magnetic; → field;

Foucault current
  جریان ِ فوکو   
jarayân-e Foucault (#)

Fr.: courant de Foucault   

Same as → eddy current.

Foucault; → current.

Foucault knife-edge test
  آزمون ِ کارد ِ فوکو   
âzmun-e kârd-e Foucault

Fr.: contrôle par foucaultage   

A method used to test the → image quality of → mirrors and → lenses. The test is performed by moving a knife edge laterally into the → image of a small → point source. The → eye, or a → camera, is placed immediately behind the knife edge, and the → exit pupil of the system is observed.

Named after the French physicist Léon Foucault (1819-1868), who invented the method; → knife; → edge; → test.

Foucault pendulum
  آونگ ِ فوکو   
âvang-e Foucault (#)

Fr.: pendule de Foucault   

A → pendulum consisting of a heavy weight on a very long wire attached to a support, that shows the rotation of Earth. The support must be nearly frictionless in order that the pendulum can continue to swing freely for long periods of time. The pendulum will swing in the same plane as it started. The → Earth's rotation is reflected in the slow turning of the plane of the pendulum's motion, which appears to rotate through 360° in T hours. The rotation time is given by the expression: T = T0/sin φ, where T0 = 23.9344 hours is the → sidereal day and φ the → latitude of the place. At the poles the rotation period is 23h 56m 04s, and at the equator is ∞, i.e. the swing plane does not move. For regions near the equator it is very long; for example at Quito, the capital city of Ecuador, with φ = 00°15'S, it is 5485 days or more than 15 years! This phenomenon shows that the Earth is a → non-inertial frame.

The experiment was performed for the first time by the French physicist Léon Foucault (1819-1868) in 1851, who set up, in the Pantheon in Paris, a simple pendulum consisting of a lead ball weighing 28 kg, suspended by a fine steel wire 67m long. At the latitude of Paris, the pendulum takes 31h 47m 38s to complete a precession cycle; → pendulum.

Foucault's Marseille reflector
  بازتابگر ِ فوکو‌ی ِ مارسی   
bâztâbgar-e Foucault-ye Marseille

Fr.: réflecteur marseillais de Foucault   

The first functioning → reflecting telescope with a silvered glass mirror. It was built by Léon Foucault in 1826 for the Marseille Observatory. The mirror of 80-cm in diameter (f/d = 5) had an excellent quality. The telescope was used for a century as a visual instrument. Edouard Stéphan (1837-1923) used it from 1871 to 1884 to find 800 high-brightness galaxies, among which the → Stephan's Quintet. From 1906 to 1962 the telescope was used by Robert Jonckheere (1888-1927) to discover 3,350 new binary stars. In 1873, following an idea of Hippolyte Fizeau (1819-1896), Stéphan attempted to use it as an → interferometer to measure the diameter of a number of stars. In 1914 Charles Fabry (1867-1945) and Henri Buisson (1873-1944) used the telescope to obtain the first astronomical Fabry-Pérot interferogram, on the → Orion Nebula.

After the French physicist and optician Léon Foucault (1819-1868); Marseille (Observatory), the second largest city of France, located on the south east coast of the Mediterranean Sea, from L. Massalia, from Gk. Massalia; → reflector.

four
  چهار   
cahâr (#)

Fr.: quatre   

O.E. feower, from P.Gmc. *petwor- (cf. O.S. fiwar, Du. and Ger. vier, O.N. fjorir, Dan. fire, Sw. fyra), cognate with Pers. cahâr, as below, from PIE *qwetwor.

Cahâr, variant câr, from Mid.Pers. cahâr; Av. caθwarô, catur-; cf. Skt. catvārah; Gk. tessares; cognate with L. quattuor; E. four, as above.

four-dimensional operator
  آپارگر ِ چهار-وامونی   
âpârgar-e cahâr-vâmuni

Fr.: opérateur à quatre dimensions   

An operator defined as: ▫ = (∂/∂x, ∂/∂y, ∂/∂z, 1/(jc∂/∂t).

four; → dimensional; → operator.

Fourier analysis
  آنالس ِ فوریه   
ânâlas-e Fourier

Fr.: analyse de Fourier   

The process of decomposing any function of time or space into a sum of sinusoidal functions using the → Fourier series and → Fourier transforms. In other words, any data analysis procedure that describes or measures the fluctuations in a time series by comparing them with sinusoids. Fourier analysis is an essential component of much of modern applied and pure mathematics. It forms an exceptionally powerful analytical tool for solving various problems in many areas of mathematics, physics, engineering, biology, finance, etc. and has opened up new realms of knowledge.

After the French mathematician Baron Jean Baptiste Joseph Fourier (1768-1830), whose work had a tremendous impact on the physical applications of mathematics; → analysis.

Fourier coefficient
  همگر ِ فوریه   
hamgar-e Fourier

Fr.: coefficient de Fourier   

One of the coefficients an or bn of cos (nx) and sin (nx) respectively in the → Fourier series representation of a function. They are expressed by:
an = (1/π) ∫f(x) cos nx dx, for n≥ 0, summed over 0 to 2π
bn = (1/π) ∫f(x) sin nx dx, for n≥ 1, summed over 0 to 2π.

Fourier analysis; → series.

Fourier integral
  درستال ِ فوریه   
dorostâl-e Fourier

Fr.: intégrale de Fourier   

An integral used in the → Fourier transform.

Fourier analysis; → integral.

Fourier series
  سری ِ فوریه   
seri-ye Fourier

Fr.: séries Fourier   

A mathematical tool used for decomposing a → periodic function into an infinite sum of sine and cosine functions. The general form of the Fourier series for a function f(x) with period 2π is:
(1/2) a0 + Σ (an cos (nx) + bn sin (nx), summed from n = 1 to ∞,
where an and bn are the → Fourier coefficients, measuring the strength of contribution from each harmonic. The functions cos (nx) and sin (nx) can be used in this way because they satisfy the → orthogonality conditions. For the problem of convergence of the Fourier series see → Dirichlet conditions. The Fourier series play a very important role in the study of periodic phenomena, because they allow one to decompose a large number of complex problems into simpler ones. The generalization of this method, called the → Fourier transform, makes it possible to also decompose non-periodic functions into harmonic components. See also → complex Fourier series, → Parseval's theorem.

Fourier analysis; → series.

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