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

A colorless, corrosive fuming liquid with pungent odor. It occurs in various plants and in the venom of many ant species. Used in dyeing, tanning, and electroplating. Also called methanoic acid. HCOOH is the simplest organic acid and the first identified in the interstellar medium (Zuckerman et al. 1971, ApJ, 163, L41). It has been observed principally in star-forming regions such as Orion KL, Sgr B2, Sgr A, and W51 and is associated with → hot molecular cores and → massive star formation. Recently, it has also been shown to be present in some → hot corinos associated with formation of stars similar to our Sun. Due to the presence of carboxyl radical (COOH), it plays an important role in the pathway formation of → prebiotic molecules like amino acids, in the interstellar clouds and comets (see, e.g., Lattanzi et al. 2008, ApJS 176, 536).

From L. formica "ant," ultimately from from PIE *morwi-, *wormiko- "ant;" cf. Av. maoiri-; Mid.Per. môr; Pers. mur, murcé "ant;" Skt. vamra- "ant;" Gk. murmeks, wormikas; O.C.S. mraviji; O.Ir. moirb; O.N. maurr.

1) Physics, Math.: A statement of facts in a symbolical or general form, by substitution in which a result applicable to particular data may be obtained.
2) Chemistry: An expression of the constituents of a compound by symbols and figures.

From L. formula "form, rule, method, formula," literally "small form," from forma, → form, + → -ule diminutive suffix.

Disul, from dis, → form, + -ul, → -ule.

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

Verbal form of → form.

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.

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.

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

→ Fornax; → cluster.

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."

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.

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.

1) Geology: The process whereby a geologic section (subsurface model of one-, two-, or three dimensions) is transformed into a synthetic seismogram (synthetic seismic record).
2) In → asteroseismology, a model that takes the physical properties of a star as input parameters and predicts the star's oscillations. Then, by finding parameters that yield oscillation frequencies (ω_nlm) close to those observed, one can infer the properties of the observed star. The quantum numbers n, l, and m must be identified before any meaningful comparison between seismic data and model predictions can be made. That mode identification requires a physical interpretation of the measured frequencies.

→ forward; → seismic; → modeling.

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.

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.

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;

Same as → eddy current.

→ Foucault; → current.

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.

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.

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.

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.

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

→ four; → dimensional; → operator.

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.