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

In the → Fanaroff-Riley classification, → radio sources with hotspots in their lobes at distances from the center which are such that R_FR > 0.5. The → radio jets in FR-II sources are expected to be highly → supersonic, allowing them to travel large distances.

→ Fanaroff-Riley classification; → class.

A classification scheme for distinguishing a → radio galaxy from an → active galaxy based on their → radio frequency  and → luminosity and their kpc-scale appearance. Analyzing a sample of 57 radio galaxies from the → 3CR catalogue, which were clearly resolved at 1.4 GHz or 5 GHz, Fanaroff & Riley (1974) discovered that the relative positions of regions of high and low → surface brightness in the → lobes of extragalactic → radio sources are correlated with their radio luminosity. They divided the sample into two classes using the ratio R_FR of the distance between the regions of highest surface brightness on opposite sides of the central galaxy or quasar, to the total extent of the source up to the lowest brightness contour in the map. → Fanaroff-Riley Class I (FR-I) , → Fanaroff-Riley Class II (FR-II). The boundary between the two classes is not very sharp, and there is some overlap in the luminosities of sources classified as FR-I or FR-II on the basis of their structures. The physical cause of the FR-I/II dichotomy probably lies in the type of flow in the → radio jets.

Bernard L. Fanaroff and Julia M. Riley, 1974, MNRAS 167, 31P; → classification.

Being at a great distance; remote in time or place.

O.E. feorr "to a great distance, long ago," from P.Gmc. *ferro (cf. Du. ver, Ger. fern), from PIE *per- "through, across, beyond" (cf. O.Pers. para "on the other side (of);" Av. parə "beyond, more than, superior," parô "except," pərətu- "crossing, bridge;" Mod.Pers. pol "bridge;" Skt. parás "far, further, beyond," Gk. pera "across, beyond," L. per "through").

Dur, from Mid.Pers. dūr "far, distant, remote;" O.Pers. dūra- "far (in time or space)," dūraiy "afar, far away, far and wide;" Av. dūra-, dūirē "far," from dav- "to move away;" cf. Skt. dūrá- "far; distance (in space and time);" PIE base *deu- "to move forward, pass;" cf. Gk. den "for a long time," deros "lasting long."

Infrared radiation in the wavelength range (25-40) to (200-350) microns emitted by cold molecular/dust clouds.

→ far; → infrared.

Ultraviolet radiation in the wavelength range 912-2000 Å. See also → extreme ultraviolet.

→ far; → ultraviolet.

The portion of the → electromagnetic radiation in the wavelength range between about 30 and 300 → microns. See also: → infrared radiation, → near-infrared, → mid-infrared, → submillimeter radiation.

→ far; → infrared.

The → SI unit of → capacitance, defined as the capacitance of a conductor whose → potential increases by one → volt when a charge of 1 → coulomb is imparted to it; symbol F.

Named after the British physicist Michael Faraday (1791-1867), who made several major contributions to the fields of electricity and magnetism.

An enclosure made of conducting material, such as wire mesh or metal plates, that shields what it contains from external electric fields. According to → Gauss's theorem, the electric field inside a hollow conductor is nil. In order to demonstrate this, Faraday, in 1836, made a large box covered with wire mesh, and went inside it himself with an → electroscope. Powerful charges were applied to the outside of the box, but he detected no effect inside the cage.

→ farad; → cage.

Same as → Faraday rotation.

→ farad; → effect.

The rotation of the plane of → polarization experienced by a beam of → linearly polarized radiation when the radiation passes through a material containing a magnetic field with a component in the direction of propagation. This effect occurs in → H II regions in which a magnetic field causes a change in the polarized waves passing through. Same as → Faraday effect.

→ farad; → rotation.

The induced → electromotive force in a circuit is equal in magnitude and opposite in sign to the rate of change of the → magnetic flux through the surface bounded by the circuit. Mathematically, it is expressed as: ∇ x E = -∂B/∂t, which is one of the four → Maxwell's equations.

→ farad; → law; → induction.

An area of land devoted to the raising of animals, fish, plants, etc.

M.E. ferme "lease, rented land, rent," from O.Fr., from Vulgar L. *ferma, derivative of *fermare for L. firmare "to make firm, confirm."

Keštzâr "farm, field," from kešt past stem of keštan, variants kâštan, kâridan "to cultivate, to plant;" Mid.Pers. kištan, kâridan "to sow, plant; to make furrows;" Av. kar- "to strew seed, cultivate," kāraiieiti "cultivates;" cf. Skt. kar- "to scatter, strew, pour out," + suffix -zâr denoting profusion, abundance, as in kârzâr "a field of battle; combat" šurezâr "unfertile, salty ground; nitrous earth," xoškzâr "arid land," and so forth.

Moving or able to move, operate, function, or take effect quickly; quick; swift; rapid (Dictionary.com).

M.E., from O.E. fæst "firmly fixed, steadfast;" O.Fr. fest, O.N. fastr, Du. vast, Ger. fest.

Tond "swift, rapid, brisk; fierce, severe," → velocity.

A bright → burst of → radio emission lasting only a few milliseconds, and thought to be of → extragalactic origin. The first ever detected such burst, called the → Lorimer burst, was in 2007. It lasted only 5 milliseconds, but the single radio → pulse was dispersed over a wide range of frequencies (→ dispersion measure). This suggested a → cosmic origin for the burst, because the radiation must have passed through very distant → intergalactic clouds to be so highly dispersed. The second FRB was detected in 2012 in archival data from the Parkes Radio Telescope, the same telescope through which the original burst was seen. No temporally coincident → X-ray or → gamma ray signature was identified in association with the bursts. Most recent results suggest FRBs as a new population of explosive events at cosmological distances of up to 3 → giga  → parsecs, that is → redshifts of 0.5 to 1. While physical interpretations for this phenomenon remain speculative, they are thought to involve highly → compact objects, such as → neutron stars. See also → blitzar.

The term fast radio burst was coined by Thornton et al., 2013, Science, 341, 53 (arXiv:1307.1628); → fast; → radio; → burst.

1) To attach firmly or securely in place; fix securely to something else.
2) To make secure, as an article of dress with buttons, clasps, etc., or a door with a lock, bolt, etc. (Dictionary.com).

From M.E. fastenen, from O.E. fæstnian; cognate with O.Fris. festnia "to make firm, bind fast," O.Sax. fastnon, O.H.G. fastnion, O.N. fastna "to pledge, betroth."

Darizidan, from Proto-Ir. *darz- "to attach, fasten;" cf. Av. darəz- "to attach;" Mid.Pers. handarz "advice, order, command," drz- "to fasten;" Mod.Pers. andarz "advice; testament," darzan "needle," darzi "tailor," razé (with elimination of the initial phoneme) "a ring or staple used to fasten a door," padarzé "a wrapper in which clothes are folded up;" cf. Skt. drah- "to fix, make firm;" Gk. drassomai "I take hold of, grasp;" Russ. deržat' "to hold, keep" (Cheung 2007).

A male → parent.

M.E. fader, from O.E. fæder "father, male ancestor;" cf. O.S. fadar, Du. vader, O.N. faðir, O.H.G. fater, Ger. Vater; PIE *pəter-; cognate with Pers. pedar, as below.

Pedar, from Mid.Pers. pidar, variant pid "father;" O.Pers. pitā- "father;" Av. patar-; cf. Skt. pitár-; Gk. pater; L. pater (Fr. père, Sp. padre).

Geology: A fracture in the Earth's crust along which the adjacent rock surfaces have been displaced relative to each other. Movement along the fault can cause → earthquakes or, in the process of mountain-building, can release underlying → magma and permit it to rise to the surface as a volcanic eruption.

M.E. faute "deficiency," from O.Fr. faute "opening, gap; failure, flaw; lack," from V.L. *fallita "a shortcoming, falling," from L. falsus "deceptive, feigned, spurious," p.p. of fallere "to deceive, be wrong."

Gosalé, noun from gosalidan "to break; to snap asunder," ultimately from Proto-Iranian *uisar-, from *ui- "apart" + *sar- "to break;" cf. Av. sairi- "fragment," asarəta- "not broken;" Skt. sar- "to break, tear apart," śūrtá- "smashed," aśīrtá- "unharmed;" Gk. keraizo "to tear, destroy," akeraios "unharmed;" PIE base *ker- "to hurt, harm."

Geology: The surface of a fracture along which dislocation of adjacent rocks has taken place.

→ falt; → surface.

The geological process leading to the formation of → faults.

Verbal noun, → fault.

One of light appendages that grow from a bird's skin and form its covering.

M.E., from O.E. fether; akin to Du. veder, Ger. Feder, O.N. fioþr, Sw. fjäder, from PIE root *pet- "to rush, to fly."

Parr "feather," variant bâl "wing," Mid.Pers. parr "feather, wing," bâl; Av. parəna- "feather," Skt. parnam, cf. O.H.G. farn "fern," PIE pornom "feather."