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

A device used on a telescope to correct for the → field rotation while tracking an object.

→ field; → rotator.

A star that does not belong to a stellar cluster, but happens to be adjacent to it.

→ field; → star.

A diaphragm located at an image plane of an optical system that determines the size and shape of the image. → aperture stop.

→ field; → stop.

1) A theory which uses the concept of → field to describe physical phenomena. It consists of two types: → classical field theory and → quantum field theory.
2) Math.: A branch of mathematics which studies the → fields.

→ field; → theory.

The precise curve required on the surface of an optical element, especially the mirror of a reflecting telescope.

From O.Fr. figure, from L. figura "a shape, form."

Šekl from Ar. šakl "figure."

The final stage of mirror making, a process of altering the mirror's shape into the one required for proper function. → grinding; → polishing.

Figuring, noun of → figure.

Šekldahi, "giving form," from šekl, → figure + dahi, a verbal noun of dâdan "to give," from Mid.Pers. dâdan "to give," O.Pers./Av. dā- "to give, grant, yield," dadāiti "he gives;" cf. Skt. dadáti "he gives," Gk. didomi "I give," tithenai "to put, set, place;" L. dare "to give, offer;" facere "to do, to make;" Rus. delat "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do." PIE base *dhe- "to put, to do."

1) A long tongue of a relatively cold matter (10,000 K), suspended in the → solar corona (2 million K). Filaments seem dark in the Hα light when they are seen projected on the solar disk; at the limb they look as what they actually are: → prominences.
2) Electricity, Electronics: In electric light bulbs and thermionic valves, a wire of metal of high melting point, which is heated by the passage of an electric current.
3) Cosmology: → cosmic filament.

From Mod.L. filamentum, from L.L. filare "to spin, draw out in a long line," from L. filum "thread," from PIE base *g^whi- "thread, tendon;" cf. Gk. bios "bow;" Skt. jiyā- "bow-string;" Av. jiiā- "bow-string;" Mod.Pers. zeh "string, bow-string" (dialectal Qomi zij "mason's cord"); Arm. jil "string, line;" Lith. gijà "thread;" Russ. žica "thread."

Rešté "thread, line, file," from reštan, ristan "to spin;" Mid.Pers. 'rws- "to turn to," abrešom "silk;" Sogdian rwyšt "spun;" Av. uruuaēs- "to twist, turn;" Proto-Iranian *uris- "to turn, spin."

A nebula, generally ionized, consisting of filament-like structures of gas, such as the Veil Nebula (NGC 6960) or the supernova remnant IC 443.

Filamentary adj. of → filament; → nebula.

An instrument used with a telescope for accurately measuring small angular separations between two celestial bodies (as between binary stars). The instrument consists of two parallel fine wires with one wire being fixed and the other movable by means of a finely threaded screw.

Filar, from L. fil(um) "a thread" (see the paragraph below) + -ar variant of the adjective-forming suffix → -al; → micrometer.

Kehsanj, → micrometer; zehi adj. of zeh "string, bow-string;" Mid.Pers. zih "bow-string," zig "string; astronomical table" (loaned into Ar. as zij); Av. jiiā- "bow-string;" cf. Skt. jiyā- "bow-string;" Gk. bios "bow;" L. filum "thread;" Arm. jil "string, line;" Lith. gijà "thread;" Russ. žica "thread;" PIE base *g^whi- "thread, tendon."

In computer science, a collection of related data or program records stored on a support.

From M.E. filen, from M.F. filer "to string documents on a thread," O.F. filer "to wind or spin thread," from L.L. filare "to spin, draw out in a long line," from L. filum "thread," from PIE base *g^whi- "thread, tendon;" cf. Gk. bios "bow;" Skt. jiyā- "bow-string;" Av. jiiā- "bow-string;" Mod.Pers. zeh "bow-string;" Arm. jil "string, line," Lith. gijà "thread;" Russ. žica "thread."

Parvandé "file," initially "a bundle, roll, truss (of clothes)," from Mid.Pers. parwastan, parwand- "to surround, enclose, contain, comprise," from par-, variants far-, par-, pirâ- "around, about" (Mid.Pers. pêrâ; O.Pers. pariy "around, about," Av. pairi "around, over;" Skt. pari; Indo-Iranian *pari- "around;" PIE base *per- "through, across, beyond;" cf. Gk. peri "around, about, beyond;" L. per "through") + vand-/band- stem of vastan/bastan "to bind, shut;" O.Pers./Av. band- "to bind, fetter," banda- "band, tie" (cf. Skt. bandh- "to bind, tie, fasten;" PIE *bhendh- "to bind;" Ger. binden; E. bind).

Of a molecular cloud or a nebula, the ratio of the volumes filled with matter to the total volume of the cloud.

Filling, from fill, from O.E. fyllan, from P.Gmc. *fullijan (cf. Du. vullen, Ger. füllen "to fill"), a derivative of adj. *fullaz→ full; → factor.

Karvand, → factor; pori, from por, → full.

1) General: A device for separating the constituents of a system according to a physical property. In particular, a device for removing solid matter suspended in a liquid by forcing the suspension through a material which retains the solid matter while allowing the liquid to pass.
2) Optics: A device for transmitting electromagnetic radiation with restricted ranges of wavelength. Two types are generally used, → glass filters and → interference filters. See also → neutral density filter.
3) Electronics: A circuit or equipment allowing the transmission of desired frequencies and the elimination of others.

From M.L. filtrum "felt," which was used to strain impurities from liquid, from W.Gmc. *filtiz.

Pâlâyé, from pâlây present stem of pâludan "to filter, purify;" Mid.Pers. pâludan, pâlây- "to strain, filter, purify," from Proto-Iranian *pari-harz-, from prefix *pari- "around," → peri-, + harz- "to let go, release;" cf. Av. pairi.harəz- "to filter," from pairi- "around, over" (cf. Skt. pari; Gk. peri "around, about, beyond;" L. per "through;" PIE base *per- "through, across, beyond") + harəz- "to release" (especially water, liquid; cf. Chorasmian pžy- "to purify, filter;" Arm. (loanword) parzel "to filter, purify;"

Pertaining to or coming at the end; last in place, order, or time.

M.E., from O.Fr. final from L. finalis "of or pertaining to an end, concluding," from finis "end."

Pâyâni from pâyân "end, extremity; limit, boundary," from pâ(y) "foot; step; track," → foot.

A meteorite that was not seen to fall, but was found at some later date, as opposed to a → fall.

O.E. findan "to come upon," from P.Gmc. *finthanan (cf. M.Du. vinden, Ger. finden), from PIE *pent- "to go, pass, path, bridge;" cf. Av. paθ-, variants paθi-, paθā-, pantay-; Mid/Mod.Pers. pand "path, advice, councel;" Khotanese pande "road, path;" Ossetic fœndœg "path, road;" cf. Skt. pánthā- "road, path, course;" Gk. patos "path, way," pontos "sea;" L. pons "bridge, path."

Yâft, past stem of yâftan, yâbidan "to find, discover; to obtain, acquire;" Mid.Pers. ayâftan, ayâpênitan "to reach, attain;" Manichean Mid.Pers. 'y'b "to attain;" Parthian, Sogdian (+ *pati-) pty'b "to reach, obtain;" Av. ap- "to reach, overtake," apayeiti "achieved, reached;" Skt. âp- "to reach, gain," âpnoti "reaches, gains;" Gk. hapto, haptomai "to touch, cling to, adhere to;" L. apiscor "touch, reach;" PIE base *ap- "to take, reach."

A low-power telescope with a wide field of view attached to a larger telescope with the optical axes of both telescopes parallel. The finder is used to help point the larger telescope to the desired viewing location.

Agent noun of → find.

A sketch or image used to recognize objects in the field of view of a telescope.

Finding, noun of → find; chart, from M.Fr. charte "card, map," from L. charta "leaf of paper, tablet," from Gk. khartes "layer of papyrus."

Negâre-ye yâbeš, from negâré, from negâr "picture, figure" (verb negârdan, negâštan "to paint"), from prefix ne- "down; into," → ni-, + gâr, from kar-, kardan "to do, to make" (Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build;" Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base k^wer- "to do, to make"); yâbeš, verbal noun of yâftan, → find.

Very thin or slender. → fine structure, → fine-structure constant.

M.E. fin, from O.Fr. fin "perfected, of highest quality," from L. finis "end, limit."

Nâzok "thin, slender, subtle," from Mid.Pers. nâzuk "tender, gentle," variant nâzik, from nâz "joy, pride, glory" + → -ik.

Meteorology: An → inhomogeneous  → mixture of tiny, part → solid, part → liquid or → gaseous  → particles that are, in average, smaller than ten → microns. The constituents are soot, heavy metals, organic substances, and dioxins. The smaller these dust particles, the deeper they penetrate into the lung. Larger particles are intercepted by mucous membrane in nose, mouth, and throat but smaller particles can penetrate the smallest lung bronchioles and may cause severe damage (various respiratory disorders, lung cancer) → particulate matter.

→ fine; → dust.

Closely spaced components seen at high resolution in a → spectral line. The phenomenon is explained by the fact that instead of a single → energy level corresponding to a given value of the → quantum number  n, there are actually a number of energy levels lying close to one another. → fine-structure constant, → fine-structure line.

→ fine; → structure.

A measure of the strength of → interaction between a → charged particle and the → electromagnetic field. It is a → dimensionless number expressed (in → cgs units) by α = e²/ħc, where e is the → electron charge, ħ is the → reduced Planck's constant, and c is the → speed of light. It is approximately equal to 1/137 or 7.3 × 10^-3. The smallness of this number is of great importance since it determines the size of → atoms and the → stability of → matter. Same as → electromagnetic coupling constant.

→ fine structure; → constant.