An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara arc Ari arr Asi ass ast ast asy atm ato att aut ave axi Bab bal ban bar bar bea Bel Bes bia Big bin bin bip Bla bla bli blu Boh Bon bos Bou bra bri bro bur cal cal can Cap car Car cat Cau cea Cen cen cha Cha cha che chi chr cir cir civ cla clo clo CMB coa coe coh col col col com com com com com com com com com con con con con con con con con con con con coo cop Cor CoR cor cos cos Cou cou CP- cre cri cro cub cur cya Cyg dan dar dau de- deb dec dec dee def deg del den den dep des deu dew dia dif dif dih dip dir dis dis dis dis dis diu doc dop dou DQ dry dus dwa dyn Dys Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext eye fac fal Far fed Fer fer fie fin fir fit fla flo flu fol for for Fou fra fre Fre fro fuz gai Gal Gal gam gas Gau gen gen geo geo geo gia glo gol gra gra gra gra gre gri gui H I hai Ham har Hau hea hec hel hel her HES hie hig his hom hor hot Hub Hul Huy hyd hyd hyl hyp ice ide ima imm imp imp inc ind ind ine inf inf inf inh inn ins ins int int int int int int int int inv ion ion Irr iso iso iso Jal JHK Jul jur Kel Kep kin kne L d Lag lam Lap lar lat law Lea len lep lib lig lin lin lin liq lit loc log lon Los low lum lun Lut Lyr mac mag mag mag mag mag maj man Mar mas mas mat Max mea mec mel Mer Mes met met met mic mid Mil min mir mix mod mod mol mon mor mov mul muo mys nan nat Nav nec nep neu new New NGC Noa nom non non nor not nuc nuc num nyc obj obs obs oce odd OH Omi Oor ope opt opt opt orb ord Ori ort osc out ove oxi pai pan par Par Par par pas pea Pen per per per per Per per pha phl pho pho pho phy Pip Pla pla PLA pla ple plu pol pol pol pol pop pos pos pot Pra pre pre pre pre pri pri pro pro pro pro pro pro pro pse pul pur qua qua qua qua qui rad rad rad rad rad rad raf ran rar ray rea rea rec rec red red ref ref reg rel rel rel rep res res res res ret rev ric rig rin roc ROS rot Rox rus Sad sal sat sca sca Sch sci scy sec sec see sel sem sen Ser sex Sha she sho sid sig sil sim sin siz sle SMA SNR Sof sol sol sol sol sou Sou spa Sp spe spe spe sph spi Spi spr sta sta sta sta sta ste ste ste sto str str Sty sub sub suc sun sup sup sup sup sur Swa syn syn tac tas tel tem ter tes the the the the Tho thr tid tim Tit top tot tra tra TRA tra tre tri tri tru tum tur TY Typ ult una und uni uni uno upp urg UX Van var veg vel ver vib vio vir vis Voi vow wan wat wav WC wea wel whi Wil wir WNh wor X-r yel ytt zer zon > >>

Number of Results: 13046 Search : far
differential geometry
  هندسه‌ی ِ دگرسانه‌ای   
hendese-ye degarsâneyi

Fr.: géométrie différentielle   

The study of curved spaces using differential calculus.

differential; → geometry.

differential image motion monitor (DIMM)
  پهره‌گر ِ جنبش ِ دگرسانه‌ای ِ وینه، ~ ~ ~ تصویر   
pahregar-e jonbeš-e degarsâneyi-ye vine, ~ ~ ~ tasvir

Fr.: moniteur de mouvements d'images différentiels, moniteur seeing   

A device that is commonly used to measure the → seeing at optical astronomical sites. The DIMM delivers an estimate of the → Fried parameter based on measuring the variance of the differential image motion in two small apertures, usually cut out in a single larger telescope pupil by a mask. The DIMM concept was introduced by Stock & Keller (1960, in Stars and Stellar Systems, Vol. 1, ed. G. P. Kuiper & B. M. Middlehurst, p. 138), whereas its modern implementation was first described by Sarazin & Roddier (1990, A&A 227, 294).

differential; → image; → motion; → monitor.

differential refraction
  شکست ِ دگرسانه‌ای   
šekast-e dagarsâneyi

Fr.: refraction différentielle   

A problem encountered in astronomical spectroscopy, which consists of a loss of light from some wavelengths due to → atmospheric dispersion. In simple terms, differential refraction means that at nonzero → zenith distances an object cannot be simultaneously placed at the same position within a → slit at all wavelengths. This problem becomes more important for increasing → airmass, larger → spectral range, and smaller → slitwidths. To remedy this drawback, the slit should always be oriented along a direction perpendicular to the horizon, since differential refraction occurs in that direction.

differential; → refraction.

differential rotation
  چرخش ِ دگرسانه‌ای   
carxeš-e degarsâneyi

Fr.: rotation différentielle   

1) Of a single body (such as a star or a gaseous planet), the axial rotation of equatorial latitudes faster than polar latitudes.
2) Of a galaxy, the orbiting of stars nearer the center faster than those at the edge.

differential; → rotation.

differentially rotating system
  راژمان ِ دگرسانه چرخان   
râžmân-e degarsâné carxân

Fr.: système en rotation différentielle   

A system characterized by → differential rotation. In such a system the → angular velocity decreases as the distance from the rotation center increases.

differential; → rotating; → system.

differentiate
  دگرسانیدن   
degarsânidan

Fr.: différencier   

General: To perceive or show the difference in or between.
Math.: To obtain the differential or the derivative of.

M.L. differentiatus "distinguished," p.p. of differentiare.

Degarsânidan, verbal form of → difference.

differentiated interior
  درونه‌ی ِ دگرسانیده   
darune-ye degarsânidé

Fr.: intérieur différencié   

A description of a planet's interior which is composed of a rocky, dense inner core and a less dense outer crust.

Differentiated, p.p. of → differentiate; → interior.

differentiated meteorite
  شخانه‌ی ِ دگرسانیده، شهاب‌سنگ ِ ~   
šaxâne-ye degarsânidé, šahâbsang-e ~

Fr.: météorite différenciée   

A meteorite that has distinctly separated stone, metal, and glass. It is derived from a differentiated parent body and hence not primitive. The parent body accreted surrounding material until it was large enough to start melting in the middle. The denser metals sank to the center and the stones and glasses floated to the top. A differentiated meteorite made completely of metal comes from the center of a parent meteoroid which was broken apart. → undifferenciated meteorite.

Differentiated, p.p. of → differentiate; → meteorite.

differentiation
  دگرسانش   
degarsâneš

Fr.: (Math.) dériver; (Astro.) différenciation   

1) Math.: The operation of finding the → derivative of a function.
2) Astro.: Process by which an originally homogeneous planetary or asteroidal body is separated into regions of different composition, such as core, mantle, and crust.

Verbal noun of → differentiate.

difficult
  دشوار   
došvâr (#)

Fr.: difficile   

Not easy to do or to understand; hard to deal with.

Back-formation from difficulty; L. difficilis. "hard," from → dis- "not, away from" + facilis "easy to do," from facere "to do," → fact.

Došvâr, from Mid.Pers. dušwâr "difficult, disagreeable," variant dušxwâr antonym of xwâr "easy; light; low; mean, abject;" with prefix duš- "ill, evil, bad," → dys-.

diffract
  پراشیدن   
parâšidan (#)

Fr.: diffracter   

Verbal form of → diffraction.

diffraction.

diffraction
  پراش   
parâš (#)

Fr.: diffraction   

A wave property of light which allows it to curl around obstacles whose size is about that of the wavelength of the light. As a → wavefront of light passes by an opaque edge or through an opening, secondary weaker wavefronts are generated, apparently originating at that edge. These secondary wavefronts will interfere with the primary wavefront as well as with each other to form a → diffraction pattern.
Related terms: → diffusion; → dispersion; → distribution; → scatter; → scattering.

From Fr. diffraction, from Mod.L. diffractionem, from L. diffrac-, stem of diffringere "break in pieces," from → dis- "apart" + frangere "to break."

Parâš "dispersion, scattering," variant of pâš, pâšidan, → dispersion.

diffraction grating
  توری ِ پراش   
turi-ye parâš (#)

Fr.: réseau de diffraction   

An optical device containing thousands of very fine parallel grooves which produce interference patterns in a way which separates out all the components of the light into a spectrum.

diffraction; → grating.

diffraction pattern
  الگوی ِ پراش   
olgu-ye parâš (#)

Fr.: tache de diffraction   

A series of concentric rings of dark and light color produced by interference.

diffraction; → pattern.

Olgu, loanword from Turkish; parâšdiffraction.

diffraction spike
  سیخک ِ پراش   
sixak-e parâš

Fr.: aigrette de diffraction   

One of several light rays emanating from a bright light source in images taken with → reflecting telescopes. They are artifacts caused by light diffracting around the support or → spider vanes of the → secondary mirror.

diffraction; → spike.

diffraction-limited
  کران‌مند به پراش   
karânmand bé parâš

Fr.: limité par la diffraction   

The quality of an → optical system that is capable of producing images with angular resolution as small as the theoretical limit of the → Airy disk.

diffraction; limited, adj. of → limit.

Karânmand "bounded, limited," from karânboundary + -mand possession suffix; parâš diffraction.

diffuse
  ۱) پخشیدن؛ ۲) پخشیده   
1) paxšidan (#); 2) paxšidé (#)

Fr.: 1) diffuser; 2) diffus   

1a) To pour out, to spread in all directions.
1b) To spread by → diffusion.
2) Spread out, diffused, scattered, as → diffuse reflection.
See also: → diffuse atomic cloud, → diffuse galactic light, → diffuse interstellar band, → diffuse interstellar band carrier, → diffuse interstellar cloud, → diffuse interstellar medium, → diffuse molecular cloud, → diffuse nebula, → diffuse reflection, → diffuse transmission, → diffusion.

L. diffusus "spread, poured forth," from dif- "apart, in every direction," variant of → dis- + fuse, from fusus "melted, poured, cast," p.p. of fundere "to melt, cast, pour out," from PIE *gheud-, from root *gheu- "to pour."

Paxšidan "to diffuse, scatter, disperse," infinitive of paxš "scattered, dispersed; withered, trodden," (Manichean) Mid.Pers. pxš "to wither, fade; to grow ripe," Proto-Iranian *paxš- "to cook," cf. Av. pac- "to cook," pacika- "cooked," Mod.Pers. paz-, poxtan "to cook, bake," Skt. pac- "to cook," pakva- "ripe," Gk. peptein "to cook, ripen," L. coquere "to cook," from which V.L. cocus "cook," from which O.E. coc "cook;" PIE *pekw- "to cook, ripen;" paxšidé, p.p. of paxšidan.

diffuse atomic cloud
  ابر ِ اتمی ِ پخشیده   
abr-e atomi-ye paxšidé

Fr.: nuage atomique diffus   

A type of cloud in the → interstellar medium with low molecular content that is fully exposed to the → interstellar radiation field, and therefore nearly all its → molecules are quickly destroyed by → photodissociation. Hydrogen is mainly in → neutral atomic form (→ neutral hydrogen), and atoms with → ionization potentials less than that of hydrogen (most notably → carbon) are almost fully → ionized, providing abundant electrons. The paucity of molecules implies that very little chemistry occurs in such clouds. Many → sightlines with low → extinction seem to pass exclusively through → diffuse atomic gas. Such sightlines typically have a → column density, NH, less than about 5 × 1020 cm-2, and are sufficiently → optically thin to be observable by means of → visible and → ultraviolet → absorption line measurements. Diffuse atomic clouds typically have a fairly low → density (~ 10-100 cm-3), and → temperatures of 30-100 K (Snow & McCall, 2006, ARA&A 44, 367).

diffuse; → atomic; → gas.

diffuse galactic light
  نور ِ کهکشانی ِ پخشیده   
nur-e kahkašâni-ye paxšidé

Fr.: lumière galactique diffuse   

A minor component of galactic light resulting from the diffusion of starlight by → interstellar dust near the → galactic plane.

diffuse; → galactic; → light.

diffuse interstellar band (DIB)
  باند ِ پخشیده‌ی ِ اندر‌اختری   
bând-e paxšide-ye andaraxtari

Fr.: bande diffuse interstellaire   

Absorption features in the spectrum of stars identified in the ultraviolet, visible, and infrared regions. They have an interstellar origin, but despite extensive efforts, their carrier(s) have not yet been clearly identified. See also → Aromatic Infrared Bands; → polycyclic aromatic hydrocarbons.

diffuse; → interstellar; → band.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara arc Ari arr Asi ass ast ast asy atm ato att aut ave axi Bab bal ban bar bar bea Bel Bes bia Big bin bin bip Bla bla bli blu Boh Bon bos Bou bra bri bro bur cal cal can Cap car Car cat Cau cea Cen cen cha Cha cha che chi chr cir cir civ cla clo clo CMB coa coe coh col col col com com com com com com com com com con con con con con con con con con con con coo cop Cor CoR cor cos cos Cou cou CP- cre cri cro cub cur cya Cyg dan dar dau de- deb dec dec dee def deg del den den dep des deu dew dia dif dif dih dip dir dis dis dis dis dis diu doc dop dou DQ dry dus dwa dyn Dys Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext eye fac fal Far fed Fer fer fie fin fir fit fla flo flu fol for for Fou fra fre Fre fro fuz gai Gal Gal gam gas Gau gen gen geo geo geo gia glo gol gra gra gra gra gre gri gui H I hai Ham har Hau hea hec hel hel her HES hie hig his hom hor hot Hub Hul Huy hyd hyd hyl hyp ice ide ima imm imp imp inc ind ind ine inf inf inf inh inn ins ins int int int int int int int int inv ion ion Irr iso iso iso Jal JHK Jul jur Kel Kep kin kne L d Lag lam Lap lar lat law Lea len lep lib lig lin lin lin liq lit loc log lon Los low lum lun Lut Lyr mac mag mag mag mag mag maj man Mar mas mas mat Max mea mec mel Mer Mes met met met mic mid Mil min mir mix mod mod mol mon mor mov mul muo mys nan nat Nav nec nep neu new New NGC Noa nom non non nor not nuc nuc num nyc obj obs obs oce odd OH Omi Oor ope opt opt opt orb ord Ori ort osc out ove oxi pai pan par Par Par par pas pea Pen per per per per Per per pha phl pho pho pho phy Pip Pla pla PLA pla ple plu pol pol pol pol pop pos pos pot Pra pre pre pre pre pri pri pro pro pro pro pro pro pro pse pul pur qua qua qua qua qui rad rad rad rad rad rad raf ran rar ray rea rea rec rec red red ref ref reg rel rel rel rep res res res res ret rev ric rig rin roc ROS rot Rox rus Sad sal sat sca sca Sch sci scy sec sec see sel sem sen Ser sex Sha she sho sid sig sil sim sin siz sle SMA SNR Sof sol sol sol sol sou Sou spa Sp spe spe spe sph spi Spi spr sta sta sta sta sta ste ste ste sto str str Sty sub sub suc sun sup sup sup sup sur Swa syn syn tac tas tel tem ter tes the the the the Tho thr tid tim Tit top tot tra tra TRA tra tre tri tri tru tum tur TY Typ ult una und uni uni uno upp urg UX Van var veg vel ver vib vio vir vis Voi vow wan wat wav WC wea wel whi Wil wir WNh wor X-r yel ytt zer zon > >>