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: 12937 Search : far
limiting magnitude
  برز ِ حد   
borz-e hadd

Fr.: magnitude limite   

The faintest magnitude reachable by an instrument.

limit; → magnitude.

limonite
  لیمونیت   
limonit (#)

Fr.: limonite   

A widely occurring ore of yellowish-brown to black color that consists of amorphous oxides of iron.

Gk. leimon "meadow" in reference to its occurrence as "bog ore" in meadows and marshes + → -ite.

Lindblad resonance
  باز‌آوایی ِ لیندبلاد   
bâzâvâyi-ye Lindblad

Fr.: résonance de Lindblad   

A kinematic resonance hypothesized to explain the existence of galactic → spiral arms. It occurs when the frequency at which a star encounters the spiral → density wave is a multiple of its → epicyclic frequency. Orbital resonances occur at the location in the disk where Ωp = Ω ± κ/m, where Ωp is → pattern speed, κ → epicyclic frequency, and m an integer representing the number of spiral arms. The minus sign corresponds to the inner Lindblad resonance (ILR) and the plus sign to the outer Lindblad resonance (OLR). The corotation resonance corresponds to Ωp = Ω. In general, the Lindblad resonances are defined for two spiral arms (m = 2), and low order. There are other less important resonances corresponding to higher m values. These resonances tend to increase the object's orbital eccentricity and to cause its longitude of periapse to line up in phase with the perturbing force. Lindblad resonances drive spiral density waves both in galaxies (where stars are subject to forcing by the spiral arms themselves) and in Saturn's rings (where ring particles are subject to forcing by Saturn's moons).

After the originator of the model, Bertil Lindblad (1895-1965), a Swedish astronomer, who made important contributions to the study of the rotation of the Galaxy; → resonance.

line
  خط، خت   
xatt (#), xat (#)

Fr.: ligne   

1) A mark or stroke long in proportion to its breadth, made with a pen, pencil, or other tools.
2) Math.: A continuous extent of length, straight or curved, without breadth or thickness; the trace of a moving point.

M.E. li(g)ne "cord, rope, stroke, series," from O.E. line "rope, row of letters," partly from O.Fr. ligne, from L. linea "linen thread, string, line," from phrase linea restis "linen cord," from fem. of lineus (adj.) "of linen," from linum "flax, linen."

Xatt, xat, used also in Ar., but it has no Hebrew counterpart. Xat is probably of Iranian origin, from *kerš-/*xrah- "to draw, plow;" cf. Av. karš- "to draw; to plow," karša- "furrow;" Mid/Mod.Pers. kešidan, kašidan "to draw, protract, trail, drag, carry," dialectal Yaqnavi xaš "to draw," Qomi xaš "streak, stria, mark," Lori kerr "line;" cf. Skt. kars-, kársati "to pull, drag, plow;" Gk. pelo, pelomai "to move, to bustle;" PIE base kwels- "to plow."

line blanketing
  پتومندی ِ خط   
patumandi-ye xatt

Fr.:   

In stellar atmosphere models, the effect of metallic lines on the atmospheric structure of stars. The additional opacities of thousands of metallic lines alter the radiative transfer, leading to changes in the temperature. The emergent spectrum is consequently modified.

line-blanketed model.

line blending
  توهم‌شد ِ خط‌ها   
tuhamešod-e xatthâ

Fr.: confusion de raies   

Mixing of two or more spectral lines of adjacent wavelengths into a broad, single line due to insufficient dispersion of the spectrograph.

line; → blend.

line blocking
  بند‌آری ِ خط‌ها   
bandâri-ye xatthâ

Fr.: blocage par raies   

Reduction of the radiative flux in a model atmosphere due to absorption by a large number of lines. Line blocking affects the radiative transfer, ionisation and temperature structures, and the atmosphere's hydrodynamics.

line; block, from M.E. blok "log, stump," from O.Fr. bloc "log, block," via M.Du. bloc "trunk of a tree."

Bandâri "blocking," from band âvardan "to block," from band "dam, tie, chain," from bastan "to bind, shut, close up" (Mid.Pers. bastan, band; Av./O.Pers. band- "to bind, fetter," banda- "band, tie;" cf. Skt. bandh- "to bind, tie, fasten," bandhah "a tying, bandage;" Goth bandi "that which binds;" O.Fr. bande, bende; O.E. bend; M.E. bende; E. band; PIE base *bendh- "to bind") + âvari verbal noun of âvardan "to cause, produce; to bring" (Mid.Pers. âwurtan, âvaritan; Av. ābar- "to bring; to possess," from prefix ā- + Av./O.Pers. bar- "to bear, carry," bareθre "to bear (infinitive)," bareθri "a female that bears (children), a mother;" Mod.Pers. bordan "to carry;" Skt. bharati "he carries;" Gk. pherein; L. fero "to carry").

line broadening
  پهنش ِ خط   
pahneš-e xatt

Fr.: élargissement de raie   

A widening of → spectral lines due to any of several factors, including the → Doppler broadening, → instrumental broadening, → microturbulence, → pressure broadening, → rotational broadening, the → Stark effect, and the → Zeeman effect.

line; → broadening.

line cooling
  سردش ِ خط   
sardeš-e xatt

Fr.: refroidissement dû aux raies   

In stellar atmosphere models, the decrease of temperature in the outer layers of atmosphere due to the escape of photons through optically thin metallic lines. Energy is transferred from the thermal pool to photons and is lost for the atmosphere, leading to a temperature decrease.

line; → cooling.

line identification
  ایدانش ِ خط   
idâneš-e xatt

Fr.: identification de raies   

The process of recognizing the spectral lines in a spectrum.

line; → identification.

line intensity
  درتنویی ِ خط   
dartanuyi-ye xatt

Fr.: intensité de raie   

A measure of the total effect of an absorption or emission line. The line intensity is equal to the integration of the absorption coefficient over the entire shape of the absorption line.

line; → intensity.

line of action
  خط ِ ژیرش، ~ کنش   
xatt-e žireš, ~ koneš

Fr.: ligne d'action   

Of a force, the straight line along which the force → vector is directed. The action of a force on a → rigid body does not change when its point of application is displaced along the line of action. Hence, forces applied to a rigid body can be regarded as non-localized, or sliding, vectors.

line; → action.

line of apsides
  خط ِ هباک‌ها   
xatt-e habâkhâ

Fr.: ligne des apsides   

Of an elliptical orbit, the straight line drawn from the → perigee to the → apogee.

line, → apsides.

line of equinoxes
  خط ِ هموگان‌ها   
xatt-e hamugânhâ

Fr.: ligne des équinoxes   

The intersection of the planes of ecliptic and celestial equator.

line; → equinox.

line of flow
  خط ِ تچان   
xatt-e tacân

Fr.: ligne d'écoulement   

Same as → streamline.

line; → flow.

line of force
  خط ِ نیرو   
khatt-e niru (#)

Fr.: ligne de force   

One of many → imaginary lines whose direction at all → points along its length is that of the electric or → magnetic field at those points. In → electric fields the lines of force are directed toward → negative charges and point away from → positive charges. In magnetic fields the lines of force are directed from the → north pole to the → south pole.

line; → force.

line of induction
  خط ِ درهازش   
xatt-e darhâzeš

Fr.: ligne d'induction   

Same as → line of force in a magnetic field.

line; → induction.

line of nodes
  خط ِ گره‌ها   
xatt-e gerehhâ (#)

Fr.: lignes des nœuds   

The line created by the intersection of the equatorial plane and the orbital plane.

line, → node.

line of sight
  خط ِ دید، دیدخط   
xatt-e did, didxatt (#)

Fr.: ligne de visée   

The imaginary straight line connecting the object and the objective lens of the viewing device.

line; → sight.

line profile
  فراپال ِ خط   
farâpâl-e xatt

Fr.: profil de raie   

The representation of a spectral line as produced by an observing instrument.

line, → profile.

<< < -es -iv -ti 217 A s abe abs abs acc acc Ach act act ADa adi adv aff age Alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg arm art ass ast ast ast atm ato att aur aut axi B-t Bai Bal bar bar Be bed Bes BHB bif bim bin Bio bis bla ble blu bod Bol bor bou bra Bre bro Bul cag cal can Can car Car Cas cat CCD cel cen Cet cha cha che che chr cir cir cit cla clo clo clu 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 cor cor cor cos cos cos cou cou cra cri cro cry cul cur cyc D r dar dat day dea dec dec dec def def deg del den dep des det deu dex dif dif dif dim dip dir dis dis dis dis dis div dom dos dou dri Dum dus dyn dyn ear eas ecl Edd eff Ein eje ele ele ele ele eli emb emi Enc ene ens eph epo equ equ eru eth Eul eve evo exc exc exi exo exp exp ext ext fab fai Fan Fea fem fer fie fil fir fis fla flo flu foc for for Fou fra fre fre fro fun G r Gal gal gam gas Gau gel gen geo geo geo Gho gla goa gra gra gra gra gre Gre gro gyr had hal har har HD Hea Hel hel Her her hid hig Hip hom hor hot Hub Hub hun hyd hyd hyg Hyp ice ide ima imm imp imp inc ind ind ine inf inf inf ini ins ins int int int int int int int int int inv ion iro ise iso iso Jab jet Jov Jur Kel Kep kil kit Kui Lag lam lan Lar Lat law lea lem lep Li- lig lim lin lin lio lit loc lod lon Lor low Lum lun Lup Lyn mac mag mag mag mag mag mai man mar mas mas mat Max mea mec mel mer mes met met met mic mid mil Min mir mix mod mol mom Moo mor mov mul mur nab nar nat neb neg nes neu New New nig nod non non non Nor nua nuc nul Nun OBC obl obs occ oct off Ohm on- ope opp opt opt orb orb org Ori ort Ost out ove p m Pal par par par par Pas pat Peg Peo per per per per per pha Phe pho pho pho phy pin pla pla pla pla pla plu poi pol pol Pol pol pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro pro pro pse pul Pup Qua qua qua qua que rac rad rad rad rad rad rad ran rap ray rea rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot rur Sac sal sat sca sca Sch sci Scu sec sec Sed sel sem sen Ser Sey Sha she sho sid sig sim sin sip ske sli smo soc sol sol sol sol sol sou spa spa spe spe spe spe Spi spi spo squ sta sta sta sta Ste ste ste sto str str str sub sub sub sun sup sup sup sup sur sus sym syn T-s tar Tei tem ter tes the the the the thi thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur Tyc Typ ult unb und uni uni unr upp Urs vac van Var veg Ven ver vib vio vir vis vol VY war wat wav WC8 Web wes whi win WN1 wob wri X-r yoc zen Zhe > >>