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 ash ass ast ast asy atm ato att aut ave axi Bab bal Bal bar bar bea Bek Bes bia Big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo cal cal can cap car Car cat cat CCD Cen cen CH 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 con Cop Cor cor cor cos cos cou cou Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp 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 phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar 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 Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>

Number of Results: 13048 Search : far
heliograph
  هورنگار   
hurnegâr (#)

Fr.: héliographe   

1) An instrument for photographing the Sun, consisting of a camera and a specially adapted telescope.
2) A simple device using a mirror to reflect sunlight to a distant observer. By moving the mirror, flashes of light can be used to send coded messages. The heliograph was a highly effective instrument for instantaneous optical communication over 80km or more in the 19th century.
3) Meteo.: An instrument which records the duration of sunshine and gives a quantitative measure of the amount of sunshine.

helio-; + → -graph.

heliometer
  هورسنج   
hursanj (#)

Fr.: héliomètre   

An instrument used to measure the angular separation of two stars that are too far apart to be included in the field of view of an ordinary telescope.  The instrument was originally designed for measuring the variation of the Sun's diameter at different seasons of the year.

helio- + → -meter.

heliopause
  هورمرز   
hurmarz

Fr.: héliopause   

The edge of the solar system where the pressure of the → solar wind balances that of the → interstellar medium plasma. In other words, the surface boundary that separates the → heliosphere from interstellar space. It is estimated to be situated 100 → astronomical units or more from the Sun. A → bow shock likely forms as the interstellar medium wind approaches the heliosphere and is deflected around the heliosphere, forcing it into a teardrop-shaped structure with a long, comet-like tail.

From → helio- + pause "break, cessation, stop," from M.Fr. pause, from L. pausa "a halt, stop, cessation," from Gk. pausis "stopping, ceasing," from pauein "to stop, to cause to cease."

Hurmarz, from hur, → helio-, + marz "frontier, border, boundary," → frontier.

helioseismology
  هورلرزه‌شناسی   
hurlarzešenâsi

Fr.: héliosismologie   

The branch of astrophysics that investigates the interior structure of the Sun by studying its surface wave oscillations. See also → asteroseismology and → stellar pulsation. The surface of the Sun vibrates much like a bell. A piano has 88 keys or musical tones, whereas the Sun has millions of notes. These vibrations are the result of internal pressure waves that reflect off the → photosphere and repeatedly cross the solar interior. They are detected through the → Doppler shift of absorption lines formed in the photosphere. Because these vibrations make the solar surface move up and down, analysis of the surface patterns is used to study conditions far below the Sun's surface. The mean period of the vibrations is about five minutes, which corresponds to a speed of 0.5 km s-1 or a frequency of about 3 mHz. See also → p mode.

From → helio- + → seismology.

heliosheath
  هورنیام   
hurniyâm

Fr.: héliogaine   

The region located between the → termination shock and the → heliopause where the turbulent and hot → solar wind is compressed as it passes outward against the interstellar wind.

Heliosheath, from → helio- + sheath, from O.E. sceað, scæð; cf. M.Du. schede, Du. schede, O.H.G. skaida, Ger. Scheide "scabbard."

Hurniyâm, from hur- "sun," → helio-, + niyâm "sheath," from Proto-Iranian *nigāma-, from ni- "down; into," → ni- (PIE), + gāma- "to go, to come" (Av. gam- "to come; to go," jamaiti "goes;" O.Pers. gam- "to come; to go;" Mod./Mid.Pers. gâm "step, pace," âmadan "to come;" cf. Skt. gamati "goes;" Gk. bainein "to go, walk, step;" L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come; PIE root *gwem- "to go, come"); cf. Skt. nigamá- "insertion, incorporation."

heliosphere
  هورسپهر   
hursepehr (#)

Fr.: héliosphère   

The vast, three-dimensional region of space around the Sun filled with the → solar wind and the remnant of the → solar magnetic field carried in it. It is bounded by the → heliopause, which is estimated to be 100 → astronomical units or more from the Sun. The radius of the heliosphere is expected to vary with the → solar cycle. The heliosphere may be very elongated owing to the presence of an interstellar wind of neutral hydrogen flowing from the direction of the Galactic center.

From → helio- + → sphere.

heliostat
  هورداشتار   
hurdâštâr

Fr.: héliostat   

An instrument consisting of a mirror moved by clockwork for tracking the movement of the Sun and reflecting the sunlight into a stationary solar telescope. A heliostat is similar to a → coelostat.

Heliostat, from → helio- + -stat prefix denoting something that stabilizes, keeps, fixes, from -stata, from Gk. -states "one that causes to stand," or statos "standing," from *sta- "to stand."

Hurdâštâr, from hur-, → helio- + dâštâr "holder, maintainer," from dâštan "to hold, maintain; to have; to possess;" Mid.Pers. dâštan; O.Pers./Av. dar- "to hold, keep back, maintain, keep in mind;" cf. Skt. dhr-, dharma- "law;" Gk. thronos "elevated seat, throne;" L. firmus "firm, stable;" Lith. daryti "to make;" PIE base *dher- "to hold, support."

helium
  هلیوم   
helium (#)

Fr.: hélium   

Chemical element; symbol He; atomic number 2; atomic weight 4.0026; melting point below -272°C at 26 atmospheres pressure; boiling point -268.934°C at 1 atmosphere pressure.

Helium, from Gk. helios "sun;" cognate with Persian hur "sun", variant xor; Mid.Pers. xvar "sun;" Av. hû-, hvar- "sun;" Skt. surya-; L. sol; O.H.G. sunna; Ger. Sonne; E. sun; PIE *sawel- "sun." The element was discovered by spectroscopy during a solar eclipse in the Sun's chromosphere in 1868 by the French astronomer Pierre-Jules-Cesar Janssen (1824-1907).

helium abundance
  فراوانی ِ هلیوم   
farâvâni-ye heliom

Fr.: abondance de l'hélium   

The relative amount of helium with respect to another → chemical species, usually → hydrogen, in an astronomical object.

helium; → abundance.

helium burning
  سوزش ِ هلیوم   
suzeš-e heliyom

Fr.: combustion de l'hélium   

The stage in the evolution of a star, after the exhaustion of hydrogen, when the star produces its energy by the fusion of helium into carbon and oxygen.

helium; → burning.

helium flash
  درخش ِ هلیوم   
deraxš-e heliom (#)

Fr.: flash de l'hélium   

The sudden onset of → helium burning in the core of an → intermediate-mass star that has exhausted its hydrogen and has become a → red giant. With a → degenerate core, the temperature increases but the pressure does not. Therefore, the core cannot expand and cool, so the temperature continues to rise. When it approaches 100,000,000 K, helium will begin to fuse into carbon in the → triple alpha process. The helium flash ends the giant star's ascent of the → red giant branch. However, the violent ignition of helium in the core does not increase the star's luminosity. On the contrary, the energy released in the helium flash expands and cools the core and ultimately results in a reduction in the energy output. On the → H-R diagram the star moves down from red giant branch to the → horizontal branch, a stable state with steady helium burning in the core.

helium; → flash.

helium I
  هلیوم I   
heliom I

Fr.: hélium I   

1) The normal component of → liquid helium (4He) existing between the superfluid transition point (→ lambda point about 2.17 K) at 1 atmosphere of pressure and its boiling point of 4.2 K.
2) In stellar and interstellar plasma spectroscopy, neutral helium.

helium.

helium II
  هلیوم II   
heliom II

Fr.: hélium II   

1) A → superfluid, colder component of → liquid helium (4He), occurring when → helium I is cooled below the → lambda point.
2) 2) In stellar and interstellar plasma spectroscopy, ionized helium.

helium.

helium shell burning
  سوزش ِ پوسته‌ی ِ هلیوم   
suzeš-e puste-ye heliom

Fr.: combustion de la coquille d'hélium   

A stage in the evolution of an → asymptotic giant branch star, when all the helium in the core is fused into carbon and oxygen. No more fusion takes place in the core, and as a result the core contracts. The core contraction generates a sufficient temperature for fusing the surrounding layers of helium. Since helium shell burning is unstable, it causes → helium shell flashes.

helium; → shell; → burning.

helium shell flash
  درخش ِ پوسته‌ی ِ هلیومی   
deraxš-e puste-ye heliomi

Fr.: flash de la couche d'hélium   

A violent outburst of energy that occurs periodically in an → asymptotic giant branch star. It occurs when helium is being burnt in a thin shell surrounding the inner dense core of carbon and oxygen. → Helium shell burning is unstable, producing energy mainly in short intense flashes. The shell flash causes considerable expansion of the star followed by collapse, thus setting up deep convection. As a consequence, the → convective zone in the outer part of the star goes deeper and may → dredge-up carbon to the surface. See also → late thermal pulse; → very late thermal pulse; → AGB final thermal pulse.

helium; → shell; → flash.

helium star
  ستاره‌ی ِ هلیومی   
setâre-ye heliomi

Fr.: étoile d'hélium   

An → evolved star which has lost most or all of its hydrogen-rich envelope, leaving just a core of helium.

helium; → star.

helium-argon calibration
  کبیزش ِ هلیوم-آرگون   
kabizeš-e heliyom-ârgon

Fr.: calibration hélium-argon   

A wavelength calibration of astronomical spectra using a helium-argon light source.

helium; → argon; → calibration.

helium-argon lamp
  لامپ ِ هلیوم-آرگون   
lâmp-e heliyom-ârgon (#)

Fr.: lampe hélium-argon   

A comparison light source containing the known spectral lines of helium and Argon.

helium; → argon; → lamp.

helix
  پیچار   
picâr

Fr.: hélice   

A curve which lies on a cylinder or cone, so that its angle to a plane perpendicular to the axis is constant.

From L. helix "spiral," from Gk. helix (genitive helikos), related to eilein "to turn, twist, roll."

Picâr "that which twists," from pic, present stem of picidan "to twist, entwine, coil" + -ar agent noun suffix (on the model of parastâr, padidâr, dustâr, xâstâr).

Helix Nebula (NGC 7293)
  میغ ِ پیچار   
miq-e picâr

Fr.: Nébuleuse de l'Hélice   

A large and bright → planetary nebula in the constellation → Aquarius. Its apparent diameter is about half the size of the full Moon, corresponding to about 2.5 → light-years for a distance of about 700 light-years. It is the nearest bright planetary nebulae to Earth and one of the most spectacular examples of such objects. The Helix Nebula possibly consists of at least two separate disks with outer rings and filaments. The brighter inner disk seems to be expanding at about 100,000 km/h and to have taken about 12,000 years to form. High-resolution observations of the inner edge of the Helix's main ring have revealed thousands of cometary knots of gas with faint tails extending away from the central star. The knots have masses similar to the Earth, but are typically the size of our Solar system. The comet-like shape of the knots results from the steady evaporation of gas from the knots, produced by the strong winds and ultraviolet radiation from the central star of the nebula.The origin of the knots is currently not well understood.

helix; → nebula.

<< < -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 ash ass ast ast asy atm ato att aut ave axi Bab bal Bal bar bar bea Bek Bes bia Big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo cal cal can cap car Car cat cat CCD Cen cen CH 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 con Cop Cor cor cor cos cos cou cou Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp 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 phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar 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 Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>