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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Number of Results: 13048 Search : far
G-type star
  ستاره‌ی گونه‌ی ِ G   
setâre-ye gune-ye G

Fr.: étoile de type G   

Same as → G star.

G star; → type.

Gaia
  گایا   
Gaia (#)

Fr.: Gaia   

A → European Space Agency  → astrometry mission launched on 19 December 2013. Gaia's goal is to create the largest and most precise three-dimensional chart of the → Milky Way galaxy by providing unprecedented positional (position on the sky and distance to the Sun) and annual → proper motion measurements for about one billion stars in our Galaxy and throughout the → Local Group. Moreover, the third component of the velocity, the → radial velocity, will be obtained for all stars down to V = 17 mag. Similarly, multi-color photometry will be carried out on all stars down to V = 20 mag. Gaia will achieve the planned astrometric requirements by repeatedly measuring the positions of all objects down to V = 20 mag with final accuracies of about 20 microarcsec at 15 mag. It will provide distances accurate to 20% as far as the → Galactic Center. The satellite is expected to be launched in 2012 and be placed in a → Lissajous orbit around the Sun-Earth → Lagrangian point L2. Gaia is a much more advanced version of the → Hipparcos mission.

Initially, GAIA was the short for Global Astrometric Interferometer for Astrophysics. Although subsequently the interferometer option was abandoned, the acronym was maintained in lower case.

gain
  بهره   
bahré (#)

Fr.: gain   

1) A measure of the → amplification of an electronic device, usually expressed as the ratio of → output power to → input power.
2) → antenna gain.

From M.Fr. gain, from O.Fr. gaaigne, from guaaignier "to obtain," from Germanic *waidanjan "to hunt, plunder," also "to graze, pasture," from P.Gmc. *wartho "hunting ground" (cf. Ger. weide "pasture, pasturage"); PIE base *weiə- "to go after something, strive after."

Bahré, from bahr "part, portion, share, lot;" Av. baxəδra- "portion," from bag- "to attribute, allot," → division.

galactic
  کهکشانی   
kahkešâni (#)

Fr.: galactique   

1) Of or pertaining to a → galaxy.
2) Usually with capital G, pertaining to our galaxy, the → Milky Way.

Adjective of → galaxy.

Galactic anticenter
  پادمرکز ِ کهکشان   
pâdmarkaz-e kahkešân

Fr.: anticentre galactique   

The point in the → Galactic plane that lies directly opposite the → Galactic center. It lies in the constellation → Auriga at approximately R.A. 05h 46m, Dec. +28° 56'.

galactic; → anticenter.

galactic bar
  میله‌ی ِ کهکشانی   
mile-ye kahkešâni

Fr.: barre galactique   

An elongated bar-shaped structure composed of stars present in some spiral galaxies. About two-third of such galaxies contain bars that cross their centers. Bars, like → spiral arms, result from a → density wave in which stars take very elliptical orbits. They form when the → galactic disk dominates the → galactic bulge, → Ostriker-Peebles criterion. Bars play an extremely important role in a galaxy's evolution. The gravity from a bar is the mechanism that drives → interstellar gas from the outer parts of a → spiral galaxy inward toward the central regions, and into the galactic nucleus itself. This causes tremendous bursts of star formation. Therefore, a majority of massive stars are born in such starbursts in the nuclei of galaxies. Bars may also channel the material that falls into black holes within active galactic nuclei, releasing enormous power in radiation and particles from tiny regions at the centers of some galaxies. Bars disappear as galactic centers grow more massive (after some 2 to 8 Gyr).

galactic; → bar.

Galactic bulge
  کوژ ِ کهکشان   
kuž-e kakhašân

Fr.: bulbe de la Galaxie   

The central → galaxy bulge of the → Milky Way.

galactic; → bulge.

Galactic Center
  مرکز ِ کهکشان   
markaz-e kahkešân (#)

Fr.: centre galactique   

1) The rotational center of the → Milky Way galaxy located in the direction of the → Sagittarius constellation at a distance of 7.62 ± 0.32 kpc (2005, ApJ 628, 246). Its equatorial coordinates (J2000 epoch) are: R.A. 17h45m40.04s, Dec. -29° 00' 28.1''. The Sun orbits around the Galactic center once every 200 million years at a speed of 220 km per second. It is believed that there is a → supermassive black hole at the Galactic center.
2) The innermost region of a → spiral galaxy characterized by high number of stars per unit volume. The center may contain a → supermassive black hole.

galactic; → center.

Galactic center cluster
  خوشه‌ی ِ مرکز ِ کهکشان   
xuše-ye markaz-e kahkešân

Fr.: amas du centre galactique   

One of the three massive clusters located toward the → Galactic center: → Quintuplet cluster, → Arches cluster, → Central cluster. Heavily extinguished by the presence of dust clouds and only accessible at infrared (and longer) wavelengths or in X-rays, each of these clusters has a population of more than a hundred → massive stars. The three clusters are similar in most respects, each containing about 104 solar masses in stars. The Arches cluster is younger than the two others.

galactic; → center; → cluster.

galactic cluster
  خوشه‌ی ِ کهکشانی، ~ کهکشانها   
xuše-ye kahkešâni, ~ kahkešânhâ

Fr.: amas galactique   

1) Same as → open cluster.
2) same as → cluster of galaxies.

galactic; → cluster.

Galactic coordinates
  هماراهای ِ کهکشانی   
hamârâhâ-ye kahkešâni

Fr.: coordonnées galactiques   

A system of astronomical coordinates using → latitude (bII) measured north and south from the → Galactic equator and → longitude (lII), measured from the → Galactic Center in the sense of increasing → right ascension from 0 to 360 degrees. In the old system (lI,bI), the Galactic center was at lI = 327°41'. Same as → galactic system.

galactic; → coordinate.

galactic disk
  گرده‌ی ِ کهکشان   
gerde-ye kahkešân

Fr.: disque galactique   

The flattened component of a → spiral galaxy which is composed of stars and concentrations of dust and molecules. → Star formation takes place mainly in the disk.

galactic; → disk.

galactic dynamics
  دینامیک ِ کهکشانی   
tavânik-e kakhešâni

Fr.: dynamique galactique   

The study of the → motions of the → stars, → gas, and → dark matter in a → galaxy to explain the main → morphological and → kinematical features of the galaxy.

galactic; → dynamics.

Galactic equator
  هموگار ِ کهکشان   
hamugâr-e kahkešân

Fr.: équateur galactique   

The great circle in the sky defined by the place of the → Galactic plane or the → Milky Way. At an angle of about 62°, the Galactic equator intersects the celestial equator at two points located in the constellations → Monoceros and → Aquila.

galactic; → equator.

Galactic habitable zone
  زنار ِ زیست‌پذیر ِ کهکشان   
zonâr-e zistpazir-e kahkešân

Fr.: zone habitable galactique   

A region of the Galaxy whose boundaries are set by its calm and safe environment and access to the chemical materials necessary for building terrestrial planets similar to the Earth. → circumstellar habitable zone; → habitable zone.

galactic, → habitable; → zone.

Galactic halo
  هاله‌ی ِ کهکشان   
hâle-ye kahkešân

Fr.: halo galactique   

A roughly spherical aggregation of → globular clusters, as well as the oldest stars and unseen mass that surrounds the Galaxy.

galactic, → halo.

Galactic latitude
  ورونای ِ کهکشانی   
varunâ-ye kahkešâni

Fr.: latitude galactique   

In the → Galactic coordinate system, the angle between the line of sight to an object and the → Galactic equator. Galactic latitude, usually represented by the symbol bII, ranges from +90 degrees to -90 degrees.

galactic; → latitude.

Galactic longitude
  درژنا‌ی ِ کهکشانی   
derežnâ-ye kahkešâni

Fr.: longitude galactique   

In the → Galactic coordinate system, the angle between the → Galactic Center and the projection of the object on the → Galactic plane. Galactic longitude, usually represented by the symbol lII, ranges from 0 degrees to 360 degrees.

galactic; → longitude.

galactic nucleus
  هسته‌ی ِ کهکشان   
haste-ye kahkešân

Fr.: noyau de galaxie   

A concentration of stars and gas in the innermost region of a galaxy, sometimes extending over thousands of light-years from the center of the galaxy.

galactic; → nucleus.

galactic outflow
  استچان ِ کهکشانی   
ostacân-e kahkešâni

Fr.: flot galactique   

galactic-scale outflow.

galactic; → outflow.

<< < -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 > >>