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
Hellas Basin
  حوضه‌ی ِ هلاس   
howze-ye Hallas

Fr.: bassin de Hallas   

One of the largest identified → impact craters both on → Mars and within the → Solar System. Hellas spans more than 2000 km across in the → southern hemisphere, a region that is much more heavily cratered and higher in average elevation than the northern hemisphere. The depth of Hellas from its bottom to its inner rim is more than 4 km. In comparison, the depth of the Grand Canyon in the United States is roughly 1.6 km, that is 2.5 times smaller! The western part of the Hellas basin contains the lowest point on Mars, about 8.2 km below the Mars datum or Martian "sea level." The formation of the impact structure is believed to have taken place in the early Noachian epoch, between 3.9 and 4.6 billion years ago (Planetary Science Institute webpage).

Hellas refers to the classical name for Greece; → basin.

helmet
  خود   
xud (#)

Fr.: casque   

1) Any of various protective head coverings worn by soldiers, policemen, firemen, etc.
2) Something resembling a helmet in form or position. → helmet streamer.

From M.Fr. helmet, diminutive of helme "helmet," from Frank. *helm (cf. O.H.G. helm "helmet"); PIE base *kel- "to cover, to hide;" cf. Av. sar- "shelter;" Laki šârd "hidden, hiddenly," šârden "to hide;" Kurd. šâr-, šârdinawa "to hide;" Skt. śárman- "cover, protection, refuge;" L. celare "to conceal;" Goth. huljan "to cover, conceal;" O.H.G. helan "to hide."

Xud "helmet," from O.Pers. xaudā- "hat, cap," tigra-xauda- "wearing the pointed cap" (as is shown in the sculpture of Skunkha the Scythian at Behistan); Av. xaoδa- "hat, cap, helmet;" Ossetic xodä; Arm. (borrowed) xoir "headband."

helmet streamer
  درفشک ِ خودوار   
derafšak-e xudvâr

Fr.: grand jet en bulbe, ~ ~ en casque prussien   

A large-scale → coronal feature with apparent → cusp, seen during a → solar eclipse. They usually arise from → sunspots and → active regions, so at the base of a helmet streamer one will often find a → prominence.  They form magnetic loops that connect the sunspots and suspend material above the surface of the Sun.  The magnetic field lines trap the material to form the streamers. The action of the → solar wind is at the origin of the peak feature.

helmet; → streamer.

Helmholtz free energy
  کاروژ ِ آزاد ِ هلمهولتس   
kâruž-e âzâd-e Helmholtz

Fr.: énergie libre de Helmholtz   

Of a system, the quantity whose decrease gives the maximum amount of external work which is performed when any physical or chemical process is carried out reversibly at constant temperature. It is defined by F = U - TS, where U is the → internal energy, T the → absolute temperature, and S the final → entropy.

After the German physicist and physician Hermann Ludwig Ferdinand von Helmholtz (1821-1894), who made important contributions to the thermodynamics of gaseous systems; → free; → energy.

Helmholtz's theorem
  فربین ِ هلمهولتس   
farbin-e Helmholtz

Fr.: théorème de Helmholtz   

A → decomposition theorem, whereby a continuous → vector field, F, can be broken down into the sum of a → gradient and a → curl term: F = -∇φ + ∇ xA, where φ is called the → scalar potential and A the → vector potential.

Helmholtz free energy; → theorem.

Helmi stream
  رابه‌ی ِ هلمی   
râbe-ye Helmi

Fr.: courant de Helmi   

A systematic trend in the motion of some → Galactic haloold stars thought to be a relic of the → merging of a dwarf satellite galaxy devoured by our Milky Way. Using kinematic data from the → Hipparcos satellite, Helmi et al. (1999, Nature 402, 53) found two halo star streams which share a common progenitor: a single coherent object disrupted during or soon after the Milky Way's formation, and which probably resembled the Fornax and Sagittarius dwarf spheroidal galaxies.

See also Helmi & White 1999, MNRAS 307, 495; → stream.

help desk
  یاری‌گاه   
yârigâh

Fr.: centre d'assistance   

A service in an organization or computer system where users are directed for technical support or assistance.

M.E., O.E. help (m.), helpe (f.) "assistance, succor," helpan "o help" (cf. O.N. hjialp, hjalpa, M.Du., Du. hulp, helpen, O.H.G. helfa, helfan, Ger. Hilfe, helfen); PIE base *kelb- "to help" (cf. Lith. selpiu "to support, help"); desk, from M.E. deske; M.L. desca, descus "table to write on," from L. discus "quoit, platter, dish," from Gk. diskos "disk, dish."

Yâigâh, from yâri "help, assistance," → gravity assist, + -gâh "place; time," → station.

hematite
  هماتیت   
hemâtit (#)

Fr.: hématite   

A mineral that is often found in meteorites. It is an oxide of iron (Fe2O3) that is similar to magnetite. It does not attract a magnet. When it is rubbed against an object harder than itself, it leaves a reddish-brown stain. Hematite is also sometimes called bloodstone.

From M.Fr. hematite, from L. hæmatites, from Gk. haimatites lithos "bloodlike stone," from haima (genitive haimatos) "blood" + -ites, → -ite, + lithos "stone."

hemeralopia
  روزکوری   
ruzkuri (#)

Fr.: héméralopie   

A defect of the eyes in which sight is normal in the night or in a dim light but is abnormally poor or wholly absent in the day or in a bright light. Also called day blindness. Opposite of → nyctalopia

From N.L., from Gk hemeralop- (stem of hemeralops having such a condition, from hemer(a) "day" + al(aos) "blind" + -ops having such an appearance) + -ia a noun suffix.

Ruzkuri, from ruz, → day, + kuri "blindness," from kur, → blind.

hemisphere
  نیم‌سپهر، نیمکره   
nimsepehr (#), nimkoré (#)

Fr.: hémisphère   

Half of a sphere bounded by a great circle, especially one of the halves into which the earth or the celestial sphere is divided.

From L. hemisphærium, from Gk. hemisphairion, from hemi- "half," (from PIE base *semi-; cf. Skt. sami, L. semi-, O.H.G. sami- "half," and O.E. sam-) + sphaira, → sphere.

From nim-, → half + sepehr, koré, → sphere.

Henry Draper system
  راژمان ِ هنری دریپر   
râžmân-e Henry Draper

Fr.: système de Henry Draper   

A catalog of stars in which every star is classified by its stellar spectrum. This system is named for the astronomer Henry Draper, but was cataloged by Annie J. Cannon (225,300 stars), and later extended by Margaret W. Mayall.

Henry Draper (1837-1882), an American pioneer of astronomical spectroscopy who established the observing techniques and program for the work that would bear his name when published, seven years after his early death; → system.

Henyey method
  روش ِ هنی   
raveš-e Henyey

Fr.: méthode de Henyey   

A powerful numerical technique to solve the stellar structure equations where the star is sub-divided in a finite number of grid cells for which the local conditions are evaluated and computed from the surface inwards to the center by utilizing a Newton-Raphson solver. Relevant physical quantities are either defined at the cell boundaries or as mean values over the complete cell.

Henyey, L. G.; Forbes, J. E.; Gould, N. L., 1964, ApJ 139, 306; → method.

Henyey track
  تر ِ هنی   
tor-e Henyey

Fr.: trajet de Henyey   

A nearly horizontal path on the → Hertzsprung-Russell diagram that a → pre-main sequence star of small mass follows in an early stage of evolution after leaving the → Hayashi track and before reaching the → main sequence. During this stage the pre-main sequence star remains almost wholly in radiative equilibrium.

After Louis George Henyey (1910-1970), American astronomer. Henyey et al. (1955, PASP 67, 154).

hepta-
  هفت-   
haft- (#)

Fr.: hepta-   

A combining form meaning "seven."

From Gk. hepta "seven;" cognate with L. septem; Pers. haft, as below; Du. zeven, O.H.G. sibun, Ger. sieben, E. seven.

Haft-, from haft "seven;" Mid.Pers. haft; Av. hapta; cf. Skt. sapta; Gk. hepta, L. septem; PIE *septm.

heptagon
  هفت‌بر، هفت‌گوش   
haftbar (#), haftguš (#)

Fr.: heptagone   

A → polygon with seven → angles and seven → sides.

hepta-; → -gon.

Herbig AeBe star
  ستاره‌ی ِ هربیگ ِ AeBe   
setâre-ye Herbig-e AeBe (#)

Fr.: étoile de Herbig AeBe   

A young → A-type or → B-type star showing → emission lines in its spectrum. Herbig AeBe stars are → pre-main sequence stars of → intermediate mass (→ intermediate-mass star). They are often called the higher mass counterparts of → T Tauri stars.

Named after George H. Herbig (1920-2013), who first classified them (Herbig 1960, ApJS 4, 337); → A star; → B star; e indicating → emission.

Herbig-Haro object
  بر‌آخت ِ هربیگ-هارو   
barâxt-e Herbig-Haro

Fr.: objets Herbig-Haro   

A small patch of → nebulosity in a → star-forming region, created when fast-moving → jets of material (with speeds up to about 1000 km per sec) from a newborn star collide with the → interstellar medium.

Herbig AeBe star; Guillermo Haro (1913-1988), who first in 1940s studied these objects in detail and recognized that they were a by-product of the star formation process; → object.

Hercules
  هراکلس، هرکول، برزانو نشسته   
Herâkles (#), Herkul (#), bar zânu nešasté (#)

Fr.: Hercule   

An ancient → constellation (right ascension about 17h, declination 30° north), one of the largest in the sky, which is located between → Lyra and → Corona Borealis. It is traditionally depicted as the hero Hercules in a kneeling position. There are no very bright stars in Hercules, the brightest one is → Rasalgethi, a variable → red supergiant of magnitude about 3.5. Abbreviation: Her; Genitive: Herculis.
See also: → Hercules cluster.

L. Hercules, from Gk. Heracles "glory of Hera," the most popular hero of Gk. mythology, son of Zeus and the woman Alcmena, who the god seduced in the shape of her husband Amphitryon, king of Thebes.

Herâkles, as above; Herkul, from Fr. Hercule, as above; Arabicized name of the constellation: هرقل. Other Ar. renderings: (al-jâthi, jâthi 'alâ rukbataihi (الجاثی، الجاثی علی‌رکبتیه) "the kneeling one," râqes (راقص) "the dancing one."
Bar zânu nešasté "the kneeling one," Pers. descriptive rendering of the Gk. mythological figure, by the famous 11-th century astronomer Biruni.

Hercules cluster
  خوشه‌ی ِ هراکلس، ~ هرکول   
xuše-ye Herâkles, ~ Herkul

Fr.: amas d'Hercule   

A small, irregular → cluster of galaxies with fewer than 100 galaxies in its core. It has no strongly dominant central galaxy and is notable for the high proportion of spirals. It lies some 500 million → light-years away in the constellation → Hercules; also known as Abell 2151.

Hercules; → cluster.

hereditable
  ریگن‌بردنی، دریگیدنی   
riganbordani, darigidani

Fr.: dont on peut hériter, qui peut hériter   

inheritable.

inherit; → -able.

<< < -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 > >>