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: 13048 Search : far
Hagen number (Hg)
  عدد ِ هاگن   
adad-e Hagen

Fr.: nombre de Hagen   

A dimensionless number characterizing the importance of → viscous force in a → forced flow.

named after the German hydraulic engineer Gotthilf H. L. Hagen (1797-1884); → number.

Haidinger fringes
  فریز‌های ِ هایدینگر   
farizhâ-ye Haydinger (#)

Fr.: franges d'Haidinger   

The interference fringes seen with thick plates near normal incidence.

W. K. von Haidinger (1798-1871), Austrian mineralogist and geologist; → fringe.

hail
  تگرگ   
tagarg (#)

Fr.: grêle   

A showery precipitation in the form of nearly spherical or irregular → pellets of ice having a diameter of up to 50 mm or more. Hail is associated with → thunderstorm cells that have strong currents of rising air and relatively great → humidity content. Hail can only form in cumulonimbus clouds. Water droplets, after the formation, freeze and begin to fall downward through the cloud, but the wind blows them back upward. As the droplets begin to fall back down again, they collect more water which also freezes, so the drop becomes bigger. Then the wind blows them back up again. This occurs several times, but eventually the frozen droplets become too big and heavy and fall as hail. See also → sleet.

From M.E. haghel, hayl; O.E. hægl, hagol; cf. O.H.G. hagal, Ger. Hagel "hail;" probably from PIE *haghlo- "pebble"; cf. Gk. kakhlex "round pebble;" Pers. Lori hogela "(big) stone."

Tagarg, from *takaraka, *tancaraka- "dense, condensed," from Proto-Ir. base *tanc- "become narrow, dense, constrict," cf. Pers. tanjidan, "to squeeze, → compress," tang "narrow, constricted;" Shahmirzadi tāž/tižd; Sariqoli tož/tižd "to pull, drag;" Pashto tat "close, thick;" Skt. tanákti "it coagulates," takrá- "buttermilk;" M.Irish techt "coagulated;" Lith. tánkus "thick;" PIE *tenk- "to twist together, become thick" (H. W. Bailey, 1979).

hair
  مو، گیس، گیسو   
mu (#), gis (#), gisu (#)

Fr.: cheveux, chevelure   

1) Any of the numerous fine filaments growing from the skin of humans or animals.
2) A mass or aggregate of hairs covering the human head. The mean diameter of human hair is about 100 μm (from 17 to 181 μm)
3) An outgrowth of the epidermis of a plant.
crosshairs; → no hair theorem; → Berenice's Hair.

M.E. heer; O.E. hær; cf. O.H.G. har, Du. haar, Ger. Haar "hair;" PIE base *kaisaro- "hair," from *ker(s)- "to bristle;" cf. Skt. kesara- "hair, mane (of a horse or lion)."

Mu(y) "hair;" Mid.Pers. môy "hair."
Gis, gisu, from Mid.Pers. ges, gesuk "hair, lock, tress," Av. gaêsa- "curly hair," gaêsav-, gaêθav- "curly, curly-haired," cf. Gk. kaite "bushy hair, mane," O.Ir. gaiset, PIE *ghaites "curly hair."

halation
  هاله‌گیری   
hâlegiri

Fr.: halo   

1) In a cathode-ray tube, the glow surrounding a bright spot that appears on the fluorescent screen as the result of the screen's light being reflected by the front and rear surfaces of the tube's face.
2) The effect in which a halo appears around the image of a bright object recorded on a photographic film or plate. It is produced by the fan-like pattern of light reflected through the emulsion by the medium's backing material.

Halation, from hal(o), → halo + -ation a combination of -ate and -ion, used to form nouns from stems in -ate.

Hâlegiri, from hâlé, → halo + giri, verbal noun of gereftan "to take, seize" (Mid.Pers. griftan, Av./O.Pers. grab- "to take, seize," cf. Skt. grah-, grabh- "to seize, take," graha "seizing, holding, perceiving," M.L.G. grabben "to grab," from P.Gmc. *grab, E. grab "to take or grasp suddenly;" PIE base *ghrebh- "to seize").

Hale's law
  قانون ِ هیل   
qânun-e Hale

Fr.: loi de Hale   

The leader and → follower spots have opposite polarities on either side of the equator. This reverses after the ~11 year → solar cycle. Also called Hale-Nicholson's law.

Named after George Ellery Hale (1868-1938), American astronomer; → law.

half
  نیم   
nim (#)

Fr.: moitié, mi-, demi-   

One of two equal or approximately equal parts of a divisible whole.

M.E., from O.E. h(e)alf "side, part," from P.Gmc. *khalbas "something divided" (cf. M.Du. half, Ger. halb, Goth. halbs "half").

Nim, nimé "half," from Mid.Pers. nêm, nêmag "half;" Av. naēma- "half;" cf. Skt.. néma- "half."

half moon
  نیمه‌مانگ، نیمه‌ماه   
nime mâng, nime mâh (#)

Fr.: demi-lune   

The moon when, at either quadrature, half its disk is illuminated.

half; → moon.

half-life
  نیم‌زیست   
nim-zist

Fr.: demi-vie   

The length of time required for half of a given quantity of → radioactive material to → decay.

half; → life.

half-power beamwidth (HPBW)
  پهنای ِ تابه در نیم‌توان   
pahnâ-ye tâbé dar nim-tavân

Fr.: largeur à mi-hauteur   

The angle between extreme points of the main lobe of an antenna pattern where the sensitivity of the antenna is half the value at the center of the lobe. This is the nominal resolving power of the antenna system.

half; → power; → beam; → width.

half-value layer (HVL)
  لایه‌ی ِ نیم-تنکش   
lâye-ye nim-tonokeš

Fr.: couche de demi-atténuation   

The thickness of material required to reduce the intensity of an → X-ray beam to one half of its initial value. The HVL is an indirect measure of the photon energies of a beam.

half; → value; → layer; → attenuation.

half-wave plate
  تیغه‌ی ِ نیم‌موج   
tiqe-ye nin-mowj (#)

Fr.: lame demi-onde   

A plate of optical material whose thickness is such that the phase difference between the extraordinary and ordinary rays after passing through the place is exactly one-half cycle. It can serve to rotate the plane of polarization of a light beam.

half; → wave; → plate.

Halimede
  هالیمده   
Hâlimedé

Fr.: Halimède   

A retrograde irregular satellite of Neptune discovered in 2002. Also called Neptune IX. Halimede is about 62 kilometres in diameter.

In Gk. mythology, one of the Nereids, the fifty daughters of Nereus and Doris.

Halley's comet
  دنباله‌دار ِ هالی، دمدار ِ ~   
dombâledâr-e Halley, domdâr-e ~

Fr.: comète de Halley   

The most famous comet orbiting the Sun once about every 75 years. The last time it appeared was in 1986, and it is predicted to return in 2061. Its earliest recorded sighting is traced back to 240 BC in China. In 1705 Edmond Halley used Newton's new theory of gravitation to determine the orbits of comets from their recorded positions in the sky as a function of time. He found that the bright comets of 1531, 1607, and 1682 had almost the same orbits. He concluded that these appearances must belong to a single recurring comet, and predicted its return for 1758. Halley's comet is the first known → periodic comet, hence its → designation 1P/Halley.

Named after the English astronomer Edmond Halley (1656-1742), who first computed its orbit and predicted its return in 1758; → comet.

halo
  هاله   
hâlé (#)

Fr.: halo   

1) Meteo.: Rings or arcs that seem to encircle the sun or moon and are the result of the refraction of light through the ice crystals that make up cirrus clouds.
2) → halo of galaxy.

Halo, from L. (acc.) halo, from Gk. halos "ring of light around the sun or moon."

Hâlé, loanword from Ar.

halo occupation distribution (HOD)
  واباژش ِ هگش ِ هاله   
vâbâžeš-e hageš-e hâlé

Fr.: distribution d'occupation de halo   

The → probability distribution of the → number of galaxies that a host → dark matter halo of a given mass contains. HOD is a powerful theoretical frame to populate dark matter halos with luminous galaxies. More specifically, it describes the bias between galaxies and dark matter by specifying (a) the probability P(N|M) that a halo of → virial mass M contains N galaxies of a particular class and (b) the relative spatial and velocity distributions of galaxies and dark matter within halos.

halo; → occupation; → distribution.

halo of galaxy
  هاله‌ی ِ کهکشان   
hâle-ye kakekašân (#)

Fr.: halo de galaxie   

The diffuse, nearly spherical cloud of stars and → globular cluster s that surrounds a → spiral galaxy.

halo; → galaxy.

halo of the Galaxy
  هاله‌ی ِ کهکشان   
hâle-ye kakekašân (#)

Fr.: halo de la Galaxie   

The → halo of galaxy belonging to our → Milky Way.

halo; → galaxy.

halo population
  پُرینش ِ هاله   
porineš-e hâlé

Fr.: population du halo   

Old stars with very low metallicities (→ metallicity) found in the → halo of the Galaxy. Also called → population II star.

halo; → population.

Halo ring
  حلقه‌ی ِ هاله، ~ هاله‌وار   
halqe-ye hâlé, ~ hâlevâr

Fr.: anneau de halo   

A faint, wide ring around → Jupiter that has the shape of a doughnut. It is about 22,800 km wide and about 20,000 km thick. This ring starts at 100,000 km from the center of Jupiter. The outer edge of the Halo merges into the → Main ring.

halo; → ring.

<< < -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 > >>