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: 13116 Search : far
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.

halogen
  هالوژن   
hâložen (#)

Fr.: halogène   

A member of a group of five chemical elements having closely related and similar properties. The halogens are: fluorine, chlorine, iodine, bromine, and astatine. They make up Group 17 of the → periodic table and can be found on the left-hand side of the → noble gases.

From Gk. halo- prefix from Gk. hals "salt" + → -gen.

Hamal (α Arietis)
  حَمَل   
hamal (#)

Fr.: Hamal   

The brightest star in the constellation → Aries. Hamal is a cool → giant of → spectral type K2 with a → luminosity about 55 times that of the Sun and lies about 65 light-years away.

Hamal, from Ar., shortened form of Ra's al-Hamal (رأس‌الحمل), "the head of the sheep."

Hamilton's equation
  هموگش ِ هامیلتون   
hamugeš-e Hamilton

Fr.: équation de Hamilton   

One of a set of equations that describe the motion of a → dynamical system in terms of the → Hamiltonian function and the → generalized coordinates. For a → holonomic system with n degrees of freedom, Hamilton's equations are expressed by: q.i = ∂H/∂pi and p.i = - ∂H/∂qi, i = 1, ..., n.

Hamiltonian function; → equation.

Hamilton's principle
  پروز ِ هامیلتون   
parvaz-e Hamilton

Fr.: principe de Hamilton   

Of all the possible paths along which a → dynamical system can move from one configuration to another within a specified time interval (consistent with any constraints), the actual path followed is that which minimizes the time integral of the → Lagrangian function. Hamilton's principle is often mathematically expressed as δ∫Ldt = 0, where L is the Lagrangian function, the integral summed from t1 to t2, and δ denotes the virtual operator of Lagrangian dynamics and the → calculus of variations.

Hamiltonian function; → principle.

Hamiltonian dynamics
  توانیک ِ هامیلتون   
tavânik-e Hamilton

Fr.: dynamique hamiltonienne   

The study of → dynamical systems in terms of the → Hamilton's equations.

Hamiltonian function; → dynamics.

Hamiltonian formalism
  دیسه‌گرایی ِ هامیلتون   
disegerâyi-ye Hamilton

Fr.: formalisme de Hamilton   

A reformulation of classical mechanics that predicts the same outcomes as classical mechanics. → Hamiltonian dynamics.

Hamiltonian; → mechanics.

Hamiltonian function
  کریای ِ هامیلتون   
karyâ-ye Hâmilton

Fr.: fonction de Hamilton   

A function that describes the motion of a → dynamical system in terms of the → Lagrangian function, → generalized coordinates, → generalized momenta, and time. For a → holonomic system having n degrees of freedom, the Hamiltonian function is of the form: H = Σpiq.i - L(qi,q.i,t) (summed from i = 1 to n), where L is the Lagrangian function. If L does not depend explicitly on time, the system is said to be → conservative and H is the total energy of the system. The Hamiltonian function plays a major role in the study of mechanical systems. Also called → Hamiltonian.

Introduced in 1835 by the Irish mathematician and physicist William Rowan Hamilton (1805-1865); → function.

Hamiltonian operator
  آپارگر ِ هامیلتون   
âpârgar-e Hamilton

Fr.: opérateur hamiltonien   

The dynamical operator in → quantum mechanics that corresponds to the → Hamiltonian function in classical mechanics.

Hamiltonian function; → operator.

hamlet
  کلا   
kalâ

Fr.: hameau   

A small → village.

M.E. hamlet, hamelet, from O.Fr. hamelet "small village," diminutive of O.Fr. hamel "village," itself diminutive of ham "village;" of Germanic origin; cf. E. home, O.E. ham, Du. heem, Ger. Heim; cognate with → city.

Kalâ, from Tabari kalâ "village, borough." Dozens of village names contain kalâ az suffix in Mâzandarân and Gilan.

hand
  دست   
dast (#)

Fr.: main   

1) The terminal part of the forelimb in humans and other primates.
2) A part serving the function of or resembling a hand.

M.E. O.E. hond, hand "hand; side; power;" cf. O.S., O.Fris., Du., Ger. hand, O.N. hönd, Goth. handus.

Dast "hand; strength; superiority;" Mid.Pers. dast; O.Pers. dasta-; Av. zasta-; cf. Skt. hásta-; Gk. kheir; L. praesto "at hand;" Arm. jern "hand;" Lith. pa-žastis "arm-pit;" PIE *ghes-to-.

handbook
  دستنامه   
dastnâmé (#)

Fr.: manuel   

A scholarly book on a specific subject that is conveniently handled.

hand; → book.

handedness
  دستالی   
dastâli

Fr.: latéralité, manualité   

1) A tendency to use one hand rather than the other.
2) The property of an object (as a molecule) of not being identical with its mirror image. Same as → chirality (Merriam-Webster.com).
See also: → B-mode polarization, → E-mode polarization.

hand + -ed + → -ness.

Dastâli, from dast, → hand, + -al, → -al, + noun suffix -i, on the model of → chirality.

Hanle effect
  اسکر ِ هانله   
oskar-e Hanle

Fr.: effet Hanle   

The → polarization arising from line scattering in the presence of "weak" magnetic fields. The effect occurs when precession around magnetic field depolarizes and rotates polarization of the scattered light. The Hanle effect is sensitive to ~103 times smaller field strengths than the → Zeeman effect. It is in particular used to measure the weak magnetic field of the solar → prominences, which is 10-3 tesla and over 10-2 tesla for the active prominences.

Named for the German physicist Wilhelm Hanle (1901-1993), who published his his discovery in 1923 (Naturwissenschaften 11, 690); → effect.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc 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 coo Cor Cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg ura uti val var vec Vel ver Ver vie Vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>