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: 419 Search : per
hyperfine transition
  گذرش ِ اَبَرنازک   
gozareš-e abar-nâzok

Fr.: transition hyperfine   

An → atomic transition involving a → hyperfine structure.

hyperfine; → transition.

hypergalaxy
  اَبَرکهکشان، هیپرکهکشان   
abarkahkašân, hiperkahkašân

Fr.: hypergalaxie   

A system consisting of a dominant → spiral galaxy associated with → dwarf satellite galaxies and intergalactic matter. Examples in the → Local Group are our Galaxy and the → Andromeda galaxy.

hyper- + → galaxy.

hypergiant star
  ستاره‌ی ِ هیپرغول   
setâre-ye hiperqul

Fr.: hypergéante   

A high luminosity star with absolute visual magnitude around -10, about 106 times as luminous as the Sun. Hypergiant stars are evolved → massive stars belonging to the luminosity class Ia+ or Ia0. Their spectra show very broadened emission and absorption lines resulting from the high luminosity and low surface gravity which favor strong → stellar wind. See also → Humphreys-Davidson limit; → yellow hypergiant.

hyper-; → giant.

Hyperion (Saturn VII)
  هوپریون   
Huperion (#)

Fr.: Hypérion   

The sixteenth of → Saturn's known → natural satellites. It is shaped like a potato with dimensions of 410 x 260 x 220 km and has a bizarre porous, sponge-like appearance. Many of the sponge holes or craters have bright walls, which suggests an abundance of → water  → ice. The crater floors are mostly the areas of the lowest → albedo and greatest red coloration. This may be because the average temperature of roughly -180 °C might be close enough to a temperature that would cause → volatiles to → sublimate, leaving the darker materials accumulated on the crater floors. Hyperion is one of the largest bodies in the → Solar System known to be so irregular. Its density is so low that it might house a vast system of caverns inside. Hyperion rotates chaotically and revolves around Saturn at a mean distance of 1,481,100 km. It was discovered by two astronomers independently in 1848, the American William C. Bond (1789-1859) and the British William Lassell (1799-1880).

Hyperion, in Gk. mythology was the Titan god of light, one of the sons of Ouranos (Heaven) and Gaia (Earth), and the father of the lights of heaven, Eos the Dawn, Helios the Sun, and Selene the Moon.

hypermetropia
  دوربینی   
durbini (#)

Fr.: hypermétropie   

A condition of the eye that occurs when light rays entering the eye are focused behind the retina; also called farsightedness, hyperopia, long sight (opposed to → myopia).

From Gk. hupermetros "beyond measure," from → hyper- + metron "measure;" → meter + -opia a combining form denoting a condition of sight or of the visual organs hemeralopia; myopia.

Durbini "farsightedness," from dur "far" (Mid.Pers. dūr "far, distant, remote;" O.Pers. dūra- "far (in time or space)," dūraiy "afar, far away, far and wide;" Av. dūra-, dūirē "far," from dav- "to move away;" cf. Skt. dūrá- "far; distance (in space and time);" PIE base *deu- "to move forward, pass;" cf. Gk. den "for a long time," deros "lasting long") + bin- "to see" (present stem of didan; Mid.Pers. wyn-; O.Pers. vain- "to see;" Av. vaēn- "to see;" Skt. veda "I know;" Gk. oida "I know," idein "to see;" L. videre "to see;" PIE base *weid- "to know, to see") + -i noun suffix.

hypernova
  هیپرنو‌اَختر   
hiper-nowaxtar

Fr.: hypernova   

A highly energetic → supernova explosion. This phenomenon, which is more violent than a typical → supernova event, is accompanied by a → gamma-ray burst.

hyper-; → nova.

hyperon
  هیپرون   
hiperon (#)

Fr.: hypéron   

An unstable elementary particles, belonging to the class called → baryons, which have greater mass than the neutron but very short lives (10-8 to 10-10 seconds).

From → hyper- + → -on a suffix used in the names of elementary particles (gluon; meson; neutron; graviton, and so on).

hypersonic
  هیپرصدایی   
hipersedâyi

Fr.: hypersonique   

In aerodynamics, adjective used to describe a → sound speed in excess of Mach 5. See also → supersonic.

Hypersonic, from → hyper- + → sonic.

hypervelocity star (HVS)
  ستاره‌ی ِ هیپرتند   
setâre-ye hipertond

Fr.: étoile hypervéloce   

A star whose velocity is so great that it will escape the → gravitational potential of our → Galaxy. Depending on the location and direction of motion, this criterion typically corresponds to a stellar velocity in the Galactic → rest frame larger than 400 km s-1, and up to about 1200 km s-1. The nature of the HVSs spans a wide range of types from → OB stars, to metal-poor → F-type stars and G/K dwarfs. While there is evidence from many late-type B HVSs in the → halo to originate from the Galactic → supermassive black hole (SMBH), other HVSs seem to originate from the → galactic disk. HVSs can obtain their large velocities from a number of different processes:
1) → Tidal disruption of → close binary stars by the central SMBH of the Milky Way. In this process one star is captured by the SMBH while the other is ejected at high speed via the → gravitational slingshot mechanism.
2) Exchange encounters in other dense stellar environments between hard binaries (→ hard binary) and → massive stars may cause stars to be ejected and escape our Galaxy.
3) Disruption of close binaries via → supernova explosions. The → runaway velocities of both ejected stars can reach large values when asymmetric supernovae are considered, i.e. when the newborn → neutron star receives a momentum kick at birth.
(see, e.g., T. M. Tauris, 2014, and references therein, arXiv:1412.0657).

hyper-; → velocity; → star.

identity operator
  آپارگر ِ ایدانی   
âpârgar-e idâni

Fr.: opérateur d'identité   

An operator which takes a real number to the same real number.

identity; → operator.

ignition temperature
  دمای ِ گیرانش   
damâ-ye girâneš

Fr.: température d'inflammation   

The minimum temperature to which a fuel must be heated in order to initiate self sustained combustion independent of another heat source.

ignition; → temperature.

imperare (L.)
  پرماتیدن   
parmâtidan

Fr.: inperare (L.)   

Latin verb meaning "to command, rule, reign."

L. imperare "to command, give orders, exercise authority," from → in- "into, in" + parare "to make ready, supply, order," related to parire "produce, give birth to," from PIE root *pere- "to produce, procure;" cf. Skt. prthukah "child, calf, young of an animal;" Gk. poris "calf, bull;" Czech spratek "brat, premature calf;" Lith. periu, pereti "to brood;" O.H.G. farro, Ger. Farre, Du. varre "bull," O.E. fearr "bull;" see below for possible Iranian cognates.

Parmâtidan, from BMP plm'(d)y "to command, order," Sogd. framat- "to command," variants of farmudan, farmâyidan "to command, to order," ultimately from prefixed Proto-Ir. *fra-maH-, from *maH- "to measure," → experiment.

imperative
  ۱) پرماته؛ ۲) پرماتی   
1) parmâte; 2) parmâti

Fr.: 1) inpératif; 2) impériux   

1a) A command or order.
1b) → imperative case.
2a) Absolutely necessary or required; extremely important.
2b) Of the nature of or expressing a command; commanding.

From L.L. imperativus "pertaining to a command," from imperat-, p.p. stem of → imperare "to command."

Parmât, noun from present stem of parmâtidan, → imperare; parmâtii, adj. from parmât.

imperative case
  کاته‌ی ِ پرماتی، ~ فرمانی   
kâte-ye parmâti, ~ farmâni

Fr.: cas impératif   

The grammatical mood of a verb that expresses a command or a request, as in close the door!.

imperative; → case.

imperatively
  پرماتانه   
parmâtâne

Fr.: inpérativement   

In an imperative manner.

Adverb from → imperative; → -ly.

imperfect
  نافرساخته، نافرساخت   
nâfarsâxté; nâfarsâxt

Fr.: imperfection   

Not perfect; faulty or incomplete.

in-; → perfect.

imperfection
  نافرساختگی، نافرسازش   
nâfarsâxtegi, nâfarsâzeš

Fr.: imperfection   

A fault, flaw, or undesirable feature; the state or condition of being imperfect.

in-; → perfection.

imperial
  پرماتیاری، پرماتگانی، شاهی، شاهانه، شاهنشاهی   
parmâtyâri, parmâtgâni, šâhi, šâhâne, šâhanšâhi

Fr.: impérial   

Of, relating to, or suggestive of an empire or a sovereign, especially an emperor or empress (TheFreeDictionary).

Adjective of → empire.

imperialism
  پرماتگانداری، امپریالیسم   

Fr.: impérialisme   

1) The extension of a nation's authority by territorial acquisition or by the establishment of economic and political dominance over other nations.
2) A political doctrine or system promoting such extension of authority (TheFreeDictionary.com).

imperial; → -ism.

integral operator
  آپارگر ِ دُرُستالی   
âpârgar-e dorostâli

Fr.: opérateur intégral   

Math.: An operator whose inverse is a differential operator.

integral; → operator.

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