An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 481

Fr.: hyperfine   

Extremely fine or thin, especially of a → spectral line split into two or more very thin components. → hyperfine structure; → hyperfine transition.

hyper-, → fine structure.

hyperfine structure
  ساختار ِ اَبَرنازک   
sâxtâr-e abar-nâzok (#)

Fr.: structure hyperfine   

In spectroscopy, the → splitting of a spectral line into a number of very thin components. It results from a small perturbation in the energy levels of atoms or molecules due to the magnetic dipole-dipole interaction arising from the interaction of the nuclear → magnetic moment with the → spin of the electron. It can be observed only at high spectral dispersion. → fine structure.

hyperfine; → structure.

hyperfine transition
  گذرش ِ اَبَرنازک   
gozareš-e abar-nâzok

Fr.: transition hyperfine   

An → atomic transition involving a → hyperfine structure.

hyperfine; → transition.

  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)
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.

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.

  هیپر-نووا، هیپر-نو-اَختر   
hiper-novâ, 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.

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).


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.


Fr.: hypo-   

A Gk. prefix denoting "under."

Gk. hypo "under" (prep.), "below" (adv.); cognate with L. sub- and O.Pers./Av. upā, as below.

Upâ-, from O.Pers. upā (prep.) "under, with;" Av. upā, upa (prep.; prevb) "toward, with, on, in" (upā.gam- "to arrive at," upāpa- "living in the water," upa.naxturušu "bordering on the night"); Mod.Pers. "with," from abâ; cf. Skt. úpa (adv., prevb., prep.) "toward, with, under, on;" cognate with Gk. hypo, as above.


Fr.: hypocycloïde   

A curve generated by the trace of a fixed point on a small circle that rolls within a larger circle.

Hypocycloid, from → hypo- + → cycloid.

vatar (#)

Fr.: hypoténuse   

In a → right triangle, the side opposite to the right angle.

L.L. hypotenusa, from Gk. hypoteinousa "stretching under" (the right angle), from hypoteinein, from → hypo- "under" + teinein "to stretch," → tension.

Vatar loan from Ar.


Fr.: hypothermie   

The failure of the body to maintain adequate production of heat under conditions of extreme cold.

Hypothermia, from → hypo- + therm, from Gk. therme "heat," from PIE *ghwerm-/*ghworm- "warm;" cf. Pers. garm "warm;" L. fornax "an oven;" O.E. wearm "warm" + -ia a noun suffix.

Upâgarmâyi, from upâ-, → hypo-, + garmâ "heat, warmth," from Mid.Pers. garmâg; O.Pers./Av. garəma- "hot, warm;" cf. Skt. gharmah "heat;" Gk. thermos "warm;" L. formus "warm," fornax "oven;" P.Gmc. *warmaz; O.E. wearm; E. warm; O.H.G., Ger. warm; PIE *ghworm-/*ghwerm- "warm" + -yi noun suffix.

  انگاره، اوپاداین   
engâre (#), upâdâyan

Fr.: hypothèse   

A statement which is based on previous observations and which serves as a starting point for further investigation by which it may be proved or disproved. See also → theory, → model, → ad hoc hypothesis, → Kant-Laplace hypothesis, → arge number hypothesis, → nebular hypothesis, → null hypothesis, → statistical hypothesis, → statistical hypothesis testing.

Hypothesis, from M.Fr. hypothèse, from L.L. hypothesis, from Gk. hypothesis "base, basis of an argument, supposition," literally "a placing under," from → hypo- "under" + thesis "a placing, proposition," from root of tithenai "to place, put, set," didomi "I give;" from PIE base *dhe- "to put, to do;" cf. Mod.Pers. dâdan "to give," Mid.Pers. dâdan "to give," O.Pers./Av. dā- "to give, grant, yield," dadāiti "he gives;" Skt. dadáti "he gives;" L. dare "to give, offer," facere "to do, to make;" Rus. delat' "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do."

Engâré, from engâridan, engâštan "to → suppose."
Upâdâyan, from upâ-, → hypo-, + dâyan, → thesis.

  انگاره ساختن، اوپاداینیدن   
engâré sâxtan (#), upâdâyanidan

Fr.: faire une hypothèse   

To form a → hypothesis.

Hypothesize, from hypothes(is), → hypothesis + -ize a verb-forming suffix, from M.E. -isen, from O.Fr. -iser, from L.L. -izare, from Gk. -izein.

Engâré sâxtan, from engâré, → hypothesis + sâxtan, sâzidan "to adapt, adjust, be fit; to build, make, fashion," Mid.Pers. sâxtan, sâz-, Manichean Parthian s'c'dn "to prepare, to form," Av. sak- "to understand, to mark," sâcaya- (causative) "to teach."
Upâdâyanidan, infinitive from upâdâyan, → hypothesis.

  انگاره‌ای، اوپاداینی   
engâre-yi (#), upâdâyani

Fr.: hypothétique   

Of, pertaining to, or involving a → hypothesis; supposed.

hypothesis; → -al.

pasmând (#)

Fr.: hystérésis   

The phenomenon exhibited by a body (especially a ferromagnetic or imperfectly elastic material) in reacting to changes in the forces, especially magnetic forces, affecting it.
In ferromagnetic materials, the lag in the change in the magnetic induction B behind the change in the intensity of the external magnetizing field, due to the dependence of B on its previous values (past history).

Hysteresis, from Gk. hysteresis "being behind or late," from hystere-, stem of hysterein "to come late, lag behind" + -sis a suffix forming abstract nouns of action.

Pasmând "lagging behind," from pas "behind" (Mid.Pers. pas "behind, before, after;" O.Pers. pasā "after;" Av. pasca "behind (of space); then, afterward (of time);" cf. Skt. pazca "behind, after, later," L. post "behind, in the rear; after, afterward;" O.C.S. po "behind, after;" Lith. pas "at, by;" PIE *pos-, *posko-) + mând stem of mândan "to remain; to be fatigued," mân "house, family" (Mid.pers. mândan "to remain, stay;" O.Pers. mān- "to remain, dwell;" Av. man- "to remain, dwell; to wait;" cf. Gk. menein "to remain;" L. manere "to stay, remain, abide," mansio "a staying, a remaining, night quarters, station" (Fr. maison, ménage; E. manor, mansion, permanent); PIE *men- "to remain, wait for."

hysteresis loop
  گردال ِ پسماند   
gerdâl-e pasmând

Fr.: cycle d'hystérésis   

A closed curve showing the change in magnetic induction of a ferromagnetic body to which an external field is applied as the intensity of this field is varied from +Hs to -Hs and back again, where Hs is the magnetic field intensity corresponding to saturation.

hysteresis; → loop.

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