An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -he haf Hal har Hay hea hel hel Hen her Hic hig his hom hor hot Hub hum hyb hyd hyd hyp hyp > >>

Number of Results: 445
high-energy astrophysics
  اخترفیزیک ِ مه‌کاروژ   
axtarfizik-e meh-kâruž

Fr.: astrophysique des hautes énergies   

A branch of astrophysics that deals with objects emitting highly energetic radiation, such as X-ray astronomy, gamma-ray astronomy, and extreme ultraviolet astronomy, as well as neutrinos and cosmic rays.

high; → energy; → astrophysics.

high-energy cosmic rays
  پرتوهای ِ کیهانی ِ مه‌کاروژ، ~ ~ پرکاروژ   
partowhâ-ye keyhâni-ye meh-kâruž, ~ ~ por-kâruž

Fr.: rayons cosmiques de hautes énergies   

Cosmic rays which typically have energies in the range 1015 to 1020 electron volts. For the most part, they are protons and other atomic nuclei, and come from distant cosmos, perhaps even from outside our own Galaxy.

high; → energy; → cosmic; → ray.

high-energy neutrino
  نوترینو‌ی ِ مه‌کاروژ   
notrino-ye meh-kâruž

Fr.: neutrino haute énergie   

A neutrino produced in high-energy particle collisions, such as those occurring when → cosmic rays strike atoms in the Earth's → atmosphere. Their energy range expands from a few → MeVs up to tenths of a → peta- (P) → electron-volts.

high; → energy; → neutrino.

high-excitation blob (HEB)
  ژیگ ِ پر-بر‌انگیزش   
žig-e por-barangizeš


A rare class of → H II regions in the → Magellanic Clouds. In contrast to the typical H II regions of the Magellanic Clouds, which are extended structures (sizes of several arc minutes corresponding to more than 50 pc, powered by a large number of exciting stars), HEBs are very dense and small regions (~ 4" to 10" in diameter corresponding to ~ 1-3 pc). They have a higher degree of → excitation ([O III] 5007Å /Hβ) with respect to the typical H II regions, and are, in general, heavily affected by local → dust. They are powered by a relatively smaller number of → massive stars.

high; → excitation; → blob.

high-mass star
  ستاره‌ی ِ مِه‌جرم، ~ پُرجرم   
setâre-ye meh-jerm (#), ~ por-jerm (#)

Fr.: étoile massive   

A star whose mass exceeds 8 solar masses. Same as → massive star. → intermediate-mass star; → low-mass star.

high; → mass; → star.

high-mass X-ray binary (HMXB)
  درین ِ پرتو ایکس ِ پرجرم   
dorin-e partow-e iks-e por-jerm

Fr.: binaire X de forte masse   

A member of one of the two main classes of → X-ray binary systems where one of the components is a neutron star or a black hole and the other one a → massive star. HMXBs emit relatively → hard X-rays and usually show regular pulsations, no X-ray bursts, and often X-ray eclipses. Their X-ray luminosity is much larger than their optical luminosity. In our Galaxy HMXBs are found predominantly in the → spiral arms and within the → Galactic disk in young → stellar populations less than 107 years old. One of the most famous HMXB is Cygnus X-1 which was the first stellar-mass black hole discovered. See also: → low-mass X-ray binary.

high; → mass; → X-ray; → binary.

high-power laser
  لیزر ِ پُرتوان   
leyzer-e por-tavân (#)

Fr.: laser de puissance   

A laser beam with the output power in the range 1012-1015 watts/cm2, capable of depositing kilo-joule order energies during nano-second time intervals in small volumes (about 1 mm3). High power lasers, which can produce temperatures of 10-50 million degrees and pressures of 10-100 million bars, are used to simulate astrophysical conditions in laboratories.

high; → power;, → laser.

leyzer, → laser; por "much, many, full," → full; tavân, → power.

high-resolution observation
  نپاهش ِ مه-واگشود   
nepâheš-e mehvâgošud

Fr.: observation à haute résolution   

An observation that provides a particularly narrow, peaked image of a point source. → point spread function.

high; → resolution; → observation.

high-velocity clouds (HVCs)
  ابرهای ِ تندرو   
abrhâ-ye tondrow

Fr.: nuages à grande vitesse   

A population of neutral or partly ionized gas clouds in the → Galactic halo which are seen as high-altitude structures in the atomic hydrogen 21 cm emission at high radial velocities (vLSR> 100 km/sec). They have substantial neutral column densities (> 1019 cm-2) and their metallicities range from 0.1 to about 1.0 times solar. The distances to the majority of them remain unknown. They may represent the continuing infall of matter onto the → Local Group. See also → compact high-velocity clouds.

high; → velocity; → cloud.

Abr, → cloud; tondrow "fast moving," from tond "fast," → speed; row, present stem of raftan "to go, walk; to flow" (Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack").

kuhsâr (#)

Fr.: région montagneuse, hauts plateaux   

A mountainous or elevated region; → plateau.

high; → land.

Kuhsâr "mountainous, hilly area," from kuh, → mountain, + -sâr suffix denoting profusion, abundance, variant -zâr, → catastrophe.

Hilbert space
  فضا‌ی ِ هیلبرت   
fazâ-ye Hilbert (#)

Fr.: espace de Hilbert, espace hilbertien   

A generalization of Euclidean space in a way that extends methods of vector algebra from the two- and three-dimensional spaces to infinite-dimensional spaces.
Multi-dimensional space in which the eigenfunctions of quantum mechanics are represented by orthogonal unit vectors.

Named after the German mathematician David Hilbert (1862-1943), recognized as one of the most influential mathematicians of the 19th and early 20th centuries for his numerous contributions to various areas of mathematics; → space.

Hilda asteroids
  سیارک‌های ِ هیلدا   
sayyârakhâ-ye Hilda (#)

Fr.: astéroides Hida   

The asteroids found on the outer edge of the main asteroid belt in a 2:3 orbital resonance with Jupiter. The group is not an asteroid family since the members are not physically related. The group consists of asteroids with semi-major axes between 3.70 AU and 4.20 AU, eccentricities less than 0.30, and inclinations less than 20°. It is dominated by D- and P-type asteroids.

Named for the prototype 153 Hilda, discovered by Johann Palisa (1848-1925) on November 2, 1875, and named Hilda after a daughter of his teacher, the astronomer Theodor von Oppolzer (1841-1886); → asteroid.

tappé (#)

Fr.: colline   

A natural elevation of the earth's surface, smaller than a mountain.

M.E.; O.E. hyll, from P.Gmc. *khulnis (cf. M.Du. hille, Low Ger. hull "hill," O.N. hallr "stone," Goth. hallus "rock," O.E. holm "rising land, island"), from PIE base *kel- "to rise, to be prominent" (cf. Skt. kuta- "summit, peak;" Mod.Pers. kutal, kotal high hill, the skirts of a hill;" Tabari dialect keti "hill; top of the head; L. collis "hill," culmen "top, summit," cellere "raise," celsus "high;" Gk. kolonos "hill," kolophon "summit;" Lith. kalnas "mountain," kalnelis "hill").

Tappé "hill."

Hill sphere
  سپهر ِ هیل   
sepehr-e Hill

Fr.: sphère de Hill   

The spherical region around a → secondary in which the secondary's gravity is more important for the motion of a particle about the secondary than the tidal influence of the → primary. The radius is described by the formula: r = a (m/3M)1/3, where, in the case of the Earth, a is the semi-major axis of the orbit around the Sun, m is the mass of Earth, and M is the mass of the Sun. The Hill sphere for the Earth has a radius of 0.01 → astronomical units (AU). Therefore the Moon, lying at a distance of 0.0025 AU, is well within the Hill sphere of the Earth.

Named for George William Hill (1838-1914), an American astronomer who described this sphere of influence; → sphere.

Himalia (Jupiter VI)
Himâliyâ (#)

Fr.: Himalia   

The tenth of Jupiter's known satellites, 186 km in diameter revolving at a mean distance of 11,480,000 km from Jupiter. Discovered in 1904 by the Argentine-American astronomer Charles Dillon Perrine (1867-1951).

Himalia was a nymph of the island of Rhodes. She was seduced by the god Zeus (Jupiter).

Hindu-Arabic numeral system
  راژمان ِ عددهای ِ هندی-عربی   
râžmân-e adadhâ-ye Hendi-Arabi

Fr.: numération indo-arabe   

Same as → Indian numeral system.

numeral; → system.

Hipparcos (#)

Fr.: Hipparcos   

A → European Space Agency satellite, which was launched in August 1989 and operated until March 1993. It was the first space mission devoted to → astrometry with an unprecedented degree of accuracy. The telescope on Hipparcos had a main mirror of diameter 29 cm. Calculations from observations by the main instrument generated the Hipparcos Catalogue of 118,218 stars charted with the highest precision (published in 1997) containing positions, distances, → parallaxes, and → proper motions. An auxiliary star mapper pinpointed many more stars with lesser but still unprecedented accuracy, in the Tycho Catalogue of 1,058,332 stars. The Tycho 2 Catalogue, completed in 2000, brings the total to 2,539,913 stars, and includes 99% of all stars down to magnitude 11. → Gaia.

Hipparcos, acronym for → High  → Precision  → Parallax  → Collecting → Satellite, chosen for its similarity to the name of the Greek astronomer Hipparchus of Nicaea (c. 190-125 BC), one of the most influential astronomers of antiquity, who compiled an extensive star catalogue in which he gave the positions of over 1,000 stars and also classified them according to their magnitude (on a scale of 1 to 6, brightest to faintest). Ptolemy later incorporated this information into his → Almagest. In addition, he discovered the → precession of the equinoxes.


Fr.: hippopède   

A curve described by the → polar equation  r2 = 4b (a - b sin2θ), where a and b are positive constants. For appropriate values of a and b, the curve looks like the infinity symbol, ∞. See also → spheres of Eudoxus.

Hippopede, literally "a horse's foot," denoting a "horse fetter (hobble)," from Gk. hippos, → horse, + -pede variant of -ped, combining form of pos,→ foot.

  نمودار ِ ستونی   
nemudâr-e sotuni (#)

Fr.: histogramme   

A type of graphical representation, used in statistics, in which frequency distributions are illustrated by rectangles.

Histogram, from Gk. histo-, a combining form meaning "tissue," from histos "mast, loom, beam, warp, web," literally "that which causes to stand," from histasthai "to stand," from PIE *sta- "to stand" (cf. Pers. ist-, istâdan "to stand;" O.Pers./Av. sta- "to stand, stand still; set;" Skt. sthâ- "to stand;" L. stare "to stand;" Lith. statau "place;" Goth. standan); → -gram.

Nemudâr, → diagram + sotuni "column-like," from sotun "column," from Mid.Pers. stun, from O.Pers. stênâ "column," Av. stuna-, Skt. sthuna- "column."

târixi (#)

Fr.: historique   

Of, pertaining to, treating, or characteristic of → history or past events ( → historical supernova.

history; → -al.

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