An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 450
horizontal branch (HB)
  شاخه‌ی ِ افقی   
šâxe-ye ofoqi (#)

Fr.: branche horizontale   

A set of roughly horizontal points in the → Hertzsprung-Russell diagram of a typical → globular cluster. It displays a stage of stellar evolution which immediately follows the → red giant branch (RGB) in stars with an initial mass < 1.2 Msun. When the star's ascent of the RGB is terminated by the → helium flash, it moves down to the HB. The star's → effective temperature on the HB is higher than it was on the RGB, but the luminosity is considerably less than at the helium flash. Usually HB stars have two energy sources: in addition to the → helium burning in their cores, they experience → hydrogen fusion in a surrounding shell. The thickness of the shell determines the color of the HB stars. A thin shell, involving low → opacity, makes the star look blue. The HB domain encompasses a very large effective temperature range with several members: → extreme HB, → blue HB, → RR Lyrae, → red HB, and → red clump stars. The locations depend on many parameters, including stellar mass, metallicity, age, helium abundance, and rotation.

horizontal; → branch.

horizontal branch star
  ستاره‌ی ِ شاخه‌ی ِ افقی   
setâre-ye šâxe-ye ofoqi

Fr.: étoile de la branche horizontale   

A star lying on the → horizontal branch.

horizontal; → branch; → star.

horizontal eclipse
  ماه‌گرفت ِ افقی   
mâhgereft-e ofoqi

Fr.: selenelion   

A type of → lunar eclipse that occurs when both the Sun and the eclipsed Moon can be observed at the same time. This is possible only when lunar eclipse occurs just before sunset or just after sunrise. At that case, both bodies will appear just above the horizon at nearly opposite points in the sky. Also called → selenelion and → selenehelion.

horizontal; → eclipse.

horizontal parallax
  دیدگشت ِ افقی   
didgašt-e ofoqi

Fr.: parallaxe horizontale   

The angle under which the radius of the Earth at the place of observation would be seen from a celestial body when it is in the horizon (at the instant of rising or setting). The amount varies with the latitude since the Earth is not exactly spherical, and is greatest at equator.

horizontal; → parallax.

horizontal refraction
  شکست ِ افقی   
šekast-e ofoqi (#)

Fr.: réfraction horizontale   

The angular distance of an object below the horizon when it appears to lie on the horizon.

horizontal; → refraction.

horizontal scaling
  مرپلش ِ افقی   
marpeleš- ofoqi


In computer science, a scaling in which the processing power is increased/decreased by adding/removing nodes with similar resources. See also → vertical scaling.

horizontal; → scaling.

  ۱) شاخ؛ ۲) شاخک؛ ۳) کرنا   
1) šâx; 2) šâxak; 3) karnâ

Fr.: 1) corne; 2) cornet; 3) cor   

1a) The bony pointed outgrowth, usually in pairs, on the heads of some animals.
1b) Astro.: Either of the ends of the → crescent Moon.
2) Something resembling a horn.
3) A wind instrument, originally an animal horn used as a wind instrument.
See also: → feedhorn

M.E. horn(e), from O.E. horn "horn of an animal," also "wind instrument" (originally made from animal horns), from P.Gmc. *khurnaz (cf. Ger. Horn, Du. horen), from PIE *ker- "head, horn, top, summit" (cf. Pers. soru "horn," sar "head," Gk. kara "head," karena "head, top," keras "horn;" L. cornu "horn," cerebrum "brain;" Skt. śiras- "head, chief").

1, 2) Mid.Pers šâk; cf. Skt. sakha- "a branch, a limb;" Arm. cax; Lith. šaka; O.S. soxa; PIE *kakhâ "branch."
3) Karnâ "a trumpet-like wind instrument," variant sornâ "a wind instrument," probably related to soru, sorun "horn," sar "head;" Mid.Pers. sar "head," sru "horn;" Av. sarah- "head," srū- "horn, nail;" cognate with E. horn, as above, from PIE *ker- "head, horn."

sâat (#)

Fr.: Horloge   

The Clock. A faint constellation in the southern hemisphere, at about 3h right ascension, 55° south declination. Its brightest star, α Horologii, is of magnitude 3.9. Abbreviation: Hor; Genitive: Horologii.

Horologium "clock," from L., from Gk. horologion, from horolog(os) "timeteller," from horo-, combining form of hora "hour" (→ year) + -log-, stem of legein "to speak, tell" (+ -os adj. suffix) + -ion diminutive suffix.
Originally named Horologium Oscillitorium by Abbé Nicolas Louis de Lacaille (1713-1762) to honour the inventor of the pendulum clock, Christian Huygens (1629-1695).

Sâ'at "clock," from Ar.

zâyecé (#)

Fr.: horoscope   

A schematic drawing showing the positions of the Sun, Moon, and planets at the time of a person's birth for baseless astrological purposes.

From M.Fr. horoscope, from L. horoscopus, from Gk. horoskopos "nativity, horoscope," also "one who casts a horoscope," from hora "hour" + skopos "watching."

Zâyecé "horoscope, thema," from Mid.Pers. zâycag "horoscope," from zâyidan, zâdan, "to give birth, bring forth;" Av. zan- "to bear, give birth to a child, be born," infinitive zazāite, zāta- "born;" cf. Skt. jan- "to produce, create; to be born," janati "begets, bears;" Gk. gignomai "to happen, become, be born;" L. gignere "to beget;" PIE base *gen- "to give birth, beget."

  ۱) اسب؛ ۲) اسبک   
1) asb (#); 2) asbak (#)

Fr.: cheval   

1) A large, solid-hoofed, herbivorous quadruped, Equus caballus, domesticated since prehistoric times.
2) In a → planispheric astrolabe, the small prominence that, inserted into a slit in the pin, prevents the parts of the instrument from coming loose when in use. The part owes its name to the fact that astrolabe-makers would often shape it into a horse's head (online museo galileo, VirtualMuseum).
See also: → horse latitude, → Horsehead Nebula, → horsepower, → horseshoe mounting, → horseshoe orbit.

Horse, O.E. hors, from P.Gmc. *khursa- (cf. M.Du. ors, Du. ros, O.H.G. hros, Ger. Roß "horse"), of unknown origin; → latitude.

Asb "horse," from Mid.Pers. asp; O.Pers. asa- "horse;" Av. aspa- "horse," aspā- "mare," aspaiia- "pertaining to the horse;" cf. Skt. áśva- "horse, steed;" Gk. hippos; L. equus; O.Ir. ech; Goth. aihwa-; O.E. eoh "horse;" PIE base *ekwo- "horse."

horse latitudes
  وَروناهای ِ اسبی   
varunâhâ-ye asbi

Fr.: calmes tropicaux, latitudes des chevaux   

The belts of latitude over the oceans, located around 30° north and south of the equator, characterized by predominantly calm or light winds and hot and dry weather.

horse; → latitude.
The origin of the term horse latitudes is not clear, despite numerous speculations. A likely explanation appears in Spanish in a natural history text (Historia General y Natural de las Indias by Lopez de Gomara) published in 1535. Therefore, the term derives from El Golfo de las Yeguas, which translates to "The Mares' Sea." The sailors called it this because in the 1500's there was active shipping of horses, particularly brood mares, from Spain to the Canary Islands, and many of the horses died during the transit of this area.

Horsehead Nebula (NGC 2024)
  میغ ِ سر ِ اسب، ~ ِ اسب-سر   
miq-e sar-e asb, ~ asbsar

Fr.: nébuleuse de la Tête de Cheval   

A huge → dark cloud of → interstellar dust that is shaped like a horse's head. It is luminous at its edges because it is in front of the bright → emission nebula IC 434. Its height and width are about 5 and 2.5 → light-years respectively. It is located at a distance of about 1500 light-years in the constellation → Orion. Also known as Barnard 33.

horse; → head; → nebula.

horsepower (hp)
  اسب ِ بخار   
asb-e boxâr (#)

Fr.: cheval-vapeur   

A unit that is used to measure the → power of engines and motors.
1) Metric horsepower is equal to the power required to carry a load of 75 kg over a distance of one meter in one second. It is equivalent to 746 → watts.
2) British (US) horsepower is the rate of work when 33,000 foot-pounds of work are done per minute. The horsepower was defined by James Watt (1736-1819), the inventor of the steam engine, to compare the output of steam engines with the power of draft horses. He determined that a horse is typically capable of a power of 550 foot-pounds per second.

horse; → power.

Asb-e boxâr "vapor horse," translation of Fr. cheval-vapeur, from asb, → horse, + boxâr, → vapor.

horseshoe mounting
  برنشاند ِ نعلی   
barnešând-e na'li

Fr.: monture en fer de cheval   

An equatorial mounting in which the upper end of the polar axis frame is made into a horseshoe shape to accommodate the telescope tube.

Horseshoe, from → horse + shoe, from O.E. scoh "shoe," from P.Gmc. *skokhaz (cf. Dan., Swed. sko, O.S. skoh, Du. schoen, O.H.G. scuoh, Ger. Schuh); → mounting.

Barnešând, → mounting; na'l "horseshoe, shoe," loanword from Ar.

horseshoe orbit
  مدار ِ نعلی   
madâr-e na'li

Fr.: orbite en fer à cheval   

A periodic orbit which passes around the → Lagrangian points L4, L3, and L5, but neither of the two primaries. This orbit is shaped like a horseshoe when viewed in a reference frame rotating with the primaries. Such orbits occur in the solar system, for example in the case of the satellites → Janus and → Epimetheus, which share the same orbit around → Saturn. The smaller Epimetheus encompasses both the L4 and L5 points associated with the larger Janus and performs a horseshoe orbit relative to Saturn and Janus. The satellites experience a close approach every 4 years during which their orbits are exchanged. → tadpole orbit.

horseshoe mounting; → orbit.

šilang (#)

Fr.: tuyau   

A flexible → pipe for conveying a → liquid.

M.E., O.E. akin to Du. hoos, O.N. hosa, Ger. Hose.

Šilang, probably loan from Russ. шлаиг (shlang) "hose."

mizbân (#)

Fr.: hôte   

One that receives or entertains guests especially in his own home. → host galaxy.

M.E. (h)oste, from O.Fr. hoste "guest, host," from L. hospitem (nom. hospes) "guest, host," lit. "lord of strangers," from hostis "stranger."

Mizbân "host," from Mid.Pers. mezdbân "host," from mêzd "offering, meal," Mod.Pers. miz "guest; offering; meal" + -bân a suffix denoting "keeper, guard," sometimes forming agent nouns or indicating relation (e.g. keštibân "sailor;" bâdbân "a sail;" mehrabân "affectionate;" mizbân "host;" âsiyâbân "a miller;" bâqbân "gardener"). This suffix derives from O.Pers. -pāvan- (as in xšaça.pāvan- "satrap"); Av. -pāna- (as in pəšu.pāna- "keeping the passage, bridge guard"), from Proto-Iranian *pa- "to prtotect, keep," → observe, + suffix *-van-; cf. Skt. -pāna- (as in tanū.pāna- "protection of the body").

host galaxy
  کهکشان ِ میزبان   
kahkešân-e mizbân (#)

Fr.: galaxie hôte   

A usually faint galaxy in which a remarkable phenomenon, such as a → supernova event, occurs.

host; → galaxy.

dâq (#)

Fr.: chaud   

Having a relatively high temperature. → hot accretion flow, → hot core, → hot corino, → hot dark matter , → hot dust-obscured galaxy, → hot Jupiter, → hot molecular core, → hot pixel, → hot star.

Hot, O.E. hat, "hot; fervent, fierce," from P.Gmc. *haitoz (cf. Du. heet, Ger. heiß "hot," Goth. heito "heat of a fever").

Dâq "hot; brand, marking," from Mid.Pers. dâq, dâk "hot," dažitan "to burn, scorch," dažišn "burning" (Mod.Pers. dežan (دژن) "acid, pugnent"), from Av. dag-, daž- "to burn;" cf. Skt. dah- "to burn;" L. fovere "to warm, heat; " Arm. dažan "violent, wild;" Lith. degu "to burn;" O.E. fefor; E. fever. PIE base *dhegh- "to burn."

hot accretion flow
  تچان ِ فربال ِ داغ   
tacân-e farbâl-e dâq

Fr.: écoulement d'accrétion chaud   

A type of → accretion flow by a → compact object such as a → black hole which has a high → virial temperature, is → optically thick, and occurs at lower mass → accretion rates compared with → cold accretion flows. In a hot accretion flow with a very low mass accretion rate, the electron mean free path is very large, and so the accreting → plasma is nearly collisionless. In this type of accretion flow, thermal conduction transports the energy from the inner to the outer regions. As the gas temperature in the outer regions can be increased above the → virial temperature , the gas in the outer regions can escape from the gravitational potential of the central black hole and form outflows, significantly decreasing the mass accretion rate.

cold; → accretion; → flow.

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