An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 378
Orion Bridge
  پل ِ شکارگر   
pol-e šekârgar

Fr.: pont d'Orion   

Same as → Orion Arm.

Orion; → bridge.

Orion Bright Bar
  میله‌ی ِ درخشان ِ شکارگر، ~ ~ اُریون   
mile-ye deraxšân-e Šekârgar, ~ ~ Orion

Fr.: barre brillante d'Orion   

A prominent emission ridge in the → Orion Nebula located approximately 2' southeast of the → Trapezium cluster. Various observations have suggested that it is an escarpment in the main → ionization front of the Nebula seen almost edge-on. The Orion Bar is one of the nearest and best-studied → photodissociation regions.

Orion; → bright; → bar.

Orion correlation theory
  نگره‌ی ِ هم‌باز‌آنش ِ اوریون   
negare-ye hambâzâneš-e Oryon

Fr.: théorie de la corrélation d'Orion   

A controversial proposition according to which a coincidence would exist between the mutual positions of the three stars of → Orion's Belt and those of the main Giza pyramids. More specifically, Khufu, Khafre, and Menkaure would be the monumental representation of → Alnitak, → Alnilam, and → Mintaka, respectively.

Orion; → correlation; → theory.

Orion molecular cloud
  ابرِ مولکولی ِ شکارگر، ~ ~ ا ُریون   
abr-e molekuli-ye Šekârgar, ~ ~ Orion

Fr.: nuage moléculaire d'Orion   

A giant cloud, or complex of clouds, of interstellar gas and dust associated with the Orion nebula (M42). It is about 1,500 light-years away and measures about 240 light-years across. Besides M42 and M43 it contains a number of famous objects, including Barnard's Loop, the Horsehead Nebula, and the reflection nebulae around M78. Within this cloud, stars have formed recently, and are still in the process of formation.

Orion; → molecular cloud.

Orion Nebula
  میغِ شکارگر، ~ ِ ا ُریون   
miq-e Šekârgar, ~ Orion

Fr.: Nébuleuse d'Orion   

The best known ionized nebula and one of the nearest regions to the Sun in which stars are presently being formed. It is visible to the naked eye in the constellation → Orion south of Orion's Belt as a fuzzy patch. It lies about 1,500 light-years away and measures about 30 light-years across. The Orion Nebula is ionized and made visible by a small group of O and B type stars known as the Trapezium cluster. Other designations: M 42, NGC 1976. → Huygens Region ; → Orion Bright Bar.

Orion; → nebula.

Orion Spur
  شخاک ِ شکارگر   
šaxâk-e šekârgar

Fr.: éperon d'Orion   

Same as → Orion Arm.

Orion; → → spur.

Orion's Belt
  کمربندِ شکارگر، ~ اُریون   
kamarband-e Šekârgar, ~ Orion

Fr.: Ceinture d'Orion   

Three prominent stars in the central regions of the constellation → Orion that align to form the "belt" of the mythological Hunter. They are → Alnitak, → Alnilam, and → Mintaka. The easternmost star Alnitak is separated from the middle one, Alnilam, by 1°.36, and the westernmost Mintaka has an angular distance of 1°.23 from Alnilam. Their distance is between 800 and 1,300 light-years from Earth. They probably formed inside the same molecular cloud less than 10 million years ago.

Orion; → belt.

Orion-Cygnus Arm
  بازوی ِ شکارگر-ماکیان   
bâzu-ye šekârgar-mâkiyân

Fr.: bras Orion-Cygne   

Same as → Orion Arm.

Orion; → Cygnus; → arm.


Fr.: orionides   

A meteor shower that appears to emanate from the constellation → Orion. It peaks between October 14 and 20 with about 20 meteors per hour.

Orion + → -ides.

yatim (#)

Fr.: orphelin   

1) A child who has lost both parents through death, or, less commonly, one parent.
2) A young animal that has been deserted by or has lost its mother ( → orphaned protostar.

M.E., from L.L. orphanus "destitute, without parents," from Gk. orphanos "bereaved;" akin to L. orbus "bereaved," Skt. arbhah "weak, child," Armenian orb "orphan," O.Irish orbe "heir," O.C.S. rabu "slave," Ger. Erbe, O.E. ierfa "heir," O.H.G. arabeit, Ger. Arbeit "work," O.E. earfoδ "hardship, suffering, trouble."

Yatim "fatherless," from Ar.

orphaned protostar
  پوروا-ستاره‌ی ِ یتیم   
purvâ-setâre-ye yatim

Fr.: proto-étoile orpheline   

A → protostellar object which has been dynamically ejected from a newborn → multiple star system, either into a tenuously bound orbit or into an escape, thus depriving it from gaining much additional mass. Recent observations have shown that → Class I protostellar sources have a population of distant companions at separations ~ 1000 to 5000 → astronomical unit (AU)s. Moreover, the companion fraction diminishes as the sources evolve. According to N-body simulations of unstable → triple systems embedded in dense cloud cores, many companions are ejected into unbound orbits and quickly escape, but others are ejected with insufficient momentum to climb out of the potential well of the cloud core and associated binary. These loosely bound companions reach distances of many thousands of AU before falling back and eventually being ejected into escapes as the cloud cores gradually disappear (B. Reipurth et al. 2010, arXiv:1010.3307).

orphan; → protostar.


Fr.: planétaire   

A mechanical device that illustrates the relative positions and motions of the planets and moons in the solar system in heliocentric model.

Named after Charles Boyle, 4th Earl of Orrery (1676-1731), for whom the device was first made.


Fr.: ortho-   

Prefix denoting right, straight, correct.
Prefix indicating that an organic compound contains a benzene ring substituted in the 1.2 position.

Ortho-, from Gk. orthos "set upright, straight, true, correct, regular;" cf. L. arduus "high, steep," O.Ir. ard "high;" also cognate with Av. ərəduua-, as below; from PIE *eredh- "high."

Ardâ-, from Av. ərəduua- "upright, erect, risen;" cf. Skt. ūrdhvá- "upright, tending upward, high;" Gk. ortho, as above.


Fr.: eau ortho   

The → water molecule in which the → nuclear spin of the constituent → hydrogen atoms are → parallel (→ orthohydrogen). In astrophysics the ratio between ortho- and → para-water is used to determine temperatures in → interstellar medium.

ortho-; → water.


Fr.: orthocentre   

Of a triangle, the point where the three → altitudes of the → triangle converge.

ortho-; → center.


Fr.: orthogonal   

In elementary geometry, pertaining to or involving right angles or perpendiculars.
Of a system of real functions, defined so that the integral of the product of any two different functions is zero.
Of a linear transformation, defined so that the length of a vector under the transformation equals the length of the original vector.
Of a square matrix, defined so that its product with its transpose results in the identity matrix.

ortho- + gonia "angle," related to gony "knee;" L. genu "knee;" Mod.Pers. zânu "knee;" Av. žnav-, žnu- "knee;" Skt. janu-; PIE base *g(e)neu-, see below, + → -al

Ardâkonj, from ardâ-, → ortho-, + konj "angle, corner, confined place" (variants xong "corner, angle," Tabari kânj, Kurd. kunj, Hamadâni kom), maybe from the PIE base *g(e)neu-, as above, and related to Mod.Pers. zânu "knee" (Av. žnu-), Skt. kona- "angle, corner," Gk. gony, gonia, L. cuneus "a wedge," Albanian (Gheg dialect) kân "angle, corner," Albanian (Toks) kënd "angle, corner."

orthogonal functions
  کریاهایِ ارداکنج   
karyâhâ-ye ardâkonj

Fr.: fonctions orthogonales   

A set of functions, any two of which, by analogy to orthogonal vectors, vanish if their product is summed by integration over a specified interval.

orthogonal; → function.

orthogonal lines
  خط‌هایِ ارداکنج   
xatthâ-ye ardâkonj

Fr.: droites orthogonales   

Perpendicular lines.

orthogonal; → line.

orthogonal trajectory
  ترایشانه‌ی ِ ارداکنج   
tarâyešâne-ye ardâkonj

Fr.: trajectoire orthogonale   

Math.: An → isogonal trajectory where the family of curves are cut at right angles.

orthogonal; → trajectory.

orthogonal vectors
  بردارهای ِ ارداکنج   
bordârhâ-ye ardâkonj

Fr.: vecteurs orthogonaux   

Two non-zero vectors which are perpendicular, i.e. their → scalar product is zero.

orthogonal; → vector.

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