An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 394
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 (ζ Ori), → Alnilam (ε Ori), and → Mintaka (δ Ori). 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's Sword
  شمشیر ِ شکارگر، ~ اریون   
Šamšir-e Šekârgar, ~ Oryon

Fr.: Epée d'Orion   

An astronomical → asterism in the constellation → Orion forming an almost vertical line beneath → Orion's Belt. From north to south, the most prominent objects in the Sword are the cluster NGC 1981, the star → 42 Orionis, the famous → Orion Nebula, and the Sword's brightest star → Iota Orionis (→ Hatsya). None of these objects is particularly bright in itself, but their proximity to one another and the nebulosity across much of this region makes the Sword stand out clearly in the night sky.

Orion; → sword.

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.


Fr.: orthogonalité   

1) The property of → orthogonal functions.
2) The following conditions satisfied by the → Fourier series:
∫ cos (mx) sin (nx) dx = 0 (summed from -π to +π) for all m, n
∫ cos (mx) cos (nx) dx = 0 (summed from -π to +π) for all m ≠ n, = 2π for m = n = 0, = π for (m = n) > 0
∫ sin (mx) sin (nx) dx = 0 (summed from -π to +π) for m ≠ n, = π for (m = n) > 0.

orthogonal; → -ity.


Fr.: orthohydrogène   

Molecular hydrogen in which the nuclei (protons) of the two hydrogen atoms contained in the molecule have spins in the same direction. → parahydrogen

ortho-; → hydrogen.

orthonormal vectors
  بردارهای ِ ارداهنجارور   
bordârhâ-ye ardâhanjârvar

Fr.: vecteurs orthonormaux   

Two non-zero vectors that are → orthogonal and have magnitude 1.

orthogonal; → vector.


Fr.: orthorhombique   

Of or relating to a crystalline structure characterized by three mutually perpendicular axes of different length. → orthorhombic crystal system.

ortho-; → rhombic.

orthorhombic crystal system
  راژمان ِ بلوری ِ اردالوزیک   
râžmân-e boluri-ye ardâlowzik

Fr.: système cristallin orthorhombique   

A → crystal system that has three mutually perpendicular axes, each of which is of a different length than the others.

orthorhombic; → crystal; → system.

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