An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 497
Barnard's loop
  گردال ِ بارنارد   
gerdâl-e Bârnârd

Fr.: boucle de Barnard   

A very faint nebular shell of huge size enveloping the central portion of Orion.

Named after → Barnard, who discovered the loop in 1895; → loop.

Barnard's star
  ستاره‌ی ِ بارنارد   
setâre-ye Bârnârd

Fr.: étoile de Barnard   

A → red dwarf in the constellation → Ophiuchus discovered in 1916 by E.E. Barnard, that until 1968 had the largest → proper motion of any star. It moves on the sky 10.3 arcseconds per year, which means that it travels the equivalent of a lunar diameter every 180 years. It is the second nearest star system to the Sun.

In honor of → Barnard; → star.

fešâr- (#)

Fr.: baro-   

A prefix meaning → pressure used in the formation of compound words, such as → baroclinic, → barometer, → barotropic.

Baro- combining form of Gk. baros "weight;" cognate with Pers. bâr "weight," gerân "heavy;" cf. Skt. guru, L. gravis; PIE *gwere- "heavy;" L. brutus "heavy, dull, stupid, brutish;" Skt. bhara- "burden, load," bharati "he carries;" PIE *bher- "carry, give birth."

Fešâr-, → pressure.


Fr.: barocline   

Of, pertaining to, or characterized by → baroclinicity. Sometimes called → barocline.

baro-; → -cline; → -ic.

baroclinic instability
  ناپایداری ِ فشارشیبی   
nâpâydâri-ye fešâršibi

Fr.: instabilité barocline   

1) A type of instability occurring within a rapidly → rotating star where non-axisymmetric motions can separate surfaces of constant pressure from → equipotential surfaces.
2) A hydrodynamic instability associated with a baroclinic layer of the atmosphere. It arises from temperature variation along the pressure surfaces. Baroclinic instability is associated with the vertical → shear of the mean flow, which is related to the horizontal temperature gradient by the thermal wind equation. Instabilities in a baroclinic region grow by converting potential energy associated with the mean horizontal temperature gradient into kinetic energy through ascending warm air and descending cold air (Rasmussen & Turner (eds.), Polar Lows, Cambridge Univ. Press, 2003).

baroclinic; → instability.


Fr.: baroclinie   

The state of stratification in a fluid in which surfaces of constant pressure do not coincide with those of constant density, but intersect. Where baroclinicity is zero, the fluid is → barotropic. Same as baroclinity.

baroclinic; → -ity.

fešârsanj (#)

Fr.: baromètre   

Instrument for measuring the atmospheric pressure. It is used in determining height above sea level and predicting changes in weather.

baro- + → -meter.

barometric law
  قانون ِ فشارسنجی، ~ فشارسنجیک   
qânun-e fešârsanji, ~ fešârsanjik

Fr.: loi barométrique   

The atmospheric pressure decreases exponentially from any reference surface as the altitude increases.

barometer; → law.

Qânun, → law, fešârsanji, fešârsanjik "barometric," from fešârsanj, → barometer.


Fr.: barotrope   

In a fluid, conditions where surfaces of constant pressure are parallel to surfaces of constant temperature. This state is equivalent to zero → baroclinicity.

baro-; → -tropic.

barotropic gas
  گاز ِ فشارگرد   
gâz-e fešârgard

Fr.: gaz barotrope   

A gas whose density is a function solely of pressure.

barotropic; → gas.

barotropic instability
  ناپایداری ِ فشارگرد   
nâpâydâri-ye fešârgard

Fr.: instabilité barotrope   

A hydrodynamical instability that arises when the horizontal → shear gradient becomes very large. Barotropic instabilities grow by extracting kinetic energy from the mean flow field.

barotropic; → instability.


Fr.: barotropie   

A state of a fluid in which the surfaces of constant density coincide with surfaces of constant pressure (isobaric).

barotropic gas.

  میله‌دار، میله‌ای   
miledâr, milei

Fr.: barré   

Having a bar like structure.


barred spiral galaxy
  کهکشان ِ مارپیچ ِ میله‌دار، ~ ~ میله‌ای   
kahkašân-e mârpic-e miledâr

Fr.: galaxie spirale barrée   

A → spiral galaxy that exhibits a bar-shaped structure in its nucleus. → galactic bar.

barred; → spiral; → galaxy.

Kahkašân, → galaxy; mârpicspiral; miledâr, → barred.

barrel distortion
  چولگی ِ چلیکی   
cowlegi-ye celiki (#)

Fr.: distortion en barillet   

A defect in an optical system in which magnification decreases with distance from the optical axis, whereby the image of a square appears barrel-shaped. Opposite of → pincushion distortion.

Barrel, M.E. barel, from O.Fr. baril; → distortion.

Cowlegi, → distortion; celiki, relating to celik "barrel".

varqé (#)

Fr.: barrière   

General: Anything that prevents passage or blocks.
Physics: 1) A region where the potential energy is greater than the total energy of a particle, whereby the particle cannot go through.
2) The depletion layer of a P-N junction in a diode.

O.F. barrière "obstacle," from V.L. *barraria, from *barra "bar, barrier."

Varqé, from varq "a mound, a dam" + nuance suffix. Varq is probably related to Av. vâra- "barrage," vara- "enclosure," var- "castle," Mid.Pers. var "enclosure," from Av. root var- "to cover, to conceal;" variants: barq (Torbat Heydariyei), valgâ (štiyâni), var (Qomi); cf. Skt. vatra- "a dike, a dam,"varana- "rampart, wall," from vr- "to obstruct, close, cover, hide; to choose."

Barringer Crater
  لاوک ِ برینگر   
lâvak-e Barringer

Fr.: cratère Barringer   

Same as → Meteor Crater.

Names after Daniel Barringer (1860-1929), American geologist, who bought the Crater in 1903, convinced that it was made by a huge → meteorite; → crater.

gerânigâh (#)

Fr.: barycentre   

The center of mass of a system of bodies.

From Gk. barus "heavy," → bar, + → center.

Gerânigâh, from gerâni "weight;" cognate with Gk. barus, → bar, + gâh "place."

Barycentric Coordinate Time (TCB)
  زمان ِ همارا‌ی ِ گرانیگاهی   
zamân-e hamârâ-ye gerânigâhi

Fr.: temps-coordonnée barycentrique (TCB)   

A → coordinate time having its spatial origin at the solar system barycenter. It is intended to be used as the independent variable of time for all calculations pertaining to orbits of planets, asteroids, comets, and interplanetary spacecraft in the solar system. → Barycentric Dynamical Time (IDB).

barycenter; → coordinate; → time.

Barycentric Dynamical Time (TDB)
  زمان ِ توانیک ِ گرانیگاهی   
zamân-e tavânik-e gerânigâhi

Fr.: temps dynamique barycentrique (TDB)   

A time scale previously used in calculations of the orbits of solar system objects (planets, asteroids, comets, and interplanetary spacecrafts). It was based on the Terrestrial Dynamical Time, but took the relativistic effect of time dilation into account to move the origin to the solar system barycenter. It is now superseded by → Barycentric Coordinate Time (TCB).

barycenter; → dynamical; → time.

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