Fr.: boucle de Barnard
A very faint nebular shell of huge size enveloping the central portion of Orion.
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.
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.: 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.
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.
Instrument for measuring the atmospheric pressure. It is used in determining height above sea level and predicting changes in weather.
qânun-e fešârsanji, ~ fešârsanjik
Fr.: loi barométrique
The atmospheric pressure decreases exponentially from any reference surface as the altitude increases.
In a fluid, conditions where surfaces of constant pressure are parallel to surfaces of constant temperature. This state is equivalent to zero → baroclinicity.
Fr.: gaz barotrope
A gas whose density is a function solely of pressure.
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.
A state of a fluid in which the surfaces of constant density coincide with surfaces of constant pressure (isobaric).
Having a bar like structure.
barred spiral galaxy
kahkašân-e mârpic-e miledâr
Fr.: galaxie spirale barrée
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".
General: Anything that prevents passage or blocks.
O.F. barrière "obstacle," from V.L. *barraria, from *barra "bar, barrier."
Varqé, from varq "a mound, a dam" + -é 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 (Âštiyâni), var (Qomi); cf. Skt. vatra- "a dike, a dam,"varana- "rampart, wall," from vr- "to obstruct, close, cover, hide; to choose."
Fr.: cratère Barringer
Same as → Meteor Crater.
The center of mass of a system of bodies.
Gerânigâh, from gerâni "weight;" cognate with Gk. barus, → bar, + gâh "place."
Barycentric Coordinate Time (TCB)
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).
Barycentric Dynamical Time (TDB)
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).