An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A rock composed of angular fragments (over two millimeter diameter) of older rocks melded together with a matrix of smaller particles or a mineral cement.

From It. breccia "broken (rock)," from a Germanic source akin to O.H.G. brecha "a breaking," ultimately from PIE *bhreg- "to break," → fraction.

Bereš, loan from Fr.

To form as → breccia.

From → breccia + → -ate.

Characterized by, converted into, or resembling a breccia; especially of a rock structure marked by an accumulation of angular fragments, or of an ore texture showing mineral fragments without notable rounding.

→ breccia, → brecciated.

A rock formed by the process of → brecciation.

→ brecciated; → rock.

The formation of → breccia.

Verbal noun of → brecciate.

A wind or current of air, especially a light or moderate one (2-14 m/sec).

From O.Sp. briza "cold northeast wind;" alternatively from East Frisian brisen "to blow fresh and strong."

Nasim "gentle breeze," from Ar.

The production of an → electron-positron pair in the → collision of two → gamma ray → photons (γγ → e⁺e^-). It is the → inverse process of → Dirac annihilation (e⁺e^-→ γγ). The Breit-Wheeler process is the simplest way by which pure → light can be potentially transformed into → matter. However, as of 2014, this process has never been observed in practice because of the difficulty in preparing colliding → gamma ray beams.

Breit, G. & Wheeler, J. A. 1934, Collision of two light quanta. Phys. Rev. 46, 1087; → process.

The → electromagnetic radiation emitted by a → fast moving → charged particle when it passes within the strong → electric field of an → atomic nucleus and is → decelerated.

Bremsstrahlung, from Ger. Bremse "brake" + Strahlung "radiation," from strahlen "to radiate," from Strahl "ray," from O.H.G. strala "arrow, stripe;" PIE *ster- "to spread."

Legâm-tâbeš, from legâm, → brake, + tâbeš, → radiation.

The → angle of incidence for which the sum of the incident angle and the → angle of refraction is 90°. The value of Brewster's angle for glass is 57° and for water is 53°. Same as → polarizing angle.

→ Brewster's law; → angle.

A → neutral point located 15 to 20° directly below the Sun.

→ Brewster's law; → point

The amount of the polarization of light reflected from a surface is a maximum when the reflected ray is at right angles to the refracted ray. See also → polarizing angle.

Named after Sir David Brewster (1781-1868), Scottish physicist; → law.

1) An apparent structure of → gas or → stars linking one → galaxy to another, such as → Magellanic Bridge.
2) Any one of a variety of → elctrical networks in which one branch connects two points of equal → potential and so carries no → current when the → circuit is suitably adjusted.
3) In → graph theory, a simple → edge whose removal disconnects a → graph.

M.E. brigge, O.E. brycge, from P.Gmc. *brugjo (cf. Ger. Brücke), from PIE *bhru- "log, beam."

Pol, Mid.Pers. puhl,, Av. pərətav- "bridge, passage."

Giving out or reflecting much light, shining.

O.E. bryht, from beorht "bright, splendid," from P.Gmc. *berkhiaz, from PIE base *bhereg- "to gleam, white" (cf. Av. brāz- "to shine, gleam, flash, radiate," Skt. bhrajate "shines, glitters," Mod.Pers. balk, warq, barx, barq "flash, flame, light," barâz "beauty, grace, elegance," barâzidan "to render good, beautiful," Lith. breksta "to dawn," Welsh berth "bright, beautiful," L. flagrare "to blaze"). → electricity.

Deraxšân and rowšan both from M.P. rôc, O.Pers. raucah-, Av. raocah- "light, luminous; daylight;" cf. Skt roka- "brightness, light", cognate with Gk. leukos "white, clear", L. lux "light" (also lumen, luna), PIE *leuk- "light, brightness". The Mod.Pers. words ruz "day," foruq "light", and afruxtan "to light, kindle" also belong to this family, as well as the E. light, Ger. Licht, and Fr. lumière.

An → evolved star which is more → luminous than normal → giant stars (→ luminosity class III) and between ordinary giants and → supergiants (class I). It is denoted by the symbol II. Examples are → Canopus and → Adhara.

→ bright; → giant.

In contrast to a → dark nebula, a bright cloud of interstellar gas and dust. The term designates both emission nebulae and reflection nebulae.

→ bright; → nebula.

The act or process of becoming bright or brighter. → limb brightening, → gravity brightening

Verbal noun of brighten, from → bright.

General:The state or quality of being bright.
Astronomy:The amount of light or other radiation received from a celestial object. It depends on the intrinsic brightness of the object, its distance and the amount of interstellar extinction. → luminosity.

→ bright + → -ness.

Deraxšandegi, from deraxš, present stem of deraxšidan "to shine," → bright, + -andé adjective suffix + -gi noun suffix.

A statistical distribution of the brightness of an astronomical extended object.

→ brightness; → distribution.

Vâbâžeš, → distribution; deraxšandegi, → brightness.

In radio astronomy, the temperature of a source calculated on the assumption that it is a blackbody emitting radiation of the observed intensity at a given wavelength. → antenna temperature.

→ brightness; → temperature.

A mathematical function appearing in the → magnetization equation of a → paramagnetic substance.

→ Brillouin zone; → zone.