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

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.

Scattering of electromagnetic waves in solids and liquids when, as a result of the scattering process, an acoustic → phonon is emitted or absorbed. Brillouin scattering is analogous to → Raman scattering.

→ Brillouin zone; → scattering.

Crystallography: One of the several regions which, in reciprocal space, represent the solution of the wave equations for the propagation of → phonons or electrons in solids. The first Brillouin zone is the Wigner-Seitz cell of the reciprocal lattice. It is a polyhedron obtained by connecting a lattice point to its first neighbors and drawing the planes perpendicular to these connecting lines and passing through their midpoints. The second Brillouin zone is obtained by a similar construction but the second-nearest neighbours.

After Léon Brillouin (1889-1969) French physicist; → zone.

1) Water saturated or strongly impregnated with salt.
2) Any saline solution.

M.E. from O.E. bryne "brine," origin unknown; cognate with Du. brijn.

Aždem, from Gilaki and Tâti aždem "very salty water" used for preserving fish.

An international collaboration between Austria, Canada, and Poland, currently comprising five nano-satellites to investigate stellar structure and evolution of the brightest stars in the sky and their interaction with the local environment. BRITE is also used to study micropulsation, wind phenomena, and other forms of stellar variability. These nano-satellites aim to monitor stars brighter than V ~ 5 mag using two color pass-bands, over various observing campaigns. Each nano-satellite hosts a 3 cm telescope, providing a wide field of view (24° x 20°) to simultaneously observe up to a few dozen stars (Weiss et al. 2014).

BRITE, short for → BRIght Target Explorer; → bright; → target; → explorer.

A → substance that has a low → elastic limit. For example → glass, which breaks if its low elastic limit is exceeded.

M.E. britel, from brit-, akin to O.E. brytan "to crush, break to pieces," + -el adj. suffix.

Tord "brittle, fragile;" ultimately from Proto-Ir. *tard- "to split, pierce;" related to tâlidan (Dehxodâ) "to spoliate, plunder," eftâlidan "to tear, break," → dissipate; cf. Shughni tidarδ- "to tear, pluck," zidarδ- "to tear, break;" Skt. tard- "to split, to pierce."

Wide in extent from side to side.

M.E. bro(o)d, from O.E. brad; cf. O.N. breiðr, Du. breed, Ger. breit, Goth. brouþs.

Pahn "wide, broad," from Mid.Pers. pah(a)n; Av. paθana- "broad, wide, spacious;" PIE root *pete- "to spread;" cf. L. patere "to be open," Gk. petannynai "to spread out," petalon "a leaf."

Photometric measurements carried out through filters with a band-width (about one-tenth the central wavelength) in the range 30-100 nm. Typical examples are Johnson photometry, Krons-Cousins RI photometry, and the six-color system.

→ broad; → band; → photometry.