Fr.: point de Brewster
A → neutral point located 15 to 20° directly below the Sun.
Fr.: loi de Brewster
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.
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.
Fr.: géante lumineuse
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.
miq-e rowšan, ~ deraxšân
Fr.: nébuleuse brillante
In contrast to a → dark nebula, a bright cloud of interstellar gas and dust. The term designates both emission nebulae and reflection nebulae.
Verbal noun of brighten, from → bright.
General:The state or quality of being bright.
Deraxšandegi, from deraxš, present stem of deraxšidan "to shine," → bright, + -andé adjective suffix + -gi noun suffix.
Fr.: distribution de brillance
A statistical distribution of the brightness of an astronomical extended object.
Fr.: température de brillance
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.
Fr.: fonction de Brillouin
Fr.: diffusion de Brillouin
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.
Fr.: zone de Brillouin
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.
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).
Fr.: cassant, friable
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."
Fr.: photométrie à bande large
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-line radio galaxy (BLRG)
radio kahkašân-e pahn-xatt
Fr.: galaxie radio à raies larges
A radio galaxy that shows broad optical emission lines. → broad-line region.
broad-line region (BLR)
Fr.: région à raies larges
The inner region of a → quasar or an → active galactic nucleus exhibiting broad → spectral lines which indicate ionized matter moving with speeds in excess of 10,000 km sec-1, probably due to the presence of an → accretion disk surrounding a → supermassive black hole. Also called Type I AGN. See also → obscuring torus.