An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 476

Fr.: rayonnement de freinage, bremsstrahlung   

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.

Brewster angle
  زاویه‌ی ِ بروستر   
zâviye-ye Brewster (#)

Fr.: angle de Brewster   

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.

Brewster point
  نقطه‌ی ِ بروستر   
noqte-ye Brewster

Fr.: point de Brewster   

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

Brewster's law; → point

Brewster's law
  قانون ِ بروستر   
qânun-e Brewster

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.

pol (#)

Fr.: pont   

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."

  درخشان، روشن   
deraxšân, rowšan

Fr.: brillant   

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.

bright giant
  غول ِ تابناک   
qul-e tâbnâk

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.

bright; → giant.

bright nebula
  میغ ِ روشن، ~ درخشان   
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.

bright; → nebula.


Fr.: embrillancement   

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

Verbal noun of brighten, from → bright.

deraxšandegi (#)

Fr.: brillance   

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.

brightness distribution
  واباژش ِ درخشندگی   
vâbâžeš-e deraxšandegi

Fr.: distribution de brillance   

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

brightness; → distribution.

Vâbâžeš, → distribution; deraxšandegi, → brightness.

brightness temperature
  دما‌ی ِ درخشندگی   
damâ-ye deraxšandegi

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.

brightness; → temperature.

Brillouin function
  کریای ِ بری‌یویءن   
karyâ-ye Brillouin

Fr.: fonction de Brillouin   

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

Brillouin zone; → zone.

Brillouin scattering
  پراکنش ِ بری‌یویءن   
parâkaneš-e 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.

Brillouin zone; → scattering.

Brillouin zone
  زنار ِ بری‌یویءن   
zonâr-e Brillouin

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.


Fr.: saumure   

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.

tord (#)

Fr.: cassant, friable   

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."

pahn (#)

Fr.: large   

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."

broad-band photometry
  شیدسنجی ِ پهن-باند   
šidsanji-ye pahn-bând

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; → band; → photometry.

broad-line radio galaxy (BLRG)
  رادیو‌کهکشان ِ پهن-خط   
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; → radio galaxy.

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