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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 3079 Search : on
bound-free transition
  گذرش ِ بندیده-آزاد   
gozareš-e bandidé-âzâd

Fr.: transition liée-libre   

A transition in which a bound electron is liberated. → free-bound emission; → free-free emission.

Bound, p.p. of → bind; → free.

boundary conditions
  بوتارها‌ی ِ کران، ~ کرانی   
butârhâ-ye karân, ~ karâni

Fr.: conditions à la limite   

1) Math: Restriction on the limits of applicability of an equation. In a differential equation, conditions that allow to fix the constant of integration and reach a unique solution. The number of boundary conditions necessary to determine a solution matches the order of the equation.
2) Physics: Conditions needed to determine the evolution of a system, given the physical laws.

boundary; → condition.

bounded function
  کریای ِ کرانمند، ~ کراندار   
karyâ-ye karânmand, ~ karândâr

Fr.: fonction bornée   

The function y = f(x) in a given range of the argument x if there exists a positive number M such that for all values of x in the range under consideration the inequality | f(x) | ≤ M will be fulfilled. → unbounded function.

bounded; → function.

Boussinesq approximation
  نزدینش ِ بوسینسک   
nazdineš-e Boussinesq

Fr.: approximation de Boussinesq   

A simplification in the equations of → hydrodynamics that treats the density as constant except in the → buoyancy term. This approximation is motivated by the fact that when pressure and temperature differences in a flow are small, then it follows from the thermodynamic → equation of state that a change in the density is also small.

Named after Joseph Valentin Boussinesq (1842-1929), a French physicist who made significant contributions to the theory of hydrodynamics, vibration, light, and heat; → approximation.

brecciation
  برشش   
berešeš

Fr.: bréchification   

The formation of → breccia.

Verbal noun of → brecciate.

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.

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 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.

BRITE-Constellation
   BRITE-هم‌اختران   
BRITE-hamaxtarân

Fr.: BRITE-Constellation   

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.

broad-line region (BLR)
  ناحیه‌ی ِ پهن-خط   
nâhiye-ye pahn-xatt

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.

broad; → line; → region.

bronze
  برنز، مفرغ   
boronz (#), mefraq (#)

Fr.: bronze   

A class of → alloys in which → copper and → tin are the dominant elements. The name is extended by usage to include many other copper-rich alloys containing → phosphorus, → manganese, → aluminium, or → silicon.

From Fr. bronze, from It. bronzo, from M.L. bronzium, of unknown origin, maybe from Iranian, cf. Mid.Pers. brinj "bronze, brass;" Mod.Pers. berenj "brass."

Boronz, loan from Fr., as above. Mefraq, from Ar.

Bronze Age
  عصر ِ برنز   
asr-e boronz (#)

Fr.: âge du fer   

A period of time between the → Stone Age and the → Iron Age when bronze was used widely to make tools, weapons, and other implements. The Bronze Age starts at different areas of the world at different times. The earliest use of bronze for making farm tools and weapons are found in Near and Middle East and date back to about 3700 BC. The Bronze Age starts about 2300 BC in Europe.

bronze; → age.

Brownian motion
  جنبش ِ براؤنی   
jonbeš-e Brawni

Fr.: mouvement brownien   

The continuous random motion of solid microscopic particles immersed in a fluid, which is due to bombardment by the atoms and molecules of the medium. It is named after the botanist Robert Brown, who in 1827 first noticed that pollen seeds suspended in water moved in an irregular motion. While there were suspicions that the motion was caused by the collision of atoms against the particles, the first quantitative explanation of the phenomenon, based on the kinetic theory of gases, was forwarded by A. Einstein in 1905. When Einstein's paper appeared, the notion of atoms and molecules was still a subject of heated scientific debate. Ernst Mach and the physical chemist Wilhelm Ostwald were among those who chose to deny their existence.

Named after Robert Brown (1773-1858), a Scottish botanist, who first in 1827 noticed the erratic motion of pollen grains suspended in water. → motion.

burst of star formation
     
belk-e diseš-e setâregân

Fr.: flambée de formation d'étoiles   

An intense → star formation activity in a region of → interstellar medium or, more globally, in a → galaxy. It is characterized by a → star formation rate which is much higher than the corresponding average. Same as → starburst.

burst; → star; → formation.

c Orionis
   c-شکارگر، c-اریون   
c-Šekârgar, c-Oyon

Fr.: c Orionis   

Same as → 42 Orionis.

Star name in the → Bayer designation scheme.

calculation
  افمارش   
afmâreš

Fr.: calcul   

The act, process, or result of calculating.

Calculation, noun from → calculate.

Afmâreš, verbal noun from afmârdancalculate.

calculus of variations
  افماریک ِ ورتش‌ها   
afmârik-e vartešhâ

Fr.: calcul des variations   

The study of maximum and minimum properties of → definite integrals.

calculus; → variation.

Afmârik, → calculus; vartešvariation.

calendar month
  ماه ِ گاهشماری، ~ گاهماری   
mâh-e gâhšomâri, ~ gâhmâri

Fr.: mois du calendrier   

One of the periods into which a calendar is divided, ordinarily 12, but in earlier systems 10 (the first Roman calendar under Romulus) or 13 (ancient Iranian calendar using a month intercalation).

calendar; → month.

calibration
  کبیزش   
kabizeš

Fr.: étalonnage, calibration   

1) The act or process of calibrating or the state of being calibrated.
2) A set of graduations that show positions or values.

Calibration, noun from → calibrate.

Kabizeš, noun from kabizidan, → calibrate.

calibration curve
  خمِ کبیزش   
xam-e kabizeš

Fr.: courbe d'étalonnage   

An empirical curve obtained through appropriate exposures in order to determine the instrument's response. For example, a curve allowing the conversion of relative intensities of an observed object into absolute fluxes, or a curve relating the detector's pixel positions to wavelengths.

calibration; → curve.

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