# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13048 Search : far
 bounded   کرانمند، کراندار   karânmand (#), karândâr (#)Fr.: limité   General: Having bounds or limits.Math.: Of a function, having a range with an upper bound and a lower bound.Adj. from → bound. bounded function   کریای ِ کرانمند، ~ کراندار   karyâ-ye karânmand, ~ karândârFr.: 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 BoussinesqFr.: 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. bow   ۱) کمان؛ ۲) فرال   1) kamân; 2) farâlFr.: proue   1a) A bent, curved, or arched object. 1b) A weapon made of a curved, flexible strip of material and a cord connecting the two ends that is used to launch an arrow. 2) The front of a ship or boat; prow; opposite to stern or poop, → Puppis.1) M.E., from O.E. boga "archery bow, arch, rainbow" (cf. O.Norse bogi, Du. boog, Ger. Bogen "bow"); PIE root *bheug- "to bend;" cf. Skt. bhujati "bends;" O.H.G. boug, O.E. beag "a ring"). 2) M.E. boue, from O.N. bogr or M.Du. boech "bow of a ship."1) Kamân "bow, arc," from Mid.Pers. kamân, related to xam "curve," cf. Breton kamm "curved, bent," Gk. kampe "a corner, a joint," L. campus "a field," Lith. kampus "corner," PIE *kamb- "to bend, crook." Farâl, from farâ "forward" (farâ raftan "to go forward, proceed," farâ rândan "to drive forward"), equivalent to → pro-, + relation suffix -âl, → -al. Compare farâl with prow "bow," Fr. la proue "prow, bow," from dialectal It. proa, prua, from L. prora "bow," from Gk. proira, related to pro "before, forward." bow shock   فرال-تش، فرال-شوک   farâl-toš farâl-šokFr.: choc de proue   A → shock wave created in front of an object moving through a medium with a velocity higher than that of the → sound waves in that medium. See, for example, → magnetosphere.→ bow; → shock. bow wave   فرال-موج، موج ِ فرال   farâl-mowj, mowj-e farâlFr.: onde de proue   The wave which appears in front of a speeding boat and goes out behind it in a distinctive "V". It is due to the fact that waves pile up on each other before they can move away.→ bow; → wave. Bowen fluorescence mechanism   ساز-و-کار ِ فلوءورستی ِ باؤن   sâzokâr-e fluoresti-ye BowenFr.: mécanisme de fluorescence de Bowen   A mechanism, made possible by certain chance coincidences between → spectral lines of He II, O III and N III in some → planetary nebulae , that explains the presence with a high intensity of a selected group of O III and N III lines while all other lines of these elements are missing.After I. S. Bowen who first discovered this mechanism in 1935; → fluorescence; → mechanism. box   جعبه، قوتی   ja'bé (#), quti (#)Fr.: boîte   A container, case, or receptacle, usually rectangular, of wood, metal, cardboard, etc. (Dictionary.com). → box-peanut bulge.M.E., O.E., probably from L.L. buxis, from L. buxis, from Gk. pyxis "boxwood box," from pyxos "box tree," of uncertain origin.Ja'bé, from Ar. ja'bah; quti, from Turk. box-peanut bulge   کوژ ِ قوتی-بادام‌زمینی   kuž-e quti/bâdâm-zaminiFr.: bulbe box/peanut   A → galaxy bulge that shows a boxy or peanut-like morphology. These bulges are usually featureless and show no signs of → dust obscuration, young → stellar populations, or → star-forming regions. They are also kinematically cold and usually referred to as → pseudo-bulges. A number of studies have shown that these structures are just the inner parts of → bars that grow vertically thick due to vertical → resonances. They have basically the same dynamics and stellar content as bars, just their geometry is somewhat different. Box/peanut bulges are not seen if the galaxy is not inclined enough. In a → face-on galaxy, if it has a box/peanut, it will be seen as part of the bar. The → Milky Way shows a box/peanut bulge. Another remarkable case is that of → M31, known to have a bar, with its box/peanut inner part (Combes & Sanders 1981, A&A 96, 164; Combes et al. 1990, A&A 233, 82; Kormendy & Kennicutt, 2004, ARA&A 42, 603).→ box; → peanut; → bulge. Boyle-Mariotte law   قانون ِ بویل-ماریوت   qânun-e Boyle-Mariotte (#)Fr.: loi de Boyle-Mariotte   In a → perfect gas where mass and temperature are kept constant, the volume of the gas will vary inversely with the absolute pressure. The law can be expressed as PV = constant, where P = absolute pressure and V = volume.After Robert Boyle (1627-1691), an Irish philosopher, chemist, and physicist, and Edme Mariotte (1620-1684), a French physicist and pioneer of neurophysiology, who discovered the law independently, the first one in 1662 and the second one in 1676; → law. Bq star   ستاره‌ی Bq   setâre-ye BqFr.: étoile Bq   An obsolete designation used in early objective-prism studies to denote → B-type stars with "abnormal spectra" characterized by → forbidden emission lines. → B[e] star.→ star. bra   برا   brâFr.: bra   In Dirac's notation for describing a quantum state, a vector which together with → ket constitutes the dual vector → bracket. A bra is shown by <|, the mirror image of the symbol for a ket vector. The scalar product of a bra vector < B| and a ket vector |A> is written < B|A >, i.e. as a juxtaposition of the symbols for the bra and the ket vectors, that for the bra vector being on the left, and the two vertical lines being contracted to one for brevity.From bra- the first syllable in → bracket. bracket   براکت   brâketFr.: bracket   In Dirac's notation, an expression which is a → scalar product of the dual vectors → bra and → ket which describe a quantum state. The bra vector appears on the left of the ket vector.From M.Fr. braguette "codpiece armor." Brackett series   سری ِ براکت   seri-ye BrackettFr.: série de Brackette   A series of lines in the infrared spectrum of atomic hydrogen due to electron jumps between the fourth and higher energy levels (Br α has wavelength 4.052 μm, Br γ 2.166 μm).Named after the American physicist Frederick Brackett (1896-1980); → series. Bragg angle   زاویه‌ی ِ براگ   zâviye-ye BraggFr.: angle de Bragg   The grazing angle between an incident beam of X-rays and a given set of crystal planes for which the secondary X-rays from the planes combine to give a single beam.→ Bragg's law; → angle. Bragg's law   قانون ِ براگ   qânun-e BraggFr.: loi de Bragg   A parallel beam of monochromatic X-rays of wavelength λ, incident on a given set of parallel crystal planes at a grazing angle θ will give rise to a reflected beam whenever: n λ = 2d . sinθ, where n is an integer representing the difference in path length, and d is the perpendicular distance between a pair of adjacent planes.Named after William Lawrence Bragg (1890-1971), British physicist, who, in collaboration with his father, William Henry Bragg (1862-1942), joint Nobel Prize in Physics 1915, pioneered X-ray analysis and spectrometry; → law. brake   ۱) لگام، ترمز؛ ۲) لگامیدن، ترمز کردن   1) legâm, tormoz 2) legâmidan, tormoz kardanFr.: 1) frein; 2) freiner   1) A device for slowing or stopping a vehicle or other moving mechanism by the absorption or transfer of the energy of momentum, usually by means of friction. 2) To slow or stop by means of or as if by means of a brake (Dictionary.com).From O.Du. braeke "flax brake," from breken "to break."Legâm originally "a horse bit," on the model of Fr. frein "horse bit; motor brake;" and Ger. Bremse "horse bit; brake;" tormoz, loan from Russ. тормоз. braking   لگامش   legâmešFr.: freinage   The act or fact of stopping by means of or as if by means of a brake. See: → magnetic braking; → radiative braking; → tidal braking; → braking index.Verbal noun of → brake. braking index   دیشن ِ لگامش   dišan-e legâmešFr.: indice de freinage   A parameter indicating the rate at which a → pulsar slows down. Neutron stars are powered by → rotational energy and lose energy by accelerating particle → winds and by emitting → electromagnetic radiation. The → rotation frequency, Ω, thus decreases with time and this slowdown is usually described by the relation Ω. = - kΩn, where k is a positive constant which depends on the → moment of inertia and the → magnetic dipole moment of the → neutron star and n is the braking index. Conventionally, the braking index is derived by differentiation of the above equation, yielding n = ΩΩ.. / Ω.2. In a highly simplified model in which the spin-down torque arises from dipole radiation at the rotation frequency, one expects n = 3 (Johnston, S., Galloway, D., 1999, arXiv:astro-ph/9905058).→ braking; → index. branch   ۱) شاخه؛ ۲) شاخه زدن   1) šâxé (#); 2) šâxé zadan (#)Fr.: 1) branche; 2) se ramifier   1a) General: A shoot or arm-like limb of a tree; anything like a limb of a tree; any offshoot from a main trunk. 1b) Astro.:→ asymptotic giant branch; → blue horizontal-branch stars; → red giant branch; → branching; → branching ratio. 1c) Math.: Any of the two halves of a → hyperbola. 1d) Math.: A section of a curve separated by → discontinuity from the rest of the curve. 2a) To put forth branches. 2b) To spread in branches.M.E., from O.Fr. branche, from L.L. branca "a claw, paw."1) Šâxé "branch," from Mid.Pers šâk, cf. Mod.Pers. šâx, šax "branch; horn," Skt. sakha- "a branch, a limb," Arm. cax, Lit. šaka, O.S. soxa, PIE *kakhâ "branch." 2) Šâxé zadan with verb zadan "to strike, beat," → outcrop.