# 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: 72 Search : bra
 algebra   جبر   jabr (#)Fr.: Algèbre   The branch of mathematics which deals with the properties and relations of numbers using symbols (usually letters of the alphabet) to represent numbers or members of a specified set; the generalization and extension of arithmetic.Algebra, from M.L., from Ar. al jabr "reunion of broken bones," the first known use in the title of a book by the Persian mathematician and astronomer Abu Ja'far Mohammad ibn Musa al-Khwarizmi (c780-c850), who worked in Baghdad under the patronage of Caliph Al-Mamun. The full title of the tratise was Hisab al-Jabr w'al-Muqabala "Arithmetic of Completion and Balancing." → algorithm.Jabr, from Ar. al jabr, as above. algebraic   جبری   jabri (#)Fr.: algébrique   Relating to, involving, or according to the laws of algebra.→ algebra + → -ic. algebraic equation   هموگش ِ جبری   hamugeš-e jabriFr.: équation algébrique   An equation in the form of P = 0, where P is a → polynomial having a finite number of terms.→ algebra; → equation. algebraic function   کریای ِ جبری   karyâ-ye jabriFr.: fonction algébrique   A function expressed in terms of → polynomials and/or roots of polynomials. In other words, any function y = f(x) which satisfies an equation of the form P0(x)yn + P1(x)yn - 1 + ... + Pn(x) = 0, where P0(x), P1(x), ..., Pn(x) are polynomials in x.→ algebraic + → function. algebraic number   عدد ِ جبری   adad-e jabri (#)Fr.: nombre algébrique   A number, → real or → complex, that is a → root of a → non-zero polynomial equation whose → coefficients are all → rational. For example, the root x of the polynomial x2 - 2x + 1 = 0 is an algebraic number, because the polynomial is non-zero and the coefficients are rational numbers. The imaginary number i is algebraic, because it is the solution to x2 + 1 = 0.→ algebraic; → number. antumbra   پادسایه   pâdsâyéFr.: anti-ombre   That part of the Moon's shadow that extends beyond the → umbra. It is similar to the → penumbra in that the Sun is only partially blocked by the Moon. From within the antumbra, the Sun appears larger than the Moon which is seen in complete silhouette. An → annular eclipse is seen when an observer passes through the antumbra (F. Espenak, NASA).→ anti- + → umbra. associative algebra   جبر ِ آهزشی   jabr-e âhazešiFr.: algèbre associative   An algebra whose multiplication is associative.→ associative; → algebra. asymptotic giant branch (AGB)   شاخه‌ی ِ ناهمساوی ِ غولان   šâxe-ye nâhamsâvi-ye qulânFr.: branche asymptotique des géantes   A region of the → Hertzsprung-Russell diagram populated by evolving → low-mass to → intermediate-mass stars. These stars have an electron → degenerate core of carbon and oxygen surrounded by two burning shells of helium and hydrogen. The H and He-burning shells are activated alternately in the deep layers of the star. An extended and tenuous convection envelope, having a radius of 104-105 times the size of the core, lies above these shells. The loosely bound envelope is gradually eroded by the strong → stellar wind, which forms a dusty → circumstellar envelope out to several hundreds of stellar radii. The convective envelope, stellar atmosphere, and circumstellar envelope have a rich and changing chemical composition provided by → nucleosynthesis processes in the burning shells in the deep interior.→ symptotic; → giant; → branch. blue horizontal branch star   ستاره‌ی ِ آبی ِ شاخه‌ی ِ افقی   setâre-ye âbi-ye šâxe-ye ofoqiFr.: étoile bleue de la branche horizontale   A member of a population of blue stars appearing on the → horizontal branch in the → Hertzsprung-Russell diagram of the Galactic → halo populations and → globular clusters. Belonging to → spectral types B3 to A0, they have evolved past the → red giant stage and are burning helium in their core.→ blue; → horizontal; → branch, → star. Boolean algebra   جبر ِ بولی   jabr-e Booli (#)Fr.: algèbre de Boole   Any of a number of possible systems of mathematics that deals with → binary digits instead of numbers. In Boolean algebra, a binary value of 1 is interpreted to mean → true and a binary value of 0 means → false. Boolean algebra can equivalently be thought of as a particular type of mathematics that deals with → truth values instead of numbers.→ Boolean; → algebra. The term Boolean algebra was first suggested by Sheffer in 1913. 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. branching   شاخه‌زد   šâxé-zadFr.: branchement   The act of dividing into branches. → branching ratio.→ branch; → -ing.

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