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: 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, ~ 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.

bow
  ۱) کمان؛ ۲) فرال   
1) kamân; 2) farâl

Fr.: 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-šok

Fr.: 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 farâl

Fr.: 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 Bowen

Fr.: 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-zamini

Fr.: 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 Bq

Fr.: 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   
brâ

Fr.: 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   
brâket

Fr.: 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 Brackett

Fr.: 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 Bragg

Fr.: 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 Bragg

Fr.: 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 kardan

Fr.: 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   
legâmeš

Fr.: 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 legâmeš

Fr.: 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.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara Arc ari Arr ash ass ast ast asy atm ato att aut ave axi Bab bal Bal bar bar bea Bek Bes bia Big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo cal cal can cap car Car cat cat CCD Cen cen CH cha cha che Che chr cir cir cit cla clo clo clu Coa coe coh col col col com com com com com com com com Com con con con con con con con con con con con con Cop Cor cor cor cos cos cou cou Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp opt opt orb ord ori ort osc out ove oxi pai pan par par par par pas pea pen per per per per Per per pha phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar ray rea rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>