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: 13176 Search : far
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.

branching
  شاخه‌زد   
šâxé-zad

Fr.: branchement   

The act of dividing into branches. → branching ratio.

branch; → -ing.

branching ratio
  وابر ِ شاخه‌زد   
vâbar-e šâxé-zad

Fr.: rapport de branchement   

A quantity used to describe a → radionuclide that has more than one → decay mode. For a particular decay mode, the ratio of the number of atoms decaying by that decay mode to the number decaying in total: BRi = ki/(k1 + k2 + ...) = ki/k, where k is → decay constant.

branching; → ratio.

brane
  برین   
breyn (#)

Fr.: brane   

In theoretical physics, an entity which can have any number of allowed spatial dimensions. It is usually accompanied by a prefix, i.e. p-brane, indicating the number of dimensions. For example, a 0-brane is a zero-dimensional point-like particle, a 1-brane is a → string, a 2-brane is a "membrane," and so forth. Our Universe is a 3-brane.

Brane, short for membrane, from L. membrana "parchment," from membrum "limb, member of the body," → member.

Breyn, loanword from E., as above.

break
  ۱) شکستن؛ بریدن؛ گسستن؛ ۲) شکست؛ برش؛ بره؛ گسست   
1) šekastan; boridan; gosastan; 2) šekast; boreš, boré; gosast

Fr.: 1) couper, rompre; 2) brisure, coupure   

1) To separate into parts or fragments violently; to become broken.
2) The act or instance of breaking; fracture, rupture; a sudden decline in a continuity.

From break, from M.E. breken, O.E. brecan, from P.Gmc. *brekan (cf. Du. breken, O.H.G. brehhan, Ger. brechen), from PIE base *bhreg- "to break" (see also → fraction).

1) Šekastan, škan- "to break, split;" Mid.Pers. škastan "to break;" Av. scind-, scand "to break, cleave;" Proto-Iranian *skand- "to break, cleave;" PIE sken- "to cut off."
Boridan "to cut off," → cut.
Gosastan "to tear, cut, break," from Mid.Pers. wisistan "to break, split;" Av. saed-, sid- "to split, break," asista- "unsplit, unharmed;" cf. Skt. chid- "to split, break, cut off;" Gk. skhizein "to split;" L. scindere "to split;" Goth. skaidan; O.E. sceadan "to divide, separate;" PIE base *skei- "to cut, split."
2) Šekast; boreš boré; gosast, respective nouns from the verbs.

break luminosity
  تابندگی ِ بره   
tâbandegi-ye boré

Fr.: luminosité de coupure   

A characteristic luminosity around which the → luminosity function of a sample of galaxies changes to a steeper slope or exponentially declines.

break; → luminosity.

break-up velocity
  تندای ِ گسست   
tondâ-ye gosast

Fr.: vitesse de rupture   

The velocity of a → rotating star at which the → centrifugal force equals the → gravitational force. Also known as → critical velocity. The simplest expression of the break-up velocity for an OB star, ignoring the → Eddington luminosity, is given by the relation: v = (GM / R)1/2, where M and R are the mass and radius of the star respectively, and G the → gravitational constant. A more realistic expression takes into account not only the → radiation pressure, but also the non-uniformity of the brightness over the stellar surface, as indicated by → von Zeipel theorem. With these conditions, the break-up velocity has a more complicated formula, corresponding to the velocity reached when somewhere on the star the → total gravity becomes zero.

break + up; M.E.; O.E. up, uppe, → hyper-; → velocity.

breakthrough
  تراشکافت   
tarâšekâft

Fr.: percée   

1) An act of overcoming or penetrating an obstacle or restriction.
2) A military offensive that penetrates an enemy's lines of defense.
3) A major achievement or success that permits further progress, as in technology (TheFreeDictionary.com).

break; → through.

Tarâšekâft, from tarâ-, → trans-, + šekâft, past stem of šekâftan "to split, break, tear," → fission.


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<< < -es -it -sc 201 951 abe abs abs aca acc acc aco act ada adh ado aer aft air Alf alg alk alp Alt alt amb ana And ang ani ann ant ant ant apo app app Apu arc arg Arn art ass ast ast ast atm ato att aur aut avo azi bac bal bar bar bat Bea Bel bet bia big bin bio Bir bla bla blo Blu bol Boo bou box bre Bri bro bur cal cal Can cap car Car cat cau cel cen cen cha Cha cha che Chi chr cir cir civ cla clo clo CMB 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 coo cor cor cor Cos cos cos cou cou cra cri cro cry cul cur cyc D l dar dat day dea dec dec dec def def deg Del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis diu dog Dop dou Dra Dsc dus dwa dyn Dys Ear ecc eco edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ eru eth Eur eve exa exc exe exi exo exp ext ext ext fab fai Fan fea fem fer fie fil fir fir fla fli flu foc for for for fra fre fre fri fun fuz gal gal gal Gam gau Gau gen geo geo geo geo Gib glo gov gra gra gra gra gre gro Gui H-a hal Ham har Hay hea hei hel Hel her het hie hig hoa hom hor hot Hub Hug hur hyd hyd hyl 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 inv ion iro Isl iso iso Jab jet Jov Jup Kar Kep kil Kip Kra Lag Lam Lan Lar las law lea Leg Leo lev lig lim lin lin lin lit loc loc log Lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal map mas mas mat Mau mea mea med Men mer Mes Met met mic mic Mie mil min Mir mix mod mol mom Moo mor mov mul mur n-b nan nat nea neg Ner neu new New NGC noc nom non non nor nor nuc nuc nul nut obj obl obs occ oct off old one ope opp opt opt orb ord org Ori osc oth ove Owl P-s Pal par par par par Pas pat pec pen per per per per per Pha pha pho pho pho phy pie pix Pla pla pla pla Pli Poi pol pol pol pol por pos pos pow pre pre pre pre pri pri pri pro pro pro pro pro pro pro pub pul pyc qua qua qua qua qui rad rad rad rad rad rad rai 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 rur S5- Sal sat sca sca Sch sci Scu sec sec sed sel sel sem seq set sha she sho sid sie sil sim sin sit sky slo sno sod sol sol sol sol son sou spa spa spe spe spe spe sph spi spo squ sta sta sta sta ste ste ste Sti sto str str sub sub sub sul sup sup sup sup sur sur syl syn sys tal Tay tel ten ter tex the the the the Tho thr tid tim Tit too Tor tra tra Tra tra Tra tri Tri tru tub tur two Typ ult ult unc uni uni uni upl ura uti val var vec vel ver Ver vie vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>