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: 13116 Search : far
B-mode polarization
  قطبش ِ ترز ِ B   
qotbeš-e tarz-e B

Fr.: polarisation en mode B   

A → polarization component in the → cosmic microwave background radiation that depends only on → curl, is independent of → gradient, and has → handedness that distinguishes left from right. The B-mode is due to only → vector perturbations or → tensor perturbations. It has two types, the first type, which constitutes the majority of the B-mode polarization, results from → lensing by galaxies that twist the → E-mode polarized light on its journey from the other side of the → observable Universe. The second type can be produced only by → gravitational waves, not by density perturbations. This type of B-mode is incredibly faint, producing temperature variations of about 0.4 microK and accounting for just one part in 10 million in the CMB temperature distribution. It is expected to be generated during cosmic → inflation shortly after the → Big Bang. The → BICEP2 team announced in March 2014 that they had detected the second type of B-modes, consistent with inflation and gravitational waves in the → early Universe. The detected degree scale B-mode polarization has a tensor-to-scalar ratio, r = 0.2 (+0.07, -0.05), which is a measure of the amplitude of the primordial gravitational waves.

B, indicating magnetic-field like; → mode; → polarization.

B-type asteroid
  سیارک ِ گونه‌ی ِ B   
sayyârak-e gune-ye B

Fr.: astéroïde de type B   

A division of → C-type asteroids whose members have relatively low albedos (0.04 to 0.08) and the → ultraviolet absorption below 0.5 μm is small or absent. Examples include → 2 Pallas, 379 Huenna (diameter 62 km), and → 101955 Bennu.

type; → asteroid.

B-type star
  ستاره‌ی ِ گونه‌ی ِ B   
setâre-ye gune-ye B

Fr.: étoile de type B   

Same as → B star.

B, letter of alphabet used in the → Harvard classification; → type; → star.

Baade's window
  روزنه‌ی ِ باده   
rowzane-ye Baade

Fr.: fenêtre de Baade   

An area of the sky with relatively low amounts of  → interstellar dust along the → line of sight, occurring toward the  → constellation of  → Sagittarius, near the → globular cluster NGC 6522. The window, through which stars in the → Galactic bulge are visible, lies 3.9 degrees south of the → Galactic center, corresponding to a line of sight that passes within 1,800 → light-years of the → Milky Way's core. It is named after Walter Baade, who used it to observe → RR Lyrae stars  in the → Galactic bulge region. 

Baade-Wesselink method; → window.

Baade-Wesselink method
  روش ِ باده-وسلینک   
raveš-e Bâdé-Veselink (#)

Fr.: méthode de Baade-Wesselink   

A method used to determine the size of certain types of pulsating stars, including Cepheids, from their magnitude variations (photometry) and the corresponding radial velocities (spectroscopy).

Baade, from Walter (Wilhelm Heinrich) Baade (1893-1960), German/American astronomer, who made important contributions to the research on variable stars; Wesselink, from Adriaan J. Wesselink (1909-1995), Dutch/American astronomer, the originator of the method. → method.

Babinet compensator
  پاهنگنده‌ی ِ ببینه   
pâhangandeh-ye Babinet

Fr.: compensateur de Babinet   

A crystal device made of two → quartz  → prisms with equal acute angles assembled in a rhombus that is used in analyzing → polarized light. The wedge-shaped prisms are placed against each other and can be displaced along their plane of contact by a → micrometer. Thus they form a parallel plate of variable thickness allowing the optical retardation to be adjusted.

Jacques Babinet (1794-1872), French physicist; → compensator.

Babinet point
  نقطه‌ی ِ ببینه   
noqte-ye Babinet

Fr.: point de Babinet   

One of several points on the sky where the degree of → linear polarization is zero in skylight. See also → neutral point; → Arago point, → Brewster point.

Babinet compensator; → point.

Babinet's principle
  پروز ِ ببینه   
parvaz-e Babinet

Fr.: principe de Babinet   

The → diffraction pattern for an → aperture is the same as the diffraction pattern for its → complementary aperture.

Babinet compensator; → principle.

back
  پس، پشت   
pas (#), pošt (#)

Fr.: dos, arrière   

1) General: Related to or located at the back "the side or surface opposite the front or face."
2) The side of the → planispheric astrolabe opposite the hollow of the → mater, → tympanum, and → rete. At its center is hinged the → alidade, whose rim slides on a set of graduated circular scales engraved on the mater. The number of scales varies from one instrument to another. On this face the user can perform observations and read the data needed to set the front side of the instrument in the proper position (online museo galileo, VirtualMuseum).

Back, from M.E., from O.E. bæc; akin to O.H.G. bah "back."

Pas-, from pas "behind" (e.g.: pas-e pardé "behind the curtain"); Mid.Pers. pas "behind, before, after;" O.Pers. pasā "after;" Av. pasca "behind (of space); then, afterwards (of time);" cf. Skt. paścā "behind, after, later;" L. post "behind, in the rear; after, afterwards;" O.C.S. po "behind, after;" Lith. pas "at, by;" PIE *pos-, *posko-.
Pošt-, from pošt, variant of pas.

back-end
  پس-ته   
pas-tah

Fr.: back-end   

In a radiotelescope, the unit forming the end part of the reception chain. It generally consists of a spectrometer and performs frequency analysis of the signals. → front-end.

Back-end, from → back + end, from M.E., O.E. ende (cf. Du. einde, O.H.G. enti "top, forehead, end," Ger. ende, Goth. andeis "end"), originally "the opposite side," from PIE *antjo "end, boundary," from base *anta-/*anti- "opposite, in front of, before."

Pas-tah, from pas, → back, + tah "end," Mid.Pers. tah "bottom." The origin of this term is not clear. It may be related to Gk. tenagos "bottom, swamp," Latvian tigas<*tingas < *tenegos "depth," PIE *tenegos "water bottom."

background
  پس-زمینه، زمینه   
paszaminé, zaminé (#)

Fr.: fond   

General: That part of a view or scene that serves as a setting for the main objects, persons, etc.
Astro.: The part of an observed field which is not physically related to the objects of interest and lies behind them.

Background, from → back + ground, from M.E., from O.E. grund; akin to O.H.G. grunt "ground."

Paszaminé, from pas-, → back, + zaminé "ground," from zamin "ground," → earth.

foreground.

background noise
  نوفه‌ی ِ پس-زمینه، ~ زمینه   
nufe-ye paszaminé, ~ zaminé

Fr.: bruit du fond   

An unwanted signal in a system which is producing or recording a signal. For instance, a randomly fluctuating signal superimposed on the signal from a cosmic radio source.

background; → noise.

background radiation
  تابش ِ پس-زمینه، ~ زمینه   
tâbeš-e paszaminé, ~ zaminé

Fr.: rayonnement du fond   

The isotropic residual microwave radiation in space left from the primordial → Big Bang. Same as → cosmic microwave background (CMB) radiation.

background; → radiation.

backscatter
  ۱) پس-پراکندن ۲)، ۳) پس-پراکنش   
1) pas-parâkandan; 2), 3) pas-parâkaneš

Fr.: rétrodiffusion   

1) (v.tr.) To deflect photons or particles in a direction opposite to their initial path.
2) Same as → backscattering.
3) The radiation or particles so deflected.

From → back + → scattering.

backscattered light
  نور ِ پس-پراکنده   
nur-e pas-parâkandé

Fr.: lumière rétrodiffusée   

The light that has undergone → backscattering.

backscatter; → backscattering.

backscattering
  پس-پراکنش   
pas-parâkaneš

Fr.: rétrodiffusion   

Scattering of radiation or particles through angles greater than 90° with respect to the original direction of motion.

scattering.

backup
  پشتوان   
poštvân (#)

Fr.: sauvegarde   

A copy of computer files that is stored separately from the original in order to protect against loss of data.

Backup "substitute, support," from → back + up.

Poštvân "prop, support, help" from pošt, → back, + -vân suffix denting protection, variant of -bân.

backup program
  برنامه‌ی ِ یدکی   
barnâme-ye yadaki (#)

Fr.: programme de remplacement   

An auxiliary observing program to be carried out at telescope in case the atmospheric conditions make the main program unfeasible.

Backup, from → back + up; → program.

Barnâmé, → program; yadaki "reserve, substitute," from yadak "a led horse."

backward
  پس-سو   
pas-su

Fr.: en arrière   

1) Toward the back or rear.
2) Directed toward the back or past.

back; → -ward.

backwarming effect
  ا ُسکر ِ فروگرمی   
oskar-e forugarmi

Fr.: effet de rétro-réchauffement   

A sort of → greenhouse effect in → stellar atmospheres where the deeper layers heat up due to overlying → opacity. The presence of numerous → bound-bound opacities of → metals amplifies the → scattering of → photons, in particular their → backscattering, forcing the → temperature to increase in order to conserve the radiation flux and the transport of energy from the interior to the outer parts of the atmosphere.

back; → warming; → effect.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc 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 Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg 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 > >>