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: 12948 Search : far
B ring
  حلقه‌ی ِ B   
halqe-ye B

Fr.: anneau B   

One of → Saturn's rings, lying beyond the → C ring and before the → A ring, extending from 92,000 to 117,300 km (width 25,300 km) from the center of Saturn. The B ring is bounded by the → Huygens Division.

ring.

B star
  ستاره‌یِ B   
setâre-ye B (#)

Fr.: étoile B   

A star of → spectral type B, whose spectrum is marked by absorption lines of hydrogen; also known as B-type star. B-type optical spectra are characterized by the presence of neutral He lines (mainly He I 4471 Å) at about type B9. He I strengthens up to about B2, then decreases. Ionized helium (mainly He II 4541 Å) first appears at about B0. Most metallic lines are absent or weak, except some absorption lines for the higher ionization states of → silicon, → oxygen, → carbon, and → magnesium. These are hot stars with → effective temperatures ranging from about 10,000 K at B9 to nearly 30,000 K at B0. They are between 3 and 20 → solar masses. Some famous examples include: → Rigel, → Achernar, → Hadar.

star.

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."

<< < -es -iv -ti 21- A r abe abs abs acc acc acc act act ada adi adu aff age alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg ari art ass ast ast ast atm ato att aur aut axi B r bac Bal Bar Bar Bay bec Ber Bet Bie bij bin bio bis bla bla blu blu bol Bor bou Bra bre bro Bug C-s cal Cam can car Car Cas cat cav cel cen cer Cha cha cha che cho cir cir cir 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 coo cor cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl dar dat daw de- Deb dec dec dee def deg del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis div dog Dop dou dra dua dus dwa dyn e-m ear ecl eco eff ein Ein elb ele ele ele ele Els emi emp ene enr env epi equ equ Eri est Euc eva evo exc exc exh exo exp exp ext ext f-n Fah fam fau fee Fer fib fil fin fir fix fle flu foc for for for fra fre fre fri fun fuz gal gal gal Gan gau GCN gen geo geo geo geo Gl glo gra gra gra gra gra gre gro GW1 hab hal han HAR haz hea hel hel Hen Her heu Hig Hil hol hop hor hou Hub Hum Hyd hyd hyd hyp hys ide ign ima imp imp inc inc ind ine inf inf inf inh INP ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jos Jun K2 Kep key kin Kol lag lam Lan lar las lav lea leg len lev lig lim lin lin lin lis lob loc log lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mea mee Men mer met met met mic mid Mil min Mir mix mod mod mol mon Mor mou mul muo mys nan nat nav nec Nep neu New New NGC nob nom non non nor not nuc nuc num Nyq obj obs obs oce oen OH omn opa ope opt opt opt orb ord Ori ort osc out ove oxy pal pan par Par par par pas pea Pen per per per per per pet pha pho pho pho phy pie Pit Pla pla pla pla ple Poi pol pol pol pol pop pos pos pow pre pre pre Pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua Qui rad rad rad rad rad rad ram ran rat rea rec rec rec red ref ref reg reg rel rel rem rep res res res ret rev rho Rie rim riv rol Ros rot rul S a Sah san Sat sca Sch Sch scr sec sec sec sei sel sem sep set sha she sho sid sig sil sim sin sit sky slu sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spl spr sta sta sta sta sta ste ste sti sto str str sub sub sub sug sun sup sup sup sup sur syl syn sys tal Tay tel ten ter tex the the the thi tho thu tid tim tod top tot tra tra tra tra tri tri tro tru tur twi Typ UFO ult unc uni uni uni upg ura uti val var vec vel ver ver vig vir vis voc von wak Was wav wax wea wei whi Wie win WN6 wom X-r yel you zer zod > >>